The Digestive system - Healthy Dog Experts

The digestive tract begins at the mouth and ends at the anus. The lips, teeth, tongue, salivary glands, mouth and pharynx are considered to be part of the digestive system. Other important digestive tract organs are the esophagus, stomach, duodenum (the first part of the small intestine), jejunum and ileum (also parts of the small intestine), (the large intestine is divided into four segments), the cecum, colon, rectum and the anal canal. The organs that aid in digesting and absorbing foodstuffs are the pancreas, gall bladder and liver. The pancreas is located next to the duodenum. The pancreatic enzymes drain into the pancreatic duct, which joins the bile duct from the liver: both ducts empty into the duodenum. The esophagus is a muscular tube that carries food down to the stomach through a series of rythmic contractions. The esophagus runs along the neck and into and through the chest cavity, on its way to the stomach. The lower esophagus enters the stomach at a sharp angle, which prevents food and liquids from refluxing back up into the esophagus. Food can remain in the stomach for up to eight hours before passing through the pylorus into the duodenum and the rest of the small intestine. Digestive juices from the pancreas and small intestine break the food down into amino acids, fatty acids and carbohydrates. The products of the meal are absorbed into the intestinal circulation and are carried to the liver, where they are converted to stored energy. Fiber and undigested food continue on through the small intestine into the colon. The function of the colon is to remove water and store waste material as feces.

The Esophagus

The esophagus is a muscular tube that propels food and water into the stomach. This is accomplished by a series of rhythmic contractions called peristaltic waves, which are coordinated with the act of swallowing. Signs of esophageal disease include regurgitation, painful swallowing (dysphagia), drooling and weight loss.

Regurgitation

Regurgitation is the relatively effortless expulsion of undigested food, without retching. It occurs because the esophagus is physically blocked or because it lacks peristaltic activity. In either case, the food accumulates until the esophagus is overloaded, after which the food is passively expelled. Regurgitation should not be confused with vomiting. Vomiting is the forceful expulsion of stomach contents, preceding by drooling and retching. The material vomited is usually sour-smelling, partly digested and stained with yellow bile. The sudden onset of regurgitation in a previously healthy dog is almost certainly due to a foreign body caught in the esophagus. Constant drooling indicates that the dog cannot swallow saliva. Chronic regurgitation (the kind that comes and goes but seems to be getting worse) suggests a partial obstruction caused by megaesophagus, stricture or tumor. A serious complication of regurgitation is aspiration pneumonia, in which the lungs become infected as a result in food being aspirated into them. When regurgitated food ends up in the lungs, aspiration pneumonia is the result. Another potentially serious complication is nasal cavity infection. This occurs when food is regurgitated into the nose.

Dysphagia (difficult, painful swallowing)

A dog with a painful esophagus eats slowly, stretches his neck and makes repeated efforts to swallow the same mouthful. As the condition becomes more painful, the dog stops eating and begins to lose weight. Difficult, painful swallowing, indicates a partial blockage caused by an esophageal foreign body, stricture or tumor. Pain on swallowing also occurs with mouth infections, sore throat and tonsillitis.

Megaespohagus means enlarged esophagus. When the esophagus is partially obstructed over a period of time, it gradually enlarges like a balloon and becomes a storage organ. This process, called megaesophagus, is accompanied by regurgitation, loss of weight and recurrent episodes of aspiration pneumonia. There are two causes of megaesophagus. The first is a failure of the esophagus to contract and propel food into the stomach. This impaired motility occurs as a hereditary disorder in puppies and as an aquired disease in adults. The second cause of megaesophagus is a physical blockage, such as a foreign body or a developmental problem with abnormal blood vessels that encircle the esophagus.

Congenital megaesophagus is a hereditary form of the disease that occurs in puppies. It is caused by a developmental disorder involving the nerve plexus in the lower esophagus. Peristaltic activity stops at the level where the esophagus is paralyzed, and food can go no further. In time, the esophagus above the inert segment enlarges and balloons out. This can been seen by lifting the puppy by his back legs and looking for a bulging out of the esophagus at the side of the neck. Congenital megaesophagus has been described in German Shepherd Dogs, Golden Retrievers, Great Danes, Irish Setters, Greyhounds, Labrador Retrievers, Newfoundlands, Miniature Schnauzers, Chinese Shar-Pei and Wire Fox Terriers. Hereditary myopathies are other causes of congenital megaesophagus. Puppies with congenital megaesophagus show signs of weaning, when they begin to eat solid foods. Characteristically, they approach the food dish with enthusiasm but back away after a few bites. They often regurgitate small amounts of food, which they eat again. After repeatedly eating the food, it becomes quite liquid and passes into the stomach. Repeated inhalation of food causes bouts of aspiration pneumonia. Another type of congenital megaesophagus is caused by retained fetal arteries in the chest. The arteries produce a constriction around the esophagus (known as vascular ring anomoly) that prevents swallowing. The most common anomoly is a persistent right aortic arch. Regurgitation and difficulty swallowing appear at 4 to 10 months of age. These puppies are stunted and malnourished.

Adult-onset megaesophagus is an aquired condition that occurs with several rare neuromuscular diseases, including myasthenia gravis. Other known causes are hypothyroidism, hypoadrenocorticism, esophagitis, autoimmune diseases and heavy metal poisoning. In most cases the cause is unknown. A chest X-ray may show an enlarged esophagus, opaque material in the esophagus or aspiration pneumonia. The diagnoses can be confirmed by administering a barium meal and then taking an X-ray of the chest. Ultrasound will also detect megaesophagus.

Foreign bodies in the esophagus are common. Bones and bone splinters are seen most often. Other objects that obstruct a dog's esophagus include string, fishhooks, needles, wood splinters and small toys. Suspect a foreign body in esophagus when a dog suddenly begins to gag, retch, drool and regurgitate. A history of regurgitation and difficulty swallowing for several days or longer suggests a partial obstruction. Sharp foreign bodies are particularly dangerous, because they can perforate the esophagus. A dog with a perforated esophagus exhibits fever, cough rapid breathing, difficulty swallowing and a rigid stance. The diagnoses can usually be made by taking X-rays of the neck and chest. Ingesting a contrast material such as Gastrografin, followed by an X-ray of the esophagus, may be required.

Esophagitis

A mucosal injury caused by a foreign body, or a burn caused by ingesting a caustic liquid can cause inflammation of the esophagus, known as esophagitis. Gastroesophageal reflux (similar to acid reflux in humans) is the other possible cause. Gastroesophageal reflux is the process in which stomach acid backs up into the esophagus, resulting in chemical burns of the mucosal lining. This can occur when a dog is tilted in a head-down position during general anesthesia. It may also occur with the use of of stomach tube, after chronic vomiting, and with a hiatal hernia. With this type of hernia, the stomach protrudes through an abnormally large esophageal opening in the diagram. The opening allows part or all of the stomach to slide up into the chest. Hiatal hernias are not common in dogs. Most of them are congenital, with an increased incidence among Chinese Shar-Pei. The major concern with hiatal hernia is that it causes gastroesophageal reflux. Signs to moderate to severe esophagitis are dysphagia, repeated swallowing, regurgitation and drooling. With chronic esophagitis the dog loses his appetite and weight. The diagnoses is made by gastroscopy, which he reveals an inflamed, swollen esophageal mucosa.

A stricture is a circular scar that forms after an injury to the wall of the esophagus. Most injuries are caused by esopageal foreign bodies, swallowed caustic liquids and gastroesophageal reflux and other causes. Tumors of the esophagus can produce a stricturelike narrowing. The principal sign of esophageal stricture is regurgitation. The dianoses can be made by X-ray after the dog has been given a barium solution, or by an esophageal endoscopy. The stricture appears as a fibrous ring that narrows the esophagus.

Primary tumors of the esophagus are rare and most are malignant. A common benign tumor is a leiomyoma. Tumors that have spread to lymph nodes around the esophagus can also press on the esophagus, creating a physical obstruction. Growth on the esophagus caused by a worm parasite (spirocerca lupi) occur in the southwestern United States. The disease is uncommon. A few of these growths can transform into cancer.

Stomach and duodenal ulcers are being diagnosed more frequently in dogs due to the wider use of gastroscopy. Seen through the endoscope, superficial ulcers are patches of inflamed and eroded mucosa covered by white or yellow pus. Deep ulcers are punched out areas involving all layers of the stomach wall. Ulcers can be single or multiple, and can range in size from less than one inch (2.5cm) to several inches in diameter. Ulcers occur more often in the stomach than in the duodenum. Bacteria are often the cause of ulcers in humans, but ulcers in dogs are not generally believed to be caused by stomach bacteria-although helicobacter species have been found in dogs. The usual cause in dogs is corticosteroids or nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen. Dogs are even more suseptible than people to the ulcer-producing affects of these drugs. Other conditions that predispose a dog to ulcers include all forms of liver disease, kidney failure, extreme stress (from severe illness or major surgery), chronic gastritis (particularly the eosinophilic type) and shock. Mast cell tumors of the skin can cause ulcers. This is because these tumors produce and release histimine, which is a powerful stimulant to acid secretion. In fact, ulcers occur in up to 80 percent of dogs with mast cell tumors. The principal sign of an ulcer is sporadic or chronic vomiting. Dogs may also lose weight and be anemic. In dogs with non-specific signs, such as chronic vomiting, the diagnoses is made by gastroscopy. Occasionally the vomitus contains old blood (which looks like coffee grounds) or fresh blood and blood clots, although the bleeding in many ulcers is microscopic. With rapid breathing the dog goes into shock and passes black, tarry stools. Stomach and duodenal ulcers can rupture into the adbomen, causing peritonitis.

At the outlet of the stomach is the pyloric canal. Scarring and contraction of the pyloric canal prevents the stomach from emptying. Stomach and duodenal ulcers close to the pyloric canal are the most common causes of inflammation and scarring. Other causes of scarring and contraction include hypertrophic and eosinophilic gastritis and gastric tumors. Foreign bodies and bezoars are other causes of gastric outflow obstruction. Gastric outflow obstruction can be partial or complete. Dogs with partial obstruction vomit intermittently, often 12 to 16 hours after eating. The vomitus usually contains undigested food and occasionally, blood. When obstruction is complete, vomiting occurs immediately after eating and is often projectile. Other signs of gastric outflow obstruction include obstruction include loss of appetite, weight loss and bloating. The diagnosis can sometimes be made by an X-ray of the abdomen or an ultrasound showing an enlarged, fliud-filled stomach. Gastroscopy or an upper GI series may be required for more complete dianosis.

A stomach tumor should be considered in an older dog with sporadic vomiting. The vomitus often contains old, partially digested blood. Enemia and weight loss are frequently found. Tumors in the pyloric canal region often cause gastric outflow obstruction. Adenocarcinoma is the most common malignant tumor of the stomach. Benign tumors, such as leiomyomas and polyps also occur. The diagnosis is made by gastroscopy and biopsy of the tumor.

Bloat is a life-threatening emergency that affects dogs in the prime of life. The mortality rate for gastric volvulus approaches about 50 percent. Early recognition and treatment are the keys to survival.

Bloat actually refers to two conditions. The first is gastric dilatation, in which the stomach distends with gas and fliud. The second is volvulus, in which the distended stomach rotates on its long axis. The spleen is attached to the wall of the stomach, and therefore rotates with the stomach. Gastric dilatation may or may not be complicated by volvulus. If volvulus occurs the stomach may twist 180 degrees or less (technically called a torsion). An actual volvulus is a twist of a 180 degrees to 360 degrees or more. During volvulus, the pylorus is pulled out of position and becomes displaced to the left of the gastroesophageal junction. This pinches off the duodenum and prevents fliud and air from escaping from the stomach through the pyloric canal. Simultaneously, the gastroesophageal junction becomes twisted and obstructed, preventing the dog from belching and vomiting. Gas and fliud are trapped in the closed-off stomach, which becomes hugely distended as the material ferments. Interference with blood circulation results in necrosis of the wall of the stomach. This sequence produces a number of other problems, including acute dehydration, bacterial septicemia, circulatory shock, cardiac arrhythmias, gastric perforation, peritonitis and death. Bloat can occur in any dog at any age, but typically occurs in middle-aged to older dogs. There may be a familiar association. Large breed dogs with deep chest are anotomically predisposed. These breeds include the Great Dane, German Shepherd Dog, Saint Bernard, Labrador Retriever, Irish Wolfhound, Great Pyrenees, Boxer, Weimaraner, Old English Sheepdog, Irish Setter, Collie, Bloodhound and Standard Poodle. Chinese Shar-Pei and Basset Hounds have the highest incidence among midsized dogs. Small dogs are rarely affected, with the exception of Dachshunds, who are also deep-chested. Bloat develops suddenly, usually in a healthy, active dog. The dog may have just eaten a large meal, excercised vigorously before or after eating, or drank a large amount of water immediately after eating. There is no evidence that the protein or soy content in the diet contributes to bloat: research has shown that the majority of gas associated with bloat is due to swallowed air.

The classic signs of bloat are restlessness and pacing, salivation, retching, unproductive attempts to vomit and enlargement of the abdomen. The dog may whine or groan when you press on his belly. Thumping the abdomen produces a hollow sound. Unfortunately, not all cases of bloat present with typical signs. In early bloat the dog may not appear distended, but the abdomen usually feels slightly tight. The dog appears lathargic, obviously uncomfortable, walks in a stiff legged fashion, hangs his head, but may not look extremely anxious or distressed. Early on, it is possible to distinguish dilatation from volvulus. Late signs (those of impending shock) include pale gums and tongue, delayed capillary refill time, rapid heart rate, weak pulse, rapid and labored breathing , weakness and collapse. If the dog is able to vomit or belch, quite likely the problem is not due to a volvulus, but this can only be determined by an examination.

In all cases where there is the slightest suspicion of bloat, take your dog to an animal hospital immediately. Time is of the essence. Gastric dilatation without torsion or volvulus is relieved by passing a long rubber or plastic tube through the dog's mouth into the stomach. This is also the quickest way to confirm a diagnosis of bloat. As the tube enters the dog's stomach, there should be a rush of air and fliud from the tube, bringing relief. The stomach is then washed out. The dog should not be allowed to eat or drink for at least 36 hours and will need to be supported with intravenous fliuds. If the symptoms do not return, the diet can be gradually restored. Passing a stomach tube is a procedure normally done by a trained professional (doggy doctor). In extreme circumstances when professional help is not available, you may be asked to perform the procedure at home. If you live in a remote location where fast access to animal services is limited, you may wish to aquire a stomach tube and add it to your home emergency medical kit. To pass a stomach tube , first mark the tube by measuring the distance from the dog's nose to his last rib Then lubricate the tube with K-Y or petroleum jelly. It is helpful to put a roll of adhesive tape in the dog's mouth to pass the tube through, so the dog cannot bite down on the tube. Insert the tube behind one of the canine teeth and advance it into the throat until the dog begins to swallow. If the dog gags, continue to advance the tube. If the dog coughs, the tube has entered the trachea. Withdraw the tube a few inches and start again. If the tube will not pass into the stomach, discontinue further attempts, as it is possible to harm the dog. If you do not have a tube available, a fairly large gauge sterile needle, such as an 18-gauge needle from a syringe may be used to poke directly through the body wall into the distended area to release gas and relieve pressure on the abdominal tissues. This is only a stopgap measure to buy you time to reach an animal hospital and only be done in a serious emergency in which there are no trained professionals available; because the needle could damage other tissue as it is pushed through the body wall. If you can pass a tube through, you should still take your dog to an animal hospital for follow-up treatment to prevent a recurrence. Being able to pass a tube through does not always rule out volvulus. Occasionally the tube passes even though the stomach is twisted. A diagnosis of dilatation or volvulus is best confirmed by X-rays of the abdomen. Dogs with simple dilatation have a large volume of gas in the stomach., but the gas pattern is normal. Dogs with volvulus have a "double bubble" gas pattern on the X-ray, with gas in two sections separated by the twisted tissue. Emergency therapy is directed toward correcting shock and dehydration with intravenous fluids and corticosteroids. Antibiotics may be needed to control infection. Ventricular arrhythmias are common. They require heart monitoring and the use of anti-arrhythmic drugs. If a dog has a volvulus, emergency surgery is required as soon as the dog is able to tolerate the anesthesia. The goals are to reposition the stomach and spleen, or to remove the spleen and part of the stomach if these organs have undergone necrosis. Future recurrence can often be prevented by suturing the wall of the stomach to the abdominal wall (a procedure called gastropexy). This important step keeps the stomach in position and prevents it from twisting.

Dogs who respond to nonsurgical treatment have about a 70 percent chance of having another episode of bloat. Some of these episodes can be prevented by following these practices:

4 Beware of the early signs and seek prompt professional help whenever you suspect bloat.

The adrenal glands, found in the abdomen above the kidneys, are important in the production of corticosteroids and other hormones that regulate body functions. Addison's Disease is caused by inadequate production of corticosteroids and mineralocorticoids. In some cases this uncommon condition arises after other illnesses; including infections, tumors and toxic drugs, which destroy the adrenal glands. An autoimmune reaction, in which antibodies are directed against the cells of the adrenal cortex (the part of the adrenal gland that produces corticosteroids), may be responsible for cases in which the cause is not known. There may be a genetic predisposition in Bearded Collies, Portagese Water Dogs and Standard Poodles. An iatrogenic form of Addison's Disease occurs after corticosteroids are administered to treat a medical condition. The corticosteroids have the side affect of putting the adrenal glands at rest. An abrupt withdrawal of the drug can produce a temporary deficit of hydrocortisone and cause an acute Addisonian crisis with shock and circulatory collapse. The signs of Addison's disease are lethargy, muscle weakness, intermittent vomiting and diarrhea, and a slow pulse. This disease should be considered when a dog unaccountably collapses. The diagnosis is made by an ACTH stimulation test. In a positive test, the adrenal cortex does not respond to an injection of ACTH by increasing the concentration of cortisol in the serum.

Acute gastritis is an irritation of the lining of the stomach that comes on suddenly. The principal sign is severe and continuous vomiting. Keep in mind that persistant vomiting is also associated with life-threatening diseases such as intestinal obstruction and peritonitis. Seek professional consultation in all cases where the cause of persistant vomiting is not known. Common stomach irritants include spoiled food and garbage, stools, grass, plastic wrappings, hair and bones. Certain drugs (notably aspirin, virtually all NSAIDs, cortisone, butazolidine and some antibiotics) produce gastric irritation. Common poisons that may cause vomiting are antifreeze, fertilizers, plant toxins and crabgrass killers. If poisoning is suspected, contact your nearest emergency animal hospital. A dog with acute gastritis vomits shortly after eating. Later the dog appears lathargic and sits with his head hanging over the water bowl. The dog's temperature remains normal unless he is suffering from acute infectious enteritis, a disease that also causes diarrhea.

Dogs with chronic gastritis vomit from time to time over a period of days or weeks. These dogs would appear lathargic, have a dull hair coat and lose weight. The vomitus sometimes contains foreign material and food eaten the day before. A common cause of chronic gastritis is a food allergy. Other causes are persistent grass eating, repeated consumption of drugs, chemicals or toxins and ingesting cellulose, plastic, paper or rubber products. Also consider the possibility of hairballs. Hair is shed more heavily in the springtime and is swallowed as the dog licks and pulls it out. Hair and other foreign materials can be incorporated into a hard mass called a bezoar. Bezoars may grow to a size that makes it impossible for them to pass out of the stomach. Note that in many cases of chronic vomiting the cause is not known.

Hypertrophic gastropathy is a thickening of the mucous membranes of the lower half of the stomach, which can lead to gastric obstruction and food retention. Vomiting occurs three to four hours after eating. Hypertrophic gastropathy occurs most in middle-aged dogs of the small breeds. It may also be seen as a congenital problem called pyloric stenosis in brachycephalic breeds such as Bulldogs and Boston Terriers. The cause is unknown in older dogs, but may be related to histimine release from mast cell tumors in some dogs.

Chronic atrophic gastritis involves a thinning of the stomach wall. This is primarily seen in Norwegian elkhounds, and may develop from an immune problem

Eosinophilic gastritis is a chronic condition characterized by the accumulation of eosinophils (a type of white blood cell) in the mucous lining of the stomach, along with thickening and scarring of the stomach wall. The cause is unknown, although a food allergy or parasites have been proposed. Eosinophilic gastritis is more likely than other types of gastritis to be associated with ulcers and bleeding. Stomach and duodenal ulcers also produce sporadic vomiting. Finally, if there is no obvious explanation for the sporadic vomiting, the dog may be suffering from a systemic disease, such as liver or kidney failure, which can be diagnosed by blood tests.

Many young dogs become sick when traveling by car, boat or air. The signs are restlessness followed by salivation, yawning, nausea and then vomiting. Motion sickness is caused by over-stimulation of the labyrinth in the inner ear.

Vomiting is common in dogs. All vomiting is the result of activating the vomiting center in the brain. The vomiting center is well developed in dogs, so dogs vomit more readily than most other animals. As a dog perceives a need to vomit, he becomes anxious and may seek attention and reassurance. He then begins to salivate and swallow repeatedly. Vomiting begins with simultaneous contraction of the muscles of the stomach and abdominal wall. There is an abrupt increase in intra-abdominal pressure. The lower esophagus relaxes, allowing the stomach contents to travel up the esophagus and out the mouth. The dog extends his neck and makes harsh gagging sounds. This sequence should be distinguished from the passive act of regurgitation.

The most common cause of vomiting is eating indigestible substances, such as grass, that irritate the lining of the stomach. Another cause of vomiting is overeating - dogs who eat more than their daily amount of food, perhaps because they have gotten into the dog food supply. Also puppies who gobble their food and exercise immediately after are likely to vomit. This after-meal vomiting is frequently caused by feeding a group of puppies from a common food pan. Since they are all competing for food, each one eats as much as he possibly can. Separating puppies, or feeding them frequent small meals, eliminates the problem of gorging. Dogs may vomit when they are upset, excited or suffering from a phobia (for example; during a thunderstorm). Phobic dogs also drool, whine, paw and tremble. Puppies with heavy loads of ringworms may vomit up some worms. Vomiting occurs with most acute infectious diseases. It also occurs with many chronic diseases, including kidney and liver failure, Cushing's syndrome, Addison's disease and diabetes mellitus. To determine the cause of vomiting, note whether it is repeated, and if so, whether it is sporadic or persistent. How soon after eating does it occur ? Is it projectile ? Inspect the vomitus for blood, fecal material and foreign objects.

If the dog vomits or retches repeatedly, bringing up a frothy, clear fluid, this suggests a stomach irritation such as acute gastritis. However, persistent vomiting also occurs with life-threatening diseases such as acute pancreatitis, gastric outflow obstruction, intestinal obstruction and peritonitis. Persistent retching without bringing up any vomitus is typical of bloat. Repeated vomiting along with diarrhea suggests acute infectious enteritis.

Sometimes a dog vomits off and on over a period of a few days or weeks. There is no relationship to meals. The appetite is poor. The dog has a haggered look and appears listless. Suspect liver or kidney disease or an illness such as chronic gastritis, stomach or duodenal ulcer, a heavy worm infestation or diabetes mellitus. A foreign body in the stomach is another possiblity. In an older dog, suspect a gastric or intestinal tumor. A check-up is in order.

Red blood in the vomitus indicates active bleeding somewhere between the mouth and the upper small bowel. (Blood from the nasopharynx and esophagus may be swallowed). Common causes are stomach and duodenal ulcers, gastrointestinal foreign bodies and gastric tumors. Material that looks like coffee grounds is old, partially digested blood. This also indicates a bleeding point between the mouth and the upper small bowel. Any dog who vomits blood should be seen by a trained professional.

A dog who vomits foul material that looks and smells like feces is most likely suffering from intestinal obstruction or peritonitis. Seek immediate professional treatment. Dogs who eat feces may also do this, but it will be an isolated incident.

Projectile vomiting is forceful vomiting in which the stomach contents are ejected a considerable distance. Typically it occurs in a dog with gastric outflow obstruction. Diseases that cause pressure on the brain (tumors, encephalitis, blood clots) also cause projectile vomiting.

Dogs may also vomit foreign objects, including rubber balls, pieces of toys, sticks and stones. Puppies with a heavy roundworm infestation may vomit adult worms.

If there is any question about the cause or seriousness of the vomiting, seek professional help. Vomiting dogs can rapidly become dehydrated as they lose body fluid and electrolytes. Home treatment is appropriate only for normal, healthy adult dogs who show no signs other than vomiting. Puppies, dogs with preexisting health conditions and old dogs are less able to tolerate dehydration and should be treated by a professional. An important initial step is to rest the stomach by withholding food and water for a minimum of 12 hours. If the vomiting stops with stomach rest, the dog can be permitted to lick a few ice chips every three to four hours if the vomiting has stopped, offer 1/4 to 1/2 cup of water (63 to 125 ml), depending on the size of the dog, every two to three hours. A pediatric electrolyte solution can be given in small amounts, in addition to the water. After 12 hours with no vomiting, start the dog on a bland diet such as two parts boiled rice mixed with one part ground beef or chicken and a little bit of cottage cheese. Begin offering small amounts (1 or 2 tablespoons, 15 to 30 ml, at a time) every two to three hours. Increase the volume over the next few days and gradually return the dog to his customary diet.

Small and Large Bowels

Problems in the small and large bowels are associated with three common symptoms: diarrhea, constipation and passing blood. Diarrhea is by far the most common.

This is a group of small and large intestines, characterized by chronic and protracted diarrhea, malabsorption, weight loss, anemia and malnutrition. They are all treatable, but are seldom cured. In each specific disease, a different type of inflammatory cell is found in large numbers in the lining of the small and/or large intestines. These cells distinguish the specific diseases. Diagnosis is made by endoscopy and biopsy of the intestine wall or by exploratory surgery.

This is the most common inflammatory bowel disease in dogs. Lymphocytic-plasmacytic enterocolitis has been associated with giardiasis, food allergy and overgrowth of intestinal bacteria. . Lymphocytes and plasma cells are the target cells seen on biopsy. Certain breeds are predisposed, suggesting a genetic influence. They are the Basenji, Soft Coated Wheaten Terrier, German Shepherd Dog and Chinese Shar-Pei. In the Basenji, the disease is known to be related to an autoimmune disorder. While signs can show up in younger dogs, most dogs are middle-aged when diarrhea starts. Lymphocytic-plasmacytic enterocolitis produces a small bowel type of diarrhea. Vomiting is common. Involvement of the colon produces signs of colitis.

This is a relatively uncommon form of inflammatory bowel disease in dogs. On biopsy, eosinophils may be found in the stomach, small intestine or colon, and the eosinophil count in the blood may be elevated. Some cases are thought to be associated with food allergy or the tissue migration and roundworms and hookworms.

This is a rare disease, similar to Crohn's disease in humans. There is thickening and narrowing of the terminal of the small bowel due to inflammation of surrounding fat and lymph nodes. Macrophages, which are cells found in tissues that fight infections, are found on biopsy of the colon. The diarrhea is the chronic large bowel type containing mucus and blood. Biopsies are processed with special stains to exclude histoplasmosis and intestinal tuberculosis.

This inflammatory bowel disease produces acute and chronic large bowel diarrhea. The inflammatory infiltrate is composed of mature white cells in the tissues and blood vessels. Diagnosis is based on a colon biopsy and stool cultures to exclude bacterial infection.

This inflammatory bowel disease occurs almost exclusively in Boxers. Signs usually appear before age 2. Affected dogs develop severe, unrelenting diarrhea that contains mucus and blood, and corresponding weight loss. The diagnosis is based on a colon biopsy.

Enteritis is an infection of the gastrointestinal tract characterized by the sudden onset of vomiting and diarrhea, rapid pulse, fever, apathy and depression. The vomitus and diarrhea may contain blood. Dehydration occurs rapidly. Dogs under 1 year of age and those over 10 are particularly susceptible to the effects of dehydration and shock. The most common cause of infectious enteritis in dogs is parvovirus. Salmonella, E. Coli, camphylobacter, and other bacteria are also responsible for some cases. The bacteria Clostridium perfringens produces canine hemorrhagic gastroenteritis. This disease begins suddenly with vomiting, followed in two to three hours by a profuse, bloody diarrhea. Small breeds, particularly Miniature Schnauzers and Toy Poodles, have a predisposition for hemorrhagic gastroenteritis. Garbage poisoning and ingesting poisons and toxic chemicals produces signs and symptoms similar to those of acute enteritis. When diarrhea and vomiting occur together, the dog's condition is serious and warrants an immediate trip to the veterinarian.

Malabsorption is not a specific disease, but occurs as a consequence of some underlying disorder of the small bowel or the pancreas. In malabsorption syndrome, the dog either does not digest food or does not absorb the products of digestion from the small intestine. Dogs suffering from malabsorption are underweight and malnourished despite a voracious appetite. Diarrhea occurs three or four times a day. The stools are typically large, rancid smelling, and contain a great deal of fat. The hair around the anus may be oily or greasy. Predisposing causes of malabsorption include exocrine pancreatic insufficiency, permanent damage to the intestinal mucosa following infectious enteritis, inflammatory bowel disease with inflamed or destroyed intestinal mucosa, surgical removal of a major portion of the small bowel, and primary diseases of the small intestine. Soft Coated Wheaten Terriers may suffer from a protein-losing enteropathy, where they don't properly digest and absorb protein.

Idiopathic villous atrophy is one of the primary diseases of the small intestine. Villi are microscopic hairlike structures that make up the absorptive surface of the small bowel. In a dog with villous atrophy these structures are blunted and poorly developed. Idiopathis villous atrophy occurs most often in German Shepherd Dogs. A similar hereditary disease is wheat-sensitive or gluten-sensitive enteropathy, described in Irish Setters.

Small intestinal bacterial overgrowth has been identified as another important cause of malabsorption. German Shepherds, Basenji's and Chinese Shar-Pei have an increased incidence. Affected dogs develop an abundant and abnormal bacteria flora in the small intestine, which causes foul-smelling diarrhea. Some cases have been associated with exocrine pancreatic insufficiency, inflammatory bowel disease or stagnant loops of bowel caused by intestinal surgery. In Germany Shepherd Dogs and Chinese Shar-Pei, the condition may be related to a specific immune deficiency. In the majority of cases, the cause of the bacterial overgrowth is unknown. In many cases the cause of malabsorption can be identified through special diagnostic tests, including stool analysis and an intestinal biopsy.

Colitis is an inflammation of the colon. It is responsible for about 50 percent of cases of chronic diarrhea in dogs. The signs of colitis are painful defecation, prolonged squatting and straining, flatulence and passing many small stools mixed with blood and mucus. These signs can easily be mistaken for constipation. The usual cause of colitis is one of the inflammatory bowel diseases. Whipworms are another frequent cause. Fungal colitis is uncommon. It targets dogs with immune deficiency and lowered resistance. Prototheca colitis is a rare disease caused by an algae. It produces a severe form of colitis and can become systemic. Treatment has not been successful. Colitis is diagnosed by colonoscopy and colon biopsy. Stool specimens are examined for parasites and fungi.

Irritable bowel syndrome describes a diarrhea motility disorder often associated with stress. It tends to occur in high-strung, nervous dogs. Dogs with irritable bowel syndrome have frequent small stools, often mixed with mucus. The diagnosis is based on the exclusion of other causes of colitis.

Dogs have been known to swallow bones, toys, sticks, stones, pins, needles, wood splinters, cloth, rubber balls, rawhide, leather, string, peach pits and other objects. With string, one end often knots up while the other gets caught in food. Tension on the string then causes it to cut through the wall of the bowel. Swallowing pennies will not usually cause an obstruction, but can lead to zinc toxicity as the metal leaches out of the coins. Batteries can also cause toxicity when swallowed. The esophagus of the dog is larger than the outlet of his stomach. Thus, dogs may swallow objects that are too large to pass out of the stomach. Gastric foreign bodies are therefore associated with chronic gastritis and episodes of gastric outflow obstruction. If an object makes it into the small intestine, it may pass through the entire GI tract without causing problems. Those that do cause an obstruction usually do so at the ileocecal valve or in the colon and rectum. Foreign bodies in the rectum cause anorectal obstructions. Sharp objects such as pins, splinters and bone chips can lodge anywhere in the GI tract and obstruct or perforate the bowel, causing intestinal obstruction or peritonitis. Unless it also causes indigestion, a swallowed foreign body will go unnoticed until it produces symptoms. Many foreign bodies can be seen on X-rays of the abdomen if they are radio-opaque. A contrast study may be needed to identify foreign bodies that are not visible on X-rays.

Any problem that interferes with the passage of intestinal contents through the GI tract results in a blocked bowel. The most common cause is a gastrointestinal foreign body. The second most common cause is intussusception - a situation in which the bowel telescopes in upon itself, like a sock pulled inside out. Most cases of intussusception occur at the cecum, where the small bowel joins the colon. As the small bowel inverts into the cecum and colon, the leadpoint travels a considerable distance, dragging the small intestine after it. Intussusceptions generally occur in puppies and young dogs. Other causes of intestinal obstruction are tumors and strictures, adhesions following abdominal surgery, and navel and groin hernias that trap loops of bowel in the hernia sac. In young puppies, heavy infestations of roundworms may obstruct the bowel. An intestinal obstruction can be partial or complete. Partial obstructions cause intermittent vomiting and/or diarrhea, which tend to occur over several weeks. Complete obstructions produce sudden abdominal pain and vomiting that continues without relief. When the blockage is in the upper small bowel, the vomiting may be projectile. Blockage in the lower GI tract can cause abdominal distension and the vomiting of brown, fecal-smelling material. Dogs with complete obstruction pass no stool or gas. Intestinal strangulation occurs when the obstruction interferes with the blood supply to the bowel. Within hours the bowel becomes gangrenous. The dog's condition deteriorates rapidly. The diagnosis of intestinal obstruction is made by abdominal X-rays or ultrasound showing distended, gas-filled loops of bowel.

Dogs who pass often gas can embarrass or distress their owners. The most common cause of flatulence is swallowing large amounts of air while gulping food. The next cause is eating highly fermentable foods such as onions, beans, cauliflower, cabbage and soybeans. Flatulence also occurs with malabsorption syndromes. The excess gas is related to incomplete digestion of carbohydrates. Boxers are renowned for flatulence problems. A sudden bout of flatulence, accompanied by abdominal discomfort, loss of appetite, or diarrhea, is an indication to seek veterinary attention.

Coprophagia is the name given to the habit of eating stools-either the dog's own or another animal's. Cats' stools seem particularly tempting to dogs. Most dogs with coprophagia are well nourished and show no evidence of a nutrient deficiency that would account for the compulsion to eat stools. These individuals may have acquired a taste preference for stools beginning in puppyhood. Other reasons sometimes suggested for stool eating include; boredom and confinement in close quarters, such as a kennel. Scolding the dog for a housetraining accident may also cause him to want to eat the evidence. Whatever the cause, once established, the habit is difficult to break. A minority of dogs have a medical reason for coprophagia. Dogs with malabsorption syndrome, in particular, have a ravenous appetite and eat stools in an attempt to acquire additional calories. Coprophagia has also been described in dogs on corticosteroid therapy and those with Cushing's syndrome, diabetes mellitus, hyperthyroidism and intestinal parasites. Stool eating is undesirable, not only for aesthetic reasons but because ingesting animal feces can bring in intestinal parasites. Dogs who eat large amounts of horse manure can develop severe vomiting and diarrhea. Dogs who eat the feces of large animals that were wormed recently may develop toxicity from the worm medication residue present in the stools.

Inflammation of the cavity containing the abdominal organs is called peritonitis. Peritonitis occurs when digestive enzymes, food, stool, bacteria, blood, bile or urine leak into the peritoneal cavity. Common causes are bloat, ruptured ulcers, perforations caused by gastrointestinal foreign bodies, intestinal obstructions, rupture of the uterus, rupture of the bladder, acute pancreatitis, penetrating wounds of the abdomen and breakdown of suture lines following intestinal surgery. Peritonitis can be localized or diffuse. In localized peritonitis an apron of fat (called the omentum) seals off and contains the source of contamination. In diffuse or generalized peritonitis, the infection spreads rapidly throughout the abdominal cavity. Dogs with generalized peritonitis have severe abdominal pain and are reluctant to move. Vomiting is common. Pressing on the abdomen causes the dog to groan. The abdomen has a tucked-up appearance and feels rigid or boardlike, owing to reflex spasms of the abdominal wall muscles. Dehydration, infection and shock rapidly ensue. The pulse is weak and thready, breathing is rapid and labored, and the gums are cool and pale. The capillary refill time is prolonged more than three seconds. Collapse and death occur in a matter of hours.

Constipation means absent, infrequent, or difficult defecation. Most healthy dogs have one or two stools a day. This varies with the individual and the diet. A day or even two without stools is not a cause for concern, if the stools remain normal in size and pass without difficulty. But when feces are retained in the colon for two or three days, they become dry and hard and require forceful straining to pass. Note that straining also occurs in dogs with colitis, obstructed bladder and anorectal obstructions. It is important to be sure the dog is not suffering from one of these other problems before treating him for constipation. Colitis, in particular, is often confused with constipation. Remember that a dog with colitis will pass many small stools that contain mucus and/or blood.

Many middle-aged and older dogs are prone to constipation. A common predisposing cause is failure to drink enough water. With mild dehydration, water is withdrawn from the colon, which dehydrates the feces. Ingesting foreign materials such as bone chips, hair, grass, cellulose, cloth, paper, and other substances is a well-recognized cause of acute and chronic constipation. The indigestible material mixes with feces to form rocklike masses in the colon. Many drugs commonly used in dogs cause constipation as a secondary side effect. Discuss this possible correlation with a trained professional. Hypothyroidism is an occasional cause of chronic constipation. The urge to defecate can also be voluntarily overridden. Dogs develop such inhibitions during housetraining. When left alone in the house for long periods, they often override the urge to defecate. Dogs may also be reluctant to empty their bowels when hospitalized, boarded, or taken on a trip. Dogs with constipation of recent onset should be examined by a trained professional. Other reasons to seek professional consultation are painful defecation, straining during defecation and passing blood or mucus.

A fecal impaction is a mass of hard stool in the rectum and colon. There may be a predisposing condition, such as an enlarged prostate, that compresses the rectal canal. Dogs with fecal impactions pass little or no stool despite repeated and forceful straining are lathargic, have no appetite, experience abdominal distension and vomiting and may have a hunched-up appearance. Digital rectum examination reveals a large tubular mass.

Diarrhea is the passage of loose, unformed stools. In most cases there is a large volume of stool and an increased number of bowel movements. The two most common causes of diarrhea in dogs are dietary indiscretion and intestinal parasites. Many canine infectious diseases are also associated with acute diarrhea. Food takes about eight hours to pass through the small intestines. During that time, the bulk of the food and 80 percent of the water is absorbed. The colon concentrates the remainder. At the end, a well-formed stool is evacuated. A normal stool contains no mucus, blood or undigested food. With rapid transit through the bowel, food arrives at the rectum in a liquid state, resulting in a loose, unformed bowel movement. This type of rapid transit accounts for the majority of temporary diarrhea in dogs. Dietary indiscretion is a common cause of rapid transit. Dogs are natural scavengers and tend to eat many indigestible substances, including garbage and decayed food, dead animals, grass, wild and ornamental plants and pieces of plastic, wood, paper and other foreign materials. Many of these are irritating to the stomach as well as to the bowel, and are partially eliminated through vomiting. Food intolerance can also cause rapid transit. Foods that some dogs seem unable to tolerate can include beef, pork, chicken, horsemeat, fish, eggs, spices, corn, wheat, soy, gravies, salts, fats and commercial dog foods. Note that food intolerance is not the same as food allergy, which causes dermatitis and possibly vomiting, but rarely causes diarrhea. Some adult dogs are unable to digest milk and milk by-products because of a lactase deficiency. Lactase is an intestinal enzyme that breaks down the lactose in milk into small-chain sugars. Undigested lactose cannot be absorbed and remains in the bowel and holds water with it. This increases motility and causes large-volume diarrhea.

Characteristics of Diarrhea
COLOR	LIKELY CAUSE	LIKELY LOCATION
Yellow or greenish	Rapid transit	Small bowel
Black, tarry	Upper GI bleeding	Stomach or small bowel
Red blood or clots	Lower GI bleeding	Colon clots
Pasty, light	Lack of bile	Liver
Large, gray, rancid	Inadequate digestion	Small bowel or absorption
CONSISTENCY
Watery	Rapid transit	Small bowel
Foamy	Bacterial infection	Small bowel
Greasy, often with oily hair around the anus	Malabsorption	Small bowel, pancreas
Glistening or jellylike	Contains mucus	Colon
ODOR
Food like or smelling like sour milk	Rapid transit/inadequate digestion or absorption	Small bowel
Rancid or foul	Inadequate digestion with fermentation	Small bowel, pancreas
FREQUENCY
Several small stools in an hour, with straining	Colitis	Colon
Three or four large stools a day	Inadequate digestion or absorption	Small bowel, pancreas
CONDITION OF THE DOG
Weight loss	Inadequate digestion or absorption	Small bowel, pancreas
No weight loss, normal appetite	Large bowel disorder	Colon
Vomiting	Enteritis	Small bowel, rarely colon

Intestinal parasites are a common cause of acute and chronic diarrhea in puppies and adults. The greatest problems are caused by roundworms, hookworms, whipworms, threadworms and giardia. Diarrhea is a common side effect of many drugs and medications, particularly the NSAIDs, which include aspirin. Some heart medications, some dewormers and most antibiotics can cause diarrhea. Dogs can experience diarrhea when they are excited or upset - for example: when they're going to the veterinarian hospital or a dog show. In fact, any sudden change in a dog's diet or living circumstances may cause emotional diarrhea. In trying to figure out the cause of a diarrhea, it is important to decide whether the diarrhea originates in the small bowel or the large bowel. The characteristics of the diarrhea, as well as the condition of the dog will help make this determination. The chart above details what to look for. Diarrhea can be classified as acute or chronic, depending on its duration. Acute diarrhea comes on suddenly and is finished in a short period. Chronic diarrhea often comes on gradually and persists for three weeks or longer, or has an episodic pattern of recurrence. Routine tests include stool examinations for parasites (Hookworms, Whipworms, Giardia), bacteria (Salmonella, Camphylobacter, Clostridia) and occasionally fungi (Histoplasmosis, Aspergillosis, Candida). A number of immune assays and fecal absorption tests are available for diagnosing maldigestion and malabsorption syndromes. Colonoscopy, with direct visualization of the interior of the colon, is an important diagnostic test for large bowel diarrhea. Liquid stool can be aspirated for culture and cytology, and biopsies taken of the bowel wall or any suspicious legions. Gastroscopy with biopsy of the duodenum and sampling of small bowel secretions helps in diagnosing in small bowel diarrhea. Ultrasound is another diagnostic tool that may help to pinpoint the cause of diarrhea.

The Anus and Rectum

The signs of anorectal disease are pain on defecation, straining to pass stool, rectal bleeding, scooting and biting and licking at the rear. Dogs with anorectal pain often attempt to defecate from a standing position. Bleeding from the anal canal is recognized by finding blood on the outside of the stool rather than mixed in with it. Scooting is rubbing the bottom along the ground. It indicates anal itching. Anal itching can be caused by flea bites, inflammation of the anal skin, anal sac disease or tapeworms.

A common cause of an anorectal obstruction is an enlarged prostate that bulges backward and compresses the rectum. This occurs in older male dogs. Foreign bodies that pass through the upper GI tract may obstruct the rectum. Pelvic fractures that have healed improperly can narrow the rectum, causing a blockage. Boston Terriers and Bulldogs are predisposed to this, and any dog born with a screw tail may have a rigid extension of the tail that pushes down upon the anal canal, pinching it against the pelvic floor. Other causes of blockage are fecal impactions, matted stool around the anus, rectal strictures, perianal gland tumors, perianal hernias and rectal polyps and cancers. Rectal stritures result from perianal infections, fistulas and surgical attempts to treat them. Perianal hernias are bulges that occur alongside the anus. They weaken the muscular support of the rectum and interfere with the mechanics of elimination. The bulges becomes larger as the dog strains. Perianal hernias primarily occur in elderly, unneutered males. The principal sign of anorectal obstruction is straining to defecate. The stool may be flat or ribbonlike. The dog may or may not pass blood. The diagnosis is made by digital rectal examination and occasionally colonoscopy.

When hair becomes densely matted with dry stool and forms a barrier to defecation, pseudoconstipation results. It occurs in long-haired dogs. usually following a bout of diarrhea. The skin becomes irritated, painful and infected. This introduces an element of voluntary retention as well. Dogs with pseudoconstipation are restless and bite and lick at the anus. Other signs are scooting, whining and attempting to defecate while standing. There is an extremely offensive odor.

Inflammation of the anal skin can be caused by pseudoconstipation. Repeated bouts of diarrhea, especially in puppies, can cause an inflamed anus. Other causes are insect bites and worms. Irritation of the anal canal is caused by the passage of bone chips and hard stools. Straining is a common sign of proctitis. Other signs are scooting, licking and biting at the rear.

Anorectal Prolapse is the protrusion of rectal tissue through the anus. It occurs after forceful and prolonged straining. Conditions associated with forceful straining include severe constipation, fecal impaction, diarrhea, an anorectal obstruction, labor and delivery, an obstructed bladder and heavy parasite loads, especially in puppies. A mucosal prolapse is confined to the lining of the anal canal. It appears as a red, swollen, doughnut-shaped ring of tissue. This might be mistaken for prolapsed hemorroids. In a complete rectal prolapse, a segment of rectum several inches long protrudes through the anus, appearing as a pink or red cylindrical mass.

Imperforate anus is a rare congenital condition in which the anus, or the anus and rectum, do not develop. In female puppies there may be a passage between the colon and the vagina called rectovaginal fistula. Newborn puppies without an anus are unable to pass gas or meconium-the dark green fecal material that is usually excreted at birth. Abdominal distention and vomiting appear during the first 24 hours. If the colon opens into the vagina, gas and stool may pass out through the vulva, temporarily averting a bowel obstruction.

The dog has two anal sacs or glands located at five and seven o'clock in reference to the circumference of the anus. They can be seen by drawing down on the skin of the lower part of the anus and looking in those locations. The anal sacs are similar to scent glands. In skunks they serve a defensive purpose. In dogs they produce an odor that identifies the individual and marks his stool to establish territory. This is why dogs greet each other by sniffing at the rear.

Impaction is the accumulation of pasty secretions in the anal sacs. The sacs become distended and mildly tender. The expressed secretions are thick and dark brown or grayish brown. The sacs become impacted when they don't empty completely. This may be due to insufficient pressure on the sacs during defecation because of small, soft stools, inadequate sphincter pressure or blockings of the openings by thick, dry secretions. Impactions tend to occur most often in small breed dogs and in overweight dogs.

Anal sac infection complicates impaction. Infection is recognized by a painful swelling on one or both sides of the anus. The anal secretions are thin, yellowish or blood-tinged. The dog will scoot, lick and bite at his rear.

Abscess is recognized by fever and the signs of anal sac infection. The swelling, usually on one side, is red at first, then later turns a deep purple. Unlike anal sac infection, the swelling of an abscess cannot be reduced by emptying the sac. An abscess often ruptures through the adjacent skin, producing a draining tract.

Fistulas are draining tracts in the perianal skin caused by infection of the skin glands in and around the anus. Initially they appear as draining puncture holes. Later they coalesce to form open sores and draining tracts. The discharge is foul-smelling. Occasionally fistulas connect internally with the anal sacs. Perianal fistulas occur most often in German Shepherd Dogs, but are found in Irish Setters, English Setters, Labrador Retrievers and other breeds. There may be an association with breeds that have a low-slung, broad-based tail. Symptoms are similar to those of anal sac infection. There may be a foul-smelling discharge. The diagnosis is made by visual inspection of the perianal area.

Polyps are benign, grapelike growths that occur in the rectum and may protrude from the anus. They are not common, but when present they should be removed. Adenocarcinoma is the most common malignant colorectal growth, followed by lymphoma. Adenocarcinomas are slow-growing gastrointestinal tumors found predominantly in older dogs, usually in the lower colon and rectum. These tumors can obstruct, ulcerate and bleed. The diagnosis is made by colonoscopy and biopsy of the tumor. Cancers can also arise from the anal sacs. This occurs primarily in older females. Anal sac adenocarcinomas have the unique property of producing parathyroid hormone and thus may be associated with a severe form of hypercalcemia. These tumors vary in size from small lumps that are barely palpable to large masses protruding from the rectum.

These common tumors, often multiple, arise from glands located around the anus and at the base of the tail. They occur primarily in intact males over 7 years of age and require the presence of testosterone. Adenomas can be recognized by their typical location and rounded, rubbery appearance. A minority undergo malignant transformation to adenocarcinomas. These cancerous neoplasms can grow to a large size, break through the skin, become infected and cause anorectal obstruction. Metastases to the lungs occur frequently.

The liver performs many vital functions, including synthesizing enzymes, proteins and metabolites; removing ammonia and other wastes from the bloodstream; manufacturing blood-clotting factors; and detoxifying the blood of drugs and poisons.

The early signs of liver disease are nonspecific.They include loss of appetite, weight loss and chronic intermittent vomiting and diarrhea. Vomiting is more common than diarrhea. Drinking and urinating more often than normal may be the first signs and the principal reason for seeking medical attention. In the early stages of liver disease the liver swells and enlarges. As the disease progresses, the liver cells die and are replaced by scar tissue. The liver then becomes rubbery and firm. This condition is called cirrhosis. It is not reversible. Before the liver reaches this terminal stage, it can recover from damage and heal itself to the point where your dog has normal liver function. This is possible if proper treatment is instituted early on; the extent of recovery depends on the exact cause of the liver damage. Eighty percent of liver cells must die before the liver begins to fail. The signs of liver failure are jaundice, hepatic encephalopathy, ascites, spontaneous bleeding and dependent edema-swollen lower limbs. Treatment of liver failure is directed toward treating the liver disease that is causing it.

With impaired liver function, bile accumulates in the blood and tissues, staining the tissues yellow. This can be seen in the yellow appearance of the white of the eyes and in the mucous membranes of the gums and tongue. The inside of the ears is another area where yellow pigment can be detected. Bile excreted in the urine turns the urine dark brown (the color of tea). Jaundice may also result from the breakdown of large numbers of red blood cells, such as in acute hemolytic anemia. Post hepatic bile duct obstruction can also cause jaundice.

This is a type of brain dysfunction caused by high levels of ammonia and other toxins in the blood. Ammonia is a by-product of protein metabolism, and is normally removed from the bloodstream by a healthy liver. When the liver is sick, ammonia accumulates to toxic levels and exerts a poisonous effect on the brain. Dogs with hepatic encephalopathy develop incoordination, sporadic weakness, disorientation, head-pressing, behavioral changes, drooling, stupor and mental dullness. Symptoms tend to wax and wane. They become more severe after a high-protein meal. Seizures and coma occur when hepatic encephalopathy is advanced.

Ascites is the accumulation of fluid in the abdomen. In a dog with liver disease, it is caused by low serum proteins and increased pressure in the veins that supply the liver. A dog with ascites has a swollen or bloated look. Thumping on the abdomen produces a dull, flat sound.

Spontaneous bleeding occurs in dogs with advanced liver disease. Common sites of bleeding are the stomach, intestines and urinary tract. Blood may be noted in the vomitus, stools or urine. Punctate (pinhead-size) hemorrhages may be seen on the gums. Bruises can appear under the lips and skin. Major blood loss from spontaneous bleeding is relatively uncommon, but uncontrollable bleeding can be a serious problem if the dog is injured or requires surgery.

Swelling of the abdominal wall and lower legs is related to malnutrition and low serum protein levels. It is not as common in dogs with liver disease as it is in those with congestive heart failure.

A number of diseases, chemicals, drugs and toxins can damage the liver. The liver is directly affected by infectious canine hepatitis and leptospirosis. It is frequently involved in heartworm infection, Cushing's syndrome, and diabetes mellitus. Primary and metastatic tumors are a major cause of liver failure in dogs. Chemicals known to produce liver toxicity include carbon tetrachloride, insecticides and toxic amounts of lead, phosphorus, selenium, arsenic and iron. Drugs capable of damaging the liver include anesthetic gases, antibiotics, antifungals, dewormers, diuretics, analgesics(including NSAIDs), anticonvulsants, testosterone preparations (Cheque drops) and corticosteroids. Most drug reactions are associated with excessive dosage and/or prolonged use. Some plants and herbs can also cause liver failure; these include ragwort, certain mushrooms and blue-green algae. Molds such as aflatoxin, which grows on corn and may contaminate foods, can cause severe liver damage. A blockage of the bile duct by gallstones, liver flukes, tumors or pancreatitis is uncommon, but becomes a consideration when a dog has unexplained jaundice.

Liver shunts, also called portosystemic shunts, are abnormal veins that enable blood from the intestines to bypass the liver. ammonia and other toxins are not metabolized or removed from the circulation, resulting in signs of hepatic encephalopathy. The majority of portosystemic shunts are congenital. Multiple shunts outside the liver may be congenital but are more often caused by cirrhosis. Dogs of a variety of breeds have been identified with liver shunts, but Miniature Schnauzers, Maltese, and Yorkshire Terriers appear to be at increased risk for congenital shunts that develop outside the liver. Large-breed dogs, such as Irish Wolfhounds, are at increased risk for shunts inside the liver that occur because a fetal vein that normally closes at birth fails to do so. Most dogs with congenital liver shunts develop symptoms of hepatic encephalopathy by 6 months of age, although some dogs may not develop symptoms until middle age or older. The diagnosis is confirmed by X-ray studies where contrast dyes are injected into the liver circulation, and by bile acid assays. Ultrasound may also be useful. These studies are available at referral centers.

This is not one disease, but a group of poorly understood liver diseases that culminate in cirrhosis. With the exception of copper-associated hepatitis, these diseases appear to have an autoimmune basis: The dog's immune sysem is somehow stimulated to manufacture antibodies against its own liver. This establishes an inflammatory process that progresses to liver failure. The basis for the autoimmune reaction is unknown.

Hepatitis related to high levels of copper occurs in Doberman Pinschers, Bedlington Terriers, West Highland White Terriers and Skye Terriers. In Bedlingtons and Westies there is an inherited defect in copper metabolism that enables toxic concentrations of copper to accumulate in the liver. In Dobermans, copper concentrations are increased in most but not all affected dogs. It is unclear in the Doberman (and Skye Terrier) whether high copper levels are the cause of the hepatitis or the result. Copper can accumulate in the liver as a consequence of hepatitis alone. As a rule, the higher the copper concentration, the more likely it is that copper is the cause. Genetic testing for copper toxicosis in Bedlington Terriers and for Doberman Pinschers is available through VetGen.

The Pancreas

The pancreas has two functions. The first is to provide digestive enzymes; the second is to make insulin for sugar metabolism. Digestive enzymes are manufactured by the acinar cells and insulin by the islet cells.

Pancreatitis is inflammation and swelling of the pancreas. It can occur in a mild or severe form. The cause of spontaneous pancreatitis in dogs is not well understood. Dogs taking corticosteroids are at an increased risk. There is a higher incidence of pancreatitis in dogs with Cushing's syndrome, diabetes millitus, hypothyroidism and idiopathic hyperlipemia (a disease of miniature Schnauzers). These diseases are associated with high serum lipid levels. Pancreatitis is also more prevalent in overweight spayed females and dogs on high-fat diets. An attack may be triggered by eating a fatty meal.

Acute Pancreatitis is characterized by the abrupt onset of vomiting and severe pain in the abdomen. The dog may have a tucked-up belly and assume a prayer position. Abdominal pain is caused by the release of digestive enzymes into the pancreas and surrounding tissue. Diarrhea, dehydration, weakness and shock may ensue. The diagnosis can be suspected based on a physical examination. It is confirmed by blood tests showing elevated amylase and/or lipase levels, along with a new serum test called canine pancreatitis lipase immuninol reactivity and TAP (trypsinogen activation peptide). Abdominal ultrasonography may reveal an enlarged and swollen pancreas.

Mild Pancreatitis produces loss of appetite, depression, intermittent vomiting, diarrhea and weight loss.

Fulminant necrotizing pancreatitis is an acute, extremely severe, usually fatal form of pancreatitis. In hours your dog will go into shock. Dogs may vomit or simply show signs of severe abdominal pain. If you suspect this problem, get your dog to an emergency hospital immediately! Following an attack of pancreatitis, the pancreas may be permanently damaged. When it is, the dog may develop diabetes mellitus if the islet cells have been destroyed or may develop exocrine pancreatic insufficiency if the acinar cells have been destroyed.

The acinar cells in the pancreas manufacture digestive enzymes that empty into the duodenum in response to the stimulation of a meal. Without them, food cannot be adequately digested and nutrients therefore cannot be adequately absorbed. For reasons that are unknown, the acinar cells may atrophy and stop producing enzymes. This condition is called pancreatic acinar cell atrophy (PAA) and is one of the major causes of pancreatic insufficiency. PAA begins in dogs under 2 years of age. All breeds are affected, but there is a predisposition in large breeds, particularly German Shepherd Dogs, in whom the disease may be inherited as an autosomal recessive trait. A less common cause of pancreatic insufficiency is pancreatitis. Following a bout of inflammation, the pancreas may become scarred and contracted. This produces the same affect as acinar cell atrophy. This form of pancreatic insufficiency tends to affect middle-aged and older dogs of the small breeds. Dogs with pancreatic insufficiency lose weight despite a voracious appetite and increased food consumption. The unabsorbed food produces a diarrhea with large, gray, semi-formed cow-pie stools with a rancid odor. The hair around the anus is often oily from undigested fat. Intense hunger may cause the dog to eat his own stool. The diagnosis of pancreatic insufficiency can be suspected from the appearance of the stool and other observations. The best and most accurate test is the serum trypsinlike immunoreative assay (TLI). Folate and vitamin B12 levels may also be used as diagnostic aids.

Diabetes mellitus, sometimes called sugar diabetes, is a common disease in dogs. Golden Retrievers, German Shepherd Dogs, Miniature Schnauzers, Keeshonden and Poodles have the highest incidence, but all breeds can be affected. Females with the disease outnumber males by three to one. The average age of onset is 6 to 9 years. Diabetes is a result of inadequate production of insulin by the islet cells in the pancreas. There may be a genetic predisposition for this in some dogs. Islet cell destruction also occurs in some cases of pancreatitis. Insulin enables glucose to pass into cells, where it is metabolized to produce energy for metaolism. Insulin deficiency results in hyperglycemia (high blood sugar) and glycosuria (high urine sugar). Glucose in the urine causes the diabetic animal to excrete large volumes of urine. In turn, this creates dehydration and the urge to drink large amounts of water. Initially, dogs who do not metabolize enough sugar have an increase in appetite and a desire to consume more food. Later with the affects of malnourishment, the appetite drops. In summary, the signs of early diabetes are frequent urination, drinking lots of water, a large appetite and unexplained loss of weight. The laboratory findings are high glucose levels in the blood and urine. In more advanced stages there is lathargy, loss of appetite, vomiting, dehydration, weakness and coma. Cataracts are common in diabetic dogs. Ultimately, it is a disease that affects all organs. Diabetic dogs will have enlarged livers, be suseptable to infections and often develop neurological problems if not treated.

Diabetic Ketoacidosis is a condition associated with severe hyperglycemia in which ketones (acids) build up in the blood. Ketones are by-products of the metabolism of fat. In diabetic Ketoacidosis, fats are metabolized for energy because sugar is unavailable. Diabetic Ketoacidosis can be recognized by weakness, vomiting, rapid breathing and the odor of acetone on the breath. Diabetic Ketoacidosis is a life-threatening emergency. If you suspect diabetic ketoacidosis take your dog to an emergency animal hospital immediately.