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Diseases of the Digestive System

Diseases of the:

Oral Cavity
Esophagus
Stomach
Intestines
Pancreas
Liver
Hernias
Vomiting
Diarrhea

Diseases of the Oral Cavity

A puppy has thirty-two teeth at birth and by the age of about four months, has a full complement of forty-two adult teeth. The adult teeth wear down rather quickly depending on the dog's eating and play habits. This is why dogs should not be given stones or hard toys. During growth spurts, a dog's teeth can be affected by various defects. First, baby teeth frequently do not fall out, especially in small breeds. These supernumerary teeth should be extracted if the dog shows signs of pain when eating. Conversely, several teeth may be missing but this will not cause problems in eating. Abnormal teeth position can also be observed, which among other things, prevent the mouth from closing properly. Some teeth may appear to be abnormally formed, with for example, poor quality enamel.

Dogs also suffer frequently from abscesses or fistula. Although rare, they may also develop tooth decay just like humans. In either case, only a veterinarian can determine whether the tooth needs to be extracted or whether dental treatment is required. However, the most frequently-encountered problem in dogs is and remains, tartar buildup. Tartar buildup causes the animal's mouth to emit a characteristic putrid odor known as halitosis. Moreover, the tartar causes severe lesions on the teeth and gums, which may result in loss of the teeth. This problem can evolve into gingival pyorrhea or parondotosis. The animal suffers immensely and can no longer feed itself. At this stage, the only relief for the dog is extraction of some, if not all of the teeth. This is why it is necessary to check the dog's teeth and if necessary, have them descaled regularly.

An examination of the oral cavity may also reveal the presence of stomatitis and small ulcers. These inflammations are either caused solely by a localized disease or they are the result of a generalized disease. They are generally benign, causing only increased salivation and irritation when food is grasped.

Among the more common lesions is ranula. This strange term, in fact, refers to the formation of a saliva pocket between the jawbone and the flews. It forms in response to an obstruction of the salivary gland ducts. Depending on the nature of the obstruction and the amount of liquid collected, the veterinarian may decide to remove the salivary glands. These lesions are sometimes observed on the neck, which indicates an obstruction high up in the salivary glands.

Dogs are often in the habit of playing with anything. Careful attention must be paid in particular to pieces of wood that can tear the palate. These tears are known as traumatic palatine fissures. Sometimes congenital palatine fissures can be observed. They bring the nasal and oral cavities into contact, causing vomiting and respiratory difficulty. Finally, some dog breeds with short noses, such as boxers and Pekinese, may suffer from a defect of the soft palate. In addition to the snoring that this defect may cause, it also gives rise to difficulty breathing, especially with effort.

Finally, the oral cavity is often injured as a result of traffic accidents or falls. The lower jaw may sustain fractures from the impact, which causes insufferable pain. Generally, these fractures can be repaired in a satisfactory manner.

Diseases of the Esophagus

Three types of disorders can affect this soft tissue. The first category is dilated esophagus, which is either generalized and corresponds to a megaesophagus, or localized in diverticulum and corresponds to an esophageal crop. A megaesophagus can be congenital or acquired. The precise origin is not yet known. The esophageal crop indicates that the esophagus passage is blocked. Depending on the age of the animal, this is thought to be due either to a congenital defect, a foreign object or a tumor. The symptoms include difficulty swallowing and regurgitating food. Progressively, the dog loses weight and grows weaker. Radiography is used to diagnose this disorder and among other things, to give a prognosis.

The second type of esophagus disorder is inflammation. The origins of esophagitises are twofold: ingestion of caustic products and reflux of gastric juices. Certain harmful foreign objects may also be responsible. The dog shows signs of hypersalivation and difficulty swallowing and refuses to eat. Esophagitis is a secondary disorder. It is important to determine the cause through adequate testing.

Finally, the esophagus may be perforated by foreign objects, in particular chicken or rabbit bones. Depending on where the perforation is located, the consequences may vary from a simple wound to a lung puncture. In general, the dog shows signs of irritation and pain. He constantly tries to vomit or cough.

Diseases of the Stomach

The characteristic symptom of gastric disorder is vomiting within a few minutes, even up to one hour, after a meal. Among the most classic disorders are lesions of the gastric lining, gastric dysfunction and stomach tumors. The first category includes acute or chronic gastritis and ulcers. The origins of acute gastritis are varied. Unsuitable food, toxic substances, foreign bodies, parasitic or infectious diseases, or even hormone imbalances are all possible causes. Chronic gastritis, which is characterized by vomiting that is often resistant to classic treatments, is part of a complex syndrome. Inflammatory, allergic or even metabolic phenomena are often causes. The general health of the dog is affected fairly quickly. Gastric ulcers are characterized by vomiting blood, poor overall health and abdominal pain. They are sometimes the result of acute gastritis. Most often, however, they are caused by medicines such as aspirin or toxic products and more rarely, infectious or parasitic agents. The occurrence of psychosomatic ulcers has not been observed in dogs.

Problems with gastric functions result in either gastroesophageal reflux or food retention that leads to vomiting undigested food several hours after the meal. The dog therefore loses weight very quickly. The cause is linked to a stenosis of the pylorus or a nerve anomaly in gastric motivity. Surgical treatment is sometimes necessary.

Finally, it is not possible to talk about gastric disorders without mentioning the gastric dilation-torsion complex. This particular disorder affects large dogs. It is characterized by abdominal bloating, episodes of vomiting that is rather violent but produces very little and rapid decline of the dog's general health. The dog goes into shock and will die if surgery is not performed as quickly as possible. To prevent the onset of this lethal disease, a few basic rules should be followed. Do not engage the dog in play after a meal and feed the dog digestible food, preferably in two meals per day.

Practical Measures to Avoid Gastric Dilation-Torsion Complex:
- Feed the dog in an isolated and calm place
- Divide the daily food ration into two meals per day
- Choose easily digested food
- Wet the food slightly before feeding it to the dog
- Observe a rest period after the meal

Diseases of the Intestines

Intestinal disorders are dominated by enteritis. Enteritis is a rather severe inflammation of the intestinal lining that has various origins: infectious agents, unsuitable food, parasites, foreign objects, etc. Depending on the length of evolution, it can either be chronic or acute. The symptoms are extremely variable, ranging from constipation to diarrhea, hyperthermia and exhaustion. Sometimes it is associated with a gastric disorder and is then referred to as gastroenteritis. Because of the metabolic disorder it entails, it can lead to severe dehydration, which is sometimes lethal for weaker animals.

Intestinal occlusions or obstructions are among the cases that require surgery the most. They are generally caused by ingesting foreign objects such as pieces of string or plastic toys.

Special attention must be paid to intestinal parasites. Dogs may be infested by round worms (Ascaris, Trichuris, Ankylostoma) and/or flat worms (Taenia, Dipylidium, Echinococcus). They ingest worms either as they are digging up ground or through the intermediary of carrier insects such as fleas. These parasites cause weight loss, vomiting and diarrhea. The dog shows his pain by dragging his hindquarters on the ground in what is called "the dragnet sign". Animals of all ages can be infected but puppies seem to have the highest risk. The infection can also be transmitted from dogs to humans. A de-worming regime needs to be established each year with the veterinarian.

Chronic colonitis is a chronic inflammation that occurs in the large intestine or the colon. Again, the origins are diverse: food or allergy-related, parasitic or metabolic, inflammatory or simply unknown. It is characterized by mucous-like feces, pain during defecation and rather severe episodes of diarrhea.

Diseases of the Pancreas

In addition to being affected by inflammation and tumors, the pancreas can also malfunction, resulting in a pancreatic insufficiency. This is observed in young animals in the form of excessive weight loss accompanied by polyphagia. Periods of diarrhea alternate with periods of constipation. In fact, the pancreas is incapable of secreting the enzymes needed for digestion. Therefore, the dog does not properly digest the food he ingests. Enzyme supplements and an adapted diet of highly digestible food help treat this disorder.

The pancreas is also where insulin is produced and just as in humans, inadequate production can lead to diabetes. Diabetes is treated with daily insulin shots at fixed times.

Diseases of the Liver

In puppies, hepatitis is brought on by poisoning or infectious diseases such as infectious canine hepatitis. The liver becomes congested and it increases in size. Hepatitis can induce irreversible and lethal cirrhotic states. Symptoms include episodes of diarrhea with loose stools, followed by constipation. The abdomen is painful and the dog is exhausted.

Acute hepatic insufficiency is characterized by disorders of the digestive and nervous systems. Its etiology is varied: infections, toxins, medicines, metabolism and trauma. Urgent treatment is required given the sometimes lethal repercussions on the body.

Chronic hepatic insufficiency evolves more slowly, but in a manner that is just as dangerous. It causes weight loss, decline in overall health and digestive disorders. A veterinarian must run complementary tests in order to determine the cause.

Hernias

Congenital umbilical hernias occur frequently in puppies and are caused when the small opening of the umbilicus does not close at birth. A small protrusion is observed, which is resorbed when pressure is placed on it. Although they pose no real danger to the animal, they can generally be corrected by surgery. Diaphragmatic hernias occur as a result of a diaphragmatic trauma that allows part of the abdominal viscera to pass into the thoracic cavity. These hernias cause respiratory and digestive problems that require surgery.

Perineal hernias

Perineal hernias are found in certain breeds such as the German Shepherd. They are characterized by the formation of multiple fistulas around the anus, which converge into a circular mass that may or may not be ulcerated. A malodorous pus oozes from this mass, which leads to constant licking and difficulty defecating. These lesions are never resorbed and require surgical treatment.

In addition to all these disorders, benign or malignant tumors can develop in the digestive tract. As the dog ages, close attention must be paid to the slightest sign of a digestive disorder.

Vomiting

Carnivores in the wild are formidable predators who are perfectly adapted to the hunt. They are capable of eating phenomenal quantities of meat in a single meal. Upon their return, they can regurgitate this food without the slightest effort in order to feed their young. This ability requires not only a stomach that is capable of holding large quantities, but also a reflex mechanism that facilitates regurgitation of food and therefore vomit.

Dogs, who are domestic carnivores par excellence, have not lost any of this ability. How many dog owners in fact have witnessed their favorite animal regurgitate a meal that was a little too copious? Most of the time, there is nothing alarming in this behavior. Sometimes, however, vomiting is the first sign of an underlying disease.

Stages of vomiting

In general, a vomiting episode is preceded by a state of nausea in which the dog appears uncomfortable, turns in circles and sometimes tries to eat grass. It is almost as if the dog is trying to "purge" himself, though this term does not accurately reflect reality. The dog then vomits. Violent heaving of the flank and thorax is observed. The dog lowers his head and appears to be smiling. Then after a final effort, the contents of the stomach are ejected. Given the violence of the phenomenon and the muscle fatigue that ensues, it may take the dog a few minutes to recuperate. In cases where only the contents of the esophagus are regurgitated, there is no noticeable effort. The food easily ejected by means of a simple reflex.

Physiological mechanisms in vomiting

Like any reflex, vomiting involves nerve mechanisms. They may originate in the central nervous system, in other words, directly from the brain (disruption of normal central nervous system functions, inflow of particle substances into the blood, even olfactory stimulus, cause the vomit center to react). The origin may also be peripheral, which involves receptors located in abdominal or thoracic organs. Information received is transmitted through a system of neurotransmitters to the vomit center in the brain. In both cases, this center responds by triggering the muscular action that causes vomiting.

Causes of vomiting

Vomiting is usually an indication of inflammation or excessive distension of organs, namely those of the digestive tract: esophagus, stomach, intestines and liver. The causes are numerous. Classic causes include poisoning, gastritis, ulcers, gastroenteritis, foreign objects, intestinal obstructions, gastric dilation-torsion or spoiled food. Vomiting may also be a symptom of an infectious or viral disease (canine distemper, canine parvovirus and leptospirosis are among the most notable, in addition to uterine infections, peritonitis, etc.). Absorbing excessive quantities of food, foreign objects or substances that prevent the stomach from emptying its contents into the small intestine also causes gastric distension and consequently, vomiting. Finally, vomiting can also be an indication of diseases that affect other organs, especially renal or hepatic insufficiencies or even nervous system disorders, such as motion sickness.

Evolution

Two types of evolution are observed with vomiting. It can either be acute or chronic. In the first case, the vomiting occurs suddenly and is temporary in nature. In the second instance, it builds progressively and is recurrent for over a month. Vomiting occurs more or less frequently during the day and may or may not be related to eating.

Consequences

Vomiting causes dehydration and rather severe malnutrition, as well as blood imbalances. Sooner or later, it will have repercussions on the general health of the dog. This is why vomiting must be treated quickly, especially in young animals.

In order to help the veterinarian establish a diagnosis, it is important to note the frequency of vomiting, the time when it occurs (after a meal? after drinking?) and its appearance. All this information will give the veterinarian indications about its origin and help him prescribe a treatment.

Diarrhea

The term diarrhea refers to an increase in the frequency of bowel movements, with rather loose, abundant stools. Diarrhea is one of the most common problems in dogs. It is important to note that stools vary greatly depending on the quality and quantity of the food given to the dog. Consequently, feeding the dog the wrong food is a major cause of diarrhea. As with vomiting, diarrhea can be either acute or chronic. The origins and symptoms of diarrhea are different. It can affect the small intestine or the colon.

Acute diarrhea

Acute diarrhea appears suddenly and is short in duration. In general, it has noticeable repercussions on the general health of the dog. There are multiple origins of this type of diarrhea.

Of course, improper food is the most frequent cause (changes in diet without a transition period destroys intestinal microflora, which is very fragile in dogs). Diarrhea can also be an indication of a viral infection such as canine distemper or parvovirus, or a bacterial infection where germs multiply on and in the intestinal lining. Intestinal parasites including worms and fungi often cause diarrhea symptoms as well, as do toxic substances or allergens. Finally, the list is completed by a certain number of metabolic disorders.

The mechanism that triggers acute diarrhea involves a disruption in the water exchange that occurs in the small intestine. Therefore, unsuitable foods require more water for digestion, which of course causes the stool to be more liquid. But water loss can also be attributed to the more or less consistent destruction of the cells in the intestinal lining that are responsible for the absorption of nutrients into the blood. The aforementioned agents are what cause these types of lesions. Finally and more rarely, diarrhea may be the result of changes in the digestive path, as is the case with stress-induced diarrhea.

Acute diarrhea is accompanied by various signs that are visible to the owner. First of all, the animal is run down, sometimes has a fever, refuses to eat and loses weight. There is often pain in the abdomen. Sometimes, diarrhea is accompanied by vomiting. In this case, the animal will quickly become dehydrated given the water loss with the bowel movement. In fact, quick action is required in order to prevent the dog from going into shock, especially with young and older animals.

Chronic Diarrhea

Chronic diarrhea is diarrhea that lasts for over a month and tends to be recurrent. The causes are somewhat different from acute diarrhea. They include inflammations of the intestinal lining that are parasitic, allergic or autoimmune in origin, as well as malfunctions in the secretion of digestive enzymes or in the mechanisms involved in the absorption of nutrients by intestinal cells. Consequently, acute diarrhea that has caused severe destruction of the digestive tract lining may evolve into chronic diarrhea. Sometimes, chronic diarrhea indicates the presence of tumors in the body. Finally, as with the previous case, diarrhea may occur intermittently as a result of a particular, repeated stress.

With chronic diarrhea, the general health of the dog deteriorates slowly. The dog progressively loses weight in greater quantities than with acute diarrhea. However, the onset of dehydration is slower and often, abdominal pain is less severe.

As with vomiting, it is important to take the dog to the veterinarian as soon as possible. In fact, the health of the dog may deteriorate rapidly, especially with younger and older dogs. In order to help the veterinarian determine the diagnosis, the owner should note the date when the symptoms first appeared and the frequency, consistency and color of the bowel movements (for example, there may be blood in the stool). Does the stool contain parasites or undigested food? Does the dog show signs of pain? etc.

All of this information will enable the veterinarian to determine the exact cause of the problem, decide which tests to run and prescribe a treatment.

As soon as diarrhea sets in, it is recommended that the dog be placed on a restricted diet and be taken to the veterinarian as quickly as possible.