pets disease

Disorders involving the esophagus will manifest themselves as difficulty in swallowing. Effortless regurgitation of solid food, which must be differentiated from vomiting and its associated abdominal spasms, often tips off the pet owner and veterinary practitioner to an existing problem with the esophagus. Because of the inability to properly swallow food, dogs and cats afflicted with esophageal disease are at high risk of accidentally aspirating food into their lungs, causing serious, life-threatening pneumonia.

Supernumerary teeth are extra teeth within the mouth. These can be retained deciduous teeth, or can actually be permanents.
Retained deciduous teeth are commonly seen in small dog breeds, including miniature poodles and Yorkshire terriers. In these dogs, the deciduous canine teeth have the greatest propensity for remaining behind. Such retained teeth can crowd the permanent ones, creating abnormal eruption pathways. In addition, because of their close proximity with their permanent counterparts, these extra teeth can serve as niduses for dental calculus buildup and infection. As long as the eruption pattern for the corresponding permanent tooth is not being interfered with, most veterinarians will postpone removal of the retained tooth (teeth) until another elective procedure, such as neutering or teeth cleaning, is performed. However, if the permanent tooth is being interfered with in any way, immediate removal is recommended.
In rare instances, duplicated permanent teeth, consisting of one or two isolated ones, or an entire arcade, can erupt. Removal of these permanent supernumerary teeth is seldom necessary unless they interfere with the normal biting action of the dog. Because of the genetic predisposition of this condition, affected dogs should not be bred.

Malocclusion occurs when the teeth lining the upper jaw fail to line up and fit properly with the teeth of the lower arcade. In the normal bite, the upper canine teeth should rest just behind the lower canines. Disruption of the normal bite pattern can be caused by trauma, improper tooth eruption, and genetics.
Brachygnathism refers to a condition in dogs in which an overbite, or overshot upper jaw, exists. Conversely, prognathism is the term referring to the undershot jaw (underbite). Both conditions are inheritable traits, passed from one generation to another. In fact, prognathism is considered normal for certain breeds, such as pugs, boxers, and bulldogs. Although not life-threatening, these anatomic maladies can interfere with normal biting action and eating, and can predispose to dental and jaw problems in affected dogs. As a result, dogs suffering from distinct overbites or underbites (unless normal for the breed) should be surgically neutered to prevent the propagation of these undesirable traits.
Malocclusion can also result from improperly positioned deciduous teeth creating abnormal eruption pathways for the permanent ones. Dental examination of the deciduous teeth performed on puppies and kittens as early as 8 weeks of age can help identify potential problems. In many instances, simply removing the offending deciduous tooth clears the path for the proper eruption of its permanent successor.
Surgical repair or reconstruction of the jaw can be used to repair trauma-induced malocclusions, which is the most common type of malocclusion seen in cats. Orthodontic correction of brachygnathism and prognathism has been utilized in select cases, yet for ethical reasons, such procedures should be performed only for medical purposes, not for cosmetic gains.

Diseases and disorders affecting the teeth or oral cavity interfere with a pet’s ability to prehense and process food for digestion. In addition, other general signs associated with conditions involving these areas usually include increased salivation, swallowing difficulties, bad breath, gagging, and decreased appetite.

The second factor to contend with is secondary bacterial invasion. Normally, the intestines are inhabited by billions of bacteria that peacefully reside there without causing any problems whatsoever. In fact, the very presence of these non-disease-causing bacteria actually helps prevent the growth of pathogenic, or disease-causing, bacteria within the intestinal setting. However, if disease strikes the small or large intestine, these “friendly” bacteria can be wiped out, allowing pathogenic ones to proliferate and cause disease themselves. If the inflammation persists, or if an intestinal perforation occurs, these and any other bacteria within the intestines can leak out of the gut and even gain entrance into the bloodstream, causing a life-threatening systemic infection and shock.
For these reasons, it is obvious that antibiotics become very important in the treatment of moderate to severe cases of gastroenteritis, even if the original cause is nonbacterial in origin.
Dehydration
The final threatening factor that arises when acute gastroenteritis strikes a pet is dehydration. Pets suffering from vomiting and/or diarrhea can quickly become dehydrated as a result of water loss through the bowels. Since inflamed bowels cannot regulate water absorption as they do when they are healthy, any fluid intake that indeed occurs will usually pass right out of the body via vomiting and/or diarrhea without being absorbed.
In fact, the disruption of normal motility and distension occurring within the affected bowel can actually attract and draw water right out of the body and into the intestinal lumen. As a result, pets that have become dehydrated or are on the verge of dehydration due to gastroenteritis require intravenous fluids to correct the dehydration occurring within the body’s cells, at least until the gut has healed sufficiently to resume these functions once again.

Considering what they have to go through each day, the stomach and intestines make up a remarkable organ system. In the performance of their daily nutritional functions, they must be on constant guard to protect themselves from auto digestion by digestive acids and enzymes produced and must constantly battle foreign organisms and agents that are inadvertently taken in by mouth.
When the stomach and/or intestines become acutely diseased, three major factors come into play that can quickly turn a sometimes seemingly harmless situation into a life-threatening predicament; these include pain, secondary bacterial invasion, and dehydration.

The digestive system of the dog and cat is made up of a collective network of organs designed to supply the body with the nutrition it needs for growth, maintenance, and repair. It also functions to rid the body of waste. Because of this, diseases involving the digestive system can have a profound effect not only on the region so afflicted but on the entire body as well.

Anatomy and Physiology
Those organs or regions of the body categorized under the digestive system include the oral cavity (teeth, tongue, salivary glands, etc.), esophagus, stomach, small intestine, large intestine, rectum, anus, pancreas, liver, and gallbladder. In order to understand diseases and their adverse effects, a brief overview of the digestive process is warranted. Keep in mind, however, that the following description is an oversimplification; the actual digestive process is so complex and involved that it warrants the devotion of an entire book in itself.
Once food enters the oral cavity, the process of digestion begins. The teeth mechanically rip, crush, and grind down the food, while the saliva secreted by the salivary glands into the mouth moistens and partially digests carbohydrate portions of the food before it is swallowed. In puppies and kittens, the eruption patterns of these teeth do not start until around 2 to 4 weeks of age. By the time the neonate is 7 weeks of age, it should have a full complement of deciduous (baby) teeth. By 7 months of age, all the permanent teeth should have fully erupted and replaced the deciduous ones.
From the oral cavity, food, water, and saliva are passed back into the esophagus with the aid of the tongue and are swallowed. The walls of the esophagus consist of bands of muscle, which contract in a rhythmic fashion, pushing the food down toward the stomach. This unique muscular action is called peristalsis.
From the esophagus, the food passes through a muscular sphincter into the stomach. This sphincter is very important, for it keeps stomach acids and enzymes from entering into and burning the esophageal lining. If it is defective, ulcers and that feeling humans describe as “heartburn” can result.
The stomach is lined with cells that secrete acids and special digestive enzymes, designed to further break down ingested proteins and carbohydrates. The muscular walls of the stomach help gently churn and mix the contents, until such time as they’re ready for passage into the small intestine. Again, the food must pass through another sphincter to reach the small intestine. Once the food passes through the sphincter, the stomach acids mixed in the digesta are neutralized and rendered harmless by secretions in the small intestine.
The small intestine is the site where most digestion occurs, and where the resulting nutritional building blocks are absorbed into the body. Bile produced by the liver and stored in the gallbladder is added to the digesta here to break down fats. Enzymes from the pancreas further digest fats, proteins, and carbohydrates until, finally, the nutrients can be absorbed through the intestinal lining and into the body.
The lining of the small intestine consists of millions of small, fin gerlike projections called villi, designed to increase the absorptive surface area within the intestine. And as if this weren’t enough, each of these tiny villi are lined by even tinier projections, called microvilli again, to further increase the surface area for nutrient absorption. One reason why a parvovirus infection can be so deadly is that the virus can effectively destroy these villi lining the small intestine, blocking absorption of nutrients and “starving” the victim.
As digested nutrients are absorbed, they enter into either the circulatory system or into the lymphatic system. End products of protein and carbohydrate digestion travel by way of the blood to the liver, where any toxic by-products are promptly eliminated. Other functions of the liver include the production of serum proteins, the storage of vitamins and other nutrients, the destruction and removal of old red blood cells from the bloodstream, and the secretion and excretion of bile into the small intestine to aid in the digestive process.
Fatty acids, resulting from fat digestion, travel initially via the lymphatic vessels and later enter into the bloodstream, where they are broken down and absorbed into the body tissues. The lymphatic system also plays an important role in immunity.
Digesta and waste that are not absorbed from within the small intestine then pass into the large intestine, which is responsible for removing water and electrolytes from the material and lubricating it for passage out of the body through the rectum and anus.
One special portion of the large intestine is called the cecum, which corresponds to the human appendix. In dogs, whipworms inhabit this portion of the large intestine and exert their deleterious effects from within.

Any inflammation and/or excessive smooth-muscle contractions occurring within the gastrointestinal system can be quite discomforting and painful. In fact, in severe cases of viral enteritis, intestinal obstructions, and intussusceptions, this pain can be so great that the patient goes into life threatening shock. As a result, the sooner therapeutic measures are undertaken to correct the problem and stifle the pain associated with it, the less chance of complications occurring.

In addition to intussusception, other items can obstruct normal flow through the gut and result in clinical signs, such as lethargy, vomiting, and black, tarry stools, and abnormal posture. Swallowed foreign bodies (such as bones, rubber balls, and stones), tumors, fungal infections, and herniations are all capable of causing either partial or complete obstructions if large or extensive enough. Unless the obstruction is relieved in a timely fashion, usually through surgical means, loss of blood supply to the affected portion can occur, resulting in the death of that portion of bowel, systemic infection, and shock.

Periodontal disease, or tooth and gum disease, is one of the most prevalent health disorders in dogs and cats. Studies have shown that most canines show some signs of this disease by 3 years of age. Early signs can include tender, swollen gums, and, most commonly, bad breath. More importantly, though, if left untreated, periodontal disease can lead to secondary disease conditions that can seriously threaten the health of affected pets.
It all begins with the formation of plaque on tooth surfaces. This plaque is merely a thin film of food particles and bacteria. Over time, however, plaque mineralizes and hardens to form calculus. Owners who lift up their pet’s lip and glance at its teeth, especially near the gumline, might notice brownish to yellowish buildup of calculus on the outer surface of the teeth.
Calculus tends to accumulate worse on the outer surface of the large fourth upper premolars and on the inner surfaces of the lower incisors and premolars. This is because canine saliva is conducive to calculus formation, and the ducts from the salivary glands empty into the mouth at these particular sites. Buildup of this substance tends to be worse in smaller breeds of dogs, such as miniature poodles, Yorkshire terriers, Maltese, and schnauzers. In fact, it is not at all unusual for some of these dogs to start losing teeth by 4 to 5 years of age without at-home preventive dental care.
Along with these breed predispositions, diet can play an important role in the development of periodontal disease. For instance, moist foods high in sugar content promote plaque formation much more readily than do the dry varieties. In addition, diets containing too much phosphorus (such as all-meat rations) have been linked to periodontal disease.
Certain underlying disease conditions might also promote periodontal disease as a side effect. For example, hypothyroidism can lead to gingivitis and dental complications associated with it. Periodontal disease can also occur incidentally with tumors involving the gum tissue and/or teeth.
Pets suffering from periodontal disease can exhibit a diverse selection of clinical signs. Early periodontal disease might be marked only by a decreased appetite due to swollen, painful gums. Pet owners often complain of bad breath in their pets, and might notice signs of gagging or retching as secondary tonsillitis sets in.
As the disease progresses, these signs might worsen, and other symptoms, such as gum recession, gum bleeding, and tooth loss, might arise. Infected teeth that do not fall out can form abscesses, marked by sinus infections, nasal discharges, and/or draining tracts appearing on the face.
But the damage caused by periodontal disease doesn’t stop there. Bacteria can gain entrance into the bloodstream by way of the teeth and gums, seeding the body with infectious organisms. In advanced cases, these bacteria can overwhelm the host’s immune system and set up housekeeping on the valves of the heart. The resulting valvular endocarditis in turn can lead to heart murmurs and eventual heart failure. Besides the heart, the bacteria that gain access to the body because of periodontal disease can lodge in the kidney, causing infection, inflammation, and acute damage. Over time, signs related to kidney failure might develop in affected pets.
Early cases of periodontal disease can be treated by a thorough scaling and polishing of the teeth to remove the offending calculus. This scaling needs to be professionally performed under sedation or anesthesia to ensure complete removal of the calculus under the gumline.
Using special instruments to hand-scale a pet’s teeth at home without anesthesia is not only dangerous but also highly ineffective at cleaning the teeth where it counts the most, up under the gumline. Furthermore, such scaling, if not followed by polishing, will leave etches in the enamel covering of the teeth that can serve as foci for future plaque and calculus buildup.
Antibiotics will also be prescribed for dogs and cats suffering from moderate to advanced periodontal disease to combat the associated bacterial infection. Teeth that are excessively loose within their sockets serve only to propagate infection, and should be extracted. For infected teeth that are still deemed viable, a root canal can be performed as a salvage procedure. See Chapter 4 for prevention tips to help protect pets against the adverse effects of periodontal disease.

The administration of certain antibiotics to a pregnant dog or cat can result in yellow-stained dentin within the teeth of her offspring. The same holds true for adolescents administered these drugs prior to eruption of their permanent teeth. Although this staining has no effect on the health of the teeth, it can be unsightly and detrimental in the show ring.
Calculus buildup can certainly discolor teeth so affected. If allowed to persist on a long-term basis, the tooth surface can often take on a yellow hue, even after the calculus has been removed. In these instances, the complete removal of the calculus is far more important than any discoloration left behind.
As mentioned previously, a brownish discoloration to the teeth could be the result of enamel hypoplasia. Enamel restoration procedures can be employed to deal with this problem.
Finally, a bluish-gray discoloration to a tooth is indicative of inflammation within the pulp cavity, warranting endodontic management if the tooth is to be saved.

This unfortunate condition involves the incomplete development of the hard, protective layer of enamel that normally surrounds the crown of the tooth. Enamel hypoplasia results when the enamel-producing cells within the dental arcade, called ameloblasts, are injured or destroyed prior to eruption of either the deciduous or permanent teeth. The canine distemper virus is the most notable culprit causing enamel hypoplasia to occur; other causes can include severe malnutrition and fluorine toxicity.
Teeth that lack enamel have coarse textures (due to exposed dentin) and tend to stain brown. The absence of the protective enamel coating makes these teeth especially susceptible to decay and to traumatic fractures.
For puppies and kittens suffering from enamel hypoplasia on their permanent teeth, enamel restoration procedures (such as crowning) performed by a veterinary dental specialist can add a protective layer to exposed surfaces. Ask a veterinarian for more details regarding these dentistry procedures now available for pets.

While pancreatitis means inflammation involving the pancreas, hepatitis involves inflammation of the liver. Contrary to popular belief, not all cases of hepatitis are infectious and contagious in nature. There can be numerous noninfectious causes of liver inflammation as well. Some of these include diabetes mellitus, heart disease, accidental poisonings, starvation, and cancer.
Hepatic lipidosis is a common type of liver dysfunction in cats that has baffled researchers for years. It is characterized by an extensive infiltration of the liver by fatty tissue that, in essence, crowds out the normal liver cells and interferes with normal liver function. It is seen in all ages of cats, and the exact cause of this condition is unknown, yet obesity and/or prolonged periods of food deprivation due to loss of appetite are thought to increase the body’s utilization of fats for energy, the metabolism of which is carried out in the liver.
As an organ responsible for metabolism of the multitude of nutrients absorbed from the intestines, and detoxification of poisons and drugs circulating in the blood, it is remarkable that the liver is normally very resistant to injury or breakdown resulting from its normal day-to-day functions. Unfortunately, because of this heartiness, clinical signs of liver inflammation seldom appear until serious damage to liver function has already taken place.
Like so many other diseases affecting the gastrointestinal tract, acute flare ups of hepatitis can cause loss of appetite, vomiting, diarrhea, and fever in affected dogs and cats. One unique sign often seen with hepatitis, both acute and chronic, is jaundice, or icterus. Jaundice, caused by elevated levels of bile pigments in the bloodstream, is characterized by a yellow discoloration of the skin, mucous membranes, and the liquid portion of the blood.
Other clinical signs that can result from chronic, long-term hepatitis and liver disease include a fluid buildup within the abdominal cavity (ascites) due to increased resistance to blood flow through the liver, bleeding tendencies, and anemia. Seizures and other neurologic disorders can also appear with advanced cases as blood levels of ammonia are allowed to build up.
Diagnosis of hepatitis is based on clinical signs, elevated serum levels of liver enzymes, and/or the demonstration of an enlarged liver on radiographs or ultrasonography. For those more subtle cases, special liver function tests and even biopsies might be required to confirm a diagnosis of hepatitis or discover its cause.
Treatment objectives for hepatitis and liver disease are aimed a teliminating the injurious agent and its harmful effect on the liver tissue and at promoting healing of the affected tissue. In cats with hepatic lipidosis, this means force-feeding them if necessary. The liver is one of the few organs within the body that can actually regenerate itself after injury, provided, of course, that the source of the injury is dealt with properly.
If vomiting is a problem, intravenous fluids might be needed until the stomach settles down enough for oral ingestion of food and water. An easily digestible diet with high biological value (available through veterinarians) is ideal for dogs and cats suffering from a liver disorder. Oral antibiotics designed to eliminate ammonia-forming organisms are useful for those cases exhibiting neurological signs. Ascites can be treated with diuretic drugs and by reducing the amount of sodium in the pet’s diet.
Finally, in chronic cases of hepatitis, steroids might be warranted to increase appetite and to counteract the loss of protein that can occur with liver disease. In addition, certain drugs for liver disease designed for use in humans are being used in animals with variable success.

Inflammatory bowel disease (IBD) is actually a group of chronic digestive disorders characterized by the infiltration of the walls of the bowels with inflammatory cells, leading to abnormal wall thickening and irregularities. IBD has been recognized as a significant cause of chronic vomiting and/or diarrhea in both dogs and cats. As far as the etiology of IBD, research to date has failed to uncover an exact cause. Many veterinarians believe that bacterial and/or dietary proteins may stimulate an autoimmune type of reaction in these pets. This reaction, in turn, manifests as a buildup of immune cells on and within the surfaces coming in contact with these proteins.
The classic clinical sign associated with IBD in cats is chronic vomiting. Often misdiagnosed as hairballs, vomiting induced by IBD usually occurs intermittently over months to years, gradually worsening and increasing in frequency with time. In addition to vomiting, bloody diarrhea and abdominal pain are also clinical signs seen in both dogs and cats suffering from IBD. In cats, lymphosarcoma is not an uncommon sequela to severe cases of IBD that cannot be controlled through medical means.
Diagnosis of IBD is made through the use of a thorough history, physical exam findings, radiographs of the abdomen, and more specifically, biopsy samples from affected portions of bowel. Diagnostic techniques such as these will help differentiate this condition from other disorders that may cause similar clinical signs, including foreign bodies, pancreatitis, tumors, and bowel obstruction.
Treatment for inflammatory bowel disease employs the use of drugs designed to reduce the inflammatory response, as well as medications designed to locally suppress the immune system response within the gut. Administration of these medications may be required on a longterm basis to control this disorder. Since food allergies are thought to be an underlying cause in some instances, most treatment regimens for IBD also employ rations that are hypoallergenic in nature.
Unfortunately, a complete cure for IBD is rarely possible. However, with appropriate treatment, most cases can be managed enough to allow the affected pet to live a relatively normal life otherwise.

Supernumerary teeth are extra teeth within the mouth. These can be retained deciduous teeth, or can actually be permanents.
Retained deciduous teeth are commonly seen in small dog breeds, including miniature poodles and Yorkshire terriers. In these dogs, the deciduous canine teeth have the greatest propensity for remaining behind. Such retained teeth can crowd the permanent ones, creating abnormal eruption pathways. In addition, because of their close proximity with their permanent counterparts, these extra teeth can serve as niduses for dental calculus buildup and infection. As long as the eruption pattern for the corresponding permanent tooth is not being interfered with, most veterinarians will postpone removal of the retained tooth (teeth) until another elective procedure, such as neutering or teeth cleaning, is performed. However, if the permanent tooth is being interfered with in any way, immediate removal is recommended.
In rare instances, duplicated permanent teeth, consisting of one or two isolated ones, or an entire arcade, can erupt. Removal of these permanent supernumerary teeth is seldom necessary unless they interfere with the normal biting action of the dog. Because of the genetic predisposition of this condition, affected dogs should not be bred.

Occasionally, teeth will break or fracture as a result of trauma or disease (such as in enamel hypoplasia). If the pulp cavity of the tooth is not exposed by the break, treatment measures, aside from filing down any sharp edges, are rarely required. However, if the damage does extend down into the pulp cavity, inflammation, infection, and pain could result.
Endodontic therapy, or root canals, can be performed to salvage teeth with exposed or infected pulp cavities and dentin. The procedure involves the removal of the pulp tissue and infected dentin, thereby alleviating pain and the further progression of disease within the tooth. Cracks and fractures in the tooth can then be filled, completing the restoration procedure.

Hemorrhagic gastroenteritis is a life-threatening condition that can be rapidly fatal if not treated promptly. Characterized by an explo sive onset of bloody diarrhea, hemorrhagic gastroenteritis can quickly cause dehydration, depression, shock, and toxemia in affected dogs. It is most often seen with dietary indiscretions and/or bouts of pancreatitis. Toxins produced by bacteria within an irritated gut cause such extensive inflammation that overt bleeding within the digestive system results. Toxins and bacteria may then permeate these blood vessels and gain entrance into the body, with serious consequences.
Diagnosis of hemorrhagic gastroenteritis is based on history and clinical signs seen, as well as ruling out other causes of digestive system disturbances. Treatment consists of intravenous fluids to control dehydration, high levels of antibiotics to combat infection, and high dosages of steroid anti-inflammatories and other medications to control shock and to counteract the effects of toxemia.