Diseases of the Liver
The liver filters many of the body's waste products and toxins from the bloodstream, so that accumulation of these substances as a result of inadequate liver function affects the brain, and blunts the sense of hunger. Common diseases of the liver in cats include chronic hepatitis (not the same as human hepatitis A, B, or C, and NOT contagious), hepatic lipidosis (fatty deposits in the liver), cirrhosis (severe scarring of the liver), liver cancer, and adverse reaction to certain drugs (e.g. carprofen, trimethoprim-sulfa, others).
Liver diseases in general often will also cause increased salivation, vomiting, and lethargy and sluggishness.
Diseases of the Pancreas
The pancreas secretes many of the digestive juices that dissolve food into tiny particles the intestine can absorb. If inflamed ("pancreatitis"), the pancreas releases some of those powerful dissolving substances into the internal organs rather than on food in the intestine. These corrosive juices may severely inflame and erode the pancreas itself and other surrounding tissues, a painful process that often makes an animal completely unwilling to eat and frequently also causes vomiting and lethargy. Another disease of the pancreas that can cause loss of appetite is pancreatic cancer.
Diseases of the Urinary Tract
Anorexia is a hallmark of kidney disease. There may be both a loss of appetite and discomfort caused by ulcers in the mouth and stomach associated with uremia (accumulation of waste products in the blood stream). Your pet's consumption of water may be the same or even greater than usual. This is an effort to make up for the tremendous amount of fluid lost by the sick kidneys through the urine. Also, vomiting and listlessness are common symptoms that occur along with loss of appetite in kidney disease. Not all types of urinary disease affect the appetite, however. For instance, most cases of bacterial cystitis (bladder infection) do not affect the appetite.
Diseases of the Blood
Generally, diseases of the blood that lead to loss of appetite also cause lethargy and sluggishness, and possibly signs of weakness such as intermittent collapse. Blood disorders causing loss of appetite include severe anemia of different causes (immune-mediated hemolytic anemia, leukemia-related anemia, blood loss due to ulcers of the stomach or rat bait poisoning), cancer of the blood (leukemia), and polycythemia (excessive red blood cells – the opposite of anemia).
Diseases of the Eyes, Mouth, Nose and Throat
These can cause unwillingness to eat as a result of pain in the mouth during chewing (dental disease, foreign object caught in the mouth or throat), inability to smell the food, which is essential in animals for recognition and acceptance of food (nasal infections or tumors), or pain or discomfort of the eyes (conjunctivitis, uveitis, glaucoma).
Essentially any disease process, when severe enough, can cause an animal to stop eating. Loss of appetite is one of the first and most common symptoms of "not feeling well" in animals. Don't hesitate to take your pet to the veterinarian when he is anorexic.
A prolonged inability or unwillingness to eat may be sign of serious illness in your pet. Development of excessive salivation (drooling) Vomiting Diarrhea Lethargy (lack of desire to exercise or be active) or sluggishness Weight loss Breathing difficulties or labored breathing Signs of infection such as discharge of pus or blood Sudden changes in behavior
If your pet refuses to eat, watch for any of the following: NOTE The presence of these in conjunction with anorexia, warrants an immediate consultation with your veterinarian, regardless of how long the loss of appetite has been present.
Medical causes of appetite loss usually are more serious than psychological causes because they mean that a disease has progressed to the point that the animal is either unwilling or unable to eat. Therefore, the animal's challenges are twofold: first, to fight the disease itself, and second, to do so without the benefit of nutrients that eating provides.
Diagnosis In-depth for Anorexia in Cats
Physical examination including buccal exam (evaluating the gums), auscultation (listening with a stethoscope), palpation of the abdomen (feeling the size and shape of organs in the belly), and taking the temperature and weight.
Complete blood panel and urinalysis (urine test) to screen for certain diseases of the internal organs. Many internal disorders are first identified with these tests. In particular, diseases of the liver, pancreas, urinary system, and blood are often first detected with these tests. Further and more specific tests may then be appropriate. For example, signs of liver disease may be seen on the blood test; then, an additional blood test ("bile acids"), and/or abdominal ultrasound may be recommended in order to better define the type of liver disease present. Ultimately with liver disease, a liver biopsy (tissue sample of the liver, usually obtained when the animal is sedated or under anesthesia) is often necessary to determine the exact type of problem present.
X-rays of the chest and the abdomen. X-rays provide an image of the bones, of course, but also of the outlines of the internal organs, and can be extremely useful for detecting changes in the shape, size, or position of the organs, which helps to pinpoint the source of the disease. Unfortunately, important structures can sometimes blend together on X-rays (e.g. tumors blending into the background of normal organs, or foreign objects having the same "opacity," or shade of grey, as the normal tissues) and therefore can be invisible on the X-ray. In general, X-rays are an excellent "screening test," but they do not detect all internal problems, and additional procedures such as ultrasound, barium (dye) swallowing for specialized X-rays, or even exploratory surgery are sometimes necessary to diagnose the problem.
Fecal examination (microscopic evaluation of the stool, looking for parasites). Your veterinarian may want a stool specimen from your pet for such tests. If your pet has defecated in the past 12 hours, you should bring a sample of the stool with you in a sealed container (e.g. Ziplock® bag) when you go to your veterinarian's office, in case it is needed for laboratory analysis.
Ultrasound. As mentioned above, ultrasound and X-rays often go hand-in-hand because ultrasound shows a motion picture of the organs while they are functioning (while X-rays are a static image) and ultrasound allows you to see inside certain organs where X-rays only show their outline. Since performing the ultrasound and interpreting its results require specialized skills and equipment, many veterinarians refer animals needing an ultrasound exam to a specialty veterinary hospital. However, some clinics have ultrasound facilities on-site, and others use the services of traveling specialists who come to the clinic and perform the ultrasound there.
Endoscopy. An endoscope is a long, flexible tube with a tiny (pinhead-size) camera and a pinch-biopsy instrument at its tip. Depending on symptoms, an endoscope is used for looking either at the inner lining of the throat, stomach, and intestine; or at the respiratory passages (nose, throat, and lungs) while an animal is under anesthesia. Small samples of these areas can be taken and then analyzed in the laboratory to try to determine the nature of the respiratory or intestinal disease. Many diseases of the digestive system and of the respiratory system are difficult to detect simply with blood and urine tests, X-rays, and ultrasound. That is, the diseases tend to be present and may be causing severe symptoms, and yet the blood and urine tests, X-rays, and ultrasound exam are "suggestive" of digestive or respiratory disease without specifically pinpointing exactly which disease is present. It is under these circumstances that anesthesia and endoscopy may be considered, and often a specialist performs it.
Treatment In-depth for Anorexia in Cats
Treatment of anorexia can be specific or supportive. Specific treatments. Specific treatments are those that deal with the underlying cause. That is, they either slow down or eliminate the problem that caused the anorexia in the first place.
Of course, specific treatment is ideal because it deals with the loss of appetite at its source by treating the underlying disease. However, specific treatment requires an exact diagnosis, meaning that in some cases many tests may need to be performed in order to precisely identify the underlying disease.
Supportive treatments. Supportive treatments are those that help sustain an animal that is debilitated as a result of not eating. Supportive treatments do not reverse the problem that led to the loss of appetite. They simply help "carry" the animal through the most difficult part of the illness.
On the other hand, supportive treatments can be given in almost all cases and are most useful in the four following situations:
To support the animal while an exact cause of the problem is being sought (e.g. tests being run)
In conjunction with specific treatments, to sustain the animal until the specific treatment takes effect
When the illness is not so severe as to warrant further tests or specific treatment, and the supportive care simply helps the animal's natural recovery
When humane or financial considerations make testing or specific treatment impossible
Supportive treatment is often simpler than specific treatment, but it also carries the risk of not addressing the underlying problem. Commonly used supportive treatments include:
Injectable fluids. These can be given intravenously ("IV") or subcutaneously (under the skin). Often, the loss of appetite produces serious dehydration, which can become life threatening long before the risk of starvation. Therefore, injectable fluids are given in an attempt to rehydrate the animal and provide some electrolytes as nutrients. They are not equivalent to a balanced meal, but can be indispensable for preventing dehydration.
Parenteral nutrition. Special solutions containing multiple nutrients (usually electrolytes, amino acids, sugars, and lipids) can be given intravenously ("IV") and are much more balanced than the simple fluid solutions described above. Major drawbacks to using parenteral nutrition include a substantial risk of infection, lesser availability compared to regular injectable fluids, cost, and the fact that most animals requiring fluids do not need more than the regular fluids described above.
Feeding tubes. These may pass through the nose (nasogastric tubes), throat (esophagostomy tubes) or stomach wall (gastrostomy tubes). In animals where lack of eating will itself produce serious consequences, these tubes may be extremely useful.
Appetite-stimulating drugs. These do not always work and they may cause grogginess. Therefore, they should be used with caution. Common drugs used include Cyproheptadine (Periactin®), Diazepam (Valium), and Mirtazepine (Remeron). Some times a few doses will stimulate a cat to eat after which he will eat on his own.
Prognosis for Anorexia in Cats
The prognosis for Anorexia in cats depends on the underlying cause for the loss of appetite and the cats response to treatment.