Anorexia or Loss of Appetite in Dogs

Overview of Anorexia (Loss of Appetite) in Dogs

Anorexia is a term used to describe the situation where a dog loses their appetite and does not want to eat or is unable to eat. Appetite is psychological, dependent on memory and association, as compared with hunger, which is physiologically aroused by the body’s need for food.

There are many causes of anorexia. Often, a loss of appetite is the first indication of illness. Diseases of the digestive system (esophagus, stomach, intestine, liver, pancreas), the kidneys, the blood, the eyes, mouth, nose, and throat, the skin, the brain, and many other organs in the body can cause a loss of appetite. Pain of any cause can also make an animal less willing to eat.

Alternatively, some animals will occasionally refuse food for reasons that are much less serious, such as dislike for a new food, or behavioral reasons (new home, new animal or new person in household, etc.)

Regardless of cause, loss of appetite can have a serious impact on an animal’s health if it lasts 24 hours or more. Very young animals (less than 6 months of age) are particularly prone to the problems brought on by loss of appetite.

Diagnosis of Anorexia in Dogs

Because of the numerous causes of anorexia, your veterinarian will recommend certain procedures to pinpoint the underlying problem. These may include:

• Physical examination including buccal exam (looking at the gums), auscultation (listening with a stethoscope), abdominal palpation (feeling the size and shape of the 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
• X-rays of the chest and the abdomen
• Fecal examination (microscopic evaluation of the stool to look for parasites)
• Additional tests, depending on initial test results

Treatment of Anorexia in Dogs

Treatments are of two kinds: specific and supportive.

• Specific treatments are those that deal with the underlying cause. That is, they either slow down or eliminate the problem that caused the loss of appetite in the first place. Examples of specific treatments that reverse loss of appetite include giving antibiotics to eliminate a severe bacterial infection, surgically removing a foreign object that was blocking the intestine, treating dental disease that made chewing painful, and so on.
• Supportive treatments are those that help sustain a dog that is debilitated as a result of not eating. Examples include fluid therapy, such as intravenous fluids (“IV”) or subcutaneous fluids (injections of fluid given under the skin), hand feeding or coaxing to eat, appetite-stimulating drugs, and others.
• 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.

Home Care for Anorexia in Dogs

• Note whether any recent change has occurred in the home environment, such as a recent move to a new home, a new person in the home, or the addition of a new pet. These may contribute to the loss of appetite and should be mentioned to your veterinarian.
• Note whether any other symptoms are present. The presence of symptoms in addition to loss of appetite should prompt a veterinary examination sooner rather than later.
• To combat dehydration, some animals can benefit from being given oral rehydration supplements, such as Pedialyte®. Ask your veterinarian whether this is appropriate and how much should be given.
• If an animal is unwilling or unable to eat, feeding may be enhanced with certain techniques, such as warming the food so it is easier for the dog to smell it, mixing in certain home-cooked ingredients specifically suggested by your veterinarian, or offering the food by hand or with an oral syringe. Any warmed food should be checked to make sure it is not too hot, which could scald the mouth or digestive system. This is particularly a concern when the food is warmed (unevenly) in the microwave.
• When therapeutic diets are prescribed for a certain medical condition, a dog may not eat that diet immediately. Mixing with the previous diet and gradually decreasing the amount of the prior diet over several days can be tried to avoid cutting the appetite completely.
• Young animals (6 months or less) are particularly fragile when not eating, and loss of appetite for even 12 hours in a puppy of 1-6 weeks of age can be life threatening. Regular milk (i.e. cow’s milk) is poorly balanced for dogs, soft drinks (soda pop) and sport drinks are usually much too sweet and are deficient in electrolytes, and soup (e.g. chicken soup) is usually too salty and does not provide enough nutrients for energy. These infant animals may need to be fed a milk replacer by syringe if they have not yet been weaned; balanced milk replacers for dogs are available. Oral rehydration solutions made for children are less well-balanced, but are still better alternatives than soda pop, chicken soup, etc. It is essential that you consult with your veterinarian to determine what to feed and to determine how much to give.

In-depth Information on Anorexia in Dogs

There are several causes for anorexia in dogs. The reasons for which animals refuse to eat may be grouped into two major categories:

Psychological and Medical

• Psychological causes imply that something in the animal’s environment has caused them to lose their appetite. Examples include moving to a new home, having a new person or new animal in the home, and switching to a new pet food.
• Medical causes are disease processes that result in the loss of appetite.
• A major difference between psychological loss of appetite and disease-related loss of appetite is that when there is disease, additional symptoms are usually present. These symptoms can include the new development of excessive salivation (drooling), vomiting, diarrhea, lethargy or sluggishness, weight loss, labored breathing, signs of infection such as discharge of pus or blood, or sudden changes in behavior.
• Common diseases that make animals unwilling to eat include the following:

Gastrointestinal Diseases

If the esophagus (tube in the throat that connects the mouth to the stomach), the stomach, or the intestine is inflamed (irritated) by disease, eating can become uncomfortable or nauseating, resulting in anorexia. Diseases that can cause this kind of irritation include parasites (worms), viruses such as parvovirus and coronavirus, other infections such as bacterial and fungal infections, ulcers, food allergy, inflammation of unknown cause (“idiopathic”), and certain infiltrative cancers.

A complete or partial blockage of the digestive tract can also cause unwillingness to eat. This most often occurs with foreign bodies (objects that are swallowed and become stuck partway down the digestive tract) and cancers of either a benign or malignant nature.

Gastrointestinal diseases can also cause increased salivation, vomiting, diarrhea, and sometimes (particularly when more severe) lethargy and sluggishness.

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 because of inadequate liver function affects the brain and blunts the sense of hunger. Common diseases of the liver in dogs include chronic hepatitis (not the same as human hepatitis A, B, or C, and NOT contagious), portosystemic shunt (a defect in the blood circulation through the liver), cirrhosis (severe scarring of the liver), liver cancer, and adverse reaction to certain drugs (e.g. carprofen, trimethoprim-sulfa, others).

Liver diseases may also cause increased salivation, vomiting, 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, sluggishness, and possibly signs of weakness like 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).

Other Causes of Anorexia in Dogs

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 they are anorexic.

A prolonged inability or unwillingness to eat may be a sign of serious illness in your pet.

If your pet refuses to eat, watch for any of the following:

NOTE: The presence of lethargy and loss of appetite in dogs or any of the following symptoms warrants an immediate consultation with your veterinarian, regardless of how long the loss of appetite has been present.

• Development of excessive salivation (drooling)
• Vomiting
• Diarrhea
• Weight loss
• Breathing difficulties or labored breathing
• Signs of infection, such as discharge of pus or blood
• Sudden changes in behavior
• Medical causes of appetite loss are usually 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

• 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. 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 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 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 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.
• Your veterinarian may want a stool specimen from your pet. 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.
• As mentioned above, ultrasound and X-rays often go together 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.
• 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

Treatment of anorexia can be specific or supportive.

• 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 to precisely identify the underlying disease.
• Supportive treatments are those that help sustain an animal that is debilitated as a result of not eating. They 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®) and Mirtazepine (Remeron).