My dog won't eat, What do I do?
It's a fact that many illness impact a dog's metabolism. Changes occur in the way the body uses proteins, fats, and
carbohydrates in a way to fight for survival. Some of these metabolic changes can become exaggerated or prolonged to
the point that they are harmful rather than beneficial. Significant weight loss and muscle wasting can occur rapidly and
can be difficult or even impossible to reverse.
The typical problem with dogs with cancer is the refusal to eat their normal food or any food at all. You may be able to
coax your dog to eat table foods, but these may lack the essential nutrients that your dogs requires at this time.
A dog with cancer loses weight either because of decreased food intake and/or the metabolic effects of the disease.
There is often more than one cause for decreased appetite. Some of the causes are related to the disease itself and
some are side effects of cancer treatment. Human cancer patients can experience changes in their sense of smell and
taste. Sometimes this is the result of the disease, sometimes secondary to a nutrient deficiency such as zinc, and
sometimes due to side-effects of drugs or other forms of treatment.
Tumors may physically interfere with eating and digesting food. For example, tumors of the oral cavity may cause
difficulties with chewing and swallowing. Tumors of the stomach or intestines may obstruct the normal passage of food or
the absorption of nutrients. Cancer therapies may also have a direct impact on the gastrointestinal tract. Some drugs
cause nausea and vomiting. Others may actually injure the cells lining the intestines. Radiation is often used to treat
tumors of the oral cavity which can cause inflammation and ulceration of surrounding mucous membranes. Surgical
removal of tumors involving parts of the digestive tract can obviously affect a patient's ability to eat or digest food. For
example, it might be necessary to remove part of a patient's jaw, tongue, or intestines. Surgery and radiation therapy
require anesthesia which involves periods of fasting before and after each episode.
One serious and unpleasant consequence is that the dog may associate them with the act of eating or even the sight or
smell of food with nausea or pain. This is called learned food aversion. Food aversion is a well-recognized phenomenon
in human patients. Most everyone has experienced an occasion when they have become ill after eating a particular food.
Whether or not that food was responsible for the illness, it becomes associated with it in our minds. Although difficult to
prove, we believe that this occurs on dogs as well. One of the greatest challenges in feeding the pet with cancer is
preventing the development of food aversions whenever possible, and dealing with this condition when it does occur.
Because we have to guess what a dog is experiencing when he refuses food it can be hard to determine the best course
of action. On the one hand we might work hard to coax a pet with palatable or novel food items in the hope of finding
something that will be eaten voluntarily. On the other hand it might be best to back off for awhile and rely on an artificial
form of nutrition (such as tube feeding) or even not feeding at all because of the risk of causing or exacerbating a
learned food aversion. Listed below are some general guidelines on how to approach these patients. Remember that
every patient is different, and requires individualized care and attention. No one thing will work in for every animal--be
patient and sensitive to the pet's changing needs.
Resist the temptation to coax a pet to eat when he or she is feeling or showing overt signs of nausea or discomfort. Pets
that gulp or drool at the sight or smell of food, turn their heads away, spit out food when placed in the mouth, or bury the
food under their bedding should be left alone. Pushing food on a patient who clearly does not want it is a good recipe for
creating a learned food aversion.
Discuss the possibility of anti-emetic drugs with your veterinarian if you think nausea and vomiting are a problem. Also
discuss the use of tube feeding. Many factors must be considered when deciding whether a pet is a candidate for
nutritional support. These techniques are not appropriate or feasible for every pet, but can be used successfully in many
cases.
A few drugs like Prednisone have been used to stimulate the appetite. It can work well at this plus it is a very strong anti-inflammatory.
It cannot be used long term. Short bursts are ok.
If your pet is showing some interest in food, there are many things you can try in order to increase interest in food.
Try novel food items. If your pet has begun to associate a previously favorite food with unpleasant sensations,
introducing a very different type of food may overcome the aversion to eating. This can backfire if the patient is still
unwell, since the aversion may simply transfer to the new food. Any type of food can be used including dog foods (for
dogs), cat foods (for dogs or cats), and palatable table foods. Remember that table foods will not provide all of the
nutrients that a pet needs. If a pet eats an exclusively home-cooked diet for any period of time, you should get some
advice on how to make that diet more complete and balanced. I just add fried eggs and cooked ground turkey with a little garlic
to the kibble/pills and add a little warm water.
Try offering food in a novel setting or have someone different do the feeding. Sometimes an animal will associate its
surroundings with past unpleasant experiences. For instance, a patient may no longer eat in the kitchen but will eat on
an outside deck. Also, remember that dogs are social animals and may be more likely to eat with their pack--which
includes you! Coaxing a dog to eat during family mealtimes or with other pets present might be successful.
Make mealtimes as comfortable and unstressful as possible. Try not to schedule them at the same time that you do other
treatments such as pilling. Avoid pushing food on your pet. Stroke and talk to your pet with food nearby and watch for
any signs of interest.
Divide the day's food into as many small meals as your schedule will permit. The food ingredients that increase
palatability for most dogs and cats are moisture, fat, and protein. Adding water to a dry pet food or switching to canned
food may improve food acceptance. A pet's tolerance of certain nutrients must be considered when trying new foods.
Animals with kidney or liver dysfunction may not tolerate high protein intake. Animals with some types of gastrointestinal
disease cannot tolerate large amounts of dietary fat.
The standard advice for getting anorexic pets to eat has been to warm foods to just below body temperature. This is
believed to increase the aroma of food, which in turn will enhance taste. But there is also some evidence that this might
be counterproductive in animals that are exhibiting food aversion. It's possible since these patients may be hungry
but have learned to associate certain smells or flavors with feeling badly. In these cases, offering food at room
temperature or even chilled may meet with more success. You will just have to try different ways.
Because the syndrome of cancer cachexia (profound weight loss) can involve more than decreased food intake, even
the best efforts in encouraging a pet to eat may not prevent weight loss. This is because cancer can involve alterations
in normal metabolism that are not overcome simply by providing calories and nutrients. Certain types of tumors can
produce substances that affect energy and protein metabolism. The tumor itself competes for some of the nutrients that
should be going to the patient. In addition, the patient's immune system produces a variety of substances in response to
the tumor. For the most part these are beneficial, but they can cause alterations in metabolism that result in decreased
appetite, weight loss, and loss of muscle mass.
Mirtazapine for Appetite Stimulation in Dogs and Cats
Rx Mirtazapine (brand name Remeron™-Organon) is approved as an antidepressant for use in humans and has activity both as an alpha 2 receptor antagonist and as a potent 5HT3 antagonist. A side effect noted in humans taking this drug is appetite stimulation. Pharmacy faculty at the Mississippi State College of Veterinary Medicine used mirtazapine in a dog after all other attempts at appetite stimulation had failed, and were very pleased to find that mirtazapine restored appetite almost immediately in this dog. In another case, a physician used mirtazapine to treat anorexia and nausea in his Boston Terrier with chronic renal failure. Due to the vast improvement in the animal’s quality of life for one month preceding its death, the dog’s primary care veterinary clinic conducted a series of uncontrolled field trials using mirtazapine over the next 4 years in 24 dogs and 17 cats with GI symptoms that were marginally responsive or refractory to standard remedies. “Mirtazapine therapy led to a robust response in 12 animals, improvement compared with standard treatment in 16 cases, and an equivocal response in 13 animals. The most vigorous responses were observed in patients in chronic renal failure or receiving concurrent chemotherapy for neoplastic disease.”
Many veterinarians have started using mirtazapine to stimulate appetite in both dogs and cats. There have been no controlled studies and dosing is still empirical, but most dogs are dosed at 0.6mg/kg orally every 24 hours and cats are dosed at 3.75mg/cat orally every 48-72 hours. The terminal half-life of mirtazapine in humans is more than 40 hours, and mirtazapine is eliminated partially through conjugation with glucuronide. For this reason, dosing intervals of less than 48 hours are not recommended for cats, as accumulation is likely. Mirtazapine is not commercially available in an oral suspension; however, compounding pharmacists have formulated suspensions upon the request of veterinarians and have anecdotally reported success with this dosage form. For cats that are vomiting as well as anorectic and cannot swallow or retain oral medications, veterinarians have instructed compounding pharmacists to formulate transdermal gels of mirtazapine (3.75mg/0.1ml), which also have left veterinarians with a positive impression of clinical efficacy. Obviously, further studies are needed to determine stability, safety and efficacy of these compounded dosage forms, but until such evidence is available, veterinarians may wish to try these dosage forms in cases that are refractory to traditional methods of appetite stimulation.
Veterinary Forum, February 2006, pages 34-36
Meeting the basic nutritional needs of a cancer patient can be a significant challenge. In human cancer patients, it is
established that malnutrition can increase the risk of complications and decrease survival rates. Patients with good
nutritional status have an improved response to therapy and better quality of life. While the effects of malnutrition have
not as yet been studied in veterinary patients, it seems likely that the results would be similar.
Sometimes you gotta just give them some KFC Chicken. I have never seen a dog not eat that.
This trick does work, but try to use it only when needed.
