Feline Weight Loss: Is Something Wrong?

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thin diabetic orange cat

Feline weight loss, when unplanned, is something to be concerned about at any age. Your cat, when healthy, will normally weigh the same year after year, except for those who gain weight. Good feline care includes knowing what your cat weighs and taking action when weight loss occurs. Many cat illnesses have weight loss as one of the primary symptoms.

I have examined thousands of cats over the last 20 years and I have seen healthy cats come in year after year weighing the same, almost to the ounce. There are two exceptions to that: (1) the cats that steadily gain weight and become overweight, and (2) cats that have an illness.

Cat weight gain is cause for concern, but not because it indicates an illness. There is no disease in cats that causes weight gain. You may have read or heard otherwise; I have seen misinformation in various places over the years about this subject.

For example, I have heard it said that cats gain weight because they are hypothyroid. Cats do not get hypothyroidism except in one type of situation. If a hyperthyroid cat has his thyroid glands surgically removed or has radioactive treatment for the hyperthyroidism, then it is possible that after the removal, the cat's thyroid levels may be low, either temporarily or permanently. However that is a man-made condition. Naturally occuring hypothyroidism doesn't exist or if it does is so rare that your chances of having a cat with that condition are pretty much nil.

The other time I have heard a disease blamed for a cat being overweight is in association with diabetes. I have heard it said that diabetes makes cats fat. That is not true. Fat cats are more likely to get diabetes which will then make them lose weight if not treated quickly, but diabetes does not make them fat.

If your cat is overweight, he is eating too much. Period.

Conversely, there are many diseases that cause cat weight loss. And because cats tend to stay the same weight year after year or they gain weight, it is ALWAYS of concern if a cat loses weight.

There are some myths associated with feline weight loss as well. I have been asked or told many times by cat owners that their cat's weight loss must be due to growing older. Wrong! Old age is not a disease! Old age does not make you lose weight. Old age make increase your cat's risk of acquiring certain feline diseases that cause weight loss. But the age itself is not a reason for weight loss.

skinny cat - feline weight loss

A major problem with feline weight loss is our inability to see that it is happening until a significant decrease in the weight has occurred. For example, a 10 pound cat can lose a pound and it may very well not be noticed by the owner. A pound is nothing, you say? Maybe to us. But a pound weight loss in a 10 pound cat is loss of 10% of the cat's body weight. That is significant.

Too often, I have seen cats brought in for an examination only after they look like the cat just above and this is MUCH too late!

Unfortunately, when you look at your cat, you may not notice early weight loss. That first pound lost is not easy to see.

cat on scale

In an ideal world of ideal cat care, every cat owner would own a pediatric or feline scale such as that seen to the right and weigh their cats regularly throughout their lives. Many conditions would be diagnosed earlier if we all did that, allowing for earlier treatment and a better outcome.

You may think I'm going on and on about cat weight loss and indeed I am because it is the cat symptom that worries me the most. It is the one symptom that most often has something serious associated with it.

What Are the Causes of Feline Weight Loss?

Anything and everything. Seriously. Cat weight loss can occur due to:

- hyperthyroidism in cats

- feline kidney disease

- cat diabetes

- feline leukemia and feline immunodeficiency virus (FIV)

- cancer

- feline inflammatory bowel disease

- upper respiratory infections

- cat dental problems

.....and on and on. There's almost nothing imaginable that can't cause weight loss in cats.

This is another reason feline weight loss is a problem. Not only is it not obvious until too much weight has been lost, but it is so nonspecific as to the cause. One can never say, "my cat lost weight so she has diabetes" or "my cat lost weight so she has dental problems". There are so many causes that only a good history and physical exam by your veterinarian can narrow the possibilities and even then, blood work is often necessary.

thin emaciated cat

Erica wrote in recently with a question about
feline weight loss. Her question was:

I have a one year male cat. About 3 months ago he started drooling, lost body weight, and was irritable towards the other animals in the house. The symptoms keep coming and going. But he has not gained all his body weight back. Had blood test done at the vet and they said his liver results were a little high but not out of the normal range. He likes to roll in dirt outside when he feels bad. He is normally an inside cat.

ANSWER: Feline Weight Loss at any age is cause for concern. If kittens and young cats lose weight, we become especially concerned.

Drooling is also abnormal and his irritability could be significant if it never occurred before and now is an intermittent event.

Rolling in the dirt outside is a normal cat activity. Most cats love to do that if given the chance.

There are a few things that come to mind if I look at all his symptoms together:

cat dental cleaning

(1) Problems in the mouth. Were his teeth and gums examined very carefully, all the way back to his throat? Was his tongue closely examined, including the area under the tongue? Was there excessive gingivitis or any ulcers? Do his teeth need a professional cleaning? Are there any abnormal masses in the mouth? Any painful areas?

(2) Toxins. Is there anything he can get into from time to time that is poisonous to him? Any plants, grasses, medications, rat poison, anti-freeze, cleaning supplies, construction materials? Does he lick anything indoors or outdoors on a regular basis? Even if a plant or grass is not truly poisonous, all can be irritating to the mouth and stomach of a cat.

(3) Blood work was mentioned, but I don't know if it included testing for Feline Leukemia Virus and Feline Immunodeficiency Virus. If not, that testing should be performed. Cats with those viruses frequently have mouth problems and have feline weight loss. He's young and has spent at least some time outdoors so he certainly has been at risk for acquiring those viruses.

Those are the top problems that come to mind with the symptoms described. Of course, other illnesses can cause those symptoms: kidney disease, other viruses, liver disease and others. However, his symptoms and his age and the blood results so far put these other things at the bottom of the list of possibilities right now for me. Also, of course, make sure he is eating a good quality, nutritious cat diet.

Recommendations then include a very complete oral exam, under sedation if necessary, and perhaps a second opinion. I also recommend FeLV and FIV testing if that wasn't done or was done over 3 to 4 months ago. In addition, think hard and look around carefully to see if there is anything that could possibly be toxic to a cat.

If none of these procedures come up with a cause and he still is too thin or losing weight and drooling, I would proceed to X-rays of his chest and abdomen.

Thank you to Erica for sending us this interesting question about Feline Weight Loss and I hope a cause is found soon and treatment is successful.

My Very Best,
Dr. Neely

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