Thursday 11 September 2008

Feline Weight Loss

cat with weight loss
Skinny cat -- photo by Janesdead

The causes of feline weight loss in cats are varied and some, perhaps not all, are set out here. The classic, perhaps simplistic response to the question, "what causes weight loss", must be that the cat is either eating less or the cat is not benefiting from the food that is eaten. There may be a number of causes. These two scenarios are at the root of the matter; the next question is why is this happening.

There are four types of Hookworm (Ancylostoma) that infest cats. They are quite small in comparison to Tapeworms (see tapeworms in felines) at about a maximum of half an inch in length. The signs of an infestation include weight loss, anemia, diarrhea and weakness. The treatment is drugs and preventative measures should be in place (proactive treatment). I'll be discussing this more in a later posting.

Feline weight loss occurs (through loss of appetite) when cats contract Feline Infectious Peritonitis (FIP), which is a nasty disease and a killer when cats develop the secondary severe infection. I discuss in more detail feline FIP and an overview plus other diseases here: Cat Health Problems FIP.

Another nasty disease and one which can cause cancer and exacerbate other diseases is Feline Leukemia Virus Disease Complex or FeLV for short. One symptom is loss of appetite and weight loss. See a lot more on FeLV.

Another very serious disease that produces a wide range of nasty symptoms including loss of appetite and feline weight loss is what is commonly known as FIV or Feline Immunodeficiency Virus Infection. FIV is the feline equivalent of human AIDS (HIV) and was first discovered in cats in California in 1986 (quite recently). It affects about 1-3% of cats. See more on Feline Aids.

A protozoan (a single celled organism) causes the disease Toxoplasmosis. It is quite well known to cat people because of the perceived dangers to pregnant women catching the disease from cat feces (see cat feces and pregnancy). Cats can acquire is by eating infected animals that they have hunted or raw or undercooked meat. Eating undercooked meat is the most common way for people to get the disease. Most often there are no symptoms and when there are signs of the disease one is feline weight loss. Prevention is probably the best treatment - indoor cat + enclosure could be one answer.

cat with weight loss
Feline weight loss? Not sure. This cat looks thin but that's all. Nice but sad picture that is why it is here. Photo by Jun Cruz Na Ligas.

Bad teeth and gum disease will be a classic reason for feline weight loss as it will be uncomfortable to eat. Periodontal disease affects the supporting tissues of teeth, namely the gums and bone. The disease starts with plaque and tartar (calculus) build up on the gum line. Bacteria live in the plaque. This leads to gingivitis (gum infection). The first signs are mouth odor but inspections of our cats teeth should be routine. This can be done on a simplistic level when our cat yawns. Cats can develop bad teeth so concerned observation will allow early steps to be taken to prevent and cure the disease. Some people think that cats eating dry kibble have better teeth. There are downsides to dry food however. This post: Feline Diabetes touches on one possible downside.

Feline weight loss can be due to an upset stomach. This may be due to an inflammation of the stomach (Gastritis). When this condition persists over a long time (i.e. it is chronic in medical parlance) it will cause weight loss plus cause vomiting and a loss of vigor. Ingestion of foreign objects can cause gastritis such as too much grass (cats eat grass for the folic acid), rubber, paper etc.. Bengal cats particularly like to use their teeth and chew paper, for example - see weird behavior. The other wildcat hybrids are similar - see Savannah cat, Chausie and Safari cat. Hairballs can also cause gastritis. These are often vomited up (see cat vomiting). There are other reasons for an inflamed or bleeding stomach lining (drugs for example) and a veterinarian's diagnosis is essential.

Inflammatory Bowl Disease (IBD) is possibly caused by the cat's immune system being primed into taking action by specific bacteria or food proteins leading to the creation of antibodies that attack the cells of the cat's intestine (in other words the immune system is malfunctioning). An inflamed intestine ensues and this can cause poor absorption of digested food from the intestine to the blood and thence to the body. This in term can lead to feline weight loss and other symptoms such as diarrhea and anemia.

A liver that is not functioning properly due to liver disease will result in a number of symptoms including lethargy and a loss of appetite (leading to weight loss). See Feline Fatty Liver disease - the most common liver disease in cats. These diseases involve the liver: FIP and toxoplasmosis.

The commonly diagnosed disease in cats, sugar diabetes (Diabetes Mellitus) in its later stages results in loss of appetite and feline weight loss. There are other symptoms such as excessive urination and drinking lots of water. The disease is due to insufficient production of insulin in the pancreas. See Feline Pancreatitis. Feline Pancreatitis also caused malabsorption syndrome causing weight loss.

Feline Anemia is another cause of feline weight loss. This is full described in this post: Feline Anemia.

Kidney disease leading to kidney failure is another cause of weight loss in cats. Once again I have a post on this condition which can be see here: Feline Kidney Disease.

Older cats are more likely to show feline weight loss due to for example kidney disease (see above), gum disease (see above), cancers (see cat health and cancer) and loss of smell - cats rely on smell hugely and judge food largely by smell. Food that they like and which is cold may be passed over as cold food gives off less smell.

Finally it goes perhaps without saying that some cats are starved by cat keepers and some are overfed, while many feral cats are undernourished all causing feline weight loss.

Feline Weight Loss to Cat Health Problems

Feline Weight Loss - Sources:
  • Cat Owner's Home Veterinary Handbook by Drs Carlson and Giffin
Photos: published under creative commons license. Attribution-NonCommercial-ShareAlike License.



  2. My cat has lost a very noticable amount of weight. He seems to be eating fine. And he still plays with my other cat. He has always had foul smelling stool and once and a while I'll find blood in his stool. I asked the vet about it and he said nothing was wrong and it could have been caused by stress. But now things have been pretty consistant at home and he is losing weight faster than I know what to do. Any ideas what could be causing it?

  3. Hi Cricket, you might like to go to this page:

    Cat Illness Symptoms

    If there are other symptoms try and factor them in to the diagnosis. But there is only one thing to do, I think, which is to go back to the vet (or a different one perhaps might be wise) if you can afford it. Good luck to you both.

  4. hi there, my cat has lost alot of weight resently, and she has lost her appitite only for cat food though, she will eat normal stuff e.g beef and ham. she is very thin. what could be causing this, i need help! p.s my cat is also very old could this be causing the weight lost??

  5. Response to last comment. She is eating human food. This may not on it own be sufficient. There are many reasons for weight loss. I can only advise a vet's visit. But as I said cats need food balanced for them and human food on its own probably does not meet that requirement. Good luck.

  6. My 14+ year old cat has been slowly getting slimmer and slimmer, last night i noticed just how drastic it's gotten. He is still extreamly affectionate, and eats at least a can of food a day in addition to a large number of cat treats, occasional 'people food', and his dry kibble. He is consuming a normal amount of water and his litter box habits have not changed. The only other change I have noticed is that he has gone from jet black in color to a beautiful brown/auburn color. His stress level has been normal as there hasn't been any new introductions into his life in the last 6-7 months, and he is strictly an indoor cat with no recent contact with the outdoors, his teeth seem fine and he does love to eat. Does this sound like something I should visit a vet for, or does anyone have any tips on what i could feed him which might lead to some healthy weight gain?

  7. hi wonder if u can help my cat felix has been not well for 1 week now has stopped eating and his mood has changed drasically he is just lyin in 1 spot and not wanting to move, i put him down to his food and he just turns his nose up and moves away, he has had 2 antiboitic injectiona and steriod injection and fluid put under ths skin but he aint respondin could u please hepl as i am very worried thanks

  8. My cat is 16 years old and has just had an intensive examination by our vet. Tigger has been on two daily injections of insulin for five years. The vet noticed the loss of weight but couldn't explain it, especially as all test results were good, including the fructosomine levels. Tigger's appetite is not very good these days and he's lost about 3 lb. in weight this year. At his prime he was 17 lbs. Now he's nearer 9 lbs. He's going downhill fast -- any suggestions would be helpful.

  9. my cat is 2 yrs old and has always been healthy until just recently she gave birth to 5 kittens 7 weeks ago she started to loose a little weight then but i thought it was because she had just given birth and was spending alot of time nursing, now she is throwing up and has diarreah she is loosing lots of weight please help me i dont know what is wrong with her, she is my little angel.

  10. Response to last comment. You obviously have to get your cat to a vet as soon as possible. It sounds serious. Delay will make matters worse. The symptoms that you describe are too general to diagnose from. Only a good vet with the cat in front of him/her can diagnose properly.

  11. Response to Lester (the comment above the last one). My cat is 19 yrs old and she has lost weight. It seems that they lose appetite perhaps due to loss of smell and simply getting old (perhaps a bit depressed). Also the digestive system becomes less efficient and the nutrients are not absorbed as well into the blood stream. These would seem to be factors that can cause weight loss in an elderly cat. Good luck.

  12. I realize this thread is old, but just in case anyone reads this researching diarrhea issues...I highly recommend Primal freeze dried beef-salmon nuggets, hydrated with goat's milk, to correct chronic diarrhea issues. The beef ones work best, crushed up with just enough goat's milk, two to three nuggets a day. I had a poor cat that had the vomit/diarrhea issue after having kittens, too, and none of the meds worked - no parasites or disease, just a digestive system completely out of whack. The primal worked like magic. Immediately stopped the runs, stool became completely normal in three days. We have now switched all the cats over to Primal products (raw frozen and freeze dried). They are expensive, but much better than processed canned products, or meds (watch out for meds, they can begin a cycle of dependency).


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