A cat losing weight is a real concern and no doubt people search for a reason why. As can be imagined there is often no clear and clean answer because losing weight is a general symptom and many illnesses and medical conditions might result in the loss of weight; the simple reason being that when a cat is ill he or she will feel poorly and not feel like eating.
I have personal experience of this with my cat, Binnie, who is about 18 years old (at 2010). She had been overweight for most of her life. Suddenly about 5 months ago she started to lose weight markedly. When an old cat losses weight it can be serious and a visit to the veterinarian is called for. Before taking her to the vet I made a judgment that the likely cause came from two possible sources (a) loss of sense of smell due to old age and/or (b) feeling unwell.
She showed no clear signs of being ill but she was going outside more and I decided that she was uncomfortable with fleas irritating her. I decided to flea comb twice daily and take other steps to control and eliminate the flea. Secondly, I bought the most palatable cat food I could find and varied it more. She ate more and gained some weight. Although she is now lighter than before, her weight has stabilised. Being lighter is a benefit to her as she can get through the cat flap for the first time in about 4 years! Changes in Older Cats | The Cat Flea: biology, ecology and control | Cat Flea Treatment.
Although it is difficult to deduce simple reasons for a cat losing weight, there are some specific illnesses that are more directly related to a cat losing weight and in order to try and assist people looking for answers I list below all the pages in the fine book: Cat Owner’s Home Veterinary Handbook, Fully Revised and Updated that relate to a cat’s weight loss as set out in the index of signs and symptoms. I recommend that you buy this book:
- A chronic infestation of hookworm (more commonly seen in the adult cat) causes diarrhea, anemia and weight loss. Hookworms are thin worms a quarter to a half inch long. Diagnosis: seeing eggs in the cat’s feces. Cat Parasites | Cat Deworming.
- Feline Hyperthyroidism – see heading picture. Caused by an excessive production of the hormone, thyroid. Symptoms: restlessness, high food consumption due excessive to hunger but accompanied by weight loss [more]
- Feline Infectious Peritonitis (wet and dry form), a serious and common disease in feral, wild and domestic cats, caused by the Caronavirus group produces symptoms that include (a) loss of appetite, (b) weight loss, (c) listlessness and depression [more info].
- Feline Leukemia Virus Disease Complex (FeLV) is “responsible for more diseases that any other infectious agent..”. Symptoms include (a) fever (b) apathy (c) loss of appetite and weight loss (d) vomiting, constipation and diarrhea [more info].
- Feline Immunodificiency Virus Infection (FIV), a “chronic cause of immunodeficiency..”. The virus is a retrovirus. Signs include fever, swelling of lymph nodes, low white blood cell count, diarrhea, mouth disease, loss of appetite and weight loss [more]
- Infection of the protozoan, Toxoplasma gondi causing the disease, toxoplasmosis. Normally no symptoms but when there are symptoms they include loss of appetite causing weight loss, cough, rapid breathing, fever, diarrhea and swollen abdomen [more].
- Periodontal disease and tooth decay – gum disease and rotten teath makes it uncomfortable to eat so the cat goes to food but does not eat. This leads to inevitable weight loss [cat drooling] [bad breath in cats].
- Chronic upset stomach (inflammed stomach – gastritis) caused by such things as hairballs shows signs that include, lethargy, dull coat and the cat losing weight [common cat illnesses] [cat vomiting].
- Inflammatory Bowel Disease (IBD) produces symptoms of chronic diarrhea, malabsorption, anemia and the cat losing weight [more]
- Liver disease commonly caused by idiopathic hepatic lipidosis results in a jaundiced appearance (yellow whites of eyes and skin), vomiting, diarrhea, excessive thirst, pain and loss of appetite and therefore weight loss [feline fatty liver disease]
- Sugar Diabetes – Diabetes Mellitus – a more commonly encountered disease than was the case years ago causes symptoms in the early stages of increased urination, increased consumption of water and food and “unexplained weight loss…” [more]
- Feline Anemia results in increased sleeping, weakness, lack of appetite and loss of weight [more]
- Kidney Failure – first signs are increased drinking and urination and as it progresses the signs are apathy, sluggishness, loss of appetite leading to the cat losing weight, dry hair, brownish tongue, ulcers on tongue and gums [more]
- The older cat – weight loss can be caused by numerous diseases some of which are described above but which also includes cancer and loss of smell. Elderly Cat Health Problems. Geriatric Cat Care.