Hello, my name is***** and I have over 20 years of experience as a veterinarian.
I am sorry to hear that Hayley is getting very thin even with a good appetite and isn't grooming herself as she should. While old age makes it more likely for us to see health problems as organ systems age and their body doesn't work as well as it used to that doesn't mean that we cannot help her. I think it best that she see her veterinarian for an examination and some testing.
When we see weight loss with an apparently normal or very good appetite we need to worry about disease processes that either don't allow her to digest and/or absorb the food
she is taking (such as diabetes
, liver disease, primary intestinal or pancreatic disease including cancers) or those that lead to a higher metabolic rate such as hyperthyroidism
In an older cat the more common diseases we see include hyperthyroidism (a tumor of the thyroid gland that overproduces thyroid hormones) or if she were drinking more and urinating a tremendous amount, diabetes. Sometimes early on with diabetes we only see weight loss.
Both diabetes and hyperthyroidism are treatable or at least manageable.
Hyperthyroidism is controlled with daily oral medication (Tapazole, also called methimazole) or a very special diet called y/d both of which must be done for the rest of her life or treatment with radioactive iodine to selectively kill tumor cells which is usually a one time therapy. There are pros and cons to each therapy which your veterinarian can discuss with you after getting a firm diagnosis.
Hyperthyroidism is not painful, but elevated thyroid hormones can make them feel edgy or nervous, increase the heart rate and interfere with sleep, like drinking way too much coffee or energy drinks. Long term if left untreated it can lead to heart disease, hypertension, possible eye damage as well as kidney
and liver damage. But if caught and treated many of these things can be reversed.
Diabetes is controlled with diet and insulin therapy.
Ideally she should have a complete blood count and biochemistry profile with T-4 checked as well as a urinalysis. These tests often give us the information that we need.
If those aren't diagnostic then it is time to move on to more specialized testing. I recommend checking vitamin B levels to look for signs of intestinal disease, a test for pancreatic insufficiency called a TLI, and an abdominal ultrasound to look for signs of changes in the walls of the intestines as well as evaluating her organs. She may need an endoscopy to collect biopsies of her intestines if they look abnormal.
If she has any evidence of dental disease then she may need some radiographs of her mouth and tooth roots.
Mouth pain can make them hesitate to groom themselves properly, thus her disheveled look, or she may have some arthritis making it uncomfortable for her to twist and groom herself. You can discuss those things with her veterinarian.
In the meantime you might try feeding her a higher calorie prescription food called Hills a/d or Iams Maximum Calorie from your veterinarian and make sure she has access to plenty of fresh, clean water.
Please let me know if you have any further questions.