Has your cat or dog lost her appetite or recently suffered from a bout of gastroenteritis or pancreatitis? If so, she could have a Vitamin B12 deficiency.
Vitamin B12 deficiencies are quite common in humans who deal with chronic gastrointestinal issues such as Crohn's disease and these deficiencies can occur in pets as well. In fact, one study demonstrated that over 60% of gastrointestinally ill cats (don't bother looking that word up..it's my invention) suffer from some degree of Vitamin B12 deficiency. Dogs with inflammatory bowel disease (IBD) or pancreatitis are also very prone.
Vitamin B12 deficiency leads to lethargy and can exacerbate loss of both appetite and weight. Affected pets also tend to have poor haircoats, and in cases of severe deficiencies, neurological impairment can occur.
Unfortunately, just giving your dog or cat a B12 supplement by mouth won't cut it, since it's not absorbed very well from the GI tract. Instead, injections are the way to go.
The good news is that you can save lots of money by giving your pet B12 injections at home instead of having your vet do them. You'll still need to purchase the injections from your vet and possibly have him/her give the first one just to show you how to do it and to determine the correct dosage. The injections don't sting and are easy to give. And you can eliminate those veterinary recheck fees by doing it yourself.
If a dog or cat is deemed B12 deficient, at least six injections will be needed to correct the problem, with one given every week for a total of six weeks. After that, if you want to, you can give one to your pet every so often to provide a nice little appetite and energy boost.