Q: This is a hard letter for me to write, and I shall cry as I do. I own a nineteen-year-old cat; rather, I should say she's owned me all these years. We've shared many crises and often I would have given up except her head-rubbing, heavy purring and lap-sitting always helped me get through it. But now her health has declined a lot, and I know I'm facing a fateful decision. Am I being selfish and cruel to prolong her life as it is, or should I put her to sleep? How can I know?

A: It can be very difficult to know when euthanasia is the appropriate course of action. It's understandable that you desire to do what's best for her, and not delay the decision to euthanize her out of any selfish motives. And because she depends on you, it is perfectly normal and proper to consider all options carefully.

As you probably suspect, there aren't any strict guidelines; the decision is usually made jointly by the cat's caregiver and the veterinarian. You, as her caregiver, are able to assess the quality of her life by observing how she functions at home. It's important that you convey this information to your veterinarian. Questions she or he may ask include:

• Is she eating?
• Does she respond to you and to her surroundings?
• Does she cry a lot? What is she doing when she cries?
• Is she staying in her familiar places or has she moved?
• Where has she moved?
• Is she using her litterbox, or is she soiling the spot where she is sleeping?
   

Your veterinarian is able to predict which conditions cause discomfort, to determine the long- and short-term prognosis both with and without treatment, and then to inform you of available options. Although euthanasia decisions must be made on a case-by-case basis, as a veterinarian I will consider a number of factors. I'll weigh the clinical data (for example, the results of diagnostic tests and physical examination). I'll consider a cat's general condition and any diseases that may be present. What are the expected results of treatment? Is it financially feasible? Can the caregiver provide adequate homecare? Is the disease curable or not? Is there a way to provide pain relief and improve the quality of life? We may be unable to cure a cat with terminal cancer, for example, but we may be able to palliate pain-a very important aspect of cancer treatment. A cat with kidney failure may temporarily respond very well to in-hospital or at-home fluid therapy; it may make her much more comfortable and perhaps extend her life.

After you carefully consider all the options, you'll be better prepared to make a decision that is in her best interests. If euthanasia is the choice, you can take comfort in knowing that you and your veterinarian did all that could be done to make sure your cat did not suffer. She has been a faithful friend for a long time and her response, no matter what your decision, will be to trust you.