Putting your pet to sleep can be one of the most difficult decisions that you have to make. Alice Villalabos, D.V.M., developed the following quality-of-life scale to take the guesswork - and guilt - out of the decision.

For each category, rate how your ailing pet is on a scale of zero to 10 0 with 10 being the fewest problems. Then compare your responses to other family members' and those of your vet. A score of less than 35 indicates your pet's quality of life is extremely low.

q Hurt Crying, labored breathing, withdrawal, depression, unrelenting vomiting, or seizures.

q Hunger Eating less, losing weight, turning his head away in the presence of food, or unrelenting vomiting.

q Hygiene Drinking less water, having skin that doesn't tbounce back when pinched, experiencing 6 to 12 hours of diarrhea or vomiting, or not eating.

q Happiness Not wagging his/her tail, keeping his/her head down, having dull eyes, and not looking up when you walk in the door.

q Mobility Not able to go out for a daily walk. A large dog who is difficult to move or does not want to be moved rates low in quality of life.

q More good days than bad Keep track of consecutive bad days. Dogs only live in the present time. If they have continuous bad times, that's all they know.