Dr. Villalobos has advocated what she calls “bond-centered euthanasia,” which allows the pet owner to be present and play a comforting role during the procedure. She has also championed sedation-first euthanasia, putting the animal into a gentle sleep before administering a lethal drug.

To help pet owners make decisions about end-of-life care, Dr. Villalobos developed a decision tool based on seven indicators. The scale is often called the HHHHHMM scale, based on the first letter of each indicator. On a scale of zero to 10, with zero being very poor and 10 being best, a pet owner is asked to rate the following:

Hurt: Is the pet’s pain successfully managed? Is it breathing with ease or distress?

Hunger: Is the pet eating enough? Does hand-feeding help?

Hydration: Is the patient dehydrated?

Hygiene: Is the pet able to stay clean? Is it suffering from bed sores?

Happiness: Does the pet express joy and interest?

Mobility: Can the patient get up without assistance? Is it stumbling?

More: Does your pet have more good days than bad? Is a healthy human-animal bond still possible?

Dr. Villalobos says pet owners should talk to their vet about the ways they can improve a pet’s life in each category. When pet owners approach end of life this way, they often are surprised at how much they can do to improve a pet’s quality of life, she said.

[Try Dr. Villalobos’s scale: Assess Your Pet: Is It Time to Say Goodbye?]

By revisiting the scale frequently, pet owners can better assess the quality of the pet’s hospice care and gauge an animal’s decline. The goal should be to keep the total at 35 or higher. And as the numbers begin to decline below 35, the scale can be used to help a pet owner make a final decision about euthanasia.

“Natural death, as much as many people wish it would happen, may not be kind and may not be easy and may not be peaceful,” Dr. Villalobos said. “Most people would prefer to assure a peaceful passing. You’re just helping the pet separate from the pack just as he would have done in nature.”

I discovered Dr. Villalobos’s scale as I was searching for answers for Fluffy in her final weeks. When she did get up, she often stumbled and seemed confused. Sometimes at night, I heard her whimper.

I had reached out to two at-home vet services, VettedPetCare.com and Instavet.com, that both offered compassionate guidance and confirmed my fears that no treatments were available to improve her condition. Fluffy was a very old dog, and they suspected her decline was a result of some combination of kidney and liver failure, but discouraged extensive testing since the physical symptoms were obvious. One visiting vet gave Fluffy subcutaneous fluids to help with dehydration and make her more comfortable and advised me to spend a final happy day with my dog before calling her for a final visit to end her suffering.

I trusted her judgment, but my tears and the fact that Fluffy still ate a little and wagged her tail when I stroked her clouded my thinking. I turned to the end-of-life scale and was able to see how poorly she was doing, despite the tail wag. I took my vet’s advice and spent a quiet day with Fluffy, giving her the cat food treats she so loved, without any scolding. I revisited the scale several times, just to remind myself that I was doing the right thing. The scale allowed me to make a more detached assessment of Fluffy, and it was a tremendous source of comfort during a very difficult time.

It wasn’t an easy decision or a pleasant one. But it was the right decision. And in the end Fluffy did drift away on her favorite soft pillow, just as I had hoped.