More than 90% of pet owners think of their dog or cat as a member of their family, according to a 2015 Harris Poll. While that close bond makes pets a boon to human happiness—and even, in many cases, to mental health—it can also come with a downside. New research suggests that when people care for ill pets, they have more depression, anxiety and caregiving distress: symptoms that are similar to how people report feeling when caring for sick relatives, the study authors say.

In the new study, published in the journal Veterinary Record, researchers surveyed 238 owners of dogs or cats. Half of the animals were healthy, and half had a chronic or terminal illness. Pet owners were asked to fill out an online survey about how taking care of a pet affects them.

Owners of sick animals reported a significantly higher caregiver burden—a condition people encounter when they’re providing informal care for a sick family member—than those with healthy pets. Sick-pet owners also reported higher stress, anxiety, symptoms of clinical depression and a lower quality of life than owners of healthy pets, and all of these measures were closely linked to the caregiving burden.

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Depression was an especially pronounced problem for these pet owners. Depressive symptoms were even worse for people who belonged to pet disease social media groups, which the researchers say could indicate the members were seeking support for their distress.

The people in the study were mostly white, female, highly educated and in a relatively high socioeconomic class, and the results could be skewed just because those who filled out the online survey may have chosen to do so because they were interested in their relationship with their animal. More research is needed to explore how different groups of people interact with their pets. The researchers note, however, that this group may be representative of people who would choose to keep an animal with a chronic or terminal disease despite the emotional and financial costs.

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This is one of the first studies to look at whether owners of sick pets experience caregiver burden, and more research is needed. But in the meantime, the researchers say their findings can help veterinarians respond to clients whose animals have serious diseases. If veterinarians understand the burden their clients with sick pets are feeling, they may have a better appreciation for their perspective, the researchers write, and this may enhance empathy and communication.

The researchers recommend that further studies explore potential ways to reduce the caregiver burden in pet owners—including some that work in human relationships, such as problem-solving training and taking breaks from caregiving. If veterinarians and their clients are aware of this burden and can talk about possible solutions, the researchers say it could help the health of people caring for ill pets.

Write to Abigail Abrams at abigail.abrams@time.com.