How Long Will Your Pets Live, and What Can They Tell Us About Human Lifespan?

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Domesticated animals may be an under-explored source of data for understanding human disease. In 2017, there were close to 95 million domestic cats and 90 million domestic dogs in the US. These animals live in the same environments as their human owners, receive comparable medical care and have detailed medical data available. Consequently, companion animals could help us to study some aspects of human health.

Here, a study of vetinary data for just under 21 000 dogs in the US investigated the factors that influence lifespan. They were funded in part by the Dog Ageing Project, which seeks to use veterinary data from dogs to benefit both dog and human health. Unsurprisingly considering previous findings, smaller dogs tended to live longer:

Perhaps more interesting was the effect of neutering on lifespan. Both males and females that were neutered had extended lifespans, but females benefited more. The researchers realised that there were two confounding factors at play here. Firstly, animals that were neutered must have at least lived to the age of neutering, which would lead to an apparent increase in average lifespan. Secondly, owners that get their animal neutered are more likely to take better care of their pets in general than those who do not. However, even taking these factors into consideration, neutered females still lived significantly longer than their intact counterparts:

Other studies suggest cats’ lifespans are also extended by neutering, although the male/female relationship may be reversed compared with dogs.

The purebred status of a dog did not appear to have a significant effect on its lifespan, but its genetic ancestry did. Dogs can be divided into five ancestral groups based on DNA analysis, and it appears that purebred dogs belonging to the Mountain group have significantly shorter lifespans compared with purebred dogs of other ancestral origins:

In contrast, crossbred cats appear to live longer than purebreds by an average of 0.6 years, while lifespan also varied substantially between purebred cats:

The authors behind the study in dogs suggest that some of this data could be relevant to human health:

We argue that epidemiological data from veterinary practice such as these can also be correlated with data from human epidemiology from the same areas, which may prove useful in establishing the privately owned dog as a model organism for human epidemiology […]

Urfer, S., Kaeberlein, M., Promislow, D., & Creevy, K. (2020). Lifespan of companion dogs seen in three independent primary care veterinary clinics in the United States. Canine Medicine And Genetics, 7(1). doi: 10.1186/s40575-020-00086-8