Last year, a 13-year-old dog, let’s call her Petunia, started having trouble walking and controlling her bladder and bowels. Distressed, her owners bought a US$65 genetic test through a direct-to-consumer (DTC) company. It suggested that the pug carried a mutation that is linked to a neurodegenerative condition similar to the human disease amyotrophic lateral sclerosis (ALS, or motor neurone disease).

What published data there are suggest that as few as 1 in 100 dogs that test positive for this common mutation will develop the very rare disease, and Petunia’s condition was also consistent with more-treatable spinal disorders. But her owners chose to put her to sleep, convinced that she would otherwise suffer progressive and irreversible paralysis and eventual death.

Genetic testing for pets is expanding. Hundreds of thousands of dogs have now been genetically screened, as Petunia was, and companies are beginning to offer tests for cats. But the science is lagging. Most of these tests are based on small, underpowered studies. Neither their accuracy nor their ability to predict health outcomes has been validated. Most vets don’t know enough about the limitations of the studies, or about genetics in general, to be able to advise worried owners.

Pet genetics must be reined in. If not, some companies will continue to profit by selling potentially misleading and often inaccurate information; pets and their owners will suffer needlessly; and opportunities to improve pet health and even to leverage studies in dogs and cats to benefit human health might be lost. Ultimately, people will become more distrustful of science and medicine.

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