Estrogen Treatments May Cause Hormonal Disruption in Pets

Pixie, a 15-month-old pug, was brought into a Florida veterinary practice with signs that she was in heat. Normally that may not be such a big deal, except Pixie had been spayed since she was 7-months-old.

Pixie's vet, Dr. Terry Clekis, had seen similar symptoms in other patients. And he's not the only one. Vets from across the country have been reporting on message boards at the Veterinary Information Network that they've been seeing spayed females and young puppies with swollen vulvas, and male dogs with enlarged mammary glands and abnormally small penises. The phenomenon had vets stumped, until they started to notice a pattern of these symptoms popping up in dogs whose owners used topical hormone replacement treatments.

Lotions, gels and sprays laced with estrogen are gaining in popularity, particularly among menopausal women, despite clinical trials that show an increased risk of breast cancer. Estrogen applied to the skin is absorbed more efficiently than estrogen in pills. There's also some concern about exposing others, like pets, through contact.

 What's even more frightening is a study from 2008, which showed detectable levels of estrogen products, not listed on the label, in over-the-counter moisturizers. These inadvertent exposures to estrogen have been raising cautionary flags for well over a decade in breast cancer patients, young girls, men ... and now, companion animals.

When a reporter contacted Dr. Cynthia Stuenkel, an endocrinologist at the University of California, San Diego, and president of the North American Menopause Society, she said this was the first she's heard of estrogen products causing hormonal disruption in pets. She made a few calls and found that none of her colleagues had heard of the problem either. But Stuenkel called the mounting reports from veterinarians "a potentially important finding," and she's talking with VIN about working together to create a formal registry to collect data to share with the Food and Drug Administration.

That collaboration is good news, because it could lead to helpful information for both human and animal health. The other good news is that this is easily preventable. Vets suspect the hormonal disruption was caused by pets licking their owners who had recently applied the lotions. Don't expose your pets to hormone products; if you use them, cover the skin where it was applied with clothing so your pet won't come into contact with the chemicals. These basic precautions apply to all topical medications and other chemical products you use around the house. If you wouldn't want a child trying to eat it, keep it away from your pets.

Photo credit: sneakerdog