Researcher looking at PFAS exposure in dogs, cats

Studies have linked these substances to adverse health outcomes in animals and humans

Evidence is mounting on the link between per-and-polyfluoroalkyl substances (PFAS) and adverse health outcomes in animals, including increased liver weight and size in dogs, reproductive delays in rodents, and possible respiratory disease in cats.

PFAS can be found in animals around the world, from fish and amphibians to horses and small mammals. This global threat affects more than 300 animal species.

Per-and-polyfluoroalkyl substances (PFAS), which are man-made chemicals that repel oil and water, are found in many everyday household items, including stain-resistant furniture.

Dr. Heather Bair-Brake, a public health veterinarian at Michigan State University College of Veterinary Medicine, talked about the hazards of PFAS and their potential impact on clinical practice in her session "Current Per- and Polyfluoroalkyl Substance Research Points to a Growing Threat in Animals" July 14 at AVMA Convention 2023. The presentation shares a title with a March 2023 JAVMA article that she coauthored.

PFAS, which are man-made chemicals that repel oil and water, have found widespread use in a variety of manufacturing processes and products, such as Teflon, stain-repellent fabrics, firefighting foam, and food packaging. Humans and animals can be exposed to the chemicals through contaminated air, water, soil, dust, and food.

Dr. Bair-Brake explained that exposed pets clear PFAS from their bodies within eight days to a couple of months, while humans may retain PFAS in their system for 10-12 years.

PFAS have been demonstrated in the serum, liver, kidneys, and milk of production animals and have been linked to changes in liver enzymes, cholesterol levels, and thyroid hormones in dogs and cats.

"What is particularly interesting to me as a veterinarian, though, is that there seem to be linkages between PFAS levels and hyperthyroidism in cats," Dr. Bair-Brake said.

PFAS use in humans has been linked to concerning health effects such as decreased fertility, increased cholesterol, decreased immune response, certain cancers, and changes in growth, learning, and behavior.

"The decreased immune response is something we have to look at as veterinarians because they're finding that children are not responding to vaccines as well as they have in the past," Dr. Bair-Brake said. "I wonder if we will see that with our animal patients."

Through her research project, PFAS in Pets, Dr. Bair-Brake intends to complete an exposure assessment of PFAS among dogs and cats living in the city of Parchment and the Belmont-Rockford areas of Michigan.

The results of this study will allow veterinarians to better identify and provide recommendations for patients exposed to dangerous levels of PFAS.

With 62.4% of Michigan households having at least one pet, Dr. Bair-Brake is exploring whether pets could be sentinels for human exposure to PFAS, particularly in contaminated sites such as those in Western Michigan. As it turns out, serum PFAS levels in dogs and cats are analogous to those found in their human counterparts.

As part of the PFAS in Pets project, veterinary personnel are visiting homes and collecting environmental samples from household dust and water bowls as well as blood samples from dogs and cats to compare with PFAS levels of people in the same home and surrounding area. Twenty households have participated so far.

The samples will undergo laboratory testing for PFAS, and blood samples will be tested for biochemical markers such as liver enzymes, lipids, and thyroid hormones.

"We're trying to figure out if blood chemistry levels in pets might be indicators that there is PFAS contamination in the household," said Dr. Bair-Brake, who also serves as associate director for communication for the Centers for Disease Control and Prevention's National Center for Environmental Health and the Agency for Toxic Substances and Disease Registry. "There is reason to believe that what we see in animals is going to be the same as what we see in people."

There are no treatments for humans or animals who have been exposed to PFAS.

"The best way to decrease PFAS exposure is to put drinking water filters on, and try to avoid items that contain PFAS," Dr. Bair-Brake said. "It is very challenging, but it is possible to try to reduce your PFAS levels."

Learn more about the ongoing PFAS in Pets study on the MSU veterinary college's website.

A version of this story appears in the October 2023 print issue of JAVMA