Dr. Karyn Bischoff chairs the AVMA Committee on Environmental Issues. She is a veterinary toxicologist and a senior extension veterinarian at the Cornell University College of Veterinary Medicine. Dr. Bischoff shared her insights about the application of veterinary medicine to environmental health and some of her committee's work with JAVMA News via email.
How do you see veterinary medicine coming into play with the environmental sciences?
Veterinarians can use environmentally friendly practices in their local environments by recycling when possible and disposing of drugs and biological wastes appropriately.
Veterinarians who work in agriculture can contribute by giving environmentally friendly advice on waste management and carcass management. Manure runoff can contribute to high nitrates and nitrites in the water system, and to nutrient overload in aquatic ecosystems, which could contribute to harmful algal blooms and oxygen depletion.
Veterinarians working in agriculture can contribute further by encouraging wildlife-friendly practices; for example, in Africa, they are protecting cheetahs by providing herding dogs for livestock protection. Clinical veterinarians can contribute by judiciously using drugs, which end up in animal waste and carcasses, and helping clients dispose of them in an environmentally friendly way. Improper disposal of carcasses has killed wildlife and domestic animals through barbiturate poisoning, and in these cases, the veterinarians are legally liable. Manure from animals that have been recently dewormed can kill environmentally important invertebrates. Also note that veterinary use of diclofenac in cattle caused the near extermination of vultures in parts of Asia.
Veterinarians who work with fish farms have recently become more important in promoting animal health while decreasing the risks associated with animal waste and antibiotic use. Veterinarians have recently become more important to apiaries, and bees are important pollinators.
Veterinarians are working with state departments of environmental conservation to manage wildlife populations.
Veterinarians work in public health, solving environmental problems that affect domestic animals and humans. Domestic animals are great sentinels for things that affect humans. I have consulted in cases of lead poisoning where we found an environmental source that was also affecting the human owners of the animals. And I have consulted in cases where I suspected carbon monoxide poisoning in companion animals and have recommended that the fire department inspect the homes.
Veterinarians are making policy at the state and national levels through the Department of Agriculture, Food and Drug Administration, and other organizations that promote environmentally sustainable food production.
Give a few examples of relevant policy issues the CEI has discussed.
One example is feral cats. The CEI spent a lot of time on this issue because it's so multifactorial. Feral cats can act as midlevel predators in ecosystems, so they can damage populations of small animals, including mammals, birds, amphibians, and reptiles. However, they also control rodent populations, which has implications for human health when it comes to spread of diseases like hantavirus pulmonary syndrome, Lyme disease, and leptospirosis, though on the other hand, they can carry zoonotic diseases. For example, unvaccinated cats can transmit rabies from wildlife to humans. So, we have to balance all of these issues and come up with ways to manage feral cats, minimize wildlife damage, and prevent zoonotic disease, but also be humane and aware of the contributions the cats make to human communities.
We recently worked on a policy statement on lead poisoning, which is a major and predominantly anthropogenic problem affecting wildlife, domestic animals, and people.
We have been working toward a better understanding of harmful algal blooms and the role of veterinarians in preventing and controlling them and treating affected patients.
We have been discussing the role of veterinarians in preventing colony collapse disorder in bees.
How does climate change factor in?
Climate change is most likely increasing the risk for harmful algal blooms since most of these blooms prefer warmer temperatures.
Climate change is expected to change patterns of certain infectious diseases, in particular, vector-borne diseases, by changing the geographic range of insect vectors. Climate change is going to change the range of wildlife as well, and many endangered species are likely to have difficulty adapting successfully, so the need for health management in these species will only increase. I know some veterinarians who are doing work on recent moose declines in the northeastern U.S., for example, which are likely to be associated with increased parasitism due in part to milder weather.
Climate change will probably affect mold growth on grain and forage, thus it could increase mycotoxin production and affect feed costs for livestock. Certainly, we've had wet weather and droughts that have affected crop quality, and drought can actually increase nitrates in certain plants, which can increase the risk of poisoning in ruminants.
Extreme weather events are going to become more important, so veterinarians are likely to be called upon to protect domestic animals and wildlife affected by hurricanes, floods, fires, and other major disasters.