Note to Reporters: Photos of wild and domestic cats captured for the study are available by contacting Dell Rae Moellenberg.
Colorado State University scientists have evidence that domestic cats, bobcats and pumas that live in the same area share diseases – and may bring them into family homes, according to results of an unprecedented study of what happens when big and small cats cross paths.
The study provides evidence that domestic cats and wild cats that share the same outdoor areas in urban environments can also share diseases such as bartonellosis and toxoplasmosis, both of which can be spread from cats to people. The study looked at urban areas of California and Colorado and shows that these diseases can spread through contact with shared habitat and how the diseases can be clustered due to urban development and major freeways that restrict animal movement.
“These results are relevant to the big picture of domestic cats and their owners in urban areas that are frequented by wild cats such as bobcats and pumas,” said Sue VandeWoude, a veterinarian at Colorado State and co-leader of the project. The study was conducted jointly in the College of Veterinary Medicine and the Warner College of Natural Resources.
“The moral of this story is that diseases can be transmitted between housecats and wildlife in areas they share, so it’s important for pet owners to keep that in mind.”
Initial results of the multi-year study were published the most recent issue of PLoS One, a scientific journal, and in a recent edition of the Journal of Molecular Ecology.
The researchers tracked whether or not wild and domestic cats in several regions of Colorado and California had been exposed by looking for antibodies in their blood. The massive, multi-year effort includes data comprised of 800 blood samples from felines of all sizes, including 260 bobcats and 200 puma, which were captured and released, and 275 domestic cats.
“As human development encroaches on natural habitat, wildlife that reside there may be susceptible to diseases we or our domestic animals carry and spread,” said Kevin Crooks, a professor in the university’s Department of Fish, Wildlife and Conservation Biology who is a co-leader on the project. “At the same time, wildlife can harbor diseases that humans and our pets can get. This all means that diseases may be increasingly transmitted as formerly natural areas are developed.”
The project also looked at whether bobcats in Southern California were segregated into different populations by major highways. By looking at genetic and pathogen data, they found that bobcats west or east of Highway 5 south of Los Angeles rarely interbred, but that they did cross into each other’s territory often enough to share diseases, such as FIV.
“The evidence suggests that bobcats are moving across major highways but are not able to easily set up new home territories. They can, however, spread diseases to one another when they cross into each other’s territory,” VandeWoude said. “This could result in inbreeding of the bobcats trapped by urban development —and the spread of diseases.”
VandeWoude and Crooks both say that the study doesn’t necessarily mean that all domestic cats that are allowed to roam outdoors are doomed or at a high level of risk, and they plan further studies to better assess that risk. It does mean that domestic cats and wild cats who share the same environment – even if they do not come into contact with each other – also can share diseases.
The study involved collaboration with field biologists, federal and state agencies, animal shelters and other institutions.
The findings show that pumas were more likely to be infected with feline immunodeficiency virus – or FIV – than bobcats or domestic cats. While FIV cannot be transmitted to people, it is highly contagious among felines. The rate of toxoplasma gondii was high in pumas and bobcats across Colorado and California. All three diseases that the group looked for – toxoplasma, bartonella and FIV, were present in each area.
Toxoplasma gondii is a parasite that, when carried by healthy people, has no impact but can cause complications for infants and people with a compromised immune system. Cats only spread toxoplasma in their feces for a few weeks following infection with the parasite. Like humans, cats rarely have symptoms when first infected.
Bartonella is a bacterial infection that also is sometimes called cat scratch disease. If a person is scratched by a cat with bartonella, the scratch may become infected – usually a mild infection.
The comprehensive study is funded by the National Science Foundation.