Voss: Reviewing rabies

Last week we reviewed vaccinations I recommend for pets here in the Roaring Fork Valley, leaving rabies for its own discussion. Rabies is a fascinating virus that ultimately hijacks its victim’s nervous system to help spread disease. It alters mental state and behavior, often inducing aggression that leads to biting the next victim.

Rabies is an RNA virus in the family Rhabdoviridae and is transmitted through saliva from the bite of an infected animal. Infection almost always causes fatal disease by attacking the central nervous system. Victims typically succumb within days of the first symptoms, which may include excessive drooling, difficulty swallowing, seizures and dramatic behavior changes.

It is important to note that there are several genetic variants of rabies that have adapted to different mammalian hosts. Dog, bat and other wildlife variants exist and are associated with specific geographic regions. Fortunately, as of 2007, North America is considered free of the dog-maintained rabies virus variant, which accounts for more than 95% of human rabies cases worldwide. Most rabies cases identified in Pitkin County are associated with the bat variant. However, dogs, cats and humans can be infected by any rabies variant, so we remain at risk despite the elimination of the dog-maintained strain from North America.

No one knows that better than Carlyn Porter, Pitkin County’s epidemiologist and emergency preparedness coordinator, who spends much of her time tracking animal bite reports and helping protect the public from rabies exposures.

According to Porter, Pitkin County has tested bears, a mountain lion, raccoons and dozens of bats for rabies after exposures involving humans or domestic animals. Last year, a bat tested positive after biting a person. Two bats also tested positive in 2023, prompting a public health advisory encouraging residents to take precautions and avoid wildlife contact.

This spring, Pitkin County has already received reports of bat activity. Porter notes that bats are the most likely rabies reservoir in our area, followed by foxes. Fortunately, skunk rabies has not yet reached this part of Colorado. Public health officials encourage residents to report exposures to any wildlife species that could potentially carry rabies.

Historically, positive rabies cases in our region have been relatively uncommon. However, as human population density increases and animal control efforts improve, public health officials are obtaining a clearer picture of local rabies risks. The bat population remains healthy and has not yet been significantly impacted by White Nose Syndrome, a fungal disease that has devastated bat populations elsewhere in North America.

There are strict protocols surrounding possible rabies exposure because the timeline, species involved and vaccination history all matter. Post-exposure recommendations depend on the species of the biting animal, the vaccination status of exposed pets and whether the animal responsible can be tested.

For wildlife exposures involving dogs or cats, with the exception of rodents and rabbits, your veterinarian will determine whether sufficient contact occurred to transmit rabies and assess your pet’s vaccination status. In the best-case scenario, the biting animal can be submitted for rabies testing, allowing veterinarians and public health officials to make informed recommendations. Unfortunately, the animal is not always available for testing. In those situations, quarantine periods may be required to ensure public safety. Depending on the circumstances, quarantine can range from 10 days to several months. 

Wildlife encounters are not as uncommon as many pet owners might think. During my shifts at the ER in Basalt last weekend, I treated multiple wildlife exposure cases, including a dog injured in a bear attack and another attacked by a coyote. While not every wildlife encounter results in rabies exposure, these incidents highlight why vaccination and appropriate follow-up are so important.

Dog bites are far more common than wildlife encounters and they also require rabies consideration. When a dog bites another dog, public health officials and veterinarians must verify the biting dog’s rabies vaccination status. If the biting dog is current on its rabies vaccine, it will typically undergo a home quarantine and observation period. If the biting dog is unvaccinated or overdue for vaccination, the requirements become much more stringent and may involve a lengthy quarantine at a licensed facility. Keeping pets current on their rabies vaccines not only protects them from disease but can also significantly reduce the stress, cost and restrictions associated with a bite incident.

It is equally important to keep cats up to date on rabies vaccination, even if they never go outdoors. Bats frequently roost in attics, garages, roofs and wall spaces. Their bites can be surprisingly difficult to detect, which may delay recognition of an exposure and increase the risk to both pets and people.

I learned this firsthand while living in Kansas during my master’s program. Ironically, I was studying infectious and zoonotic diseases while working in a rabies laboratory. The home I rented, unbeknownst to me, had a family of bats living in the walls and attic. Fortunately, my cat was current on his rabies vaccine. However, everyone living in the house had to undergo post-exposure prophylaxis, which consisted of four vaccinations over a two-week period.

The key takeaway is simple: vaccinating our dogs and cats against rabies matters. The overall risk of rabies exposure may be low, but the consequences are devastating. In the event of a true exposure, maintaining current rabies vaccination can save your pet’s life and significantly simplify the response for veterinarians, physicians and public health officials. As Porter reminds us, wildlife is best admired from a distance.

Dr. Kelly Voss is a veterinarian at Aspen Animal Hospital, where she practices small animal medicine and surgery. She has a background in emergency and critical care and is passionate about bringing high-quality veterinary care to the mountains. Have a question for the column? Email her at dr.kellyvoss@gmail.com.