A new journal article questions the public health benefits of programs that trap, neuter, vaccinate, and release feral cats to the areas where they were captured. Feral cats are estimated to number 60 to 100 million in the United States. A portion are managed under systems in which some percentage of the colony cats are trapped, neutered, occasionally given some level of vaccination, and then returned to the area in which they were captured. When vaccines are administered, they are known as trap-neuter-vaccinate-release (TNVR) programs.
The review article, “Rabies Prevention and Management of Cats in the Context of Trap-Neuter-Vaccinate-Release Programmes,” was published online in the scientific journal Zoonoses and Public Health. It will be published in print in the coming months. Authors represented the American Bird Conservancy, the Centers for Disease Control and Prevention (CDC), and the U.S. Department of Agriculture.
Specifically, the article said that “… TNVR programs are not effective methods for reducing public health concerns or for controlling feral cat populations. Instead, responsible pet ownership, universal rabies vaccination of pets, and removal of strays remain integral components to control rabies and other diseases.”
“Solutions are needed to address the growing feral cat population in the United States. Allowing populations of feral cats to persist in communities does not reduce public health problems related to feral cats. Any effective control program will need to be multifaceted and will likely need to include the removal of free-roaming cats. Most importantly, people need to be educated so they are aware of what it takes to be a responsible cat owner—this includes vaccinating, spaying or neutering, and preventing cats from roaming freely,” said CDC epidemiologist Jesse Blanton, the article’s corresponding author.
Rabies is a concern because cats can spread this deadly virus to people, especially children, as they are more likely than adults are to approach cats. The report cites dramatic shifts in the number of dogs versus cats that have rabies. In 1946, 8,384 dogs were found to be rabid compared to only 455 cats. In 2011, only 70 dogs were documented as being rabid compared to 303 cats. The article attributes the complete reversal in rabies incidence to relatively stringent control measures enforced on dog populations—much more stringent than control measures enforced on cat populations.
In North America, more than 90 percent of rabies cases in animals occur in wildlife. The primary reservoirs of rabies are bats, raccoons, foxes, and skunks. The interaction of feral cats with these wildlife reservoirs is of particular concern as unvaccinated cats pose a risk to transmit rabies to humans. A propensity to underestimate the risk of rabies from cats has led to multiple large-scale rabies exposures.
On the issue of vaccination, the report said “… maintaining adequate rabies vaccination coverage in feral cat populations is impractical, if not impossible. Therefore, these populations [of feral cats] must be reduced and eliminated to manage the public health risk of rabies transmission.”
Most cats in managed feral cat colonies are only trapped and vaccinated once in their lifetimes, which may not offer lifetime protection from rabies, the article says. As a result, trapping and vaccination rates do not reach a sufficient proportion of the population to establish and maintain herd or colony immunity over time. The article also cited a lack of consistent, verifiable documentation of vaccination for colony cats.
Group-feeding of cats by colony caretakers was cited as a problem on several levels. Those actions put cats at greater risk for contracting diseases since transmission is augmented by increased animal density and contact rates among cats. Group feeding also puts wildlife at increased risk of contracting diseases, such as toxoplasmosis, since wild animals might be attracted by the food. A 2011 study found one-third of raccoons and opossums that associated with feral cat populations were infected with toxoplasmosis.
The article called into question claims that feral cat colony management reduces the number of stray cats, based on evidence that colony populations might actually “… increase in response to supplemental feeding.”
Feral cat effects on native wildlife species were described as “profound,” citing numerous examples of studies that illustrated diminished wildlife populations in cat colony areas yet no decreased populations of pest animals, such as house mice.
Additionally, the article said “feeding of feral cat colonies sustains their populations, and it likely subjects them to increased disease transmission ... [it] does not adequately meet feral cat population control needs that public health and animal welfare necessitate.” It indicated that feral cat population control methods be determined with input from all stakeholders with a wide range of interests.
The closing point of the report was succinct, saying that: “… requirements for rabies vaccination and prohibitions against free-roaming should be applied to cats as they are generally applied to dogs.”
The authors go on to say that humane, ethical, and financial concerns and scientific-based approaches must be considered to solve the problem. Control programs must also address responsible pet ownership, spaying and neutering, and decreased abandonment of unwanted cats. These steps could help to the control of feral cat populations and the cross-species transmission of zoonotic diseases, including rabies.
CDC does not currently have an official position on trap-neuter-vaccinate-release. The American Veterinary Medical Association (AVMA) neither endorses nor opposes properly managed cat colony programs. Presently, AVMA strongly supports reducing the number of unowned free-roaming abandoned and feral cats through humane capture (with placement in homes where appropriate) by local health departments, humane societies, and animal control agencies.