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DENVER/May 28, 2020 – Shelter cats could soon benefit from a new treatment protocol for painful eye infections caused by  feline herpesvirus (FHV-1). Morris Animal Foundation-funded researchers at Louisiana State University are conducting a clinical trial of three common antiviral drugs to determine which drug is best to treat the disease in animal shelters. Results of the study should help veterinarians more effectively treat this widespread, potentially blinding condition in the cat population.

“This virus can be debilitating, with outcomes pretty variable from cat to cat,” said Dr. Andrew Lewin, Assistant Professor at Louisiana State University’s School of Veterinary Medicine and principal investigator on the study. “We want to be able to make a meaningful recommendation for veterinarians to improve the welfare of these animals.”

Feline herpesvirus is a highly contagious virus in cats usually transmitted through sneezing or grooming. Like many herpesviruses, FHV-1 can infect cells and remain dormant indefinitely, often referred to as a latent infection. Because most cats have latent FHV-1 infections, many will have severe issues at some point in their lives. Afflicted cats can present with respiratory issues and discharge from their noses and eyes. In extreme cases, it can cause corneal scarring and loss of vision as well as chronic upper respiratory disease.

Shelter cats are one of the most at-risk groups for FHV-1 infections because of their high population density and close living quarters. A cat infected by FHV-1 is less likely to be adopted which in turn increases their risk of being euthanized. Previous studies using antivirals in shelter cats with FHV-1 have produced mixed results.

Dr. Lewin is taking a different approach. His study will look at more than 120 cats from animal shelters in the Louisiana area that have evidence of FHV-1 eye infections. They will be divided into four groups, each of which will receive one of three currently available antivirals (cidofovir, ganciclovir and famciclovir) or a placebo. After a week of treatment, researchers will use a scoring system to see if the cats’ eyes have improved. The team also will take eye swabs before and after treatment to measure each antiviral’s efficacy.

Next, the team will try and assess if the virus develops a resistance to the antivirals, similar to antibiotic resistance demonstrated by bacteria. Researchers will test this by swabbing the cats’ eyes and growing the virus in a lab, in the presence of an antiviral. If the virus continues to grow, that could indicate it has resistance. Researchers also will use a DNA sequencing technique to look specifically at the regions of the virus genome which would mutate if resistance developed.

Since many afflicted cats also suffer from secondary bacterial infections in their eyes, the team will sequence the DNA of any bacteria isolated from affected cats to determine if the type of bacteria present is related to response to therapy. This will help researchers assess the impact of secondary bacterial infections on the outcome of the FHV-1 infection.

“Feline herpesvirus is a huge welfare issue for shelter cats and it is important that we find a viable method to address it,” said Dr. Janet Patterson-Kane, Morris Animal Foundation Chief Scientific Officer. “We want all animals to have a chance at a full, healthy life and, because this virus has such an impact on adoptability, a study like this could do wonders for cats waiting for a permanent home.”

Morris Animal Foundation, headquartered in Denver, is one of the largest nonprofit animal health research organizations in the world, funding more than $155 million in studies across a broad range of species.

About Morris Animal Foundation

Morris Animal Foundation’s mission is to bridge science and resources to advance the health of animals. Founded by a veterinarian in 1948, we fund and conduct critical health studies for the benefit of all animals. Learn more at