Antiviral medication for feline herpes accelerates recovery in kittens with upper respiratory disease

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A new clinical study from the UC Davis School of Veterinary Medicine found that famciclovir, an antiviral medication for feline herpes, speeds up recovery in kittens suffering from infectious upper respiratory disease (IURD) and may help mitigate corneal disease in some kittens.¹

“…IURD is a common and major health problem for kittens worldwide, especially those housed in multi-cat environments, such as animal shelters, rescue groups and breeding catteries,” wrote the study’s authors.²

The main pathogens responsible for IURD in cats are feline herpesvirus type 1 (FHV-1), feline calcivirus (FCV), Chlamydia felis, Bordetella bronchiseptica and Mycoplasma felis.² In environments with multiple cats, methods like quarantine, reduced crowding, and vaccination are used to control IURD. However, these have their drawbacks, as quarantining can take up time, resources, and space; and reduced crowding may call for revisions in shelter policies related to animal admissions and euthanasia. Additionally, kittens aged less than 4 weeks may face challenges when it comes to vaccinations, as vaccinations are generally not recommended for feline patients less than 4 week of age.²

Another treatment method for IURD is the antibiotic doxycycline, which is frequently prescribed due to its effectiveness against C felis, M felis, and B bronchiseptica, along with several other typical respiratory bacterial infections.² According to the study’s authors, this antibiotic is often favored over azithromycin and topical treatments specifically for C felis.²

The study by UC Davis researchers explored the effects of adding famciclovir to doxycycline in a cohort of 373 kittens suffering from ocular disorders linked to IURD. The kittens were divided into 3 age groups and categorized based on the severity of their condition—mild or severe.

Over a 3-week period, the kittens were randomly assigned to receive either doxycycline along with a placebo or doxycycline in combination with famciclovir. Results indicated that kittens with mild disease who received famciclovir achieved full recovery 4 to 5 days sooner than those treated with doxycycline alone. Moreover, fewer kittens receiving famciclovir developed corneal disease.

The study's large sample size may also pave the way to further research opportunities, according to a university release.¹ “Because we had so many kittens and looked at their growth every day, we noticed potential for side projects,” Karen M Vernau, DVM, DACVIM (Neurology), lead author of the study, said in the release. “Some of these kittens had hypothyroidism, ringworm, and other conditions we can study.”

In the release, Vernau commended the Orphan Kitten Project, which is run by veterinary students at UC Davis, and YOLO County SPCA for taking initiative to maintain the project on foot during the COVID-19 pandemic when shelters’, rescues’, and fosters’ ability to care for animals was affected.¹

“With many shelters closed during that time, those two groups did a tremendous amount of work caring for an overabundance of homeless kittens,” expressed Vernau in the release.¹ “This clinical trial could have easily been shut down, but the school’s partnerships with these rescues, as well as animal-focused organizations like Maddie’s Fund and the Orphan Kitten Club, were paramount in completing this study. I’m so proud of these teams working together to make it happen.”

References

1. Min E. Antiviral discovered to speed recovery and reduce corneal disease in kittens with herpesvirus. News release. UC Davis School of Veterinary Medicine. November 1, 2024. Accessed November 4, 2024. https://vetmed.ucdavis.edu/news/antiviral-discovered-speed-recovery-and-reduce-corneal-disease-kittens-herpesvirus#:~:text=A%20recent%20clinical%20trial%20conducted,upper%20respiratory%20disease%20(IURD).
2. Vernau KM, Kim S, Thomasy SM, et al. Doxycycline with or without famciclovir for infectious ophthalmic and respiratory disease: A prospective, randomized, masked, placebo-controlled trial in 373 Kittens. Journal of Feline Medicine and Surgery. 2024;26(11). doi:10.1177/1098612x241278413