Seeing Clearly: Identifying New Causes and Treatments for Feline Conjunctivitis
By Alex Jimenez
It’s not uncommon for cats to develop cold-like symptoms such as sneezing, runny eyes and a cough, especially in shelters or other environments in which many cats are housed. These same signs can be caused by both bacteria and viruses, and appropriate treatment requires an accurate diagnosis of the cause.
In a Morris Animal Foundation–funded study at the Colorado State University Center for Companion Animal Studies, Dr. Michael R. Lappin sought to improve treatment of cats with conjunctivitis – inflammation of the tissues surrounding the eyes – by identifying the most common causes of this condition in shelter cats. “Conjunctivitis is an extremely common problem, and when considering the economic factor, it is really hurting the overall health of our shelters as well as the cats themselves,” explains Dr. Lappin.
Working closely with Dr. Cynthia C. Powell and Dr. Dara Zirofsky, Dr. Lappin and his team evaluated cats with and without conjunctivitis in two shelters. Cats were tested for the presence of feline herpesvirus-1 (FHV-1) and feline calicivirus (FCV), viruses thought to be common causes of conjunctivitis, and Mycoplasma and Chlamydophila, bacteria that have been associated with conjunctivitis. Surprisingly, the investigators detected the presence of FHV-1 in cats with and without conjunctivitis and were unable to detect the presence of FCV in either group. These results do not support the commonly held belief that these two viruses are responsible for the majority of conjunctivitis in cats. Equally surprising was the result that Mycoplasma was detected most frequently in cats with conjunctivitis but not in healthy cats.
The investigators also evaluated two treatments for conjunctivitis, namely, cidofovir, a new drug developed to treat conjunctivitis caused by FHV-1, and tetracycline antibiotic ointment, which is used to treat bacterial infections (Mycoplasma spp. and Chlamydophila felis). The study determined that cidofovir was well tolerated by the cats and was effective treatment in approximately 40 percent of cats with conjunctivitis caused by FHV-1. The study also determined that tetracycline antibiotic ointment was an equally effective treatment in cats with conjunctivitis of unknown cause (likely the result of conjunctivitis being caused by Mycoplasma). Results of this study indicate that veterinarians should consider first treating conjunctivitis of unknown cause with the less expensive antibiotic ointment and reserve treatment with the more expensive cidofovir for those cats that don’t respond to the initial treatment.
This research has added greatly to our knowledge about the most common causes of conjunctivitis and cost-effective treatments for the condition. “Our major objectives and hypotheses produced many valuable insights now available to veterinary health care providers,” Dr. Lappin says. “This information is likely to affect case management for many cats around the world.”
Powell CC, Veir JK, Radecki SV, Lappin MR, “Effect of Topical Ophthalmic Application of Cidofovir on Experimentally Indued Primary Ocular Feline Herpesvirus-1 Infection in Cats”, American Journal of Veterinary Research 2008; 69: 289-293
Posted by MAFon January 10, 2012. Permalink