Ron Hines DVM PhD 9/14/07

Please also read:

http://www.2ndchance.info/respiratorydiscat.htm
http://www.2ndchance.info/rhinotracheitis.htm
http://www.2ndchance.info/cough.htm and http://www.2ndchance.info/cornealulcer.htm and http://www.2ndchance.info/sneezing.htm

Two of the most common infections of cats are Feline Herpes-1 virus (which is also called rhinotracheitis virus) and infection with the organisms, Chlamydia psittaci and mycoplasma. When these organisms first infect cats they result in generalized upper respiratory infections with fever, weepy eyes, crusty nose and sneezing (see article: Respiratory Infections In Your Cat). These infections clear up after a few weeks with or without treatment, and most cats are never again bothered with the problem. A small percentage of cats infected with Herpes virus 1, however, become chronic carriers of the virus and relapse from time. In most cats, these relapses are limited to nasal drainage or sinusitis. In some, relapses occur in the eyes with periodic drainage, inflammation and the formation of rounded milk white corneal scars. The condition is then called Infectious Feline Keratoconjunctivitis. Between episodes, this virus resides in the nerves of the face. Corneal scars range in size from pinpoint to over a centimeter in diameter. Herpes-1 of cats is similar to herpes simplex, the causes of fever sores in humans, in that both these viruses live in the nerves and relapse during periods of stress. During relapse cats tend to hold their eye(s) partially shut. Usually these flare ups are associated with the stress of boarding, weather change, other disease or new cats in the family. During this period the outer coating of the cornea is lost to the invading virus. Secondary bacterial and mycoplasmal infection of these areas can lead to deep ulcers of the cornea and occasionally to eye-threatening penetration of the eye itself. There are non-infectious conditions that mimic this disease. These include allergic and eosinophilic conjunctivitis and sensitivity to eye medications, environmental irritants and trauma. Cats rub eyes that itch for any reason and the result can be corneal tears and scrapes. Diseases that increased ocular pressure (glaucoma) and inflammation of the forward chamber of the eye (uveitis) can also cause damage and scaring of the cornea. Persian cats are susceptible to dry eyes, which also cause corneal ulcers.

Treatment:
Diagnosis of Herpes-1 eye infection based on gross examination of the eye is difficult. We often do so only by ruling out other causes. So we often medicate these eyes with a number of agents that are effective against secondary invaders like mycoplasma and chlamydia but not against Herpes-1.

The amino acid, l-lysine, has been found to help many cases of rhinotracheitis resolve. This amino acid reduces the amount of another amino acid, arginine, that is present in the cat's body. Arginine is thought to be necessary for herpesvirus to reproduce. The suggested lysine dose is 250-500 mg per day sprinkled on canned cat food. I would give this suplement until the acute flare-up has resolved. But many cat owners continue the suplement indefinitely. Lysine can be purchased at health food stores. Pick a brand that is propylene glycol-free.

Eosinophilic keratitis (corneal inflammation) is diagnosed by staining a preparation of corneal cells. Treatment of that condition utilizes corticosteroid eye drops. Eye irritation due to environmental contaminants and allergies also respond well to corticosteroids. If steroids are given to Herpes-1 carrier cats the problem can actually get worse. Dry eyes are diagnosed with a test (Schirmer tear test) that gauges the amount of tears that are produced. Cats that are squinting should have their eyes stained with fluorescein dye. This allows us to see early corneal ulcers and gauge their depth. Deep ulcers sometimes need a temporary emergency corneal patch. I have found that Herpes-1 cats respond better to simple T.L.C. than to all the medications I can dispense. Since I am never one hundred percent certain which agents are involved I put all these cats on Tetracycline (Terramycin) or chloramphenicol ophthalmic ointment. Although this does not affect the virus, it does eliminate secondary bacterial infections. If the condition does not begin to resolve within two weeks, I place the cats on trifluorothymidine (Viroptic) eye drops or Trifluridine eye ointment. Because both these products can irritate the eye I give the body’s own immune system time to eliminate the virus on its own before resorting to these medications Chicken soup is an excellent first-line treatment for Herpes-1 virus. It can be fed through a dropper if need be to prevent dehydration and tempt depressed cats and those with eye problems into eating. Sometimes pungent foods like sardines and tuna will be accepted when all else fails.

Prevention:
A portion of the cats that have this problem test positive for feline leukemia or feline immunodeficiency virus. When these have been ruled out, lowering the stresses in a cats life is the best preventative. Some of these cats do much better in a single cat family. Diets rich in vitamin A may also decrease the frequency and severity of relapses. Good vaccines are available to prevent this disease. I give them to kittens at 9, 12 and 14 weeks of age. The problem is that many kittens are already infected with herpes-1 virus before they leave their mothers and come to see me. The stress of pregnancy, and more so nursing, causes these carrier mothers to relapse and infect their kittens. Many cats from shelters are in the middle of a relapse infection when I first see them. In these instances the vaccines will not work. Until recently, vaccinations were given yearly to cats in the United States. There is evidence that rhinotracheitis and Calicivirus vaccines do not need to be given that frequently. When they are given they should be administered through 25-guage needles on the anterior side of a rear leg and the injection site should then be vigorously massaged. This may decrease the very rare instances where tumors forms at injection sites in cats.

Recently, an article reported that 58% of cats with uveitis or inflammation of the anterior portion of the eye,51% of cats with conjunctivitis and 86% of cats with chorioretinitis (inflammation of the retina) as well as 75% and 58% respectively of cats with keratitis and corneal ulcers respectively, were positive for Bartonella. This would make Bartonella one of the most common causes of eye inflammation in the United States. This condition responded well to treatment with Doxycycline (5mg/pound twice a day for 6 weeks) azithromycin (5mg/pound once a day for 21 days) or rifampin (5mg/pound once a day for 21 days). When using doxycycline capsules one must follow the capsule administration with a considerable amount of water to keep the capsule from lodging in the esophagus. Journal of the American Animal Hospital Association pages 6-12 January/February 2004.

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