“Kitty Colds,” as they used to be referred to, are the sneezing, runny nose/eyes, cough, and fever that accompany upper respiratory infections (URI’s). Although there can be many viruses and bacteria associated with URI’s, the majority are caused by two highly contagious viruses: feline herpesvirus-1 (FHV-1) and feline calicivirus (FCV).
Another cause of feline respiratory disease is Chlamydophila (formerly Chlamydia). Because these disease agents cause overlapping clinical signs, they are often grouped together and termed the upper respiratory infectious disease complex.
All agents that cause feline infectious upper respiratory disease are contagious, but it is important to realize that in single cat households where Kitty is indoors only, they are at a low risk for contracting these diseases. To get this kind of infection cats must have exposure to an infected cat outdoors. As well if they have contact with a person who has handled a diseased cat, share the same litter box, toys, or food bowl with an infected cat, or are boarded in a facility where the agents occur they can be exposed that way. Young kittens, unvaccinated cats, feral neighborhood cats, and cats confined in catteries or shelters have the greatest risk of infection.
The FHV is susceptible to drying and most disinfectants will kill the virus. It can survive 18-24 hours outside the host animal. In contrast, FCV is a resistant virus and can survive outside the cat longer. Dilute bleach, or solutions designed to kill viruses can be used to disinfect the surfaces of contaminated cages, food and water dishes, and human hands. One interesting fact is that an infected cat can spread viruses and bacteria up to four feet away in the air just by sneezing and coughing!
Once cats have acquired an upper respiratory infection and recover, up to 80% are still contagious for months to years. Although these “carriers” will look normal, they can pass on the disease and serve as the main source for outbreaks when they are brought into close contact with other cats. Some cats get periodic flare ups of the infection later, especially if they become stressed or ill.
The FHV signs particularly like to keep coming back! Stresses such as surgery, boarding, or introduction of a new cat into the house may induce a return of the signs of upper respiratory illness. Shedding, or passage of virus into the environment is often triggered in mother cats at the time when the kittens are 5-7 weeks old, when they are losing the natural immunity acquired through their mothers milk. This means they acquire the disease at a time when their own immune systems are still immature. This is often why young kittens sold in pet stores or from shelters will look healthy, then after arriving home will come down with so-called “kitty colds.”
Most of the time, these infections are a nuisance but not life threatening. However, upper respiratory infections can be potentially serious. The FHV can lead to ulcers in the cornea (the clear coating surface) of the eye. Calicivirus can enter the cells of the lung, and attack the tongue, mucous membranes, and even occasionally the tip of the nose causing serious ulcers. Chlamydophila is most often associated with infections in the eye, but can sometimes spread and be serious.
If a cat is sick enough to stop eating and drinking, a stay at the hospital will be necessary. Supportive care is given while their immune systems fight the disease. Dehydration, copious nasal discharge, ulcers in the eyes or mouth, and a high fever may also occur so if Kitty is going downhill, drive to your vet sooner rather than later.
Most cats that need hospitalization are treated with fluids, either in the vein or under the skin. Although most cases of feline upper respiratory disease are viral in origin, antibiotics may be used as part of the therapy since even though these have no effect against viruses, they will act if bacterial invaders move in to take advantage of the weakened cat. E ye medications may be prescribed to help alleviate eye tissue inflammation (conjunctivitis) and corneal ulcers. Severe herpes ulcers of the eyes will require anti-viral eye medication. Recently, several new oral anti-viral and immune system stimulating drugs have been shown to help some severely infected kittens and cats. L-lysine (Enasyl-F™) is an example of this type of therapy.
One of the most important ways you can help manage feline upper respiratory infections is by appropriate vaccination. Feline panleukopenia/calicivirus and Chlamydophila vaccines may help reduced severity of signs.
It is important to remember that immunization protects against serious clinical illness, but not always an infection. It also does not prevent or eliminate chronic carrier statesso it won't help previously infected cats stop shedding the virus. Vaccines are started early, to protect those kittens who lose maternal protection quickly or whose mothers do not pass on adequate natural protection. Boosters are given a few times during the kitten’s early growth phase, then annually, or on a follow-up schedule determined to be appropriate for your cat’s lifestyle and risks.