|Feline Upper Respiratory Infection
Oral or nasal ulcers
Despite the highly contagious nature of all the feline upper respiratory agents, it is important to realize that
most cats are at small risk for exposure. In other words, in order to get this kind of infection, a cat must be in
the same home as an infected cat or share the same human caretaker, toys or food bowls. Typically, infected
cats come from the shelter, are outdoor cats, or are housed in close contact with lots of other cats
(experiencing crowding stress). Persian cats are predisposed to upper respiratory infection due to their
inherent facial flattening. The average house cat who is not exposed to any rescued kittens, lives with only
one or two other cats at most, and never goes outside is unlikely break with infection. Kittens are
predisposed due to their immature immune systems and are usually hit the hardest.
The chief infectious agents that cause feline upper respiratory infections are: herpesvirus and calicivirus,
together accounting for about 90% of infections. Other agents include: Chlamydophila, Mycoplasma,
Bordetella, and others. Of course, a cat or kitten may be infected with more than one agent.
Viruses are spread by the wet sneezes from infected or carrier individuals. The herpesvirus is fragile, surviving
only 18 hours outside its host; calicivirus is tougher, lasting up to 10 days. Bleach will readily inactivate either
virus but calicivirus is able to withstand unbleached laundry detergents.
Course of Infection
To some extent, the combinations of symptoms and course of infection is determined by which of numerous
infectious agents is responsible. Ninety percent of feline upper respiratory infections are caused by either
feline herpes (also called the rhinotracheitis virus) or feline calicivirus. Neither of these infections is
transmissible to humans or to other animals.
Most feline colds run a course of 7 to10 days regardless of treatment but it is important to realize that these
infections are permanent and that herpesvirus infections are recurring (a property of all types of herpes
infections). In kittens, herpes infections are notorious for dragging out. Stresses such as surgery (usually
neutering/spaying), boarding, or introduction of a new feline companion commonly induce a fresh herpes
upper respiratory episode about a week following the stressful event and the active virus sheds for another
couple of weeks. These episodes may recur for the life of the cat, although as the cat matures, symptoms
become less and less severe and ultimately may not be noticeable to the owner. Cats infected with calicivirus
may shed virus continuously, not just in times of stress, and may do so for life, although about 50% of
infected cats seem to stop shedding virus at some point.
A cat with herpes is contagious to other cats for a couple of weeks after a stressful event. Cats infected with
calicivirus are contagious for several months after infection but do not appear to have recurrences the same
way cats with herpes do.
When to be Concerned
SIGNS A CAT REQUIRES HOSPITALIZATION
Loss of appetite Congestion with open mouth breathing High fever (or the extreme listlessness that implies a
high fever if you cannot take the cat’s temperature).
A cold for a cat is usually just a nuisance like a cold usually is for one of us. Sometimes, though, an upper
respiratory infection can be serious. If a cat is sick enough to stop eating or drinking, hospitalization may be
needed to support him or her through the brunt of the infection. A cat (usually a kitten) can actually get
dehydrated from the fluid lost in nasal discharge. Painful ulcers can form on the eyes, nose or in the mouth.
Sometimes fever is high enough to warrant monitoring. In young kittens, pneumonia may result from what
started as an upper respiratory infection.
If you think your cat or kitten is significantly uncomfortable with a cold, you should seek veterinary assistance
with an office visit.
How is this Usually Treated?
Since 90% of cases are viral in origin and we have no antibiotics against viruses, it seems odd that most feline
upper respiratory infections are treated with anti-bacterial medications. The reason for this is that it is
common for these viral infections to become complicated by secondary bacterial invaders. The antibiotics act
Occasionally infections can lead to more chronic symptoms, such as gingivitis (gum inflammation),
conjunctivitis, or nasal congestion.
What are the Vaccination Options?
The Vaccine we use is for distemper, herpesvirus, calicivirus, Chlamydophila felis and Hemorrhagic
A Few Words about Hemorrhagic Calicivirus
A particularly virulent strain of calicivirus, commonly referred to as hemorrhagic calicivirus, has appeared to
pop up out of nowhere. While few outbreaks have been reported, it is possible more have occurred and
gone unrecognized. Hemorrhagic calicivirus is highly contagious and rapidly fatal. A vaccine called Calicivax
is available from Fort Dodge Animal Health just for this form of calicivirus. The Vaccine we use includes the
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