The great majority of feline respiratory disease results from two easily transmitted infections, feline viral rhinotracheitis (FVR), caused by a hepesvirus, and feline calicivirus (FCV, pronounced kah-LEE-see virus) infection. FVR and FCV infection result in similar illnesses, characterized by nasal and ocular discharge, conjunctivitis, ulcers of the oral cavity, anorexia, depression and inflammation of the upper respiratory tract. Cats usually recover in 1 to 2 weeks, although cats with FVR can become persistently infected after returning to normal, shedding the virus during periods of stress. FVR can result in abortion of infected fetuses. Kittens are at greatest risk of FVR and FCV because they usually have had no prior vaccination or exposure and are highly susceptible to infection. Chlamydia psittaci (klah-MID-ee-ah SIT-ah-kye) bacteria are a less common cause of feline respiratory disease, but can increase the severity of FVR or FCV infection. Vaccines are available for FVR, FCV, and Chlamydia psittaci.
What is feline herpesviral conjunctivitis?
Conjunctivitis is a medical term used to describe inflammation of the tissues
surrounding the eye. These tissues include the lining of the lids and the third
eyelid as well as the tissues covering the front part of the eye or globe. Conjunctivitis
may be a primary condition (caused by an infection) or may be secondary to an
underlying systemic or ocular disease.
Feline herpesviral conjunctivitis is a form of primary conjunctivitis caused by the highly infectious feline herpesvirus (FHV-1). Herpesvirus infection is common in cats and is the most common cause of conjunctivitis in cats. Many cats are infected with FHV-1 and do not show any signs of clinical illness (i.e. they have a latent infection). Fortunately, less than 45% of adult cats with latent herpesvirus infection develop recurrent ocular disease such as conjunctivitis. In most cases, herpesvirus conjunctivitis is self-limiting and will resolve within two weeks.
What are the clinical
signs of feline herpesviral conjunctivitis?
The most common clinical signs of conjunctivitis are squinting or closing of
the eye, red, swollen tissue surrounding the eye and eyelids, ocular discharge
that may range from clear to yellow-greenish in color, and upper respiratory
infection symptoms such as sneezing or nasal discharge. These signs often appear
suddenly and are especially common after stressful situations such as travel,
boarding, surgery or illness. Chemosis, a condition in which the membranes that
line the eyelids and surface of the eye appear to have fluid in them, is more
commonly associated with chlamydial infections.
What diagnostic
testing is indicated for feline herpesviral conjunctivitis?
Diagnosis is based primarily on medical history and physical examination. Corneal
staining is often performed to look for any ulcers that may have developed.
Identification of feline herpesvirus DNA by polymerase chain reaction amplification
(PCR testing) is the most sensitive test available for diagnosing infection
by FHV-1. Unfortunately, diagnostic testing is usually not rewarding during
times of viral latency or in the absence of clinical signs. Since decreased
tear film production has been associated with FHV-1 conjunctivitis, specific
tests to assess the tear production may be recommended.
What is the treatment
for feline herpesviral conjunctivitis?
Treatment is determined by your cat’s specific clinical signs and problems.
It is important to remember that these infections are usually mild and self-limiting.
However, if there are corneal ulcers, it is important to treat these appropriately.
The following is a list of common treatment regimens used in treating recurrent
feline herpesviral conjunctivitis:
• Antiviral
medications are used in severe or poorly responsive cases
• Idoxuridine ophthalmic solution
• Vidarabine 3% ophthalmic ointment
• Trifluridine ophthalmic solution
• L-lysine
• Interferon-alfa
What is the prognosis
for a cat diagnosed with herpesviral conjunctivitis?
There is no cure. The therapeutic goal is to reduce the frequency and severity
of recurrences. Most cats respond well to medical management and lead relatively
normal lives. Minimizing the chance of infection, feeding a premium diet, supplementing
the diet with l-lysine daily, reducing stressful situations and proper vaccination
against preventable causes are your cat’s best defense.
What is a feline
oral resorptive lesion?
One of the more common oral abnormalities seen in veterinary practice is the
feline oral resorptive lesion (FORL). Feline oral resorptive lesions have also
been called cavities, caries, cervical neck lesions, external or internal root
resorptions, and cervical line erosions. FORLs are usually found on the outside
surface of the tooth where the gum meets the tooth surface. Although the premolars
of the lower jaw premolars are most commonly affected, lesions can be found
on any tooth. A majority of the cats diagnosed with FORL are over four years
of age.
What causes feline
oral resorptive lesions?
The exact cause is unknown, but research suggests a correlation between problems
with calcium metabolism, chronic calicivirus infections, or an autoimmune response.
Whatever the underlying cause, the end result is loss of enamel on the affected
tooth, through a process of resorption.
How do I know if
my cat has a feline oral resorptive lesion?
The resorptive oral lesion erodes into the sensitive underlying dentin, causing
a cat to experience pain, manifested as muscular spasms or trembling of the
jaw whenever the lesion is touched. Cats with FORLs may show increased salivation,
oral bleeding, or difficulty eating. The lesions can often be observed on close
examination or when a cat is undergoing a dental cleaning and polishing. In
some cases, the FORL will be covered with inflamed gum tissues.
How are feline
oral resorptive lesions treated?
The FORL can present in many stages and treatment is based on the severity of
the lesion. During early or Stage 1 FORLs, an enamel defect is noted. The lesion
is usually minimally sensitive because it has not eroded the enamel exposing
the sensitive dentin. Treatment of this stage usually involves a thorough dental
cleaning, polishing, and smoothing out the defect. In Stage 2 FORLs, the lesion
penetrates enamel and dentin. These teeth may be treated with restoratives which
release fluoride ions to desensitize the exposed dentin, strengthen the enamel,
and chemically bind to tooth surfaces. The long term (greater than two years)
effectiveness of restoration of Stage 2 lesions has not been proven. Restorative
application to the FORL does not stop the progression or the disease. Dental
radiographs are essential to determine if the lesions have entered the pulp
chamber (Stage 3 FORL) requiring either root canal therapy or tooth extraction.
Radiographs will also reveal whether resorption has extended into the tooth
root, requiring extraction of the affected tooth. In Stage 4 FORLs, the crown
has been eroded or fractured. The gum tissue grows over the root fragments leaving
a sometimes painful or bleeding lesion. Treatment for Stage 4 FORLs is gingival
flap surgery and extraction of the remaining tooth root fragments.
FORLs are a common
condition that requires vigilance and, often, aggressive treatment to reduce
the cat’s pain and discomfort. Your veterinarian will outline a treatment
plan that will minimize pain and suffering.