Feline Respiratory Disease

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.


Additional Information About Feline Respiratory Disease

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.