Upper respiratory infections are extremely common in cats. In fact, nearly all cats are exposed to upper respiratory pathogens at some point in their lives. Because these infections are so prevalent in cats, all cat owners should learn what causes them, how to recognize them, how to treat them and how to prevent them.
A number of bacterial species and viruses produce feline upper respiratory infections. These include the following:
- Feline herpesvirus type 1, also called feline viral rhinotracheitis or FVR.
- Feline calicivirus, commonly abbreviated as FCV.
- Chlamydia felis.
- Mycoplasma felis.
Combined, FVR and FCV are responsible for most upper respiratory infections in cats, and FVR is more common than FCV. Cats can be infected with both viruses, a single virus or any combination of the viruses and bacteria listed above. In addition, secondary infections with a variety of bacterial species often occur in cats with viral infections.
Both FCV and FVR are extremely contagious, and infection occurs through direct and indirect contact with infected mucus and saliva. Common routes of infection include the following:
- Contact with infected cats.
- Contact with toys, bedding and other items used by infected cats.
- Contact with humans who have handled infected cats.
Infected cats can shed virus particles for several months after infection, and cats infected with FVR remain infected for their entire lives. Most of the time, the virus remains quiescent, and infected cats show no symptoms after they have recovered from the initial illness. However, during times of stress, the virus can reactivate. When this occurs, the infected cat can pass FVR to other cats even if it has been years since the animal was initially infected.
Acute Upper Respiratory Infections
The symptoms of most feline upper respiratory infections are similar, and they often include some or all of the following:
- Loss of appetite.
- Watery eyes.
- Red eyes.
- Mouth ulcers, especially in cats with FCV.
- Limping in young cats with FCV.
- Swelling around the eyes.
- Eye ulcers, which are especially common in cats infected with herpes.
Except in young kittens and aged, chronically ill or debilitated animals, upper respiratory infections are usually not life threatening.
Virulent Systemic Calicivirus
A particular strain of FCV, known as virulent systemic calicivirus, is much more dangerous than other upper respiratory infections. According to an article in the Journal of Feline Medicine and Surgery, this particular strain is often deadly and primarily affects healthy adult cats. Outbreaks tend to occur in clinics, shelters and catteries, and symptoms include the following:
- Ulcers on the head and legs.
- Yellowing of the gums, skin and other mucous membranes.
Recurrent FVR Infection
In an otherwise healthy adult cat, reactivation of FVR most commonly produces conjunctivitis or ulcerative keratitis. Typically, symptoms occur in just one eye and include the following:
- Redness of the eye.
- Discharge from the eye.
- Corneal ulcers.
- Pawing at the eye.
- Light sensitivity.
Treatment of upper respiratory infections in cats is symptomatic, and common treatments include the following:
- Systemic antibiotics to treat and prevent bacterial infections.
- Soft food with a strong odor to encourage affected cats to eat.
- Antibiotic eye drops or ointments for cats with corneal ulcers.
- Antiviral eye drops for cats suspected of having FVR-associated corneal ulcers.
Cats, especially young kittens, that refuse to eat or become dehydrated may require hospitalization for supportive care and fluid therapy.
Adult cats with recurrent FVR infections are also treated symptomatically. Common treatments include the following:
- Stress reduction.
- Lysine supplementation.
- Antiviral eye drops.
- Antibiotic eye drops or ointments.
- Systemic antiviral drugs.
Guidelines published in the Journal of Feline Medicine and Surgery recommend vaccinating kittens with the FVRCP vaccine to protect them from FVR, FCV and panleukopenia, a potentially deadly virus. After the initial series, all cats should have a one-year booster, and at-risk cats should be vaccinated annually. All other cats should be vaccinated every three years. While the FVRCP vaccine does not completely prevent FVR infection, it does help lessen the symptoms of the virus and reduce the incidence of recurrence.
In addition to vaccination, it is important to practice good hygiene and to quarantine sick animals. Adult cats with a history of herpes infection should be carefully monitored, and since disease recurrence is associated with stress, all efforts should be made to minimize stress in these cats.
For more information on feline upper respiratory infection, see the following sites:
- Feline Upper Respiratory Disease Complex from the Merck Veterinary Manual.
- Feline Upper Respiratory Infection from the Koret Shelter Medicine Program at the University of California, Davis, School of Veterinary Medicine.