Vets describe feline respiratory disease complex as a grouping of respiratory conditions caused by several viruses that can work alone or jointly to cause illness.

Feline respiratory disease complex can show up as one of several illnesses in cats. These include conjunctivitis (inflammation of the eye lining), inflammation of the linings of the sinuses and nasal passages, sores in the cat’s mouth, excessive tearing, and salivation. The illnesses typicall responsible for causing these respiratory diseases are feline calicivirus and feline herpesviral rhinotracheitis. These aren’t the only two illnesses that can cause this disease complex, and cats may develop both viruses at the same time. 

When cats get sick with respiratory disease complex, their main symptoms are respiratory, although other body symptoms can be affected:

Symptoms of feline herpesviral rhinotracheitis:

Symptoms of feline calicivirus:

Cats infected with both illnesses at the same time may develop mouth ulcers, making eating and drinking water painful. 

When cats come down with a “cold,” they may have been infected by at least one, if not more, viruses or bacteria:

Feline respiratory disease complex is highly contagious when healthy cats come into contact with the mouth, nasal, or eye discharges of infected cats. Because the viruses live on objects, they can make healthy cats sick as well. Feline herpesvirus can live on hard objects for up to 24 hours and feline calicivirus can survive up to 10 days. Anything or anyone the sick cat comes into contact with can spread the illness. This includes food and water bowls, cages, blankets, toys, clothing, blankets, and human hands.

When infected cats sneeze or cough, they spread the viruses by aerosolizing their saliva and nasal discharge. The discharge aerosol lands on hard surfaces, which can lead to other cats in the household getting sick.

When a sick cat is brought to the vet, the doctor will observe the clinical signs of illness. If the cat has been infected with both typical viruses, it may be more difficult for the vet to make a diagnosis. Because of this, the vet has to isolate samples (nasal, eye and mouth) from the cat. These samples will be examined under a microscope, enabling the vet to make a definite diagnosis. Chlamydophila felis may be diagnosed after the vet collects samples from the conjunctiva of the cat’s eyes. If the cat’s illness has spread to its lungs, the vet will do a transtracheal wash to collect samples. When a cat’s respiratory symptoms become chronic, the vet will want to carry out more testing, which will include X-rays of the cat’s skull and chest. Blood work will also be done, as well as culturing abnormal discharges to identify possible allergic reactions.

To complicate matters even more, the virus from feline herpesviral rhinotracheitis is not shed consistently. Some cats with feline herpesviral rhinotracheitis virus in their systems may not show signs of illness. Vets want to be able to identify the specific virus causing illness if a cat isn’t responding to treatment or if that cat is breeding.

Because feline respiratory disease complex can infect the eyes, nasal passages, mouth and throat of the cat, vets try to prescribe medications for not only symptoms, but for the cat’s comfort.

Broad-spectrum antibiotics to treat presenting illness and secondary bacterial infections are prescribed. If the cat is congested, the vet prescribes an antihistamine. Nasal mist or nose drops can help to soften and remove hard mucus secretions, making it much easier for the cat to breathe. Sometimes, the nose drops may also have a blood vessel constrictor, which reduces how much the cat’s nose runs. Cats who are having trouble breathing may receive an oxygen treatment inside a special oxygen tent.

If the illness has moved into the cat’s eyes, the vet prescribes an eye ointment with an antibiotic, reducing corneal irritation. If the cat has developed corneal ulcers, the vet will give eye medications with antiviral medication in the eye medication. 

At home, the owner can expose the cat to increased humidity, such as with steam in the bathroom, to help get relief from its symptoms. This should be done for 10 to 15 minutes at a time, several times daily. Using a moistened tissue or wipe, the owner can wipe nasal and eye discharge from the cat’s nose, face or eyes. Cats are like humans. When they have colds, their sense of smell decreases and their appetite goes down as well. The owner can offer a tasty, canned cat food, encouraging the cat to eat more. 

Dehydrated, depressed cats may need hospitalization to receive intravenous fluids or other treatments.

Cats diagnosed with feline respiratory disease complex generally have good prognoses. Once they recover, which is typically within seven to ten days, they can resume their normal activities. 

For multi-cat households, the owner and vet will need to watch the condition of the carrier of the illness to reduce the chance of re-infection. Some cats may develop chronic nasal symptoms, especially if infection leads to damage of the tissues and underlying bones of the nose. These cats can develop chronic nasal symptoms and are called “chronic snufflers.” If a cat has developed feline herpesvirus or chlamydial conjunctivitis, it may go on to develop a chronic eye discharge. Neither of these conditions is life-threatening. They will simply need regular monitoring and treatment.

Prevention of infection from related diseases can be provided via vaccinations. Vaccination protects from signs of illness, not infection. Cats who have been properly vaccinated can still be carriers.