Symptoms & Treatments for Cat Upper Respiratory Infecti

Common pathogens affecting cats include viruses (herpesvirus, calicivirus), bacteria (Pseudomonas aeruginosa, Staphylococcus aureus, Chlamydia felis), and fungi (Cryptococcus). Among these, feline herpesvirus, calicivirus, and Chlamydia are the most prevalent. However, Chlamydia primarily affects the eyes.

Pathogen Overview:

(1) Feline Herpesvirus

The feline herpesvirus primarily infects cats worldwide, thriving in conjunctival and respiratory epithelial cells. It can also replicate within neuron cells, leading to lifelong latent infection.

This virus is primarily transmitted through contact, and young kittens can suffer severe symptoms upon infection.

(2) Feline Calicivirus

Feline calicivirus has a high incidence rate but a low mortality rate. The virus reproduces in the brain tissue.

(3) Feline Chlamydia

Feline Chlamydia is a Gramnegative coccobacillus that mainly causes conjunctivitis, but can also lead to upper respiratory infections in cats. It may cause pneumonia in kittens. Cats between 5 weeks and 9 months of age are more susceptible.

(4) Cryptococcus

Cryptococcus is a fungus that has a strong affinity for the upper respiratory tract and can also impact a cat's nervous and skin systems. Feline cryptococcosis is a systemic fungal disease.

Symptoms:

(1) Viral Upper Respiratory Infection

Initially, cats may exhibit signs of lethargy, decreased appetite, increased sneezing, and watery discharge from the eyes and nose. Some may have a fever, oral ulcers, excessive drooling, and conjunctivitis with mucopurulent discharge. Severe cases may present with coughing and difficulty breathing. Infections can also lead to keratitis, corneal ulcers, and uveitis. Symptoms of feline herpesvirus infections, particularly those affecting the upper respiratory and ocular areas, tend to be more severe than those caused by calicivirus. Calicivirus infections often result in tongue ulcers.

(2) Bacterial Upper Respiratory Infection

Chlamydia can cause upper respiratory infections in cats, with prominent ocular symptoms such as conjunctival redness, mucopurulent discharge, and adhesions of the nictitating membrane, conjunctiva, and cornea. Upper respiratory symptoms are mild, with slight rhinitis and sneezing.

(3) Fungal Upper Respiratory Infection

Cryptococcus infections present with chronic coughing, nasal congestion, grayish mucopurulent nasal discharge (occasionally with blood), and, in cases of longterm infection, swelling of the bridge of the nose and facial deformation.

Differential Diagnosis:

When clinical symptoms such as ocular and nasal discharge and sneezing are present, it is essential to consider differential diagnoses beyond the aforementioned pathogens, including:

(1) Allergic Reactions: Such as pollen allergies

(2) Oral Diseases: These may present with facial swelling, tartar, periodontitis, loose teeth, halitosis, and excessive drooling, in addition to upper respiratory symptoms

(3) Tumors: Common in older cats, such as adenocarcinoma and lymphoma

(4) Nasal Obstructions: Such as sand or plant matter blocking the nasal passages

Treatment and Prevention:

(1) Implement reasonable supportive therapy to ensure adequate hydration and nutritional needs.

(2) Cleanse the eyes and nasal discharge.

(3) For feline herpesvirus, supplement with lysine.

(4) Administer 30 to 50 million IU/kg of feline rhinotracheitis inhibitory protein intravenously every 12 hours for 5 days; and 30 to 50 million IU/kg of feline interferon omega.

(5) Antibiotic treatment: Oral amoxicillinclavulanate potassium, doxycycline hydrochloride, and azithromycin.

(6) Eye drops.

(7) For cats with oral ulcers, use mouthwashes or dental gels to clean the mouth.