Complete Guide to Feline Upper Respiratory Infection (Cat Cold) | Causes, Symptoms, Treatment, and Vaccination | ブリちょく
Cats| ✍️ BreederDirect Editorial
Complete Guide to Feline Upper Respiratory Infection (Cat Cold) | Causes, Symptoms, Treatment, and Vaccination
A comprehensive explanation of the causative viruses (herpesvirus and calicivirus) and bacteria (chlamydia) of feline "cat cold" (upper respiratory infection), including symptoms, treatment methods, vaccine prevention, and management in multi-cat households.
Key Takeaways
A comprehensive explanation of the causative viruses (herpesvirus and calicivirus) and bacteria (chlamydia) of feline "cat cold" (upper respiratory infection), including symptoms, treatment methods, vaccine prevention, and management in multi-cat households.
Feline "cat cold" is precisely called "feline upper respiratory infection (Upper Respiratory Infection: URI)" and is a collective term for infectious respiratory diseases caused by multiple pathogens. In kittens and immunocompromised cats, the risk of severe disease is high, and outbreaks in multi-cat facilities and shelters are also a concern. This article provides a detailed explanation of the causes, symptoms, treatment, and prevention of cat cold.
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Main Causative Pathogens of Feline Upper Respiratory Infection
Feline upper respiratory infection involves multiple pathogens, and mixed infections are often observed.
Feline Herpesvirus 1 (FHV-1)
It is the most common causative virus of feline upper respiratory infection. Approximately 80% of infected cats become carriers, maintaining the virus in a latent state throughout their lives. It reactivates and symptoms resurge when triggered by stress, immunosuppression, or corticosteroid administration.
Main symptoms: sneezing, nasal discharge, ocular discharge (including keratitis and conjunctivitis), fever, and loss of appetite. In severe cases, corneal ulcers can develop, potentially leading to blindness.
Feline Calicivirus (FCV)
Another major respiratory virus. Unlike herpesvirus, oral ulcers (ulcers on the tongue and palate) are characteristic symptoms. Certain strains can cause severe systemic disease (virulent systemic FCV: vsFCV), with skin ulcers, multi-organ failure, and high mortality rates (rare but serious).
Because it is a highly mutable virus, vaccines do not guarantee complete protection against infection, but are effective at preventing severe disease.
Chlamydophila felis
A bacterium (obligate intracellular parasite) that primarily causes conjunctivitis. It commonly affects kittens (5 weeks and older), and infection spread in multi-cat environments is a concern. Antibiotics (doxycycline) are effective, and vaccines (optional) are also available.
Bordetella bronchiseptica
Also known as the causative agent of canine "kennel cough," it can also infect cats and cause bronchitis and pneumonia. Infection is common in multi-cat environments and densely populated cat populations (such as rescue shelters).
Symptoms and Severity Assessment
Typical symptoms of cat cold are as follows:
Severe sneezing
Clear to purulent nasal discharge
Ocular discharge and conjunctivitis (eye swelling, redness, mucus)
Fever (39.5°C or higher)
Loss of appetite and lethargy
Oral ulcers (when infected with calicivirus)
Warning signs (consider emergency veterinary care):
- Open-mouth breathing
- Cyanosis (tongue and gums appear pale or bluish)
- Unable to eat or drink for more than 24 hours
- Unable to fully open eyes, or white cloudiness on the cornea
- Signs of dehydration (reduced skin turgor, dry mouth)
In kittens (8 weeks and younger), senior cats, and immunocompromised cats (FIV/FeLV positive, on corticosteroid therapy, etc.), symptoms can deteriorate rapidly.
Diagnostic Methods
In most cases, clinical diagnosis is made based on symptoms and infection history (multi-cat environment, shelter origin). When definitive diagnosis is needed, the following tests are performed.
PCR testing (nasopharyngeal swab): Detects DNA/RNA of FHV-1, FCV, and Chlamydia. It is the most sensitive diagnostic method, but can be positive in carrier cats, requiring clinical judgment for result interpretation.
Viral isolation and culture: Testing performed at specialized facilities, used for research and outbreak investigation.
Ophthalmologic examination: Fluorescein staining and other procedures are performed to evaluate the presence of corneal ulcers.
Treatment
While specific antiviral treatments for cat cold are limited, supportive therapy and prevention of secondary infections are the mainstay of treatment.
Antivirals:
- Famciclovir (effective against FHV-1): An oral antherpes medication. It is effective at shortening symptom duration and reducing recurrence frequency.
- Lysine (amino acid): Previously used to suppress FHV-1 replication, but is now considered to have weak evidence of efficacy and is generally not recommended.
- Interferon (feline alpha-interferon): May be used as an immune stimulant.
Antibiotics: While not directly effective against viral URI, they are used to treat and prevent secondary bacterial infections (pneumonia, sinusitis). Doxycycline is the first-line treatment for Chlamydia infection.
Supportive care:
- Topical medications (antibiotic eye ointment and drops): Management of conjunctivitis and corneal ulcers
- Fluid therapy (intravenous or subcutaneous): Correction of dehydration
- Tube feeding or force feeding: Nutritional support when appetite is lacking
- Humidification and steam inhalation: Promotes secretion clearance
- Appetite stimulants (such as mirtazapine): Improvement of anorexia
Vaccination and Prevention
Core vaccines (essential): The feline trivalent vaccine (FHV-1 + FCV + feline panleukopenia virus) is the core vaccine. It is recommended for all cats.
Vaccines do not completely prevent infection, but are highly effective at preventing severe disease and reducing symptom duration. Because FCV is highly mutable, polyvalent vaccines that cover multiple strains are used.
Non-core vaccines (as appropriate): Chlamydia and Bordetella vaccines are recommended for cats in multi-cat environments, from shelters, or in high-risk settings.
Schedule:
- Kittens: Initial vaccination at 8-9 weeks, 12 weeks, and 16 weeks of age (3-dose series)
- Adult cats: Booster 1 year after final vaccination, then every 3 years (annually depending on risk)
- Regular vaccine updates are recommended even for indoor cats
Infection Management in Multi-Cat Environments
Outbreak management in shelters and catteries (breeding facilities) is particularly important.
Isolation of new cats: Newly acquired cats should be isolated from existing cats for at least 2-3 weeks to confirm absence of symptoms.
Environmental disinfection: FHV-1 and FCV can be inactivated with 1:32 diluted sodium hypochlorite (bleach, etc.). Litter boxes, food dishes, and bedding used by infected cats should be thoroughly disinfected.
No sharing of towels or food dishes: Since viruses transmit through secretions (nasal discharge, ocular discharge, saliva), avoid sharing equipment.
Management of carrier cats: Stress reduction in FHV-1 carrier cats (providing individual space and maintaining a consistent routine) helps prevent viral reactivation.
While cat cold can be difficult to cure completely, severe disease can be prevented through vaccination, proper management, and early treatment. Breeders and multi-cat households should develop knowledge of infection management and maintain a healthy environment. Through br-choku, you can adopt cats from breeders who prioritize vaccination and health management.
