Respiratory infections are a common health issue for cats, particularly in environments where many cats live together, such as shelters or breeding facilities. These infections, often referred to as Upper Respiratory Infections (URI) or sometimes colloquially as “cat colds,” can be caused by a range of pathogens including viruses, bacteria, fungi, and protozoa. While vaccinations have significantly decreased the severity of these diseases, they haven’t eradicated the highly contagious agents that cause them. Understanding Uri In Cats is crucial for cat owners to ensure the health and well-being of their feline companions.
Respiratory infections in cats can affect both the upper and lower respiratory tracts. The upper respiratory tract comprises the nasal passages, sinuses, oral cavity, pharynx (the back of the oral and nasal cavity), and larynx (vocal folds). In contrast, the lower respiratory tract includes the trachea, bronchi, and lungs (Figure 1).
Alt text: Anatomical illustration of a cat’s respiratory system, clearly showing and labeling the upper respiratory tract including nasal passages, sinuses, oral cavity, pharynx, larynx and the lower respiratory tract including trachea, bronchi, and lungs.
Symptoms of upper respiratory infections are varied and can include discharge from the eyes or nose (which may be clear or colored), coughing, sneezing, conjunctivitis (swelling of the mucous membranes around the eyes, Figure 2), mouth ulcers, lethargy, and anorexia. In more severe, though less common instances, cats may experience breathing difficulties.
Alt text: Close-up photograph of a cat’s eye exhibiting conjunctivitis, characterized by redness and swelling of the eye membranes, indicating a potential upper respiratory infection.
Lower respiratory tract infections in cats can manifest through symptoms like coughing, lethargy, anorexia, and breathing that is either labored or rapid. It’s important to monitor a cat’s resting breathing rate, which should ideally not exceed 35 breaths per minute.
Several specific pathogens are known to cause URI in cats. Let’s explore some of the most common ones:
Feline Herpesvirus (FHV-1)
Feline herpesvirus, also known as FHV-1, is a highly prevalent virus among cats, especially affecting young and adolescent felines. It’s estimated that a staggering 97% of cats are exposed to FHV-1 during their lives, and up to 80% of those exposed become lifelong carriers. Among carriers, about 45% will periodically shed the virus, often triggered by stress.
Clinical Signs of Feline Herpesvirus
Clinically, FHV-1 infection is often referred to as feline viral rhinotracheitis (FVR). The infection primarily manifests as upper respiratory signs, mirroring the general symptoms of URI described earlier. These include sneezing, nasal congestion, and discharge. Additionally, FHV-1 can cause corneal ulcers (keratitis) and fever.
Diagnosis of Feline Herpesvirus
Diagnosis of FVR typically involves recognizing the characteristic upper respiratory symptoms, especially in young or unvaccinated cats. Recurring conjunctivitis or keratitis in older cats can also be indicative. Veterinarians may employ diagnostic tests to confirm FHV-1, such as polymerase chain reaction (PCR) to detect viral DNA, or virus isolation tests to culture the virus from clinical samples.
Treatment for Feline Herpesvirus
Treatment strategies for FHV-1 are tailored to the severity of the disease and focus on supportive care. Maintaining proper nutrition and hydration is paramount. Nasal decongestants can provide relief in some cases. However, it’s crucial to minimize stress during medication administration, as stress can exacerbate keratitis and conjunctivitis.
In acute cases, particularly in young cats, antiviral drugs can be effective in treating corneal lesions and upper respiratory symptoms. Systemic antibiotics are often used to manage secondary bacterial infections, which are common complications of FVR. Recurrent keratitis or conjunctivitis can be managed with antivirals, corticosteroids, and by reducing stress factors like overcrowding, surgeries, new pets, or relocation. The use of lysine supplementation remains controversial, with studies suggesting it may be ineffective and possibly worsen symptoms and viral shedding.
Prognosis for Feline Herpesvirus
Once a cat is infected with FHV-1, it remains a carrier for life and may experience recurrent episodes of URI and eye disease. While these flare-ups are often mild and resolve on their own, severe complications and even death can occur in cats with underlying health issues.
Prevention of Feline Herpesvirus
Vaccination against feline herpesvirus is a cornerstone of preventative care for all cats. While vaccines may not completely prevent infection, they significantly reduce disease severity and viral shedding, protecting both the vaccinated cat and other cats in contact.
Feline Calicivirus (FCV)
Feline calicivirus (FCV) is another highly contagious virus, prevalent in cat populations worldwide. In smaller groups of cats, around 10% may be infected, but in crowded environments like shelters, infection rates can soar to 90%.
Clinical Signs of Feline Calicivirus
FCV infections commonly present with upper respiratory signs, similar to FHV-1. However, FCV can also spread to the lower respiratory tract, leading to pneumonia. Viral pneumonia can be complicated by secondary bacterial infections, worsening breathing difficulties. In some cases, oral inflammation and ulcers may develop.
A more severe systemic form of FCV, though rare, is highly fatal, with a mortality rate of approximately two-thirds. Systemic FCV can cause facial and limb swelling, crusting sores and hair loss around the nose, eyes, ears, and footpads. Jaundice, gastrointestinal bleeding, and subcutaneous bleeding may also occur. Temporary limping can occur during infection or post-vaccination in rare instances.
Diagnosis of Feline Calicivirus
Diagnosis of FCV infection is often suspected when oral ulcers are present alongside acute URI signs. Confirmation can be achieved using reverse transcriptase polymerase chain reaction (RT-PCR) to detect viral genetic material in blood or swabs from the mouth or eyelids. Virus isolation through lab culture can also confirm diagnosis.
Treatment for Feline Calicivirus
Supportive care is vital for treating FCV. Ensuring hydration and nutrition is crucial, but can be challenging due to painful mouth lesions and nasal congestion affecting appetite. Non-steroidal anti-inflammatory drugs can alleviate oral pain. Nasal passages should be cleared using mucolytics, saline nebulization, and regular saline wiping. In severe cases, a feeding tube may be necessary until oral lesions heal.
Antibiotics are used to treat secondary bacterial infections. Unfortunately, effective antiviral drugs for FCV are limited or have significant side effects. While some severe systemic FCV cases have shown improvement with corticosteroids and interferon, further research is needed to confirm the safety and efficacy of this treatment. For chronic oral ulcers related to FCV, veterinarians may recommend dental cleaning, immune-modulating drugs, antibiotics, and pain relief, although more studies are needed to determine optimal treatment strategies.
Prognosis for Feline Calicivirus
The prognosis for FCV infection varies with severity. Cats with uncomplicated URI, pneumonia, or oral ulcers typically recover within days or weeks. Systemic FCV carries a much poorer prognosis.
Prevention of Feline Calicivirus
Vaccination against FCV is recommended for all healthy cats. While not 100% protective, it reduces the likelihood of severe disease. However, vaccines do not prevent viral shedding or cure existing infections.
Feline Chlamydiosis
Chlamydia felis is a bacterium responsible for feline chlamydiosis. This bacterium requires close cat-to-cat contact for transmission, primarily through eye secretions. Young cats and cats in crowded environments are most susceptible. Approximately 20% of cats with URI signs and 3% of healthy cats may carry C. felis.
Clinical Signs of Feline Chlamydiosis
The hallmark of C. felis infection is conjunctivitis with eye discharge. Initially clear, the discharge becomes mucous-like and yellowish or pus-like. Lethargy and anorexia are rare symptoms.
Diagnosis of Feline Chlamydiosis
PCR testing of eye swabs is the preferred diagnostic method to detect C. felis DNA. Culture is possible but less sensitive. Antibody tests are also available for unvaccinated cats.
Treatment for Feline Chlamydiosis
Antibiotics like doxycycline or amoxicillin/clavulanic acid are effective against chlamydiosis. Systemic treatment is more effective than topical eye applications.
Prognosis for Feline Chlamydiosis
With proper diagnosis and treatment, the prognosis for feline chlamydiosis is generally good.
Prevention of Feline Chlamydiosis
Vaccines are available but do not prevent infection, only minimize symptoms. Vaccination is recommended for multi-cat households and environments with a history of C. felis.
Fungal Infections
Various fungi can cause respiratory disease in cats. Cryptococcus neoformans is the most common. Infection occurs through inhalation of fungal spores. The infection can remain in the nasal cavity or spread to other areas, including the central nervous system and lower respiratory tract. C. neoformans is widespread, with about 4% of cats being asymptomatic carriers. Cats are more susceptible to developing disease post-exposure than dogs. Bird droppings and decaying plant matter are potential sources. Cryptococcus gattii is a related fungus causing similar symptoms.
Clinical Signs of Fungal Infections
C. neoformans infections often manifest in the nasal form, causing facial and nasal swelling, sneezing, chronic nasal discharge (possibly bloody), and non-healing wounds or polyp-like growths in the nose and throat. Voice changes, noisy breathing, snoring, anorexia, and weight loss may occur. Lung involvement can lead to labored or rapid breathing. Infections can also affect the central nervous system, skin, and systemically spread to multiple organs.
Diagnosis of Fungal Infections
Diagnosis is best achieved by detecting C. neoformans proteins in body fluids, particularly blood. Cytology of nasal discharge can be helpful due to the fungus’s characteristic appearance. X-rays, CT scans, or MRIs may assess the extent of fungal invasion and monitor treatment response.
Treatment for Fungal Infections
Antifungal drugs are used, but definitive guidelines are lacking. Treatment choices and outcomes may depend on organ involvement, especially the brain.
Prognosis for Fungal Infections
Early diagnosis and absence of central nervous system involvement offer a more favorable prognosis. Treatment compliance, which can be long-term (months to years), is crucial.
Prevention of Fungal Infections
Keeping cats indoors reduces exposure to C. neoformans and minimizes infection risk, as outdoor cats are more frequently exposed.
Other Fungal Infections
Other fungi like Aspergillus fumigatus, Histoplasma capsulatum, and Blastomyces dermatitidis can cause respiratory infections in cats. Unlike C. neoformans, these commonly spread to the lungs, causing pneumonia (Figure 3) and breathing difficulty.
Alt text: X-ray image of a cat’s chest, showing lungs affected by pneumonia, indicated by increased opacity and consolidation within the lung fields, a potential consequence of lower respiratory tract infection.
Bordetella bronchiseptica
Bordetella bronchiseptica is a bacterium causing URI, particularly in high-density cat populations. Approximately 5% of cats with URI signs and 1.5% of healthy cats in these settings may harbor B. bronchiseptica. Transmission is through oral and nasal secretions. Infections range from mild to severe. Dogs can transmit the bacteria to cats, and rarely, humans can be infected.
Clinical Signs of Bordetella bronchiseptica
Symptoms vary from mild, self-limiting coughing, sneezing, and eye discharge to severe breathing difficulty, cyanosis (blue mucous membranes), and death. Severe signs are more common in young cats with lower respiratory tract infections, but can occur in older cats too.
Diagnosis of Bordetella bronchiseptica
Respiratory samples can be cultured or tested by PCR for B. bronchiseptica. However, these tests may yield false negatives in infected cats.
Treatment for Bordetella bronchiseptica
Antibiotics, typically doxycycline, are the main treatment. Supportive care, including nutrition and hydration, is also essential. Antibiotics may be recommended even for mild cases to prevent worsening infection.
Prognosis for Bordetella bronchiseptica
Most cats with uncomplicated B. bronchiseptica infections recover within 10 days of antibiotic treatment. Without treatment, the disease can progress to severe URI or life-threatening pneumonia.
Prevention of Bordetella bronchiseptica
A nasal vaccine is available, recommended for cats in high-density housing, but not a core vaccine for all cats. It should not be given to cats under four weeks old or those on antibiotics. Mild URI signs can occur post-vaccination.
Other Infections
Various other organisms can cause URI in cats, including avian and canine influenza viruses (transmitted from humans and dogs, respectively). Avian influenza can also be transmitted from cats to humans. Other infectious agents include Yersinia pestis (plague), Toxoplasma gondii, and Pasteurella multocida (a common feline respiratory bacteria that can cause secondary infections).
Conclusion
Upper respiratory infections are a common concern in cats, with a variety of causes and levels of severity. Recognizing the symptoms of URI in cats, understanding the potential pathogens involved, and implementing appropriate preventative and treatment strategies are vital for maintaining feline health. If you observe signs of URI in your cat, consulting with a veterinarian is crucial for accurate diagnosis and effective management. Early intervention and proper care can significantly improve your cat’s comfort and recovery from URI.
