In the August, 2012, edition of Today’s Veterinary Practice Dr. Claire R. Sharp, BSc, BVMS (Hons), MS, CMAVA, Diplomate ACVECC, Assistant professor and small animal medicine and critical care at Tufts University Cummings School of Veterinary Medicine, published an incredibly comprehensive review of feline upper respiratory tract (URT) diseases. While her article was intended for veterinarians, the information is equally important for cat owners, helping you to understand just how complex URT infections in cats can be. Below I have “translated” the medical jargon into language that still conveys the information while making it useful to pet owners. Feel free to bookmark this page for future reference.
• Pathogens
• feline herpes virus (rhinotracheitis)
• feline calici virus
• these two account for 90% of cats’ upper respiratory diseases
• Risk Factors
• kittens
• stressed cats
• immunocompromised cats (FeLV, FIV, FIP, chemotherapy)
• Transmission
• enter through oral and nasal mucus membranes and conjunctiva
• FHV and FCV replication occurs in the mucosa of the nasal septum, nasal turbinates, nasopharynx and tonsils
• clinical signs resolve in most cats in 2 weeks
• many shed after resolution of clinical signs for 2 weeks to permanently
• Virus reactivation
• 80% have neuronal latency of FHV in trigeminal ganglion
• stress, illness or immunocompromise can reactivate
• reactivation results in further shedding
• “recrudescence” is the term applied to clinical signs associated with reactivation of the virus
• Etiology of clinical signs
• whether signs are acute or chronic depends on immune status of individual cat (and possibly other factors not yet
elucidated by researchers)
• multifocal epithelial necrosis
• neutrophilic inflammation
• fibrinous exudation
• Prevention
• vaccines are not necessarily protective. designed to decrease the severity of clinical signs (especially with FCV due
to its great antigenic diversity)
• URT viruses are generally transmitted cat to cat via URT secretions and aerosol transmission over short distances
• environmental contamination can occur, especially in multi-cat households, where infectious organisms may be in
higher concentrations and the chance of another cat getting to “fresh” virus quickly before it dies on a fomite
• FHV is susceptible to common disinfectants, antiseptics and detergents
• FCV can persist in environment for about a month, resistant to many common disinfectants bleach is the preferred
agent for killing FCV
• affected individual should be isolated during hospital stays or at home in multi-cat households
• Less-common causes of feline URT
• H1N1 (swine flu) has been identified in cats and there is concern about the possibility of return infection to people
• first identified in 2009 during the human pandemic that year. Cats probably got it from people. The virus is
absent from feral cat populations studied
• usually results in acute upper and lower respiratory tract infection
• mortality occurs secondary to pneumonia
• Bacterial infection
• Chlamydophila felis, Mycoplasma felis, Mycoplasma gatae, Bordetella bronchiseptica
• can be primary agents, but most commonly concurrent with and secondary to viral invaders. Viral agents
damage respiratory epithelium, especially in young cats, making cats more susceptible to opportunistic infections
such as staphylococci, steptococci, pasturellae and coliforms.
• Fungal infections, such as cryptococcus, can occur, but are less common
• Nasopharyngeal polyps
• originate in Eustachian tube or middle ear and can cause upper airway obstruction
• inflammatory in nature, exact cause not known
• polyps mostly occur in young cats
• older cats may develop cancer
• Nasal/nasopharyngeal tumors: laryngeal lymphoma, squamous cell carcinoma and adenocarcinoma. These
tumors tend to be locally invasive and are relatively unlikely to metastasize.
• Nasal foreign bodies: usually plant material lodged above the soft palate
• Nasopharyngeal stenosis: rare. Usually secondary to chronic infection or aspiration
• Laryngeal disease
• rarely reported
• Inflammatory, neoplastic, associated with trauma or idiopathic
• inflammatory
• diffuse neutrophilic or lymphoplasmacytic infiltration and inflammatory polyps
• cause unknown
• neoplastic
• neoplasia (includes both benign and cancerous growths), especially in FIV (reverse transcriptase) cats
• lymphoma and SCC > adenocarcinoma and round cell tumors
• Laryngeal paralysis: few reports
• cause unknown for most cases
• can be secondary to cancer, neck surgery, trauma to the cords or other inflammatory causes
• Tooth Root disease
• commonly listed as a possible cause
• uncommonly reported
• Clinical signs
• Similar in all cases, regardless of cause
• Local signs:
• sneezing, nasal congestion, open-mouth breathing
• eye discharge
• nasal discharge
• usually bilateral (both nostrils)
• viral causes usually start out serous (watery)
• secondary bacterial infection may lead to the discharge becoming purulent (pus-containing)
• nares (nostril openings) may become crusted over
• eyelids may become crusted closed
• poor self-grooming may accompany these signs
• oral ulcers may occur
• Systemic signs:
• fever
• lethargy
• loss of appetite
• Disease-specific signs
• Feline Calicivirus
• oral ulceration, including tongue
• oral pain
• drooling
• Feline Herpesvirus
• broad spectrum of severe upper respiratory tract signs (rhinotracheitis)
• eye lesions
• eyelid muscle spasms, holding eyelids closed
• eyelid mucus membrane swelling
• bilateral conjunctivitis
• corneal inflammation
• corneal ulceration (which may not completely resolve)
• Fungal rhinitis
• facial deformity (including Roman nose)
• skin ulceration
• nasal discharge
• enlarged nearby lymph nodes
• Laryngeal disease
• Increased breathing effort on inhalation phase
• may or may not exhibit: loss of voice, coughing, gagging and/or retching
• Nasopharyngeal foreign bodies
• sudden onset of sneezing and reverse sneezing
• gagging
• repeated swallowing
• Nasopharyngeal polyps
• noisy, difficult breathing
• ear infections
• Diagnostic tests
• Feline Leukemia Virus and Feline Immunodeficiency Virus testing because chronic upper respiratory
tract diseases are often associated with immune system suppression. FIV-infected cats often succumb to cancer.
• CBC, Chemistry Profile and Urinalysis
• Virus-identification tests (PCR and others)
• Radiographs (X-ray) of the head, neck and chest
• Ultrasound of the neck and chest
• Dental radiographs
• Computed Tomography (CT scan)
• Magnetic Resonance Imaging (MRI)
• Rhinoscopy (scoping the nose)
• Nasal flush (the material flushed out can be used for cytology and/or culture
• biopsy (masses)
• latex cryptococcal agglutination test (when fungal infection is suspected, although this may be revealed by cytology)
• Treatment
• IV fluids for dehydrated patients
• nutritional support if appetite is significantly decreased
• antibiotics if bacterial infection is suspected or confirmed by culture
• isolation (if other cats in the household have not already been exposed. Many of these conditions are highly
contagious.)
• corticosteroids and antihistamines may help if medically indicated
• topical antiviral agents for corneal lesions
• nasal flushing can sometimes dislodge foreign bodies
• surgery, chemotherapy and radiation may be indicated for some growths
• some other modes of therapy have questionable efficacy, so we have not included the controversial ones.
See you next week, Dr. Randolph.
MMURIFEL
