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Upper respiratory tract disease in cats (Proceedings)

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Nov 01, 2010

A variety of disorders can affect the upper respiratory tract of cats; while the feline upper respiratory infection complex is one of the most common URT disorders, this lecture will focus more on more complex disorders such as chronic rhinitis, nasopharyngeal polyps and nasopharyngeal stenosis, as well as feline laryngeal disease.

Acute upper respiratory tract infection
Signalment:
      - especially common in kittens

Diagnostics:
      - diagnosis is based on history and physical examination (ocular and nasal discharge, stertor etc.)
      - no specific diagnostic tests are needed
      - PCR can be performed but rarely adds anything clinically

Treatment:
      - supportive care
           o parenteral fluids if dehydrated, and/or anorexic
           o antibiotics are warranted in some cases for secondary bacterial infection
               ■ azithromycin has gained popularity in high volume facilities due the prolonged dosing interval, but is not clearly a better antibiotic than others
               ■ amoxicillin / clavulanate is commonly used
           o nutritional support:
               ■ especially in small kittens as they have little reserves
      - role of antiviral agents is as yet undetermined
           o One recent report of chronic herpes viral infection suggested some benefit to oral famciclovir
      - Isolation!!! Given the contagious nature of the disease

Prognosis:
      - typically self-limiting in adult, immunocompetant cats
      - moribund kittens typically have a grave prognosis.
      - neurological complications are a negative prognostic factor.

Chronic rhinitis
Definition:
      - rhinitis that persists for greater than one month, particularly without signs of systemic disease

Etiology:
      - while idiopathic rhinosinusitis remains a common ultimate diagnosis, there is a reasonable chance of identifying another source with a complete diagnostic evaluation
      - possible underlying diseases include:
           o fungal infection (e.g. Nasal cryptococcosis) +/- concurrent FeLV
           o tooth root abscess
           o neoplasia etc.
      - Bartonella was recently excluded as a likely possible cause
      - most cats with idiopathic disease are considered to have had viral (FHV or FCV) infections in their early life

Diagnostics:
      - oral examination under anesthesia (looking for dental disease, oronasal fistula etc.)
      - upper airway imaging (radiographs vs. CT vs. MRI)
      - rhinoscopy and nasal flush
      - culture:
           o usually positive, documenting multiple organisms BUT
           o primary bacterial rhinitis is very, very rare.
      - blind nasal biopsy:
           o performed under anesthesia, with cat intubated and cuff inflated
           o oropharyngeal gag used (e.g. Gauze squares with tie)
           o insert a 5-8FR polypropylene (stiff!) catheter into the nostril- mark the distance to the medial canthus of the eye
           o aspirate several times, and submit material for histopathology.
           o additionally, using a 20-30 ml syringe, flush saline forcefully through the nose to attempt to dislodge some of the suspected mass.