A seven-year-old male, neutered, domestic short haired (DSH) cat was presented to a veterinarian for evaluation of chronic coughing and increased respiration of several months’ duration. A radiograph of the lungs showed a diffuse bronchial pattern. A trans-tracheal wash (TTW) was performed and the fluid was submitted to the Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) in College Station for analysis. The fluid was composed of significantly increased numbers of eosinophils and a few neutrophils and macrophages. There were no bacteria, fungal hyphae, or yeast seen. A culture of the fluid had no growth of bacteria or fungi. A heartworm antigen test and fecal examination were negative. Additionally, a Baermann test was performed and yielded negative results. With these considerations, the primary differential diagnosis was feline asthma (also termed eosinophilic bronchitis, allergic bronchitis, feline bronchial asthma, and feline chronic obstructive pulmonary disease).
Feline asthma is a common disease that has been described in cats of all ages. The Siamese breed seems to have an increased incidence. Clinical signs vary from mild coughing with or without dyspnea to extreme respiratory distress. The signs may be acute or chronic. There are typically increased numbers of leukocytes that are predominantly eosinophils on a trans-tracheal wash or bronchoalveolar lavage (BAL). Heartworm disease and other parasitic infections (lungworm) are differential diagnoses in a cat with increased numbers of eosinophils in a TTW or BAL. Fungal infections are another consideration, but the inflammatory response with fungal disease is typically pyogranulomatous with only mildly increased numbers of eosinophils. A fecal or Baermann test can be done to rule out a parasitic infection (Aelurostrongylus abstrusus and Capillaria aerophila).
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