Today's Veterinary Practice

MAR-APR 2018

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PEER REVIEWED 82 AVIAN ASPERGILLOSIS On pathology, lesions typically involve the respiratory system; chronic lesions usually involve the entire respiratory system, but acute cases can have lesions in the lungs and air sacs. Birds with aspergillosis typically have white or yellow plaques or nodules/granulomas and a mold-like lesion, or a general cloudiness, in the air sacs. 2,4 Aspergillosis can disseminate into other body systems, but this is rare. Invasive forms have been reported to be localized to the trachea or syrinx ( FIGURE 4 ). 2 Histopathology with periodic acid-Schiff or Gridley staining can demonstrate the fungal structure inside granulomas, and immunohistochemistry can help identify specific fungal species. Histopathology can be used to diagnose granulomatous air vasculitis and/ or pleuritis, a thickened air sac with inflammatory cells and germinating conidia in macrophages, heterophilic and lymphohistiocytic lung lesions, and/or pneumonia with edema and hemorrhage. 2 Other tests, such as acute-phase proteins, specific antigen detection, serologic assays, and Aspergillus toxin identification, are available but require further research of their diagnostic value. 2 TREATMENT Initial supportive treatments typically include stabilization, stress reduction, and collection of adequate samples to confirm the diagnosis. Once the patient is stabilized and the diagnosis is confirmed, specific treatment can be administered. Acute treatment includes fluid therapy with crystalloids (SC, IV, or intraosseous) at 50 to 150 mL/kg q24h (maintenance) and correction of fluid deficiencies. The fluid rate should be 10 to 25 mL/kg over 5 minutes or 100 mL/kg q24h as a constant-rate infusion. Alternatively, the daily requirement can be calculated and one- third of this dose can be given via the SC route q8h. Environmental changes include increasing the humidity (relative humidity, ~40%–50%) and keeping the temperature between 85°F and 90°F. Nutritional support should also be considered depending on the needs of the individual patient. 1 Antifungal therapy is typically prolonged and can last several months. 1,3 Routes of administration include nebulization, oral, parenteral, and topical. Medications of choice include amphotericin B, itraconazole, fluconazole, clotrimazole, and terbinafine hydrochloride. 1 Ideally, antifungal choice should be based on a sensitivity test. Dr. Mayer uses the Fungal Testing Laboratory at the University of Texas in San Antonio to verify that the fungus is susceptible to the chosen antifungal agent ( strl.uthscsa.edu/fungus ). Amphotericin B can act as a fungistatic or fungicidal depending on its dosage, and it must be diluted with water before administration. 2,3 It can be systemically Initial supportive treatments typically include stabilization, stress reduction, and collection of adequate samples to confirm the diagnosis. BOX 2 Dosages of Antifungal Drugs Commonly Used to Treat Aspergillosis Amphotericin B IV route (typical): 1.5 mg/kg IV q8h for 3 to 5 days combined with itraconazole at 5–10 mg/kg PO q12h for 5 days Nebulized: Administer with 1 mg/mL sterile water/ saline for 15 min q12h Intratracheal: 1 mg/kg q8–12h 1 Itraconazole Recommended: 5–10 mg/kg PO q12h for 5 days, then q24h until treatment is complete Fluconazole Oral: 5–15 mg/kg PO q12h 1 Clotrimazole Nebulized: 1% aqueous solution for 30 min q24h for localized aspergillosis Topical or administered directly into the tracheal or air sac lesion: 10 mg/kg 1,3 Terbinafine hydrochloride Oral: 10–15 mg/kg PO q12–24h in conjunction with itraconazole Nebulized: 1 mg/mL aqueous solution for 20 min q8h 1

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