Today's Veterinary Practice

MAR-APR 2018

Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.

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PEER REVIEWED 78 AVIAN ASPERGILLOSIS PRESENTATION Typically, birds present with vague and nonspecific signs (depression, inappetence, difficulty breathing, reluctance to fly/perch, drooped wings). Initial physical examination findings typically include weight loss, respiratory abnormalities (dyspnea, tachypnea, cyanosis), lethargy, polyuria/polydipsia, vocalizing, open-beak breathing, tail bobbing, and/or enlarged nares. The patient's respiratory system should be examined. Infection in the lower respiratory tract should be associated with an audible expiration, while inspiratory stridor may be due to an upper respiratory tract or tracheal infection. A sudden change in voice pitch during vocalization is often observed in psittacines with a granuloma in the upper respiratory tract. Some affected birds can have biliverdinuria (green discoloration of the urates). 1,2 Birds have a unique respiratory system in which air sacs direct airflow in one direction through the lungs. This makes respiration extremely efficient; it is also the reason aspergillosis typically starts in the air sacs before reaching the lungs. Lack of an epiglottis, diaphragm, and surface macrophages, along with limited pseudostratified ciliated columnar cells, may be predisposing factors in the spread of aspergillosis after initial infection. 4 Hyphae can also penetrate the air sacs and/or invade into blood vessels, consequently leading to a systemic infection through hematogenous spread. 4,5 Signs of ocular aspergillosis typically include discharge, dull/cloudy cornea, blepharospasm, photophobia, swelling, and/or conjunctival yellow exudate. 2,4 DIAGNOSIS Diagnostic testing includes blood work (complete blood count, biochemistry), fungal culture, serology, imaging, endoscopy, and histopathology. 1 Blood work may reveal moderate to severe leukocytosis with heterophilia (25,000–100,000 cells/mcL) with a reactive left shift. 1,2,4 Repeated blood work can be used to evaluate disease progression and treatment success. Chronic inflammation may reveal nonregenerative anemia. 3,4 Elevated liver values (aspartate aminotransferase and lactate dehydrogenase), elevated creatine kinase, hypoglycemia, hypoalbuminemia, and hyperglobulinemia (beta and gamma) are characteristic. Increased uric acid or BOX 1 Risk Factors for Avian Aspergillosis 1,4,5 Stress Environmental conditions Inappropriate husbandry Nutritional deficiencies Immunosuppression Corticosteroid use Long-term antibiotic use Wild-caught animal Trauma Physical exertion (eg, migration) Toxicosis Genetics (eg, inbreeding) Preexisting disease FIGURE 1. Ventrodorsal radiograph of an eclectus diagnosed with aspergillosis. Soft tissue opacities can be appreciated in the cervical region of the coelom. FIGURE 2. CT scan of the eclectus parrot shown in Figure 1 diagnosed with aspergillosis. Note the detailed view of the lesion compared with the radiograph in this image.

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