Histopathological and diagnostic aspects of glanders based on a case series from Brazil

•Glanders disease described in 16 horses and one fetus from 3 outbreaks•The clinical and gross alterations mainly comprised nasal and respiratory forms•Of the 17 animals presented, 7 (41.2%) did not show clinical signs•All animals (n=17) were positive by polymerase chain reaction (PCR).•B. mallei detected in 41.3% necropsy samples by PCR and 8.2% by bacterial isolation Glanders is a zoonotic disease of equids caused by the bacterium Burkholderia mallei, responsible for considerable economic loss. This study aimed to describe the clinical manifestations, pathological findings, and also bacteriological and molecular methods for agent detection in naturally infected animals (16 adult horses and one fetus) detected by serological survey from three glanders outbreaks. Of the 16 horses, 6 (37.5%) did not show clinical signs. After necropsy,samples of organs, lymph nodes, lesions and secretions were collectedfor histopathology, bacterial isolation, and PCR. The clinical and gross alterations mainly comprised nasal and respiratory forms in the three outbreaks, and less of the cutaneous form. All tested animals were positive by PCR (100%, n=17) on at least one sample. Of 121 samples analyzed 8.2% (10/121) isolated B. mallei and 41.3% (50/121) were polymerase chain reaction (PCR) positive. This work highlights the importance of combining diagnostic techniques, such as histopathology microbiological culture and PCR,to confirm cases and characterize the morbidity of glanders as well as considering seropositive animals without glanders clinical signs as potential carrier animals affecting disease control programmes.