TOWARDS THE ACCURATE DIAGNOSIS OF OVINE ASIA SYNDROME: DETECTION OF ALUMINUM-INDUCED, POST-VACCINATION GRANULOMAS BY COMPUTED TOMOGRAPHY IN SHEEP.
- Ana Rodríguez-Largo, Spain
Abstract
Background and Aims
Autoimmune syndrome induced by adjuvants (ovine ASIA) has been related to aluminum (Al)-induced persistent subcutaneous post-vaccination granulomas. They consist on Al-laden macrophages that can translocate to the lymph node and other tissues. A suitable in vivo detection method is not yet available: granulomas cannot be properly assessed by palpation or routine imagine diagnostic techniques such as ultrasounds or radiographic evaluation. Computed tomography (CT) scan has been recently applied to sheep and the aim of this study is to test its performance in the detection of subcutaneous Al-induced granulomas in sheep.
Methods
Thoracic CT scans of 56 sheep submitted to the Veterinary Teaching Hospital for clinical reasons were undertaken. Age was variable and vaccination schedule was mostly unknown. CT subcutaneous masses were evaluated by cross-sections, visualization after intravenous administration of a contrast agent and 3D reconstructions. Histopathologic and microbiologic studies were performed in a selection (n=8) of the total number of masses compatible with granulomas detected by CT scan (n=36).
Results
Subcutaneous soft tissue masses, compatible with Al-induced granulomas were observed in 36 out of 56 sheep (64.3%) by CT. The necrotic center was clearly defined after intravenous contrast. Histologically, all selected masses showed the characteristic pattern of post-vaccination Al-induced granulomas. Microbiology was negative.
Conclusions
CT scan is able to easily detect Al-induced granulomas in sheep and provides unmatched information (location, extension, necrosis, and mineralization). CT detection of Al-induced granulomas could improve the diagnostic tools available to diagnose ovine ASIA syndrome and perhaps guide future therapeutic approaches.