Standing gustatory papillae biopsy procedure for antemortem diagnosis of equine grass sickness.

The research paper presents a new method for diagnosing equine grass sickness (EGS) in living horses by performing a biopsy of the gustatory papillae. Through this surgical procedure performed on the tongue, the team could assess the quality of samples obtained and the presence of EGS in clinically presented cases.

Study Design and Procedure

• The researchers designed a standardized lingual biopsy sampling method with a transbuccal approach. This procedure was tested in six healthy standing horses.
• After sedating and placing the horses in stocks, a mouth gag was inserted to keep the mouth open. Following local anesthesia, doctors made a full thickness incision on both cheeks of each horse.
• The team collected foliate papillae biopsies using an arthroscopic rongeur, an instrument typically used to remove bone or cartilage, which was inserted through each incision site, guided by oral endoscopic control.
• To restrict tongue movements during the procedure, the horses were treated with diazepam, a medication used to regulate anxiety and muscle spasms.
• Following biopsy collection, longitudinal sections of the samples were stained with Hematoxylin and Eosin (H&E) for histological assessment of taste buds and subgemmal plexi neurons.

Results and Findings

• All horses tolerated the procedure well. Some of the minor complications noted included transient facial paralysis, incisional fluid collection, and abscesses.
• Out of 12 samples, 10 were found suitable for assessing neuronal perikarya–the cell body of a neuron
• The researchers concluded that this procedure is a safe method for performing a subgemmal plexus biopsy in healthy standing horses.
• They also found that the obtained samples were of suitable quality, provided they were neatly cut lengthwise for accurate assessment.

Method Application and Conclusions

• This newly developed biopsy technique was applied to two clinical cases, which revealed a complete absence of neuronal perikarya, confirming the diagnosis of chronic EGS.
• Their results show promise in developing a method accessible to veterinarians for antemortem, or pre-death, diagnosis of EGS, which was previously reliant on post-mortem biopsies.