Feasibility and variability of corneal esthesiometry in Hermann's tortoises (Testudo hermanni) depending on age and body weight

Background: Hermann's tortoise is one of the most popular reptiles kept as pet which underlines the importance to reinforce the information needed to provide advanced and adequate veterinary care in exotic animal species. Therefore, the purpose of this study, performed in Testudo hermanni, was to evaluate corneal touch threshold (CTT) and its feasibility according to age and body weight. Methods: Fifty-one healthy tortoises were classified in 2 groups (≤2 years [young; n = 25] and 8–10 years [subadult; n = 26]). Central CTT was measured by means of a Cochet-Bonnet esthesiometer and defined as the filament length required to elicit a blink in at least 3/5 applications. CTT feasibility according to body weight was also evaluated by diving the individuals in weight groups consisting of “lighter” (<400 g [n = 31]) and “heavier” (≥400 g [n = 20]) animals. Results: Mean CTT was 5.99 cm for the whole population (90% CI: 5.87–6.11), being 5.98 cm for young (90% CI: 5.81–6.15) and 6 cm for all subadult (90% CI: 6.00–6.00) tortoises, and 5.98 cm for lighter (90% CI: 5.84–6.13) and 6 cm for all heavier (90% CI: 6.00–6.00) tortoises. No statistical differences were detected between age and weight groups (P = 0.159 and P = 0.159, respectively). Three animals presented unilateral faint fluorescein uptake postesthesiometry (3/51; 2.9%) that resolved spontaneously within 48 hours. Conclusions and clinical relevance: Cochet-Bonnet esthesiometer was a safe means of confirming high corneal sensitivity in all tortoises, which was high regardless of age. Increasing filament lengths would ultimately be required to determine the true corneal sensitivity scope of Testudo hermanni.