Standardized neurological examinations in Sonoran Desert toads (Incilius alvarius) demonstrate species-specific...

To evaluate the application of published standard clinical neurological examination techniques in Puerto Rican crested toads (PRCTs; Peltophryne lemur) in Sonoran Desert toads (Incilius alvarius) and to establish expected species-specific results for the selected neurologic tests.

A research population of healthy Sonoran Desert toads at Oklahoma State University was used in July 2025. A prospective experimental study design was utilized to perform neurological examinations. Standard tests described in PRCTs were performed on each individual and evaluated for feasibility, and expected results were compared to other species.

19 toads were available, with 3 excluded due to mild pododermatitis. Sixteen toads were included for evaluation. Multiple tests were inconsistent or produced absent responses in this species, including menace response (0 of 16 [0%]), facial stimulation (5 of 16 [31%]), physiologic nystagmus (0 of 16 [0%]), withdrawal reflex (0 of 16 [0%]), myotatic reflexes (0 of 16 [0%]), vent tone (0 of 16 [0%]), tactile placing (5 of 16 [31%]), proprioceptive placement (0 of 16 [0%]), and hopping (4 of 16 [25%]). The tests that were consistent and reproducible across individuals (ie, 100% positive response) were the righting reflex, wheelbarrowing, pupil symmetry, pupillary light reflex, corneal reflex, and palpebral reflex.

Expected responses during neurologic examinations differed in Sonoran Desert toads compared to PRCTs, with a notable difference being that Sonoran Desert toads did not show a withdrawal reflex, proprioceptive placement, and hopping as well as facial stimulation that was seen in PRCTs.

The findings demonstrated that neurological examinations in amphibians should be evaluated against species-specific parameters.