The sensory field and repeatability of the cutaneous trunci muscle reflex of the dog.

Objective: To describe the cutaneous trunci muscle (CTM) reflex in dogs.

Study Design: Prospective descriptive study.

Animals: Normal dogs (n = 155) and 10 dogs with thoracolumbar myelopathies.

Methods: The CTM reflex caudal border was assessed from the ilial crests moving cranially until a CTM contraction was elicited. The lateral borders were evaluated at 4 levels and the distance from the midline to the lateral border was expressed asa percentage of the trunk hemicircumference. The caudal border was assessed in 10 dogs with myelopathies by 4 different observers and by 1 observer on 3 occasions;the inter- and intraobserver kappa coefficient was calculated.

Results: The CTM reflex was elicited in all dogs. Its caudal border was at L5 or L6 in 153 dogs and at L1 and L3 in 2 dogs. The lateral field of the reflex occupied>50%of the hemicircumference of the trunk at each level tested. The mean difference in measurement of the reflex caudal border was 0.55 cm between observers and 0.28 cm for the same observer. The inter- and intraobserver kappa coefficient was 0.67 and 0.87, respectively.

Conclusions: The CTM reflex is elicited caudal to L5 in most normal dogs, and the lateral sensory field extends to 50% or more of the circumference of the trunk.Inter- and intraobserver differences in assessment of the caudal border are low.