Cutaneous Trunci Reflex in Cats

In the Literature

Paushter AM, Hague DW, Foss KD, Sander WE. Assessment of the cutaneous trunci muscle reflex in neurologically abnormal cats. J Feline Med Surg. 2020. https://doi.org/10.1177/1098612X20917810

The Research …

As with all reflexes, there is a sensory and motor component to the cutaneous trunci reflex (CTR). The sensory input is via each segmental spinal nerve from T1 to L6, and the motor output is via the lateral thoracic nerve found between C8 and T1.¹ Sensory and motor innervation is bilateral; however, stimulation of one side can result in a contraction bilaterally. The CTR is used to reliably monitor neurologic progression in dogs with thoracolumbar spinal cord injury (eg, disk herniation, spinal fracture/subluxation, fibrocartilaginous embolism).² Evidence of ascending loss of CTR following thoracolumbar spinal cord injury could suggest a progression of myelomalacia and a worsening prognosis. Similarly, evidence of descending presence of the CTR could suggest improvement in spinal cord injury due to resolution of bruising, edema, and/or compression.

This study evaluated the CTR in 182 neurologically abnormal cats with neuroanatomic lesion localization anywhere in the central or peripheral nervous system; CTR was detectable in 64.8% of the cats. Statistical analysis did not identify an association between elicitation of the CTR and age, BCS, sex, breed, evidence of traumatic spinal cord injury, metabolic disease, level of mentation, or neuroanatomic lesion localization. Although evidence of spinal pain and CTR outcome was significantly associated, the authors were unable to illuminate the reason for this finding. 

This article supports the anecdotal clinical evidence that the CTR is unreliable in cats and should not be used to assess prognosis or determine the presence or absence of thoracolumbar spinal cord disease in cats. Furthermore, the authors suggest that evaluating the CTR may irritate the cat during the examination and make it less cooperative.

… The Takeaways

Key pearls to put into practice

• Eliciting the CTR in cats is unreliable.

• Evaluating the CTR in cats may aid neuroanatomic lesion localization if present but asymmetric; however, this may result in additional irritation to the patient and contribute to poor patient cooperation.

• The absence of a CTR in cats has little to no significance and should be disregarded by the clinician when attempting to determine the neuroanatomic lesion localization.