Polymelia in a chimeric Simmental calf: nociceptive withdrawal reflex, anaesthetic and analgesic management, anatomic and genetic analysis

• Published in: BMC veterinary research Vol. 15; no. 1; p. 102
• Main Authors: Morath-Huss, Ute, Drögemüller, Cord, Stoffel, Michael, Precht, Christina, Zanolari, Patrik, Spadavecchia, Claudia
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 29.03.2019; BioMed Central; BMC
• Subjects: Analgesia - methods; Analgesia - veterinary; Analgesics; Anesthesia; Animals; Beef cattle; Birth defects; Calf; Calves (Cattle); Care and treatment; Case Report; Case reports; Case studies; CAT scans; Cattle; Cattle - abnormalities; Cattle - genetics; Cattle - physiology; Cattle - surgery; Chimeras; Chimerism; Chronic postsurgical pain; Computed tomography; Disease management; Electrical stimuli; Electromyography; Electromyography - veterinary; Female; Genetic analysis; Genetic aspects; Genetic disorders; Genetic research; Genetics; Health aspects; Limb Deformities, Congenital - diagnostic imaging; Limb Deformities, Congenital - physiopathology; Limb Deformities, Congenital - surgery; Limb Deformities, Congenital - veterinary; Musculoskeletal abnormalities; Neuralgia; Nociception; Nociceptive withdrawal reflex; Pain; Pain management; Pain Measurement - veterinary; Pain perception; Polymelia; Reflex; Sensory neurons; Spina bifida; Supernumerary; Surgery; Systematic review; Tomography; Tomography, X-Ray Computed - veterinary; Switzerland; Polymelia; Chronic postsurgical pain; Chimerism; Nociceptive withdrawal reflex; Calf
• ISSN: 1746-6148; 1746-6148
• DOI: 10.1186/s12917-019-1846-4

Polymelia is a congenital defect characterized by one or more supernumerary legs. The genetics and aetiology of this condition in cattle have not yet been thoroughly investigated even though several case reports do exist. The model of the nociceptive withdrawal reflex (NWR) has been characterized in several species to study spinal nociceptive processing. It is a polysynaptic spinal reflex that can be elicited by noxious electrical stimulation and recorded by electromyography. Thorough nociceptive examination and preventive analgesic management has not yet been an aspect in the perioperative management of polymelia cases. A 4-month-old female Simmental calf was presented with notomelia. The animal was in good health and showed no neurologic deficiencies. Preoperatively, computed tomography was performed to gain more detailed anatomical information. To evaluate the sensitivity of the accessory limb, NWR testing was performed and revealed a connection of the afferent reflex pathway of the accessory limb to the efferent of the normal limb. The accessory limb was surgically removed under general anaesthesia. Intensive care included multimodal pain therapy adapted to the pain intensity scored during regular pain assessment. A gross anatomical dissection as well as a genetic analysis of the accessory limb were performed postoperatively. The calf was identified as a chimera. This calf was successfully relieved of its accessory limb. Chimerism has not been described in the congenital defect polymelia. As the accessory limb was pain sensitive and a common nociceptive reflex pathway was identified, thorough perioperative pain management was performed with the intention to prevent chronic neuropathic pain development.