# Evaluation of Cervical Myoclonus in Dogs with Spinal Diseases: 113 Cases (2014–2023)

## TL;DR

This study examines 113 dogs with neck spasms to determine their causes and outcomes, finding that various spinal conditions can lead to this symptom across multiple breeds.

## Contribution

The study provides a comprehensive analysis of cervical myoclonus in dogs, identifying multiple underlying spinal conditions and breed predispositions beyond intervertebral disc disease.

## Key findings

- French Bulldogs were the most commonly affected breed, followed by Beagles, Chihuahuas, and Shih-Tzus.
- Neck pain was the most common neurological finding, and MRI showed nerve root impingement in 17% of cases.
- Most dogs (97.4% of those followed) showed resolution of cervical myoclonus after treatment.

## Abstract

Neck spams have been associated with acute intervertebral disc herniation (IVDH) in dogs, with a higher prevalence in French Bulldogs. It is unknown if neck spasms occur in other breeds with other diseases. This multicentred study aimed to describe neck spasms in a large number of dogs, including its distribution regarding signalment, neurological signs, magnetic resonance imaging (MRI) findings, suspected diagnosis, treatment and outcome. A total of 113 dogs with neck spasms as part of their presenting clinical signs were included in the study. The French Bulldog (n = 52/113), Beagle (n = 8/113), Chihuahua (n = 6/113) and Shih-Tzu (n = 6/113) were the most frequently affected breeds. Neck pain as a single finding was the most common abnormality in the neurological examination. The most common diagnosis was acute IVDH, followed by inflammatory, neoplastic, congenital and vascular diseases. The median age of dogs with neoplastic lesions (134 months) was higher than those of dogs with inflammatory (96 months), degenerative (72 months), vascular (24 months) and congenital (21 months) conditions. Follow-up was recorded in 77 dogs (68%), and 75 of those had resolution of the neck spasms at that time. The results supported that neck spasms can be caused by various underlying conditions and can affect different dog breeds.

Cervical myoclonus (CM) has been associated with intervertebral disc extrusion (IVDE), with a higher prevalence in French Bulldogs. The presence of CM in other breeds and with other aetiologies has not been reported. The purpose of this study was to describe the signalment, neurological examination, neuroanatomical localisation and grade, imaging findings, diagnosis, treatment, follow-up and resolution of CM in dogs. An observational multicentred retrospective analysis identified 173 dogs with CM; of those, 113 met the inclusion criteria. French Bulldogs (n = 52/113, 46%), Beagles (n = 8/113, 7.1%), Chihuahuas and Shih-Tzus (n = 6/113 for each, 5.31%) were the most affected breeds. Apparent cervical pain was the most common finding on neurologic examination (n = 70/113, 62%). Magnetic resonance imaging (MRI) was consistent with nerve root impingement in 17% (n = 19/113) of the dogs. The most frequently diagnosed conditions were degenerative (n = 100/113, 88.5%), inflammatory (n = 8/113, 7.1%), neoplastic (n = 3/113, 2.7%), vascular (n = 1/113, 0.9%) and congenital (n = 1/113, 0.9%) in origin. Dogs with a neoplastic aetiology tended to be older than those with other causes. Follow-up was recorded in 77 dogs, and 75 of these (n = 75/77, 97.4%) had resolution of the CM. The results supported that cervical myoclonus can be caused by various underlying conditions and can affect different dog breeds.