Unexplained forelimb lameness possibly associated with radiculopathy

Abstract

SummaryThere are limited descriptions of forelimb lameness that is not improved by diagnostic analgesia. The objectives of this retrospective study were to describe the clinical features, response to diagnostic analgesia and imaging findings in such horses (n = 25), to apply a ridden horse ethogram to video recordings of a subset of horses (n = 13) and to document post‐mortem findings (n = 3). Clinical records from 2006 to 2016 were reviewed, and data concerning signalment, history, lame limb(s), lameness characteristics, response to diagnostic analgesia and diagnostic imaging were recorded. A ridden horse ethogram was applied to 13 horses to document pain‐related behaviour. Results showed that nine horses had idiopathic hopping‐type forelimb lameness only when ridden; two horses exhibited a hopping‐type gait only on the lunge or worse on the lunge than ridden, and 14 horses had conventional lameness. Head and neck tilt was observed in 24% of horses. Lameness was different on a long rein compared with a contact in 28% of horses. Forelimb stumbling was a feature in 16% of horses. Exacerbation of lameness by diagnostic analgesia was seen in 76% of horses. Radiographic abnormalities of the caudal cervical and cranial thoracic vertebrae of potential clinical significance were observed in 92% of horses. Pain behaviour scores were higher than those reported for nonlame horses. Post‐mortem examination of three horses provided the evidence of caudal cervical or cranial thoracic nerve root compression. Limitations of the study were that it cannot be assumed that there was a common aetiology of lameness in all horses. It was concluded that there is increasing evidence that nerve root injury may cause forelimb lameness.