Case summary A 4-month-old male entire domestic shorthair cat presented for sudden onset of right thoracic monoparesis following a fall; within 18 h, the clinical signs progressed to non-ambulatory right hemiplegia with absent sensation in the distal right thoracic limb and left hemiparesis. MRI revealed changes consistent with a C6–C7 acute non-compressive nucleus pulposus extrusion with suspected secondary C5–C7 spinal cord haemorrhage. Rehabilitation exercises were started immediately after the diagnosis of acute spinal cord trauma. Sensation in the right thoracic limb improved and, with the help of a splint applied to that limb, the cat was ambulatory on all four limbs. Unfortunately, clinical signs started to progress over the course of 10 days. The cat developed progressive discomfort on manipulation of the right elbow and carpus, and a hyperflexion of the right carpus. Radiographs revealed no skeletal abnormalities. Muscle contractures were suspected. Under general anaesthesia the triceps and flexor muscles of the carpus and digits were injected with a total of 100 U of botulinum toxin type A (BTX-A). No complications were associated with the procedure and 24 h after the injection the carpal hyperflexion resolved. Relevance and novel information The use of BTX-A to treat muscle contractures in human medicine is an established and increasingly used technique. For example, in subacute stroke patients with a non-functional arm, BTX-A forearm injection appears to prevent disabling finger stiffness, likely by minimising the development of contractures. Here, we demonstrate that intramuscular BTX-A is an effective treatment for acquired muscle contractures in a cat.