EQUINE VETERINARY EDUCATION / AE / MARCH 2015
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standing CT scan of the head was performed at the owner’s request.
Computed tomography findings
Standing CT was performed at Helsingborg Regional Animal Hospital using a Philips Brilliance Big Bore 16 slice CT scanner1 with platform and stocks designed by Solving2 and Helsingborg Regional Animal Hospital. A helical scan was performed with a slice thickness of 0.8mm per slice, 140 kV and 340 mAs. The rotation time was 0.5 s with a platformspeed of 1.6 mm/s. The horse was sedated with acepromazine (Plegicil Vet)3 (0.01 mg/kg bwt), detomidine (Domosedan)4 (0.01 mg/kg bwt) and butorphanol (Torbugesic Vet)4 (0.015 mg/kg bwt) intravenously (i.v.). Computed tomography examination revealed bilateral subchondral sclerosis and irregularity of the mandibular condyles at the TMJs. These findings were slightly worse on the left. Furthermore, a small subchondral cyst-like lesion was detected on the left mandibular condyle (Fig 1). Mild periarticular osteophyte production on the medial aspect of both TMJs was noted and the joint space was decreased bilaterally. There was bilateral, mild proliferation at the temporohyoid joints.
Further diagnostics
Following CT scan, the horse was re-evaluated ridden and a low grade left front limb lameness was still evident, as well as the lack of correct engagement, poor flying changes and tense head carriage on the right rein. Considering the imaging findings, 10 ml mepivacaine hydrochloride (Carbocain 2%)5 was injected into the dorsal synovial pouch of the left temporomandibular joint, as previously described by Rosenstein et al. 2001 (Fig 2). The horse was ridden again 10 min after the injection. There
was a substantial improvement in the performance of the horse to both rider and clinicians; the head carriage on the
a)
right rein became less tense, the horse engaged better and the flying changes were correct. Despite the improved performance, the horse still showed
lameness in the left forelimb which at this time also was recognised by the rider/owner. The lameness did not improve following an abaxial sesamoidean nerve block but improvement was seen after a subcarpal high 4 point block. However, after the positive block of the left front limb, a similar lameness was detected in the right forelimb. Due to the conformation of the horse, bilateral suspensory ligament strain was suspected. Ultrasonography of the suspensory ligaments and flexor tendons was performed in both front limbs but no abnormalities were found. No further diagnostics were performed.
Treatment
The day after analgesia, the dorsal synovial pouch of the left TMJ was treated with 18 mg triamcinolone acetonide (Kenalog)6 and 51 mg sodium hyaluronate (HiFifty)7 due to the CT findings and a suspected associated synovitis. The initial treatment of the front limb lameness was done using corrective farriery, by shortening both front limb toes and making the breakover point further back in the hooves to create a better anterior–posterior balance. The use of wedges was abandoned to reduce stress on the suspensory ligaments. The horse was maintained in light work and no anti- inflammatory or other drugs provided.
Follow-up
Ten days following TMJ treatment the rider reported, that the horse was performing well and the initial complaint had disappeared. Three months later the rider informed that the horse was continuing to performmuch better, not being heavy on the right rein, collecting better and was more relaxed at events. Furthermore, the horse had stopped yawning and
b) P
RL
A
Fig 1: Sagittal CT image at the level of the TMJs to compare a) normal image and b) this case showing a small subcondral cyst-like lesion in the left mandibular condyle.
© 2014 EVJ Ltd
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