Lameness in Horses – CASE STUDY Why getting the whole clinical picture is so important

December 15, 2021

Almo Staniforth is a 13-year-old thoroughbred gelding. His owner contacted Towcester Equine Vets as she was concerned that he was presenting with a forelimb lameness. Read our case study to understand how our equine veterinary team tackled Almo’s case, and why a combination of diagnostic analgesia, imaging, and clinical presentation is key in horse lameness evaluation and assessment.

Firstly, our experienced equine Vets assessed Almo and graded the right forelimb lameness as 4/10 in a straight line, 5/10 on the left rein on a circle, and 3/10 on the right reign on a circle, on both hard and soft surfaces.

Ninety percent of Almo’s forelimb lameness was in the foot, so the shoe was removed to look for any solar pain or abscess tracts. Neither was found, so our team started nerve blocking to localise the source of pain. Nerve blocking, or ‘diagnostic analgesia’, involves injecting a local anaesthetic either around a specific nerve, or into a joint or synovial sheath. This aims to numb the area and therefore reduce or abolish any pain within that area.

The nerve blocking procedure began with a Palmar Digital nerve block, which should numb most of the foot, hoof wall, and coronet band apart from the very front aspect. Sometimes this block can also numb the pastern and the fetlock, so whilst fairly non-specific, it is useful to localise pain to the foot/pastern region. In Almo’s case, we had no improvement in the lameness following this nerve block.

Next, an Abaxial Sesamoid nerve block was placed, which should numb the pastern region and the whole of the foot. Again, there was no improvement in Almo’s lameness. There was a moderate effusion (increase in fluid) of his right fore fetlock joint, which can sometimes indicate inflammation within the joint. Therefore, a fetlock joint block was performed next, however, this also proved negative.

Following this, a Low 4 Point nerve block was placed, which resulted in an improvement in the level of lameness. This should numb the fetlock region, digital flexor tendon sheath, pastern region, and the whole of the foot.

Diagnostic imaging
The next part of Almo’s lameness work-up involved diagnostic imaging. This involved radiography (X-ray) of the fetlocks, pasterns, and feet. The opposite limb was also imaged as a comparison. Radiographs showed no changes to the fetlock or pastern. However, a historic fracture to the lateral wing of the pedal bone was found, as well as gas pocketing at the medial seat of corn region in the foot. This was investigated more aggressively and a deep tract was found and pus released.

Almo’s foot was tubbed and dressed with Epsom salts daily to encourage draining of the abscess. His foot was also trimmed and shod appropriately to temporarily relieve pressure over this area. Thanks to our equine team’s thorough investigations, Almo is on his way to making a full recovery.

Almo’s case is interesting because it shows the importance of taking the full clinical picture into account. It would usually be expected for pain associated with the foot abscess to improve following a Palmar Digital block, and the lateral pedal bone fracture found on radiography could have been assumed to be clinically significant had the medial gas pocket been missed. However, observing the lameness worse with the limb on the outside of a circle, the pain should have been on the inside of the leg.

Nerve blocks are often non-specific and some types of pain are not abolished with the normal blocking pattern, so it can be a long process of nerve blocking and diagnostic imaging to reach a diagnosis. Horse lameness work-ups can be challenging, but it is important to be systematic and thorough, taking all pieces of the puzzle into account. This is especially highlighted when a horse lameness case, such as Almo’s, does not follow the expected response during investigations.

Abscess and gas tract seen circled

Wing of pedal bone fracture site circled