A large proportion of lameness cases are associated with a recognisable cause and therefore do not require protracted/costly investigative procedures. However, if required, the majority of these can be carried out at the patient’s residence.
The most common starting point is regional anaesthesia (“nerve blocks”) that involves the deposition (via fine needles) of local anaesthetic around certain nerve bundles in order to desensitise the area supplied by those nerves.
A common example of this technique is the abaxial sesamoid nerve block where the local anaesthetic is injected adjacent to the lateral (outside) and medial (inside) digital nerve at the level of the fetlock. A lack of sensation should then occur close to and below that point (i.e., the pastern and the foot is desensitized after approx. 5 mins).
Abolition or a marked reduction in the degree of lameness confirms that area as the origin of the lameness. A lack of improvement means either the nerve block “didn’t do what it says on the side of the bottle” or the site of the pain producing the lameness is higher (more proximal) up the limb.
Further nerve blocks are then carried out higher up the leg.
In order to narrow down the site of lameness local anaesthetic can be placed into certain joints that should become desensitized after about 15 minutes. A sterile approach is imperative for the latter procedure but is of less importance for regional “blocks”.
Prior to these techniques the lameness will be assessed during various forms of locomotion e.g. straight lines and circles at walk, trot, canter and quite often on different surfaces e.g. grass, tarmacadam, and mènage surface and in the same manner following the nerve blocks.
Flexion tests are also performed before and after these assessments and repeated in conjunction with any subsequent nerve blocks.
Following a clinical appraisal of the above tests it is highly likely that some form of diagnostic imaging i.e., ultrasound scanning, X-Rays, gamma scintigraphy (bone scan) or M.R.I. will be required to achieve a diagnosis.
A “lameness work up” is likely to take approx. 40 minutes and any associated nerve block desensitization can last for up to 3-4 hours.
Treatment options are likely to be discussed once a diagnosis has been reached but the majority of these e.g., intravenous infusion of Tildren (Equidronate), intra-articular medication etc. can be carried out at home.