The Lameness Examination – What to expect?

image001By Dr. Emmanuel Engeli, Med.Vet., DVM, Diplomate ECVS, Diplomate ACVS, MRCVS

European, American & Royal College of Vet. Surgeons Specialist in Equine Surgery

Consultant for Equine Orthopaedics

at

Lady Dane Veterinary Centre, Faversham – www.ladydanevets.com

 

The full lameness examination requires the owner of the lame horse and the veterinarian to set aside enough time to untangle the history of when and how the lameness developed, to identify the exact location of pain in the limb and the type of condition that might be causing it. Most lameness examinations take at least two hours and some investigations may even take an entire day, especially if multiple limbs are involved.

I recommend that owners of lame horses consider the following points before bringing their animal to the veterinary centre for a lameness examination:

  1. Current legislation states that a horse must always travel with its passport and every veterinarian is required to check the passport before examining and treating a horse.
  2. Pain killing medications such as bute (Equipalazone and other forms of phenylbutazone) should not be given in the five days prior to the appointment to ensure the horse is not rendered sound by medication at the time of the investigation.
  3. Where possible, no farriery should be performed on the horse’s feet in the ten days prior to the visit and shoes should not be removed. Any of the above may interfere with the vet’s ability to accurately diagnose the origin of lameness.
  4. We also recommend bringing all relevant tack as we may need to see the horse move under saddle, as well as in hand and on the lunge.

History Taking

I usually spend a good 15 – 20 minutes talking to the owner or trainer of the lame horse. It is crucial we gather as much information as possible about the horse and the type, level and intensity of work the horse is currently working at. In depth information on when and how the lameness started, what signs the horse has been showing and the circumstances under which the lameness shows at its worst, will provide your vet with valuable information and help put the findings from the lameness examination into perspective.

image003The Physical Examination

It is critically important to take time and perform a thorough clinical examination of the horse as a whole, with a special focus on the lame leg and further inspection and palpation of the non-affected limb on the other side. Even subtle signs of swelling or inflammation will help us determine the affected limb and where the problem might be located within the leg. This then guides the vet to perform a targeted and focused investigation which may save having to perform time-consuming and expensive but possibly unnecessary investigations.

The horse is asked to stand squarely in its front and hindlimbs; his/her foot and limb conformation is evaluated; and the vet will be looking for any signs of joint / soft tissue swelling, muscle asymmetry or abnormal use of the limbs. After the visual inspection, each limb is thoroughly palpated in a standing and non-weightbearing position in order to identify any joint or soft tissue swelling, heat, pain or other anomaly. The range of motion of the different joints is checked and the horse’s response to forced flexion observed. Hoof testers should always be applied to the lame foot with the goal to identify any painful process located under the sole (e.g. foot abscess, coffin bone fracture) and the horse’s response to hoof testers should always be compared to the response in the non-affected foot.

image004 Dynamic Examination

Following the physical examination, the horse is walked and trotted in a straight line and observed from the front, the back and the side. The horse’s limb advancement, foot fall and stride length are evaluated. As discussed in the previous article (November issue), a frontlimb lameness is recognized by the head dropping onto the non-affected frontlimb, short-striding, tripping and stumbling. A hindlimb lameness is usually characterized by short-striding of the affected limb, a one-sided dropping or rising of the quarters and asymmetry behind. In the UK, lameness is usually graded on a scale from 1 to 10 with 0 being sound and 10 being non-weightbearing.

After the trot-up, flexion tests are usually performed and consist of forced flexion of either the lower or upper limb over a time period of 30 – 90 seconds. This is a crude attempt at pinpointing if the problem is located in the lower or upper part of the lame limb and the vet will be evaluating the horse’s response during the forced flexion and his/her gait following flexion. An obvious and sustained worsening of the lameness in the flexed limb at the trot would in general be interpreted as a ‘positive’ response. This response is then compared with the flexion response of the non-affected limb.

The horse is then lunged at the walk, trot and canter on both reins on a soft surface, allowing the veterinary surgeon to assess the horse’s uninhibited gait. On the lunge the horse’s lameness is again graded and the movements of the limbs, neck and back will be assessed. I also lunge horses on a hard, flat and even surface (tarmac or concrete) as it provides less cushioning and thus tends to exacerbate a weightbearing or foot lameness. These tests are often the only reliable method for revealing a lameness that affect both front feet and should, in my opinion, be a routine part of the detailed lameness examination.

Assessment under saddle (ideally performed by a professional rider) is sometimes necessary, especially in horses that are suspected of having a back or sacroiliac problem or in horses with an obscure hindlimb lameness.

Diagnostic Options

In some cases, the cause of lameness will be relatively easy to determine based on an abbreviated initial assessment, followed by x-rays and/or ultrasonography. Examples might include a horse with a damaged tendon, club foot or active splint. However, in many cases, it is necessary to perform nerve and joint blocks after the initial evaluation, to find the region that is painful and causing the lameness. Your vet will usually start with leg injections (to numb each area) at the bottom of the limb and work progressively upwards, unless there is obvious joint swelling somewhere. This procedure can be very time consuming, as the horse is continually re-assessed (by trotting and lunging) after each injection, thus taking between 40 and 60 minutes for each block. If your horse requires multiple nerve blocks to be performed, it is therefore possible that the examination will take the entire day.

Once nerve blocks have caused the horse to become more sound (because the last nerve or joint block has numbed the pain), x-rays of the affected region will be taken to evaluate the bones, joints and ligament/tendon attachments. If no abnormalities can be found, the local ligaments, tendons, muscles and other soft tissues may need to be assessed with ultrasonography.

Because of the vast individual variability in the ultrasonographic appearance of normal soft tissue structures in the horse, it is recommended to compare the images from the lame limb with the ones from the non-affected limb. If x-rays and ultrasonography do not lead to a specific diagnosis or if certain structures are not accessible to ultrasonography (for example in the foot), then your horse might be referred to another institution where advanced imaging modalities like nuclear scintigraphy (bone scan), computed tomography (CAT scan) or a magnetic resonance imaging (MRI scan) can be performed.

Once a definitive diagnosis has been reached, your veterinary surgeon will provide you with a treatment plan consisting of rest / exercise recommendations combined with other treatment modalities, which may include surgery, all of which will be targeted to increase your horse’s chances of making a full recovery.

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