Newsletter Vol 9 2017
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Contents of this newsletter

01 Miserable melanomas

02 How horses sleep standing up

01 Miserable melanomas
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Melanomas are extremely common in grey horses. Around 80% of greys over 15 years of age may be affected!

Although melanomas are usually slow growing and cause minimal discomfort, they do have the ability to metastasize (spread to other areas of the body). Primary melanomas are often seen around the undersurface of the tail, the perineum, and the genitals. We may then find secondary metastatic melanomas throughout the body, including lymph nodes, body cavities, liver, kidney, heart, and the gut.

Unlike melanoma in humans, which is almost always serious and life threatening, in horses problems mainly arise from the space-occupying nature of the growths. For example, a melanoma in the perineal region may grow large enough to obstruct the passing of manure. Occasionally, melanomas outgrow their blood supply and become necrotic and infected. Other times, melanomas cause problems when they are traumatised and become ulcerated and painful.

Multiple treatments are available, but the most reliable is early surgical removal. Early treatment of small melanomas is ideal to prevent them from spreading. Research to produce more effective treatments (such as a vaccine) is ongoing.

Know your horse - keep an eye on their lumps and bumps and if you're worried, give us a call.

02 How horses sleep standing up
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Have you ever wondered - how can a horse sleep standing up? To enable a horse to sleep standing, the stifle is able to 'lock' into position with the help of ligaments attached to the patella.

However, problems can arise when a horse has difficultly 'unlocking' this mechanism – a condition known as stifle lock.

Stifle lock usually occurs intermittently. The back leg will appear locked straight and stiff behind the horse, sometimes with toe dragging along the ground. The leg will usually spontaneously 'unlock' in a rapid snapping motion, but occasionally the horse may require assistance.

A number of factors are thought to be associated with the development of stifle lock:

  • Conformation (straight legs)
  • Weakness or wastage of the rump muscles (e.g. lack of fitness or lack of body condition)
  • Immature, rapidly growing young horses
  • Injury

We can easily diagnose a horse with an examination. We may recommend X-rays to rule out other causes, and also to check for secondary wear and damage to the joint.

The condition will often improve with a targeted exercise program aimed at improving fitness and building up the rump muscles. Corrective farriery can aid in improving the biomechanics of the hindlimb. Occasionally, intramuscular injections may be administered in an attempt to alter the tension of the ligaments involved in the locking mechanism.

Surgery or more invasive measures are usually reserved for more severe cases, or cases which fail to respond adequately to more conservative management. There are several surgical approaches including injecting the ligament itself, or completely transecting (cutting) it.

If you're concerned about your horse, please give us a call.