Thursday, November 19, 2015

Understanding Navicular Disease In Horses

By Mattie Knight

Navicular disease is a chronic condition that affects particularly those that take part in races. The cause of this problem remains obscure but the common denominator in all cases is destruction of navicular bones and other tarsal bones. The condition significantly reduces the competitiveness of the horse and is associated with considerable pain. We will look at some facts on navicular disease in horses in this article.

The disease has a gradual onset and initially manifests with intermittent lameness. Since both anterior limbs are usually affected simultaneously, it may go unnoticed for some time. One of the earliest instances that the problem is suspected is during a lunge. Preforming a nerve block on one of the limbs helps to confirm or rule out the problem. Flexing the distal forelimbs may exacerbate the lameness transiently.

It has been demonstrated through research that there are a number of conformational defects that increase the risk of suffering from this problem. Some of the problems include small feet, long toes, and upright pasterns. All these disorders are associated with abnormal pressure distribution especially during movement. There is, in addition, an increased probability of damage to the tarsal bones over time.

Horses that race on hard irregular ground are at a high risk. Such ground has been shown to increase the stress that is exerted on tendons and bones of the feet. The same may happen if your animal spends time in the standing position for prolonged periods. In this position, a lot of weight is transmitted through the feet leading to increased damage to the bones and tendons.

Improper fitting shoes are a known cause of damage to feet. This has been affirmed by the fact that the incidence of this problem is higher in domesticated horses compared to those living freely in the wild. Metallic shoes do not allow for expansion of the toes during movement. This impairs the flow of blood into the tarsal ligaments and bones. Barefoot trimming and proper shoe section can help reduce this problem.

Several treatment options exist. These are categorized as either conservative or invasive (surgical). Conservative options involve proper shoe selection and administration of analgesic drugs. NSAIDs are arguably the most commonly used class of drugs. They provide relief in most affected horses but may lead to some side effects especially in the renal and gastrointestinal systems. Stopping drug administration intermittently helps minimize these side effects.

Steroids should be considered if NSAIDs fail to relieve the pain. The steroids are usually injected into the navicular bursa directly bringing the drug very close to the affected structures. There is reported improvement in up to 80% of affected horses after 4 months of drug administration. The main worry with this mode of administration is an increased risk of tendon rupture.

There are several surgical procedures that may be performed but only as a last resort. It should be emphasized that these surgical operations will by no means cure the condition; they only provide symptomatic relief. One of those that are commonly performed is known as palmer digital neurectomy. Apart from relieving pain, this operation helps to improve competitiveness.

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