The navicular bone is one of the tarsal bones in humans and other animals located in the ankle region. It lies between the talus and cuneiform bones. Understanding the anatomy of the foot is vital for one to institute proper management of navicular disease in horses. This condition is caused by damage to the bone and its supportive structures. The effect of this is progressive lameness primarily in the forefeet.
The exact cause of this condition remains unclear but there are a number of theories that have been forwarded. One of the commonest predisposing factors is the repetitive movement of the navicular bone and its support structures. For this reason, the incidence has been found to be higher in horses that are frequently take part in competitive races. Genetic factors and diet also contribute.
Inflammation of surrounding ligaments reduces blood flow to the bone and increased pressure in the hoof. The earliest sign is heel pain and lameness follows within days or weeks and progresses in severity over time. Typically, the horses start exhibiting a tip-toeing gait as they attempt to exert pressure on the heel. They lose coordination and stumble frequently. Lameness may affect one or both feet with the second being involved due to overcompensation.
There are a number of conformational defects that serve as a risk factor for the disease. Most of the known defects increase the risk of concussion and by extension, bone damage. Narrow feet, small feet and long toes are all examples of conformations that increase pressure on the tarsal bones. This effect is multiplied several times during movement due to the large amount of shock produced.
If horses are trained on hard and irregular terrain, the risk is increased. This is because there is a tremendous amount of stress put on the main tendons predisposing them to wear and tear. This effect may also be seen in horses that spend a lot of time in the upright position. In this case, the cause is increased load transmission through the hoof. This is worsened by a high weight to foot ratio.
Poor selection of shoes or trimming is another cause of lameness. This is more common in the domestic horse as compared to that which lives on the wild. There are experts who have proposed the adoption of barefoot trimming among domestic horses. The argument is that the hooves should be allowed to expand and contract during movement. This movement is said to assist in blood flow a feature that is not present when metallic shoes are used.
There are very many causes of this problem and as such the treatments are not uniform. For instance, when the causative agent is a degenerative change, only supportive treatment is given. Reversal of the damage is virtually impossible. Proper trimming of feet helps to achieve biomechanical and neurological balance. Exercise should be reduced as much as possible.
Pharmacotherapy has a role to play. Drugs are used for carefully selected cases. For instance, when blood flow is suspected to have been compromised, vasodilators are administered. They maintain patency of vessels and ensure blood is supplied to the affected areas. Other drugs that help with other aspects of this disease include NSAIDS, gallium nitrate, corticosteroids and bisphosphonates. Surgery is performed for cases that have failed to respond to other treatments.
The exact cause of this condition remains unclear but there are a number of theories that have been forwarded. One of the commonest predisposing factors is the repetitive movement of the navicular bone and its support structures. For this reason, the incidence has been found to be higher in horses that are frequently take part in competitive races. Genetic factors and diet also contribute.
Inflammation of surrounding ligaments reduces blood flow to the bone and increased pressure in the hoof. The earliest sign is heel pain and lameness follows within days or weeks and progresses in severity over time. Typically, the horses start exhibiting a tip-toeing gait as they attempt to exert pressure on the heel. They lose coordination and stumble frequently. Lameness may affect one or both feet with the second being involved due to overcompensation.
There are a number of conformational defects that serve as a risk factor for the disease. Most of the known defects increase the risk of concussion and by extension, bone damage. Narrow feet, small feet and long toes are all examples of conformations that increase pressure on the tarsal bones. This effect is multiplied several times during movement due to the large amount of shock produced.
If horses are trained on hard and irregular terrain, the risk is increased. This is because there is a tremendous amount of stress put on the main tendons predisposing them to wear and tear. This effect may also be seen in horses that spend a lot of time in the upright position. In this case, the cause is increased load transmission through the hoof. This is worsened by a high weight to foot ratio.
Poor selection of shoes or trimming is another cause of lameness. This is more common in the domestic horse as compared to that which lives on the wild. There are experts who have proposed the adoption of barefoot trimming among domestic horses. The argument is that the hooves should be allowed to expand and contract during movement. This movement is said to assist in blood flow a feature that is not present when metallic shoes are used.
There are very many causes of this problem and as such the treatments are not uniform. For instance, when the causative agent is a degenerative change, only supportive treatment is given. Reversal of the damage is virtually impossible. Proper trimming of feet helps to achieve biomechanical and neurological balance. Exercise should be reduced as much as possible.
Pharmacotherapy has a role to play. Drugs are used for carefully selected cases. For instance, when blood flow is suspected to have been compromised, vasodilators are administered. They maintain patency of vessels and ensure blood is supplied to the affected areas. Other drugs that help with other aspects of this disease include NSAIDS, gallium nitrate, corticosteroids and bisphosphonates. Surgery is performed for cases that have failed to respond to other treatments.
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