What is Fracture of the Navicular Bone ?
Unfortunately, your horse may not ever be able to return to the previous physical condition and activities. In fact, there have been instances when it is better to euthanize rather than continue to allow your horse to be in such excruciating pain. This may be extreme, but horses spend most of their lives standing up so a diagnosis like this can be fatal.
Navicular bone fracture in horses is not common and is most often a result of an injury or excessive concussion to the foot. However, some causes are never discovered. It is not as common as certain other fractures such as a distal phalanx fracture, but is more common than others such as fracture of the fourth branchial arch. Pain is moderate, as is the amount of lameness, but when manipulated with a hoof tester, pain is almost always present. MRI or x-rays will usually show a sagittal crack lateral or medial to the midline.
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Symptoms of Fracture of the Navicular Bone in Horses
Some of the most common signs of navicular bone fracture in horses are:
- Sudden onset of mild to severe lameness
- Refusing to stand on affected leg
- Abnormal change in gait
- Favoring one leg
There are two types of fractures of the navicular bone, which are:
Causes of Fracture of the Navicular Bone in Horses
The causes of navicular bone fractures can be from injury, mechanical, or from a pre-existing disease. Some of the situations that can cause a fracture are:
- Kicking a stationary object such as a wall or post
- Running too hard on concrete or other hard surfaces
- Idiopathic (unknown)
Diagnosis of Fracture of the Navicular Bone in Horses
To diagnose your horse, the veterinarian will need medical history, immunization records, incident leading up to the injury if known, and the symptoms you have noticed. A comprehensive and detailed physical examination will be needed as well, which includes observing your horse from a distance to see demeanor and behavior at first. Then, the veterinarian will come closer to check weight, height, body condition score, coat condition, color of mucous membranes, conformation, body temperature, distal and heat pulse in feet, listen to the digestive system sounds, take pulse and respiratory rates, listen to the heart and lungs with a stethoscope, check blood pressure, and assess the gums for capillary refill time.
A lameness examination will be performed next, which includes watching your horse’s muscle movement and joint activity while at a walk, trot, and maybe at canter. This is usually done by walking your horse in a circle and a straight line to view the movement in all conditions. Flexion examination is also a good tool to diagnose your horse. The veterinarian will first put the affected leg under stress for several minutes before sending you out at a trot again. Hoof testing may also be done by using a pincer like tool to induce pain in the foot to find the area where it hurts the most. A joint block will be given (injected) to numb the area before sending your horse out again for another movement test.
In addition, a bone scan, x-ray, and MRI will be conducted to determine the placement and severity of the fracture. In some cases, an ultrasound and CT scan may also be necessary to get a better view. Some diagnostic tests that may be needed to rule out other conditions are a chemistry panel, complete blood count (CBC), urinalysis, fecal examination, blood urea nitrogen (BUN), glucose and insulin levels, bacterial and fungal cultures, and a packed cell volume (PCV) to check for dehydration.
Treatment of Fracture of the Navicular Bone in Horses
Treating your horse for a fracture of the navicular bone depends on the placement and severity of the break. If the fracture is small and not too severe, complete stall rest is done for up to six months. Some other treatments are as follows:
Some cases require immediate surgery in which the veterinarian uses a lag screw to stabilize the fracture. Afterward, your horse will need to be on complete stall rest for up to one year.
There are fractures that are able to be stabilized with an egg bar or heart bar shoe. The shoe should also be applied with a raised heel up to 12 degrees.
Non-steroidal anti-inflammatory drugs are used to decrease pain and swelling. Naproxen, ibuprofen, aspirin, phenylbutazone (bute), and isoxsuprine are all good to promote blood flow and reduce inflammation.
Another treatment that can be used in conjunction with other treatments (or alone) is a foot cast. This is just like a cast for humans, but in most cases the horse has to be under anesthesia when performing this procedure.
Recovery of Fracture of the Navicular Bone in Horses
Unfortunately, your horse’s foot may never heal correctly even with treatment. Of course, this depends on the injury and how young and healthy your horse is.