What is Odontoid Process Dysplasia?
Odontoid process dysplasia is considered to be hereditary in most cases, especially with toy and miniature breed dogs such as Cavalier King Charles Spaniels, Beagles, Miniature Keeshonds, Maltese Terriers, Pekingese, Toy Poodles, Japanese Chins, Pomeranians, Chihuahuas, and Yorkshire Terriers. However, the same condition has been recorded as a congenital condition in larger breeds such as Doberman Pinschers and Rottweilers. This condition may also be caused by a traumatic injury to the neck that damages the dens or the ligaments needed to hold the dens in place.
The odontoid process (also called dens) is a peg-like projection from the second cervical vertebrae that is used for rotating the head back and forth. The apical and bilateral alar ligaments hold the dens to the occipital condyles and foramen magnum and when there is an abnormality in any of these parts, the joint will dislocate and cause compression of the spinal cord. In some dogs, the dens is missing or too small to support the process of turning the head. This is a dangerous and painful condition that can cause weakness and even paralysis or death due to the spinal cord compression. In other cases, the dog may have been born with a healthy odontoid process but the dens or ligaments could have been damaged in an accidental injury.
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Symptoms of Odontoid Process Dysplasia in Dogs
Depending on the severity of the odontoid process dysplasia, the symptoms may be very mild or debilitating enough to cause paralysis. However, the most common signs of odontoid process dysplasia are:
- Obvious neck pain
- Holding the head abnormally
- Hypersensitivity of the spine
- Not wanting to exercises
- Weakness of one or more legs
- Inability to move one or more legs
- Hopping when walking
- Holding feet or legs abnormally (paws knuckled under or legs crossed)
- Exaggerated movements
- Walking stiffly or abnormally
- Sudden death
- Genetic (hereditary) odontoid process dysplasia is inherited by a family trait
- Congenital odontoid process dysplasia is caused by something that happens during pregnancy
- Traumatic odontoid process dysplasia is caused by a traumatic neck injury
Causes of Odontoid Process Dysplasia in Dogs
Odontoid process dysplasia is considered to be hereditary in some dogs and congenital in others. The most susceptible breeds include:
- Cavalier King Charles Spaniels
- Miniature Keeshonds
- Maltese Terriers
- Toy Poodles
- Japanese Chins
- Yorkshire Terriers
- Doberman Pinschers
Diagnosis of Odontoid Process Dysplasia in Dogs
The veterinarian will need your dog’s medical history including any abnormal behavior, recent illnesses or injuries, and any medication you have given him. A physical examination will be done, vital signs recorded, and routine blood tests will be performed to rule out other conditions. However, a definitive diagnosis requires the use of x-rays, CT scans, or an MRI to determine the malformation or damage to the dens, ligaments, or other abnormalities.
Treatment of Odontoid Process Dysplasia in Dogs
There are several types of surgical procedures and medical solutions that can be used to treat odontoid process dysplasia.
Stabilization of the atlantoaxial joint (AAJ) is a commonly used surgical procedure that will fix the ligaments to the bone with screws or pins. This will not only stabilize the odontoid process and joint but will also allow the dog to rotate his head without pain or paralysis. There is also a plate called an atlantoaxial fixation plate, that can be fixed to the atlantoaxial joint, which will fuse the area and stabilize the odontoid process.
The fixation plate allows the dog to move his head without pain or loss of feeling. As a last resort, if the other procedures are not possible, the veterinarian can fuse the first two vertebrae and the dens with a bone graft or metal plate to hold it in place. In this procedure, the dog will not be able to turn his head, but it will relieve the pain and paralysis.
If the veterinarian believes your dog’s condition is not serious enough for surgery, a stabilization collar or other external stabilizing device (halo) can be used.
In mild cases, the veterinarian may choose to prescribe prednisolone and furosemide to reduce the pressure in the spinal cord and ease the pain. Analgesics or other pain relievers may also be given.
Recovery of Odontoid Process Dysplasia in Dogs
Your dog’s prognosis depends on the severity of the odontoid process dysplasia and how well the treatment worked. If the dysplasia was able to be stabilized, your pet should have a complete recovery within a few weeks. You will have to keep your dog on cage rest for several days until he is completely healed. Be sure to return for your dog’s follow-up appointment and if you have any questions or concerns, call your veterinarian right away.