Have you ever noticed how some breeds of dogs have a little cork screw or screw-tailed appearance? Often these dogs tend to be the short muzzled or brachycephalic breeds as well, and their short little kinky tails tend to balance out their short, pushed in faces.
While the short little kinked tails may be cute in appearance, it is also an indicator of a deformation of the vertebrae of the spine, known as hemivertebrae. There are also some types of hemivertebrae or hemivertebra that can occur in other areas of the spine as well resulting in other malformations and movement problems. The breeds most likely to have hemivertebrae at the tail include Pugs, Boston Terriers and the English and French Bulldogs. The breeds that are most commonly seen with hemivertebrae in other areas of the spine include German Short Haired Pointers and the German Shepherd. In these breeds the hemivertebrae in the middle of the back can lead to roaching or arching of the back, pain in movement, or even a weak area of the spine that may be more susceptible to injury later in life. In the two later breeds the condition is hereditary and is preventable with careful breeding and immediate removal from breeding programs of any dogs exhibiting the condition. In the brachycephalic dogs the conditions is often not a problem for the dog and may never be noted in the appearance or behavior of the dog. Occasionally a vertebrae will be so deformed as to cause pressure on the spinal cord in these breeds, leading to trouble moving, pain or even paralysis or inability to get up or lie down. For both cases the condition is congenital which means the puppy is born with the problem, it is not due to injury or disease after the puppy is born.
A normal vertebrae in a dog's spine looks cylindrical in shape with a rounded hole in the middle for the spinal cord. In dogs with hemivertebrae the individual vertebrae are wedge shaped from the side or front and look like butterfly wings spread open when viewed from the top. Often the first sign of the problem is a weakening in the hindquarters where the dog does not want to move, does not try to stand up or seems to be unable to move the hindquarters in a normal fashion.
The condition can be confirmed through a special x-ray technique known as myelograms can detect if the pain or movement problems are caused by the compression of a hemivertebrae. Surgical procedures can be used to correct the problem depending on the location of the hemivertebrae in the spinal column. Pain management drug therapies as well as restriction from activity will be required in the recovery period.
Any breeder of a screw-tailed breed should be familiar with the signs of hemivertebrae and should have any questionable dogs x-rayed completely to assure the condition is not present before breeding.