Dermoid Sinus
Dermoid sinus is a tubular indentation of the skin in the middle of the back, that may go as deep as the spinal canal. The tracts may be single or multiple.
This condition occurs because of an abnormality early in embryonic development, in which there is incomplete separation of the tissues that will become the skin and the nervous system.
The main breeds tha are affected with this condition are the Rhodesian Ridgeback, Shih-Tzu and Boxer. Not only purebred dogs, but dogs who are mixed with any of these breeds may have this.
Dermoid sinus is present from birth, although the condition is usually not noticed until later. The tracts contain debris from the skin - sebum (waxy lubricating substance), dead skin cells, and hair - and commonly become infected and painful. If the tract extends to the spinal canal, infection may cause meningitis or myelitis, resulting in various neurologic signs such as local or general spinal pain, stiffness, or weakness (depending on the location of the sinus).
In an affected dog, the only successful treatment is surgical removal of the the whole tract, which may be a simple procedure or it may be fairly complicated if the tract extends into the vertebrae and spinal canal. Incomplete removal results in recurrence.
There is evidence that suggests folic acid supplementation of breeding females (both before and during pregnancy) can reduce the occurrence of this condition.