Dermoid Sinus

A Closer Look at Canine Dermoid Sinus


Canine dermoid sinus is a condition that is known for affecting dogs but it can also show up in cats. This condition is one that doesn’t get a lot of publicity because it simply isn’t very common, but the affects that it can have on an afflicted dog can be quite significant. The sections below will explain how dermoid sinus develops, the symptoms that accompany this condition, risk factors, the diagnosis process, and treatment options.


About Dermoid Sinus


Dermoid sinus is a congenital defect, which means that the defect is the result of a problem that occurred in the early stages of cellular division during pregnancy. Normally, when the cells are dividing to create the brain and spinal cord of the fetus, the subsequent layers of ligament, muscle, fat, and skin are separated so that a thick, protective cushion of tissue protects the spinal cord. In the case of a dermoid sinus, cellular division doesn’t happen the way it is supposed to and instead of the spinal tissue, ligament, muscle, and skin being completely separated, the cells form a tube-like structure that connects some or all of these tissues together. The severity of this condition ranges from “Type 1″ to “Type 4.” With the Type 1 condition, the tube-like structure appears more like a dimple in the skin as the tube only penetrates down as far as the fatty layer. With a Type 2 condition, the tube runs from the outer surface of the skin down into the dog’s muscular tissue. In a Type 3 situation the tube runs from the skin down into the ligament that lies just over the spinal column. Type 4, which is the most severe form of dermoid sinus, is characterized by a tube-like structure that runs from the skin to the spinal cord.




The primary symptom of this condition is the visual aspect—the dimpling that can be seen in the skin. Dogs with thicker coats are more likely to suffer this as an undiagnosed condition as the dimpling may be very difficult to see without severely parting or shaving the fur. The dimpling occurs in the midline of the neck, back, and tail. There have been several cases in which the tube development occurred in pairs which heightens the dog’s risk of suffering side effects. The makeshift tube does act as an actual drainage pipe, as most sinus structures do. On a dog, the opening is likely to have a slight swirling effect on the dog’s skin and fur. One may even be able to feel the tube beneath the opening.


The primary problem with this open tube is that it can easily be infected, especially when one considers the natural bacteria that most dogs carry on their skin and fur. If bacteria manages to get deep inside the tube or if dead skin cells or natural oils from the dog’s skin block up the tube, then this could result in a serious infection. Imagine the damage that could be done if bacteria use the tube as a means to get from the surface of the dog’s skin all the way down to the spinal cord. The threat of neurological abnormalities would be much greater in this situation. The symptoms of a spinal infection include pain of the spine, rigidity or difficult moving, and fever.


Risk Factors


Although any breed of dog can be born with dermoid sinus, this condition seems to be most common in the Rhodesian ridgeback breed. In this breed, the condition can be hereditary which means that a family history of this condition will dramatically increase the chances of pups being born with this congenital deformity. For breeders, any dogs that are afflicted with this sinus should not be used as breeding stock, nor should any pups that come from parents who have this condition, regardless of whether or not the pup itself is afflicted.




For the most part, dog owners can make a diagnosis by doing to dermal sinus test. This test works best on puppies but it can be performed on a dog of any age. Gently part the fur along the dog’s spine starting at the head and working all the way down to the rump at the base of the tail. Abnormal swirling of the fur or dimpling of the skin are often indicators of the condition. To verify, gently try to lift the skin up, as one might do when picking a puppy up by the scruff. Do not apply much pressure, but simply take note at how easy or difficult the skin is to lift. If the skin seems stuck or tethered to the back in one or two areas then one should use his/her fingertips to feel for a tube like structure. This is the dermoid sinus. For a proper diagnosis it is always best to take the dog to a veterinarian.


Treatment Options


For cases in which the dimpling is only slight or the tube is not completely hollow, there may not be any treatment necessary as long as the dog isn’t suffering any ill side effects of the condition. When the dog does suffer side effects, such as pain caused by an abscess or recurring infections, then it might be necessary to correct the issue with a surgical procedure. This can be costly but is a very effective treatment for this condition that will enable the dog to have a much better quality of life.