What Is a Dermoid Sinus?
A dermoid sinus is a narrow, tube-shaped pocket of skin that forms before birth when the skin and the developing spinal cord fail to separate completely. The tube starts at a small opening on the skin, usually along the midline of the neck or back, and runs inward. In some puppies it ends blindly under the skin; in others it reaches all the way to the membranes around the spinal cord.
Because the tube is lined with skin, it fills with hair, oil and dead skin cells. That debris can become infected, and if the sinus connects to the spinal canal, infection can spread to the spinal cord.
Ridgeback connection
Dermoid sinus is strongly linked to the gene that creates the ridge in Rhodesian and Thai Ridgebacks. Responsible ridgeback breeders check every puppy by feel shortly after birth.
Breeds at Risk
- Rhodesian Ridgebacks and Thai Ridgebacks (by far the most common)
- Occasionally Shih Tzus, Boxers, Yorkshire Terriers, Siberian Huskies and other breeds; see our Shih Tzu breed guide
- Rarely seen in cats
Signs to Watch For
- A tiny hole or tuft of hair along the top of the neck or back, sometimes with a cord-like strand felt under the skin
- Swelling, discharge or a recurring abscess at that spot
- Pain when the back or neck is touched
- Fever, stiffness, wobbliness or weakness if infection reaches the spinal cord
When it is urgent
A puppy with a known sinus that develops fever, neck pain or trouble walking may have meningitis or a spinal infection. See a vet the same day.
Diagnosis
Most dermoid sinuses are found by carefully feeling along the spine. To learn how deep the tube goes, vets may use a special X-ray with contrast dye (sinography), MRI or CT before any surgery is planned.
Treatment
- Surgical removal: the whole tube is dissected out, sometimes down to the spinal canal. Removing it completely is what prevents recurrence.
- Antibiotics: used for active infection, but they do not cure the sinus on their own.
- Monitoring: very shallow sinuses that never cause trouble are sometimes watched, but most vets recommend removal.
Outlook and Breeding
Outlook after complete surgical removal is generally very good, especially when surgery happens before neurological signs appear. Because the condition is inherited, affected dogs should not be bred, and buyers should ask breeders whether litters were checked. Many owners of affected puppies combine the surgery with routine neutering.
Frequently Asked Questions
Is a dermoid sinus painful?
Not always. Many are painless until they become infected or affect the spinal cord.
Can I squeeze out the debris myself?
No. Squeezing can push infection deeper. Leave it to your vet.
Does every Rhodesian Ridgeback have one?
No. Most ridgebacks do not, but the risk is much higher than in other breeds, so every puppy should be checked.
Found a small hole or hair tuft along your puppy’s spine? Find a veterinary clinic near you for an exam.