Dermoid Sinus in Dogs

This defect is found at the birth of a puppy and while it can be found in newborns, there are cases in which it is found later on in life. It is indicated that if your dog is found to have a DS, he had it at birth but it was not evident. 

These areas typically will not cause your dog any pain unless they become infected or inflamed. A DS is called such due to its tube-like shape which is similar to a sinus and the fact that it is a skin- like dermoid. A DS can be spotted on your dog due to a swirling hair pattern at the site. It can also be found if your dog is noted to have a slight discharge, however most often you will have to bring him into the veterinarian to have it diagnosed and treated.

Dermoid sinus (DS) is a neural tube defect that is typically found along your dog’s back, neck and tail. Dermoid sinus appears to be a condition that can be found at birth and is found primarily in Ridgeback breeds with some evidence of it being found in other breeds as well. These tubes are meant to drain out dead cells, tissue, and hair and when they do not form correctly they can become infected and possibly develop an abscess.

Symptoms can vary depending on where the DS is located on your dog, how deep it is under his fur, and whether or not it is currently infected or inflamed. However, there are some signs and symptoms to be aware of. 

• Can be recognized on your puppy by an opening along his back with hair in a swirl pattern (can be found as early as 3-5 weeks)
• You may feel a tube or rope under his skin under the opening on his back
• Mild discharge without any other symptoms
• Infection
• Abscesses
• Neurological concerns

Types

There are 5 types of dermoid sinus. They are identified by the severity of the tube itself.

Type I

• Extends towards the stomach or abdomen region
• Tube shaped sac

Type II

• Sac portion is located closer to the skin surface than Type I

Type III

• Sac is superficial once again with no attachments 

Type IV

• This type goes into and communicates with brain and/or spinal tissues

Type V

• The only “true” cyst
• The sac is lined with epithelium

There are no known causes of this disorder, however, it is hereditary in certain breeds and is present at birth.

• Primarily found in Rhodesian Ridgebacks and Thai Ridgeback dog breeds
• Inherited via one or both parents 
• Present from birth (may not be detected as indicated above for the first few weeks)

Diagnosing will have to be done by your dog’s veterinarian as most of the time it is impossible to spot a dermoid sinus without knowing what you are looking for. Due to many veterinarians not being familiar with this disorder, it is important to speak with your veterinarian should you have concerns about whether she is comfortable assessing your dog for this or not. The veterinarian may suggest you visit another office where there is a doctor with experience in this particular disorder. 

When preparing for your visit to your veterinarian it is important to share what breed your dog is if you know what he is. It is also important to share with your veterinarian any concerns you have noticed with your dog, such as a spot of discharge, or any lumps or cord like areas you feel along your dog’s back. 

After a physical examination of your dog’s back, neck, and head via touch, your veterinarian may want to run tests to determine the concerns you have with your dog. These tests can include  using a catheter to explore the cavity. A contrast material can also be injected into the sinus and an X-ray taken to get a better look. MRI and CT scans have also been used to determine how large and severe the DS is. These higher contrast imaging tools are used due to the dermoid sinus becoming filled with hair and dead cells. In addition, the other contrast may not show the entire DS and how deep or large it is.

Depending on the location, severity, size and whether an infection is present or not with your dog’s dermoid sinus, will determine how your veterinarian will proceed with treatment. If left untreated, the sinus can become infected repeatedly causing your dog pain and discomfort. 

Medication

• Antibiotics for any infection present

Surgery

• Removal of the sinus may be necessary
• This can be easily done if the sinus has not attached or wrapped itself around your dog’s spinal cord
• In the event the DS has wrapped around the spinal cord and removal is not possible, it may be tied off

Some concerns with surgery are related to the healing process and the potential for reoccurrence of the DS. When the surgery is simple and straightforward with easy removal of the DS, the prognosis for your dog is good with a relatively easy recovery period. However, if the surgery is more complex due to how intricate the sinus is, recovery can become more difficult.

Some post-surgery difficulties can be painful and there may be a buildup of fluid around the site. It is recommended that that fluid buildup be left alone as it will resolve itself. Another complication can be that your dog will need to be isolated from other puppies and animals due to the nature of how your dog will want to play. Typically, dogs will grab one another by the scruff and that can harm the incision site. 

If the DS is not entirely removed there is a risk of reoccurrence and infection in the same spot, therefore it is important to find a veterinarian who is knowledgeable about this condition and comfortable performing this surgery and follow up. It is possible that removal is not possible and quality of life of your puppy may suffer as well.

Follow up will be needed as recommended by your surgeon. Precautions are related to not allowing your puppy to move more than is recommended, and not allowing him to play rough with his litter mates or siblings. It will also be important to bring your puppy back into the clinic should any symptoms reappear or if he begins to show signs and symptoms of pain or discomfort again. If the tube is not removed completely there is the risk of it reoccurring as discussed above, so this is something to keep an eye on with your veterinarian. Recovery time can take anywhere from 12 to 14 days without any complications.