Dermoid Sinus
by Jennie Bullock
        Dermoid Sinus (D.S.) has been known by many names; among this list of names are dermoid cyst, dermoid inclusion cyst, epidermal inclusion cyst, hair cyst, African cyst and trichiasia spiralis.  All of these terms describe some of the possible presentations of this condition, however Dermoid Sinus is the most appropriate.  Sinus - in that it is a tubular channel or fistula and Dermoid because of it's skin-like nature.  The most common presentation of this condition is in the tubular form (with an opening to the surface of the skin) although cases have been reported of this condition in a cystal (closed sac) formation.  At the present time D.S. is only known to exist in Rhodesian Ridgebacks.
        The most common presentation of this condition is in the midline neck region, although D.S. can also occur in the rump area connected to the dura (spinal cord covering).  One or more D.S. can be found in the same animal.  Dermoid Sinus is congenital (present at time of birth) and can usually be palpated (felt) as cords running from the skin to the spine.  Palpation should only be done by an experienced breeder of Rhodesian's or a veterinarian familiar with this disorder.
        The Dermoid Sinus is a thick-walled tube composed primarily of fibrous tissue and lined with skin cells.  The surrounding tissue may or may not contain hair, hair follicles, sebaceous glands and sweat glands which open to the hollow center of the tube.  In it's uncomplicated state the sinus is filled with sebum (oil), skin debris and hair. Bacterial contamination will result in inflammation and abscessation which can lead to swelling and infection of the spinal cord, its covering and the brain.
        Complete surgical removal of a Dermoid Sinus is not always possible; depending upon location, extent, complications and spinal cord involvement.  Most D.S. puppies are euthanized, as this is the most humane method of handling this condition.  Puppies which have undergone corrective surgery for D.S. can not be shown in conformation competition and should of course, be spay or neutered.


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