D.M.V. Article
E. Clough, DVM
| Duncan, had Dermoids removed |
| These are the Dermoids removed from Duncan during surgery |
Dermoid Sinus - A Summary
E. Clough, DVM
1010 Daniel Webster Highway
Merrimack, New Hampshire 03054
INTRODUCTION:
Dermoid sinus (D.S.) was first used to describe the
Rhodesian Ridgeback skin anomaly by Steyn, et al. This skin
condition has also been called trichiasis spiralis, dermoid
cyst, dermoid inclusion cyst and epidermal inclusion cyst. All
of these terms have some applications; however, Dermoid,
skin-like sinus, channel or fistula; (cyst means sac, i.e., not
open to the surface) is most applicable. The Rhodesian
Ridgeback Club of the U.S., Inc. prefers to use D.S. to
describe the condition.
DESCRIPTION:
No reports have been located which substantiate the author's
impression that D.S. has been found in other breeds.
Dermoid sinus included in the ridge has been reported only
once. They also occur in the sacral (rump) area and in this
location are sometimes connected to the dura (spinal cord
covering). This is not the case in the more common cervical
(neck area) D.S. which connects the skin to the dorsal
spinous ligament (the ligament which connects the top parts
of the vertebrae). One or more D.S. may occur in the same
animal. These sinuses are congenital (present at birth)
and can be palpated (felt) as cords running between the skin
and the spine. They form a small external opening which can
be readily seen once the hair has been shaved.
Histologically (microscopically) the sinus is a thick-walled
tube composed chiefly of fibrous tissue and lined with
stratified squamous epithelium (skin cells). The surrounding
connective tissue may or may not contain hair follicles,
sebaceous glands and sweat glands which open into the
lumen (hollow center) of the sinus. In uncomplicated cases
the sinus is filled with sebum (oil), skin debris and hair. Once
infected with bacteria the resulting inflammation and
abscession can lead to myelitis and encephalitis (swelling
and infection of the spinal cord, its covering, and the brain).
The reason for discrimination against animals with D.S. is the
almost inevitable abscess which forms.
INHERITABILITY:
Although not well understood, transmission of D.S. seems to
be a dominant, polygenic problem with inconstant
penetration. Another geneticist thinks that D.S. is due to a
single completely recessive autosomal gene. This is not
likely because normal parents do produce pups affected with
D.S. Because of the genetic complexity and the difficulty in
arranging, coordinating and collating the breeding studies
necessary to prove the heredity of D.S., it is unlikely that we
will be able to substantiate the exact mechanism of genetic
transmission. There is a widely held belief that breeding
Ridgebacks with D.S. produces an increased prevalence of
pups with D.S. The R.R. Club of the U.S., Inc. believes that
this could be substantiated if breeders had accurate records
which could be collated and computed. It is our belief that
careful controlled breeding studies would prove the
inheritance of D.S. to be not only complex but also
inter-related with other characteristics. Therefore, the
likelihood seems to be remote that we will ever have
Ridgebacks which are entirely free of D.S.
Because selective breeding will unquestionably reduce the
prevalence of D.S., but probably not eliminate its occurrence,
and because the condition results in difficult to treat
abscesses unless surgically removed, it is our opinion and
strong recommendation that dogs which have D.S. not be
acceptable as show or breeding candidates. Surgical
correction can be accomplished; however, culling at birth is a
more humane way to handle the affected pups.
Dermoid Sinus - A Case History
Duncan, a 4 month old liver-nosed Ridgeback was bred on a
Missouri puppy farm and sold via a broker to a pet shop in
Orange, California. After being informed by a Ridgeback
breeder that Duncan was affected with dermoid sinuses, the
pet shop gave Duncan away. However, the new owners were
not fully aware of the seriousness of Duncan's condition.
Unable to cope emotionally with Duncan's need for extensive
surgery, that he might not survive, and the long recovery
period, his new owners surrendered him to Ridgeback
Rescue so that he could be cared for by experienced
Ridgeback people.
The dermoids could be felt in Duncan's neck and are pictured
here as they looked from the surface with the hair clipped.
Dr. Gregg Rex in Highland, California (Starland Rhodesian
Ridgebacks) performed the surgery to remove Duncan's
dermoids for free as a donation to rescue. Dr. Rex removed
four dermoids, which are shown above.
E. Clough, DVM
1010 Daniel Webster Highway
Merrimack, New Hampshire 03054
INTRODUCTION:
Dermoid sinus (D.S.) was first used to describe the
Rhodesian Ridgeback skin anomaly by Steyn, et al. This skin
condition has also been called trichiasis spiralis, dermoid
cyst, dermoid inclusion cyst and epidermal inclusion cyst. All
of these terms have some applications; however, Dermoid,
skin-like sinus, channel or fistula; (cyst means sac, i.e., not
open to the surface) is most applicable. The Rhodesian
Ridgeback Club of the U.S., Inc. prefers to use D.S. to
describe the condition.
DESCRIPTION:
No reports have been located which substantiate the author's
impression that D.S. has been found in other breeds.
Dermoid sinus included in the ridge has been reported only
once. They also occur in the sacral (rump) area and in this
location are sometimes connected to the dura (spinal cord
covering). This is not the case in the more common cervical
(neck area) D.S. which connects the skin to the dorsal
spinous ligament (the ligament which connects the top parts
of the vertebrae). One or more D.S. may occur in the same
animal. These sinuses are congenital (present at birth)
and can be palpated (felt) as cords running between the skin
and the spine. They form a small external opening which can
be readily seen once the hair has been shaved.
Histologically (microscopically) the sinus is a thick-walled
tube composed chiefly of fibrous tissue and lined with
stratified squamous epithelium (skin cells). The surrounding
connective tissue may or may not contain hair follicles,
sebaceous glands and sweat glands which open into the
lumen (hollow center) of the sinus. In uncomplicated cases
the sinus is filled with sebum (oil), skin debris and hair. Once
infected with bacteria the resulting inflammation and
abscession can lead to myelitis and encephalitis (swelling
and infection of the spinal cord, its covering, and the brain).
The reason for discrimination against animals with D.S. is the
almost inevitable abscess which forms.
INHERITABILITY:
Although not well understood, transmission of D.S. seems to
be a dominant, polygenic problem with inconstant
penetration. Another geneticist thinks that D.S. is due to a
single completely recessive autosomal gene. This is not
likely because normal parents do produce pups affected with
D.S. Because of the genetic complexity and the difficulty in
arranging, coordinating and collating the breeding studies
necessary to prove the heredity of D.S., it is unlikely that we
will be able to substantiate the exact mechanism of genetic
transmission. There is a widely held belief that breeding
Ridgebacks with D.S. produces an increased prevalence of
pups with D.S. The R.R. Club of the U.S., Inc. believes that
this could be substantiated if breeders had accurate records
which could be collated and computed. It is our belief that
careful controlled breeding studies would prove the
inheritance of D.S. to be not only complex but also
inter-related with other characteristics. Therefore, the
likelihood seems to be remote that we will ever have
Ridgebacks which are entirely free of D.S.
Because selective breeding will unquestionably reduce the
prevalence of D.S., but probably not eliminate its occurrence,
and because the condition results in difficult to treat
abscesses unless surgically removed, it is our opinion and
strong recommendation that dogs which have D.S. not be
acceptable as show or breeding candidates. Surgical
correction can be accomplished; however, culling at birth is a
more humane way to handle the affected pups.
Dermoid Sinus - A Case History
Duncan, a 4 month old liver-nosed Ridgeback was bred on a
Missouri puppy farm and sold via a broker to a pet shop in
Orange, California. After being informed by a Ridgeback
breeder that Duncan was affected with dermoid sinuses, the
pet shop gave Duncan away. However, the new owners were
not fully aware of the seriousness of Duncan's condition.
Unable to cope emotionally with Duncan's need for extensive
surgery, that he might not survive, and the long recovery
period, his new owners surrendered him to Ridgeback
Rescue so that he could be cared for by experienced
Ridgeback people.
The dermoids could be felt in Duncan's neck and are pictured
here as they looked from the surface with the hair clipped.
Dr. Gregg Rex in Highland, California (Starland Rhodesian
Ridgebacks) performed the surgery to remove Duncan's
dermoids for free as a donation to rescue. Dr. Rex removed
four dermoids, which are shown above.
| Duncan's neck after surgery. |
| Duncan almost healed. Being almost healed doesn't mean he is cured. They could come back. This is traumatic since it will puss and the fluid must be removed daily with a needle and syringe. This is very painful for the puppy and owner. |
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