Dermoid sinus
Encyclopedia
Dermoid sinus is a genetic, autosomal skin condition in dog
s. It is also known (apparently incorrectly) as pilonidal sinus because it resembles pilonidal sinus in humans. However, unlike pilonidal sinus in humans, dermoid sinus in dogs is a neural tube defect. Dermoid sinus is sometimes also confused with dermoid cyst
(a teratoma
).
A dermoid sinus is rare in dogs and cats. It can appear as single or multiple lumps on the dorsal
midline. The sinus is caused in the embryonic stage of development. In normal development, the neural tube from which the spine develops separates from the skin. In the case of a dermoid sinus, this separation has not fully taken place. The result is that in some cases, the dermoid sinus remains connected to the animal's spinal cord; in other cases, the sinus terminates in a "blind sac" that is less dangerous to remove. Histologically
, the dermoid sinus contains hair follicle
s, sebaceous gland
s, and sweat gland
s. If the sinus becomes infected, it can result in meningitis
and myelitis
, symptoms of which are spinal pain, rigidity, and fever. In serious cases, the condition can be life threatening.
The dermoid sinus gene is believed by some to be recessive, meaning that the animal must receive one defective gene from each parent in order to develop the condition. Where one parent carries the gene and the other does not, the offspring remain carriers and can continue to pass the defective gene on to their offspring in turn. Others believe that the dermoid sinus condition is more appropriately characterized as polygenic, involving multiple genes. In any case, because of the genetic nature of this potentially dangerous condition, most breeders and veterinarians advise against breeding animals that have a dermoid sinus, or have a parent that is known to carry the gene.
It has been shown that the problem can be reduced with the use of folic acid
in the bitch by administration a week before mating and continuing through the first trimester of pregnancy. It is not a harmful product and is readily available at a minimal cost from the local pharmacist. Surgery is also a popular remedy, with veterinary surgeons removing abnormal tissue and closing any connections to the spine, although in some cases, regrowth of the sinus occurs. A variety of tests, such as a myelogram or a fistulogram may be undertaken to determine how deep the sinus goes. Other, more basic tests, such as a complete blood count
, biochemical profile, and urinalysis
can be performed to determine if infection or other problems exist. Computed tomography
scans and magnetic resonance imaging
may be undertaken to determine if neurological signs exist as a result of the sinus.
Breeds known to be affected include Rhodesian Ridgeback
and Thai Ridgeback
, in which it is hereditary, Kerry Blue Terrier
s, Shih Tzu
s and Boxer
s.
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s. It is also known (apparently incorrectly) as pilonidal sinus because it resembles pilonidal sinus in humans. However, unlike pilonidal sinus in humans, dermoid sinus in dogs is a neural tube defect. Dermoid sinus is sometimes also confused with dermoid cyst
Dermoid cyst
A dermoid cyst is a cystic teratoma that contains developmentally mature skin complete with hair follicles and sweat glands, sometimes clumps of long hair, and often pockets of sebum, blood, fat, bone, nails, teeth, eyes, cartilage, and thyroid tissue. Because it contains mature tissue, a dermoid...
(a teratoma
Teratoma
A teratoma is an encapsulated tumor with tissue or organ components resembling normal derivatives of all three germ layers. There are rare occasions when not all three germ layers are identifiable...
).
A dermoid sinus is rare in dogs and cats. It can appear as single or multiple lumps on the dorsal
Dorsum (biology)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...
midline. The sinus is caused in the embryonic stage of development. In normal development, the neural tube from which the spine develops separates from the skin. In the case of a dermoid sinus, this separation has not fully taken place. The result is that in some cases, the dermoid sinus remains connected to the animal's spinal cord; in other cases, the sinus terminates in a "blind sac" that is less dangerous to remove. Histologically
Histology
Histology is the study of the microscopic anatomy of cells and tissues of plants and animals. It is performed by examining cells and tissues commonly by sectioning and staining; followed by examination under a light microscope or electron microscope...
, the dermoid sinus contains hair follicle
Hair follicle
A hair follicle is a skin organ that produces hair. Hair production occurs in phases, including a growth phase , and cessation phase , and a rest phase . Stem cells are principally responsible for the production of hair....
s, sebaceous gland
Sebaceous gland
The sebaceous glands are microscopic glands in the skin that secrete an oily/waxy matter, called sebum, to lubricate and waterproof the skin and hair of mammals...
s, and sweat gland
Sweating
Perspiration is the production of a fluid consisting primarily of water as well as various dissolved solids , that is excreted by the sweat glands in the skin of mammals...
s. If the sinus becomes infected, it can result in meningitis
Meningitis
Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
and myelitis
Myelitis
Myelitis is a disease involving inflammation of the spinal cord, which disrupts central nervous system functions linking the brain and limbs. The name is derived from Greek referring to the "spinal cord", and the suffix -itis, which denotes inflammation....
, symptoms of which are spinal pain, rigidity, and fever. In serious cases, the condition can be life threatening.
The dermoid sinus gene is believed by some to be recessive, meaning that the animal must receive one defective gene from each parent in order to develop the condition. Where one parent carries the gene and the other does not, the offspring remain carriers and can continue to pass the defective gene on to their offspring in turn. Others believe that the dermoid sinus condition is more appropriately characterized as polygenic, involving multiple genes. In any case, because of the genetic nature of this potentially dangerous condition, most breeders and veterinarians advise against breeding animals that have a dermoid sinus, or have a parent that is known to carry the gene.
It has been shown that the problem can be reduced with the use of folic acid
Folic acid
Folic acid and folate , as well as pteroyl-L-glutamic acid, pteroyl-L-glutamate, and pteroylmonoglutamic acid are forms of the water-soluble vitamin B9...
in the bitch by administration a week before mating and continuing through the first trimester of pregnancy. It is not a harmful product and is readily available at a minimal cost from the local pharmacist. Surgery is also a popular remedy, with veterinary surgeons removing abnormal tissue and closing any connections to the spine, although in some cases, regrowth of the sinus occurs. A variety of tests, such as a myelogram or a fistulogram may be undertaken to determine how deep the sinus goes. Other, more basic tests, such as a complete blood count
Complete blood count
A complete blood count , also known as full blood count or full blood exam or blood panel, is a test panel requested by a doctor or other medical professional that gives information about the cells in a patient's blood...
, biochemical profile, and urinalysis
Urinalysis
A urinalysis , also known as Routine and Microscopy , is an array of tests performed on urine, and one of the most common methods of medical diagnosis...
can be performed to determine if infection or other problems exist. Computed tomography
Computed tomography
X-ray computed tomography or Computer tomography , is a medical imaging method employing tomography created by computer processing...
scans and magnetic resonance imaging
Magnetic resonance imaging
Magnetic resonance imaging , nuclear magnetic resonance imaging , or magnetic resonance tomography is a medical imaging technique used in radiology to visualize detailed internal structures...
may be undertaken to determine if neurological signs exist as a result of the sinus.
Breeds known to be affected include Rhodesian Ridgeback
Rhodesian Ridgeback
The Rhodesian Ridgeback is a dog breed developed in Southern Africa, where it was used to hunt Lions. This is most likely why this dog is known for its bravery...
and Thai Ridgeback
Thai Ridgeback
The Thai Ridgeback is an ancient breed of dog. The breed was formerly unknown outside of Thailand, but is gaining notice in the Western world. The Thai Ridgeback is one of only three breeds that has a ridge of hair that runs along its back in the opposite direction to the rest of the coat...
, in which it is hereditary, Kerry Blue Terrier
Kerry Blue Terrier
The Kerry Blue Terrier is a breed of dog. Mistakenly thought to be from County Kerry in South West Ireland, it's actually from Tipperary in South Central Ireland. In Ireland it is often called the Irish Blue Terrier...
s, Shih Tzu
Shih Tzu
The Shih Tzu is a breed of dog weighing with long silky hair. The breed originated in China and is among the earliest breeds. Shih Tzu were officially recognized by the American Kennel Club in 1969...
s and Boxer
Boxer (dog)
Developed in Germany, the Boxer is a breed of stocky, medium-sized, short-haired dog. The coat is smooth and fawn or brindled, with or without white markings. Boxers are brachycephalic , and have a square muzzle, mandibular prognathism , very strong jaws and a powerful bite ideal for hanging on to...
s.