Genetics at root of hair trouble in dogs
By Brian Cross
Researchers from Germany and the University of Saskatchewan have taken a major step forward in determining the cause of black hair follicular dysplasia – a condition responsible for causing premature graying, hair loss and dermatological problems in certain breeds of dogs – by finding the gene causing dilute coat colour.
U of S genetics expert Sheila Schmutz recently teamed up with researchers Tosso Leeb and Ute Philipp from the University of Veterinary Medicine in Hannover, Germany and isolated the gene responsible for causing dilute coat colour in dogs. The results of their work, which were published in the June 16, 2005 issue of BMC Genetics, will allow dog owners whose breeds have dilute colours to test their dogs to determine if they carry a “d” or dilute gene.
Black hair follicular dysplasia, or BHFD, also known as Colour Dilution Alopecia, affects some dogs in breeds like Great Danes, Italian Greyhounds, Doberman Pinschers, Large Munsterlanders, and Newfoundlands. Health defects associated with the condition can include hair loss, coat brittleness, bald patches, skin wrinkling and the formation of pustules in areas where hair loss has occurred.
“BHFD is not really a life threatening disorder but it’s clearly very uncomfortable for the dogs,” said Schmutz, a professor in the department of animal and poultry science in the College of Agriculture. “The major thing that most people will notice is brittle or fragile hair that breaks off. In other, more severe cases, the dogs will develop wrinkles or pustules that are prone to infection and deteriorating skin around their muzzles or on their backs.”
Identifying dogs that are prone to BHFD has long been a priority among dog breeders whose animals are affected by the condition. The German-Canadian study determined that mutations within the melanophilin or MLPH gene — one of three genes responsible for transporting pigment into the hair follicles — are at the root of the problem.
When mutations of the MLPH gene occur, pigment is delivered unevenly, said Schmutz.
In addition to adding colour to an animal’s coat, pigment also adds strength and flexibility to hair, nails, hooves, eyelashes and other body parts. “The problem is that when the middle of these three genes goes wrong, the ratchet mechanism works in lags and starts, and the pigment gets produced or moved in clumps,” said Schmutz, who raises Large Munsterlanders and in 1996, had a litter in which four of nine puppies had BHFD.
Researchers involved in the study are now hoping to learn more about the role of the MLPH gene to determine what other functions it serves and how it interacts with other genes. For example, the two other genes that serve as a pigment ratchet mechanism are also associated with neurological and immunological disorders. And researchers are still unclear why some dog breeds that have a mutation in the MLPH gene are more prone to BHFD than others.
Large Munsterlanders and other spotted breeds that have the MLPH gene mutation are almost always affected by severe hair loss and skin problems. Other breeds like Great Danes are less prone to health problems.
“Some dogs with the mutation have serious health defects while others live long lives with no serious difficulties with their hair or skin,” Schmutz said. “That’s where we’re hoping to go with this next, is to try and understand how this gene interacts with other genes (to affect the dog’s health).”
Brian Cross is a Saskatoon freelance writer