Scientists at University of California, Davis have discovered a gene mutation responsible for causing bladder problems in Dalmatians, a finding that may help researchers uncover clues to the cause of similar problems in humans.

The team of UC Davis researchers found that a gene mutation causes high levels of uric acid and bladder stones in some Dalmatians, a defect that is particular to the entire Dalmatian breed, a university news release states.

The findings were published last week in the scientific journal "Public Library of Science."

The defect was "probably unintentionally introduced as breeders worked to select more distinctive spotting patterns," veterinary geneticist Danika Bannasch, the lead author on the study, stated in the release.

The trait can now be removed from the breed by crossing Dalmatians with the normal offspring of the original Dalmatian-pointer breeding of the early 1970s, she said.

The university's Veterinary Genetics Laboratory will begin offering DNA testing for the mutation in dogs to allow breeders to eliminate the trait beginning Dec. 1.

While all mammals excrete waste in their urine, only humans, great apes and Dalmatians produce elevated levels of uric acid in their urine and blood. In humans, high levels of uric acid can result in kidney stones, hypertension and gout. In Dalmatians, high levels can result in bladder stones, which have to surgically removed, the release states.

Scientists have known since the early 1900s that Dalmatians have the trait, but the gene responsible has been elusive, the release states.

To conduct their research, the UC Davis scientists collected DNA samples, as well as urine samples, from hundreds of dogs to identify the gene responsible for high levels of uric acid.

Researchers found that dogs that are a cross between pointers and Dalmatians have a gene, labeled SLC2A9, which recently has been reported to be important to regulating uric acid levels in humans, the release states.

Genetic analysis showed that mutations in the gene were responsible for the elevated uric acid in Dalmatians.

Researchers found that the mutations also were present in some bulldogs and black Russian terriers, breeds that are not known to be closely related to Dalmatians, suggesting that the mutation is old and could have predated formation of the Dalmatian breed.

Bulldog and black Russian terrier breeders can simply use genetic selection to eliminate the unhealthy trait from those breeds, but because the mutation occurs in all Dalmatians, breeders will have to look outside the breed to correct the problem, the release states.

"In recent years, dogs that are about 99 percent Dalmatian and 1 percent pointer have been bred, successfully eliminating the elevated uric acid trait," Bannasch stated in the release. "The result is a healthy dog that looks like a Dalmatian, maintains the Dalmatian breed characteristics and is genetically almost identical."

The "backcrossed" dogs have been registered as Dalmatians with the United Kennel Club and offer a resource for correcting the genetic defect.

Humans also carry the gene, but scientists haven't yet identified what causes humans and great apes to have elevated uric acid levels. The researchers' findings regarding Dalmatians likely will help scientists better understand the related problem in humans, the release states.

The study was funded in part by a fellowship from the Morris Animal Foundation and the National Institutes of Health.

For more information about the UC Davis' School of Veterinary Medicine's genetic testing program, go to www.vgl.ucdavis.edu/