LUA Dalmatians
Dalmatians and Uric Acid HUA and LUA
This is a simplified overview of LUA and HUA Dalmatians—resources for further information will be provided at the end of the article.
A serious health issue recognized in Dalmatians is the tendency to form uric acid stones, which can cause urethral blockage and lead to extensive veterinary care. Male dogs are most often affected due to the relatively small diameter of their urethra. As early as the early 1900’s the tendency for Dalmatians to form urine with a high level of urate was recognized, and over time it was found that all Dalmatians inherited that tendency. The pattern of inheritance was “fixed” in the population, and no effort to selectively breed for dogs with lower levels of urates would successfully decrease urate stone formation.
A Brief History
In 1973, Dr. Robert Schaible bred a male Pointer—the only non-Dalmatian ever used—to a female Dalmatian to introduce the “normal” or low uric acid (LUA) genetics into the Dalmatian population. He and others continued to breed offspring back to Dalmatians over generations, which resulted in the term “Backcross” to be used to describe the Dalmatians and the project.
The American Kennel Club (AKC) agreed to register two of the fifth generation of puppies resulting from the project in 1981. Controversy among the members of the Dalmatian Club of America (DCA), resulted in a vote taken in 1984 where the majority opposed the registration. The AKC subsequently rescinded the registration of any offspring from the registered dogs.
As efforts to introduce the LUA gene were largely unappreciated, and offspring could not be registered by the AKC, very few descendants remained by 2005, when the project was revived by breeders who continued to use the remaining LUA progeny in their breeding lines. DCA members were polled in 2006, and a majority voted that testing and breeding of LUA dogs should continue. In 2009 participants in the project made a formal request to the AKC to register LUA dogs. The request was referred to the AKC Health and Welfare Advisory Panel. Support from the California Veterinary Medical Association and a report from the AKC Health and Welfare Advisory Board led to acceptance of descendants of the backcross project into the AKC stud book. The AKC registration numbers for these dogs and their descendants start with “NY”.
About Uric Acid: Metabolism
Protein is converted in the liver to uric acid, which is normally metabolized into allantoin and excreted in the urine. High Uric Acid (HUA) dogs are missing a transporter protein, so the uric acid stays in the body and is excreted in the urine. Uric acid is excreted as urate, a salt, which can aggregate into crystals and eventually form stones. HUA Dalmatians have 10 to 20 times more urate in their urine than LUA Dalmatians and other breeds of dogs.
Several factors in addition to the elevated urate levels contribute to urate stone formation, including the concentration of the urine and the amount of time it is allowed to sit in the bladder, as well as the amount of protein, particularly in the form of purines, in the diet. Early neutering will decrease the urethral diameter and can contribute to blockage. Most Dalmatians never form stones or have a blockage, as long as a low purine diet, adequate water consumption, and necessary exercise are provided, and as long as males are not neutered before 18 months of age.
Genetics
Every gene has two alleles, one from the sire and one from the dam. The gene that codes for high uric acid metabolism is inherited as a simple recessive, so as long as a dog has one copy of the dominant (low uric acid) allele, they produce low uric acid. “U” is the dominant (LUA) allele, “u” is the recessive (HUA) allele. HUA Dalmatians who were never from the backcross lines are all “uu”. Dalmatians who have low uric acid can be “Uu”—or heterozygous, which means that they have one copy of each allele; the dominant (normal uric acid level) allele is the one that is expressed, or they can be “UU” —or homozygous, where they have two copies of the introduced gene.
The specific gene that codes for uric acid (SLC2A9) was identified in 2006, and a test was developed, allowing breeders to identify which dogs are homozygous UU (LUA) or uu (HUA), or heterozygous Uu (LUA). The ability to test for these alleles is significant because as LUA dogs continue to be bred to HUA dogs, both HUA and LUA dogs will be produced. (Just because a dog has NY at the beginning of its AKC registration number does not mean that it is an LUA Dalmatian.). Dogs who are from lines that have never been part of the project do not need to be tested, as they are all uu (HUA).
Why the Controversy?
Initial concerns about health issues that could come from breeding to a Pointer have largely dissipated over many generations of breeding back to Dalmatians from lines that were not part of the backcross project. Conformation issues that are of concern to breeders in all Dalmatians continue to be evaluated in the breed ring. Dalmatians are a distinctly spotted dog, and there appears to be association between the gene that codes for high uric acid and the genetics of distinct spotting. Some of the LUA dogs have less distinct spotting which deviates from the classic Dalmatian style. The spots in some LUA dogs can appear as fewer spots, smaller spots and/or “frosty” spots where white hairs are interspersed with the black or liver, making them appear “frosty”. It may be that historically, selective breeding for the Dalmatian’s distinctive spotting came at the expense of high levels of uric acid in the urine due to close association of those genes along the chromosome. Breeders make choices depending on their goals, and while some choose to produce LUA dogs in an effort to prevent urate stones, others choose to remain committed to the classic lines.
To read more about LUA Dalmatians from the point of view of LUA breeders and see some of the documents referenced above, you can visit: