UC Davis School of Veterinary Medicine Veterinary Genetics Laboratory
Canine Hyperuricosuria
Introduction

Hyperuricosuria (HUU) means elevated levels of uric acid in the urine. This trait predisposes dogs to form stones in their bladders or sometimes kidneys. These stones often must be removed surgically and can be difficult to treat. HUU is inherited as a simple autosomal recessive defect. A mutation in exon 5 of the gene Solute carrier family 2, member 9 (SLC2A9) has been found to be associated with hyperuricosuria in dogs. HUU can occur in any breed but is most commonly found in the Dalmatian, Bulldog and Black Russian Terrier. While traditional Dalmatians are homozygous for HUU (HU/HU), the introduction of “low uric acid” dogs, derived from Dalmatian x Pointer backcrosses, into the purebred gene pool has provided a means for breeders to reduce incidence of the disease and maintain the breed characteristics. Normal (N/N) and carrier (N/HU) Dalmatians are now present in the breed, and trace to the backcross lineage.


A DNA test for the SLC2A9 mutation can determine the genetic status of dogs for HUU. Dogs that carry two copies of the mutation will be affected and susceptible to develop bladder/kidney stones. The SCL2A9 mutation is not the sole cause of urate bladder stones in dogs. Other factors such as liver disease and diet need also be considered in clinical evaluation.

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Detailed Hyperuricosuria Information

The VGL offers a DNA test for hyperuricosuria to assist owners and breeders in identifying affected and carrier dogs. The test uses DNA collected from buccal swabs thus avoiding invasive blood collection. Breeders can use results from the test as a tool for selection of mating pairs to avoid producing affected dogs. The test is offered to all breeds, including American Pitbull Terrier, American Staffordshire Terrier, Australian Shepherd, Black Russian Terrier, Bulldog, Catahoula Leopard Dog, Dalmatian, Danish-Swedish Farmdog, French Bulldog, German Hunting Terrier, German Shepherd, Giant Schnauzer, Jack Russel/Parsons Terrier, Kromfohrländer, Labrador Retriever, Lagotto Romagnolo, Large Munsterlander, South African Boerboel, Spaniel de Pont-Audemer, Swedish Vallhund, Vizsla and Weimaraner.


The following chart details the expected outcomes of matings for all possible combinations of hyperuricosuria genotypes.

Female

Male

N/N

N/HU

HU/HU

N/N

100% N/N

50% N/N, 50% N/HU

100% N/HU

N/HU

50% N/N, 50% N/HU

25% N/N, 50% N/HU, 25% HU/HU

50% N/HU, 50% HU/HU

HU/HU

100% N/HU

50% N/HU, 50% HU/HU

100% HU/HU

Results reported as:

N/N

No copies of hyperuricosuria mutation detected. Dog is normal

N/HU

1 copy of hyperuricosuria mutation detected. Dog is a carrier and unaffected. If bred to another carrier, 25% of offspring are predicted to be affected.

HU/HU

2 copies of hyperuricosuria mutation detected. Dog is affected with HUU and susceptible to develop bladder/kidney stones.

We recommend testing any dog that has formed kidney or bladder stones composed of urate or uric acid. If the dog has the mutation then treatment modalities for Dalmatians can be used to treat the dog.

References:

Bannasch D, N Safra, A Young, N Karmi, RS Schaible and GV Ling. 2008. Mutations in the SLC2A9 Gene Cause Hyperuricosuria and Hyperuricemia in the Dog. PLoS Genetics 4(11): e1000246. [PubMed 18989453]


Karmi N, EA Brown, SS Hughes, B McLaughlin, CS Mellersh, V Biourge, and DL Bannasch. 2010. Estimated Frequency of the Canine Hyperuricosuria Mutation in Different Dog Breeds. J Vet Intern Med 24(6):1337–1342. [PubMed 21054540]


Karmi N, Safra N, Young A, Bannasch DL. 2010. Validation of a urine test and characterization of the putative genetic mutation for hyperuricosuria in Bulldogs and Black Russian Terriers. Am J Vet Res 71(8):909-914. [PubMed 20673090]

 
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