Molecular mechanism

Hyperuricosuria and Hyperuricemia (HUU) is an inherited metabolic disorder characterised by impaired uric acid transport, resulting in increased urinary excretion and blood concentrations of uric acid. Affected dogs are predisposed to the formation of ammonium urate uroliths within the urinary tract, although not all dogs carrying the causative variant will develop the disease (Bannasch et al., 2008). Clinical signs are associated with stone formation and may include haematuria, pollakiuria, dysuria and urethral obstruction, while severe obstruction can result in systemic illness including anorexia, vomiting, collapse and metabolic disturbances (Bartges et al., 1999; Bartges and Callens, 2015).
Hyperuricosuria and Hyperuricemia is inherited as an autosomal recessive condition; however, the SLC2A9 variant represents a genetic risk factor for urate urolithiasis rather than a definitive predictor of clinical disease. Bannasch et al., (2008) identified a missense mutation (c.616G\u0026gt;T; p.Cys188Phe) in the SLC2A9 gene on canine chromosome 3 (CFA3) as the causative variant. The variant is fixed in Dalmatians, with all dogs reported to be homozygous, but has also been identified at lower frequencies in several other breeds, including Labrador Retrievers, Bulldogs, German Shepherd Dogs and Pomeranians (Bannasch et al., 2008; Karmi et al., 2010; Cosgrove et al., 2015).