Assessment of urinary cystine concentration in dogs in the Czech Republic

Abstract

The prevalence of cystinuria as an inborn error of metabolism in dogs is unknown. The purpose of this study was to evaluate the prevalence of cystinuria in dogs of various breeds in the Czech Republic. In total, 326 voided urine samples from client owned dogs were obtained. Samples were divided into four groups according to the breed - Irish Terriers (n = 58), Dachshunds (n = 67), French Bulldogs (n = 64) and a group of various breeds (n = 137). Urinary cystine concentration was measured using liquid chromatography/mass spectrometry, urinary creatinine concentration was determined by Jaffe method. Samples with urinary cystine concentrations above 178 µmol/g creatinine were considered as cystinuric. Urinary cystine concentration above the upper limit was found in 71 dogs (21.8%) with significantly higher incidence in intact males of Irish Terriers. In general, cystinuria was more common in intact males. In Irish Terriers, Dachshunds, French Bulldogs, German Shorthaired Pointer, Pomeranian, and Fox Terrier, cystinuria was identified in females. Cystinuria appears to be a relatively common finding in dogs in the Czech Republic, with some breeds being more affected. The finding of cystinuria in two female Irish Terriers calls into question the classification of cystinuria in this breed as androgen dependent only. The detection of cystinuria in related dogs suggests that other individuals in the same family should be examined as part of the management of a cystinuric patient.