Abstract

Simple SummaryCystinuria, as an inborn error of metabolism, is a problem with worldwide distribution and has been reported in various canine and feline breeds. Transepithelial transport of cystine is mediated by COLA transporter and the mutation in genes coding this transporter may cause cystinuria. Urolithiasis associated with typical clinical signs may be the clinical consequence of cystinuria. The mutation causing cystinuria and the mode of inheritance have been determined only in several canine breeds. This makes cystinuria difficult to control and gradually decreases its prevalence. In cats, cystinuria occurs only rarely.The purpose of this review is to summarize current knowledge on canine and feline cystinuria from available scientific reports. Cystinuria is an inherited metabolic defect characterized by abnormal intestinal and renal amino acid transport in which cystine and the dibasic amino acids ornithine, lysine, and arginine are involved (COLA). At a normal urine pH, ornithine, lysine, and arginine are soluble, but cysteine forms a dimer, cystine, which is relatively insoluble, resulting in crystal precipitation. Mutations in genes coding COLA transporter and the mode of inheritance were identified only in some canine breeds. Cystinuric dogs may form uroliths (mostly in lower urinary tract) which are associated with typical clinical symptoms. The prevalence of cystine urolithiasis is much higher in European countries (up to 14% according to the recent reports) when compared to North America (United States and Canada) where it is approximately 1–3%. Cystinuria may be diagnosed by the detection of cystine urolithiasis, cystine crystalluria, assessment of amino aciduria, or using genetic tests. The management of cystinuria is aimed at urolith removal or dissolution which may be reached by dietary changes or medical treatment. In dogs with androgen-dependent cystinuria, castration will help. In cats, cystinuria occurs less frequently in comparison with dogs.

Highlights

  • Cystinuria is an inherited disorder characterized by the impaired reabsorption of cystine in the proximal tubule of the nephron and the gastrointestinal epithelium

  • Only cystinuria results in urolithiasis because these dibasic amino acids are relatively soluble in urine, despite the fact they may reach high concentrations in the urine of affected animals [1]

  • The COLA transporter (b0,+) was originally thought to be a heterodimer, but is likely a heterotetramer formed from two heterodimers consisting of the rBAT and b0,+AT subunits joined by a disulfide bridge [14,15,16]

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Summary

Introduction

Cystinuria is an inherited disorder characterized by the impaired reabsorption of cystine in the proximal tubule of the nephron and the gastrointestinal epithelium. The defective transport involves the other dibasic amino acids ornithine, lysine, and arginine. Cystinuria was first described by Wollaston in 1810 when he extracted a large cystolith from one of his patients. He named it cystic oxide, because he believed that it had such chemical properties and that the stone had originated from the bladder wall [2]. It was later shown not be an oxide nor secreted from the urinary bladder, when isolated, the amino acid was named cystine in recognition of this historical discovery [1]. The purpose of this review is to summarize the current knowledge on cystinuria in dogs and cats

Etiopathogenesis of Cystinuria
COLA Transporter
Genetic Aspects
Solubility of Cystine in Urine
Method of Analysis
Diagnosis of Cystine Urolithiasis
Urinalysis
Canine
Genetic tests
Treatment and Prevention
Dietary Treatment
Protein
Sodium
Urinary pH
D-Penicillamine
Captopril
Bucillamine
Castration
Future Therapies
Alpha-Lipoic Acid
Selenium
Tolvaptan
Cystinuria in Cats
Findings
Conclusions

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