A retrospective study on epidemiology and management of canine cystine uroliths in one part of Norway from 2015 to 2020

Abstract

Background: Urinary tract problems are a common complaint in small animal medicine and urolithiasis is considered to be an important cause of urinary tract disease in dogs. In this study the main aim was to investigate whether the occurrence of cystine urolithiasis increased during a five-year period. A second aim was to evaluate possible risk-factors as breed, age and gender. This study also evaluated how urine specific gravity, pH and level of cystine in urine responded to preventive strategies. Medical records of dogs with urolithiasis presented at nine Norwegian animal clinics and one animal hospital between 2015 and 2020 were retrospectively reviewed.

Results: The incidence of cystine uroliths increased significantly during the five study years (R² = 0.72, P = 0.0199). Dogs with cystine uroliths were significantly younger (5.0 years (n = 84, 95% CI [4.4-5.6])) when they were diagnosed with cystine uroliths compared to dogs with other types of uroliths (8.1 years (n = 255, 95% CI[7.8-8.5]) P < < 0.0001). Cystine levels in urine were increased in 93% of the dogs with cystine urolithiasis. Cystinuria decreased significantly after neutering (P < 0.0001). Breeds most commonly affected with cystine urolithiasis in this study were Staffordshire bull terrier, Danish Swedish farmdog and Chihuahua.

Conclusions: The results from this study supports a suggested genetic basis for cystine urolithiasis as described in previous studies. Neutering is considered an important part of preventing reoccurrence since cystine values decreased significantly after neutering.

Keywords: Age; Breed; COLA; Occurrence.

Fig. 1

(a) Cumulative number of dogs (y-axis) diagnosed with different urolith types (x-axis) between 2015–2020, and (b) Urolith type per year (2015–2020)

Fig. 2

Box-plot of the age at first diagnosis of urine urolithiasis according to type of urolith: cystine vs. calcium oxalate. Lower and upper box boundaries 25th and 75th percentiles, respectively, line inside box median, lower and upper error lines 10th and 90th percentiles, respectively, filled circles data falling outside 10th and 90th percentiles (two male dogs diagnosed with cystine urolithiasis at age 11 and 12)

Fig. 3

Box and whisker plots of pH in urine measured at diagnosis (blue), at first follow-up (red) and second follow-up (green) for respectively 22, 22 and 21 dogs. Only dogs with available data for all three datapoints are included in the figure