PREVALENCE OF CYSTINURIA IN SERVALS ( LEPTAILURUS SERVAL) IN THE UNITED STATES

Variation in mineral types of uroliths from ferrets (Mustela putorius furo) submitted for analysis in North America, Europe, or Asia over an 8-year period

OBJECTIVE

To compare mineral types of naturally occurring uroliths in ferrets (Mustela putorius furo) from North America, Europe, and Asia and to identify potential risk factors associated with cystine urolithiasis in ferrets.

SAMPLES

1,054 laboratory submission records of uroliths obtained from ferrets between January 1, 2010, and December 31, 2018.

PROCEDURES

For this cross-sectional study, the medical records databases at 4 diagnostic laboratories were searched for records of submissions of uroliths obtained from ferrets. Data collection included submission date; ferret sex, neuter status, and age; receiving laboratory and continent; and urolith mineral type. Regression analyses were performed to identify variables associated with cystine uroliths.

RESULTS

Of the 1,054 urolith submissions, 1,013 were from North America, with 92.6% (938/1,013; 95% CI, 90.8% to 94.1%) cystine uroliths, and 41 were from Europe and Asia, with only 26.8% (11/41; 95% CI, 15.7% to 41.9%) cystine uroliths. Median age was 2.0 years for ferrets with cystine urolithiasis versus 4.0 years for those with other types of uroliths. Submissions were more likely cystine uroliths for ferrets in North America versus Europe and Asia (adjusted OR [aOR], 59.5; 95% CI, 21.4 to 165.6), for ferrets that were younger (aOR, 0.67; 95% CI, 0.58 to 0.77), or for submissions in 2018 versus 2010 (aOR, 21.1; 95% CI, 5.1 to 87.9).

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that the proportion of submissions that were cystine uroliths dramatically increased in North America between 2010 and 2018. There is an urgent need to determine underlying causes and mitigate cystine urolithiasis in ferrets.

Cystinuria in Dogs and Cats: What Do We Know after Almost 200 Years?

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.

RADIOLOGIC MEASUREMENT AND DETERMINATION OF KIDNEY-TO-VERTEBRA RATIOS AS A METHOD OF ESTIMATING RENAL SIZE IN SERVALS (LEPTAILURUS SERVAL)

Numerous conditions, from acute to chronic renal changes, have the potential to alter the renal size on radiographs. However, current literature does not provide any radiographic reference range for the normal renal size in the serval (Leptailurus serval). This retrospective study includes 13 healthy adult servals, seen between 2004 and 2017 at the UTCVM Veterinary Medical Center, deemed healthy based on physical examination and blood work. Orthogonal radiographs were anonymized, calibrated, and evaluated blindly by three observers of different experience levels. Renal and individual lumbar vertebral body lengths were measured on both orthogonal views, and ratios of kidney length to each lumbar vertebral length were calculated on both views. On the ventro-dorsal projection, the kidney length to L5 vertebra ratio had the lowest standard deviation (SD) with a mean of 1.82, SD of 0.27, and 95% confidence interval (CI) (1.63-2.00). On the lateral view, the kidney length to L3 vertebra ratio had the lowest SD with a mean of 2.03, SD of 0.25, and 95% CI(1.86-2.20). Statistically, all three observers were shown to be in agreement, indicating reproducibility of the measurements among observers with different levels of expertise.