Reference intervals for electrophoretograms obtained by capillary electrophoresis of dialyzed urine from healthy dogs

Abstract

Electrophoresis of urine to evaluate protein fractions in dogs with proteinuria to differentiate glomerular from tubular damage has increased in recent years; however, capillary electrophoresis (CE) of urine has not been reported in a study of > 40 healthy animals, to our knowledge. We aimed to establish reference intervals (RIs) for the urine protein fractions obtained by CE of urine from healthy dogs. We obtained urine samples from 123 clinically healthy dogs of both sexes between December 2016 and April 2019; urine was frozen until CE was performed. The electrophoretic patterns obtained were divided into 5 protein fractions, and RIs were established in percentages and absolute values using nonparametric methods. RIs were obtained for the fractions (F) as follows: 5.5 to 56.2% for F1, 3.2 to 16.5% for F2, 3.5 to 16.2% for F3, 17.8 to 69.8% for F4, and 5.1 to 23.9% for F5. These RIs obtained by CE might be useful clinically as a basis for comparison with pathologic samples. Age was a statistically significant factor for F2 ( p = 0.01) and F3 ( p = 0.02), and sex was a statistically significant factor for F1 ( p = 0.03).

Urinary Electrophoretograms Performed by Capillary Electrophoresis: Comparison between Dogs and Cats

“…Previous studies that performed gel electrophoresis in urine from healthy individuals have found that this fraction contains proteins related to the defense of the urinary tract. According to previous studies, the Tamm-Horsfall protein or uromodulin is usually excreted in healthy individuals due to its protective properties against lower urinary tract infections [8,29,37]. The high-resolution electrophoresis technique detected that one of the major proteins in the urine of healthy cats was uromodulin [29], so this protein could be excreted in a higher proportion in the F4 urinary fraction in the feline species.…”

“…UCE was performed according to the standardized method described by Navarro et al (2021). Urine was dialyzed before CE to eliminate salts and compounds that could interfere with the wavelength used for reading and cause artifact peaks.…”

“…The urinary electrophoretogram obtained is commonly divided into five different fractions from low to high molecular weight and charge, as is usually done in serum: fraction 1 migrates in the albumin zone; fraction 2 in the alpha 1 -globulins zone; fraction 3 in the alpha 2 -globulins zone; fraction 4 in beta-globulins; and fraction 5 in the gammaglobulins zone [6][7][8].…”

“…UCE is a technique still under study, although interval references for the canine species have been determined [8]. Moreover, electrophoretogram patterns for dogs with azotemia due to Leishmania infantum (L. infantum) or chronic kidney disease not associated with Leishmaniosis, compared to healthy ones, have been described with UCE [25].…”