Levels of retinol and retinyl esters in plasma and urine of dogs with urolithiasis

Vitamin A (VA) deficiency and Tamm-Horsfall glycoprotein (THP), a protein that binds retinol and retinyl esters in canine urine, might be involved in the pathogenesis of urolithiasis in dogs. In the present study, we assessed levels of retinol, retinyl esters, retinol-binding protein (RBP) and THP in plasma and urine of dogs with a history of urolithiasis (n = 25) compared with clinically healthy controls (n = 18). Plasma retinol concentrations were higher in dogs with uroliths of struvit (P < 0.01), calcium oxalate (P < 0.05), urate (P < 0.01) and cysteine, but there were no differences in the concentrations of plasma RBP and retinyl esters. Excretion of urinary retinol and retinyl esters were tentatively, but not significantly higher in the stone-forming groups, which was accompanied by increased levels of urinary RBP (P < 0.01) and lower excretions in THP (P < 0.01). The results show that VA deficiency may be excluded as a potential cause for canine urolithiasis. However, the occurrence of RBP and a concomitant reduction of THP in urine indicates a disturbed kidney function as cause or consequence of stone formation in dogs.     

The distribution of vitamin A and retinol-binding protein in the blood plasma, urine, liver and kidneys of carnivores

The contents of retinol and retinyl esters as well as retinol-binding protein (RBP) in the plasma, urine, liver and kidneys of dogs, raccoon dogs and silver foxes were investigated. In the plasma and urine of all three species, vitamin A was present as retinol and retinyl esters. Vitamin A levels (1376+/-669 microg x g(-1)) were significantly higher in the livers of dogs than in the kidneys (200+/-217 microg x g(-1), P < 0.001 ). However, vitamin A levels in the kidneys of raccoon dogs (291+/-146 microg x g(-1)) and silver foxes (474+/-200 microg x g(-1)) were significantly higher than in the liver (67+/-58 microg x g(-1) and 4.3+/-2.4 microg x g(-1), respectively, both P < 0.001). RBP was immunologically detected in the blood plasma of all species, but never in the urine. In the liver, immunoreactive RBP was found in hepatocytes. In the kidneys of all species, RBP was observed in the cells of the proximal convoluted tubules. The levels of vitamin A in the livers of raccoon dogs and silver foxes were extremely low, which would be interpreted as a sign of great deficiency in humans. This observation might indicate that the liver status cannot be used as an indicator of vitamin A deficiency in canines. The high levels of vitamin A in the kidneys in all three species may indicate a specific function of the kidney in the vitamin A metabolism of canines.     

Effect of exercise on the mobilization of retinol and retinyl esters in plasma of sled dogs

Fasting dogs do transport vitamin A (VA) in plasma not only as retinol but predominantly as retinyl esters. Contrary to retinol, nothing is known concerning the effects of athletic performance on plasma retinyl ester concentrations. The aim of this study was therefore to examine whether physical stress because of exercise and modification of the oxidative stress by supplementation of alpha-tocopherol influences the concentrations of retinol and retinyl esters in plasma of sled dogs. The study was carried out on 41 trained adult sled dogs, which were randomly assigned into two groups. One group (19 dogs) was daily substituted with 50 mg dl-alpha-tocopheryl acetate per kilogram body weight and the control group (22 dogs) was maintained on a basal diet during 3 months prior to exercise. The plasma concentrations of retinol, retinyl esters, alpha-tocopherol and triglycerides were measured immediately before, directly after and 24 h after exercise. The supplementation of alpha-tocopheryl acetate had no effect on plasma retinol and retinyl ester concentrations at any measurement time point. However, retinyl ester levels doubled in the non-supplemented group immediately after the race (p < 0.001), whereas in the supplemented group similar high levels were observed not until 24 h post-racing (p < 0.001). The high levels of retinyl esters were paralleled to some extent by an increase in plasma triglyceride concentrations, which were significantly higher 24 h post-racing than immediately before (p < 0.001) and after exercise (p < 0.001) in both groups. The increase in retinyl ester concentrations might be indicative of their mobilization from liver and adipose tissue. Whether plasma retinyl esters can be used as an indicator for the extent of nutrient mobilization during and post-exercise in sled dogs remains to be elucidated.     

Vitamin A excreted in the urine of canines is associated with a Tamm-Horsfall like protein

Under physiological conditions canines transport vitamin A in blood plasma primarily as retinyl esters bound to lipoproteins and excrete substantial amounts of vitamin A as retinol and retinyl esters with urine. In the aqueous environment of urine, the hydrophobic vitamin A has to be associated with a protein. This vitamin A-protein complex was purified to homogeneity, prepared by preparative ultracentrifugation (density 1.21 g/mL), native polyacrylamide gel electrophoresis (PAGE) and size exclusion chromatography. The vitamin A-protein complex has a high molecular mass of > 5,000 kDa under native conditions. SDS PAGE under reduced conditions revealed a single band with a molecular mass of about 100 kDa for the protein moiety. Peptides obtained after limited proteolysis with trypsin from the 100 kDa protein were characterised by MALDI-TOF mass spectrometry and showed amino acid sequence homology to the human Tamm-Horsfall Protein (THP). This was further confirmed by a positive immunoreaction of the isolated protein with crossreacting human THP antibodies. The localisation of THP in dog kidneys was determined by using immunohistology. The reaction was strong along the entire thick ascending limb ofthe Henle loop and distal convoluted tubule. Our data point to the possibility that THP functions as a novel carrier for vitamin A in the urine of canines.     

Content of retinol and retinyl esters in blood plasma,liver, kidney and reproductive organs of Japanese quails

Due to its importance in many physiological processes such as cell proliferation and differentiation, vitamin A plays a key role in reproduction. The present study examines the content and distribution of retinol and retinyl esters in the blood plasma, liver, kidney, ovary and oviduct (infundibulum, magnum, isthmus and uterus) of the laying Japanese quail. (1) The results show that the stage of egg laying had no influence on the level of vitamin A (retinol or retinyl esters) in plasma, kidney and liver. (2) The results further indicate that in the oviduct there are quantitative and qualitative differences in the concentration of retinol and retinyl esters, but that these differences are not altered by the stage of egg formation. (3) The highest levels of vitamin A in the isthmus and uterus were associated with a predominance of retinyl esters (palmitate and stearate); sections with lower total levels of vitamin A (infundibulum, magnum) had retinol as the more dominant form of vitamin A. (4) Changes in the ratio of retinol to retinyl esters in the various sections of the avian oviduct might point to metabolic differences. The storage of vitamin A might therefore be the predominant function of the uterus and isthmus; in the infundibulum and magnum, where vitamin A is predominantly present as retinol, vitamin A serves rather as a precursor for the modulation of the cellular metabolism of these structures.     

Characterisation of transthyretin and retinol-binding protein in plasma and cerebrospinal fluid of dogs

The aim of this study was to investigate differences in concentrations of vitamin A, transthyretin (TTR) and retinol-binding protein (RBP) between plasma and cerebrospinal fluid (CSF) in dogs. RBP was detected using ELISA, and both RBP and TTR by Western blot analysis after separation on SDS-PAGE. Vitamin A was determined by high performance liquid chromatography. RBP and TTR as well as vitamin A were detected in all samples but at substantially lower concentrations in CSF compared to plasma. RBP in dog plasma showed a similar molecular mass to that of humans, whereas canine TTR had a lower molecular mass. Comparison between plasma and CSF showed that both RBP and TTR were of lower molecular mass in CSF. In CSF, RBP and retinol were present at 10-100-fold lower concentrations compared to plasma. Retinyl esters were present only in minute amounts in 5/17 samples. In conclusion, the CSF of dogs compared to humans is significantly different in terms of both quality and quantity of transport proteins for vitamin A.     

Immunochemical Localization of Megalin,Retinol-binding protein and Tamm–Horsfall Glycoprotein in the Kidneys of Dogs

Megalin, retinol-binding protein (RBP) and Tamm–Horsfall glycoprotein (THP) are involved in the renal metabolism of vitamin A in canine species. The presence of megalin, RBP and THP in the kidneys of dogs was investigated using immunohistochemical methods. Megalin was highly expressed in the apical membrane of the proximal convoluted and straight tubule cells. Immunoreactive RBP was detected below the apical plasma membrane, as well as in basolateral granules of the proximal convoluted tubule cells. THP immunoreactivity was seen in the epithelial cells lining the thick ascending limb of the loop of Henle. Furthermore, THP was displayed in a scattered pattern within the distal convoluted tubules. The co-localization of megalin and RBP coincides with biochemical studies that have shown megalin to be responsible for renal RBP absorption in the proximal convoluted tubules after filtration through the renal glomerulus. The presence of THP, the carrier for vitamin A in canine urine, showed that vitamin A excretion in the urine of dogs is not merely a filtration process but also seems to be a pathway located in the distal part of the nephron.     

Vasopressin, cortisol, and catecholamine concentrations in dogs with dilated cardiomyopathy

OBJECTIVE: To evaluate plasma concentrations and urinary excretion of vasopressin and cortisol and urinary excretion of catecholamines in dogs with dilated cardiomyopathy (DCM). ANIMALS: 15 dogs with clinical signs of DCM, 15 dogs with preclinical DCM, and 15 control dogs. PROCEDURE: Physical examinations, thoracic radiography, ECG, and echocardiography were performed on all dogs. Blood and urine samples were collected. RESULTS: Plasma concentration of vasopressin and the urine cortisol-to-urine creatinine ratio were significantly increased in dogs with clinical signs of DCM and dogs with preclinical DCM, compared with control dogs. Plasma vasopressin concentration was significantly higher in dogs with clinical signs of DCM, compared with dogs with preclinical DCM. Urine vasopressin-to-urine creatinine ratio was significantly increased in dogs with clinical signs of DCM, compared with dogs with preclinical DCM and control dogs. Urine epinephrine-to-urine creatinine ratio and urine norepinephrine-to-urine creatinine ratio were significantly increased in dogs with clinical signs of DCM, compared with control dogs. Plasma concentration of cortisol and urine dopamine-to-urine creatinine ratio did not differ significantly among groups. CONCLUSIONS AND CLINICAL RELEVANCE: According to this study, the neuroendocrine pattern is changed in dogs with preclinical DCM. These changes are even more pronounced in dogs with clinical signs of DCM. Analysis of concentrations of vasopressin, cortisol, and catecholamines may aid in identification of the clinical stages of DCM. These findings may also provide a basis for additional studies of the possible beneficial effects of vasopressin antagonists and beta-adrenergic receptor antagonists in the treatment of dogs with congestive heart failure and DCM.     

Individual differences in the vitamin A metabolism of the order Carnivora--a review

Vitamin A transport in blood of most species in the order carnivora is fundamentally different from other animals and man. Very high levels of vitamin A in blood plasma of canines and mustelides are due to a high percentage of retinyl esters. These esters (basically retinyl palmitate and stearate) are transported nonspecifically bound to lipoproteins with very-low and low density lipoproteins representing the major fractions (about 70% of total vitamin A esters). A high percentage of retinyl esters could also be found in the families Ursidae, Procyonidae, Viverridae and Felidae in which total vitamin A in blood was low. In man and rat severe signs of vitamin A intoxication can be observed due to a similarly high percentage of nonspecifically bound vitamin A esters. No clinical or clinical-chemical signs of vitamin A intoxication were observed in the animals investigated. Because vitamin A esters are transported by lipoproteins, their blood levels are readily affected by dietary vitamin A supply as it is known to be the case for vitamin E. Furthermore, canines seem to be the only ones that excrete vitamin A as retinol and retinyl esters (basically retinyl palmitate) under physiological conditions with the urine. These fat-soluble metabolites of vitamin A are bound to a protein with a molecular weight between 50,000 and 125,000 Da which shows characteristics of a lipoprotein when subjected to ultracentrifugation or selective precipitation. Higher levels of vitamin A in organs and tissues, as well as the excretion of vitamin A with the urine, might be a consequence of the nonspecific binding of large amounts of retinyl esters to lipoproteins in blood.(ABSTRACT TRUNCATED AT 250 WORDS)     

Renal pathology and urinary protein excretion in a 14-month-old Bernese mountain dog with chronic renal failure

The renal pathology and urinary protein pattern of a 14-month-old female Bernese mountain dog with chronic renal failure was investigated. Sodium dodecyl sulphate-polyacrylamid gel electrophoresis and subsequent Western blot analysis of urine showed the presence of heavy and light chains of immunoglobulin, transferrin, albumin, vitamin D-binding protein, transthyretin and retinol-binding protein (RBP), but no excretion of Tamm-Horsfall protein (THP). Histopathological examinations of the kidneys revealed severe membranous glomerulonephritis accompanied by tubular dilatation, tubular atrophy and interstitial fibrosis. The renal expression of megalin, the main endocytic receptor for the re-uptake of proteins in proximal tubules, RBP and THP was reduced or completely absent, indicating severe tubular dysfunction. The identified urinary proteins may be of interest as additional markers for the diagnosis of juvenile nephropathy in Bernese mountain dogs.     

Proteomic analysis of urine from male dogs during early stages of tubulointerstitial injury in a canine model of progressive glomerular disease

Background: Sensitive and specific noninvasive biomarkers for tubulointerstitial injury are lacking, and proteomic techniques provide a powerful tool for biomarker discovery. Objective: The aim of this study was to identify novel urinary biomarkers of early tubulointerstitial injury in canine progressive renal disease using both 2‐dimensional differential in‐gel electrophoresis (2‐D DIGE), which identifies individual proteins, and surface‐enhanced laser desorption ionization time‐of‐flight mass spectrometry (SELDI‐TOF), which generates protein peak profiles. Methods: Urine was collected from 6 male dogs with X‐linked hereditary nephropathy (XLHN) at 2 time points (TP): 1) the onset of overt proteinuria (urine protein:creatinine ratio>2) and 2) the onset of azotemia (creatinine ≥1.2 mg/dL); corresponding renal biopsies were analyzed from 3 of the dogs. Urine samples from the 6 dogs were subjected to analysis by 2‐D DIGE and SELDI‐TOF. Urinary retinol‐binding protein (RBP) was evaluated in 25 male dogs with XLHN and normal control dogs by Western blot analysis. Results: Clinical data and histologic evaluation revealed reduced renal function and increased tubulointerstitial fibrosis at TP 2. A number of urine proteins and protein peaks were differentially present at the 2 time points, with several known biomarkers of renal disease identified in addition to several promising new biomarkers. RBP was first detected in urine approximately 2 months before onset of azotemia (TP 2), but after onset of overt proteinuria, and amounts increased with progression of disease. Conclusions: Proteomic techniques were successfully used to identify urinary biomarkers of renal disease in dogs with XLHN. Urinary RBP is a promising biomarker for early detection of tubulointerstitial damage and progression to end‐stage renal disease.     

High Urine Concentrations of Basic Fibroblast Growth Factor in Dogs With Bladder Cancer

Because dogs with bladder cancer often have advanced disease at the time of diagnosis, the identification and use of a tumor marker that could facilitate earlier diagnosis is a valid approach to improve prognosis. The objective of this study was to determine if urine concentrations of the proan-giogenic peptide, basic fibroblast growth factor (bFGF), are high in dogs with bladder cancer compared with normal dogs and dogs with urinary tract infection. We used a commercially available enzyme-linked immunosorbent assay test kit to quantitate bFGF in the urine of 17 normal dogs, 10 dogs with urinary tract infection, and 7 dogs with locally active transitional cell carcinoma of the urinary bladder. In normal dogs, the median urine bFGF concentration was 2.23 ng/g creatinine (quartile range, 1.53 to 5.12 ng/g creatinine). The median urine bFGF concentration in dogs with urinary tract infection did not differ significantly from normal dogs. Dogs with bladder cancer had significantly higher urine bFGF concentrations than normal dogs ( P < .002) and dogs with infection ( P < .02). The median urine bFGF concentration in dogs with transitional cell carcinoma was 9.86 ng/g creatinine (quartile range, 7.40 to 21.63 ng/g creatinine). Six of 7 dogs with bladder cancer had urine bFGF concentrations that were up to 7.4 times the 90th percentile value for normal dogs. Only 1 of 10 dogs with infection had a urine bFGF concentration that exceeded the 90th percentile of normal. These data suggest that canine bladder cancers export bFGF, and that urine bFGF may be useful as a diagnostic tumor marker or noninvasive indicator of treatment response. J Vet Intern Med 1996;10:231–234. Copyright © 1996 by the American College of Veterinary Internal Medicine .     

The effect of vitamin C supplementation on plasma concentration and urinary excretion of vitamin C in cattle

We investigated the plasma concentration and urinary excretion of vitamin C in cows supplemented with vitamin C. Five cows (mean BW = 597 kg) were allocated to a 5 x 5 Latin square design and supplemented with a vitamin C preparation coated with hydrogenated soybean oil at 0, 10, 20, 40, or 60 mg of vitamin C per kg of BW per day for 9 d. Plasma and urine samples were collected for measuring vitamin C concentration. Urinary excretion of vitamin C was expressed as the ratio of vitamin C to creatinine. Plasma vitamin C concentration and urinary vitamin C excretion increased quadratically as dietary vitamin C increased (P < 0.001); that is, the lowest dose affected neither plasma vitamin C concentration nor urinary vitamin C excretion but the plasma vitamin C concentration and urinary vitamin C excretion increased (P < 0.05) with increasing supplementation of vitamin C at greater doses. This suggests that plasma vitamin C concentration affects urinary excretion of vitamin C in cattle and that plasma vitamin C concentration exceeded the renal threshold for vitamin C in the cows receiving vitamin C at 20 mg/kg of BW per day. Furthermore, increased urinary excretion of vitamin C appears to limit plasma vitamin C concentration in response to vitamin C intake. The daily excretion of vitamin C was estimated by the reported value of daily creatinine excretion, indicating that the daily amount of vitamin C excreted into urine was more than half of supplied vitamin C. Therefore, a large part of supplied vitamin C probably escapes ruminal degradation and is absorbed but excreted into urine.     

Urinary Catecholamine and Metanephrine to Creatinine Ratios in Dogs with Hyperadrenocorticism or Pheochromocytoma,and in Healthy Dogs

Background: Urinary catecholamines and metanephrines are used for the diagnosis of pheochromocytoma (PHEO) in dogs. Hyperadrenocorticism (HAC) is an important differential diagnosis for PHEO. Objectives: To measure urinary catecholamines and metanephrines in dogs with HAC. Animals: Fourteen dogs with HAC, 7 dogs with PHEO, and 10 healthy dogs. Methods: Prospective clinical trial. Urine was collected during initial work‐up in the hospital; in dogs with HAC an additional sample was taken at home 1 week after discharge. Parameters were measured using high‐pressure liquid chromatography and expressed as ratios to urinary creatinine concentration. Results: Dogs with HAC had significantly higher urinary epinephrine, norepinephrine and normetanephrine to creatinine ratios than healthy dogs. Urinary epinephrine, norepinephrine, and metanephrine to creatinine ratios did not differ between dogs with HAC and dogs with PHEO, whereas the urinary normetanephrine to creatinine ratio was significantly higher (P= .011) in dogs with PHEO (414, 157.0–925.0, median, range versus (117.5, 53.0–323.0). Using a cut‐off ratio of 4 times the highest normetanephrine to creatinine ratio measured in controls, there was no overlap between dogs with HAC and dogs with PHEO. The variables determined in urine samples collected at home did not differ from those collected in the hospital. Conclusion and Clinical Importance: Dogs with HAC might have increased concentrations of urinary catecholamines and normetanephrine. A high concentration of urinary normetanephrine (4 times normal), is highly suggestive of PHEO.     

Blood vitamin concentrations in privately owned dogs fed non-standardized commercial diets and after intake of diets with specified vitamin concentrations

The objective was to investigate in a survey study the blood vitamin concentrations in healthy dogs fed non-specified commercial complete diets and in an intervention study to determine the effects of defined dietary vitamin intakes on blood vitamin levels and hair and skin condition. Sixty-four privately owned dogs, aged from 1 to 8 years, without history of skin or coat problems were included. All animals were fed commercial complete diets with uncertain vitamin concentrations before enrolment. The animals were assigned, according to weight and gender, to four groups with graded vitamin intakes. The blood vitamin levels and skin and coat quality of the dogs were investigated at days 0 and day 122. Coat and hair condition was not influenced by the experimental diets. The retinol concentrations were reduced at the end of the experiment compared with the baseline levels, retinyl esters were not influenced. 25-Hydroxycholecalciferol decreased in all groups, alpha-tocopherol was constant or tended to decrease. Ascorbic acid, thiamine pyrophosphate and riboflavin concentrations were not affected by treatment, flavin adenine dinucleotide and pyridoxal-5'-phosphate were partially reduced on day 122. Cobalamin, pantothenate and biotin concentrations increased with higher dietary intakes, folate levels in tendency. In conclusion, this study gives a survey of blood vitamin concentrations in healthy dogs and provides a data base for the evaluation of the vitamin status in health and disease.     

Measurement of urinary 11-dehydro-thromboxane B2 excretion in dogs with gastric dilatation-volvulus

OBJECTIVE: To measure 11-dehydro-thromboxane B2 (11-dTXB2) in urine of healthy control dogs, dogs undergoing ovariohysterectomy, and dogs with gastric dilatation-volvulus (GDV) and assess the relationship between urinary 11-dTXB2 concentrations in dogs with GDV and postoperative outcomes. SAMPLE POPULATION: Urine samples from 15 nonsurgical control dogs, 12 surgical control dogs, and 32 dogs with GVD. PROCEDURE: Urine samples were obtained from healthy pet dogs (ie, nonsurgical control dogs), dogs undergoing ovariohysterectomy at anesthetic induction and 1 hour following surgery (ie, surgical control dogs), and dogs with GDV at hospital admission and 1 hour following surgical derotation of the stomach (ie, GDV dogs). Urinary 11-dTXB2 concentrations were determined with an ELISA and normalized to urinary creatinine (Cr) concentrations by calculation of the 11-dTXB2 -to-Cr ratio. Differences in median 11-dTXB2 -to-Cr ratios among dogs and before and after surgery were analyzed. RESULTS: Urinary 11-dTXB2-to-Cr ratios did not differ between nonsurgical control dogs and surgical control dogs before or after surgery. Urinary 11-dTXB2-to-Cr ratios were significantly higher in GDV dogs at the time of hospital admission and 1 hour after surgery, compared with those of nonsurgical control dogs. Postoperative urine samples from GDV dogs had significantly higher 11-dTXB2-to-Cr ratios than postoperative urine samples from surgical control dogs. Median urinary 11-dTXB2-to-Cr ratios increased significantly in GDV dogs that developed postoperative complications. CONCLUSIONS AND CLINICAL RELEVANCE: Urinary 11-dTXB2 concentration is increased in GDV dogs at the time of hospital admission and after surgical derotation of the stomach, compared with that of healthy dogs. An increased urinary 11-dTXB2-to-Cr ratio following surgery is associated with an increased incidence of postoperative complications in dogs with GDV.     

Protein profiling of urine from dogs with renal disease using ProteinChip analysis.

Measurement of total urinary proteins in individuals that tested positive by urinary dipstick is a typical method for assessing the presence of potentially serious renal disorders. In the absence of such overt proteinuria, however, measurement of specific urinary proteins may be useful in the diagnosis of nephropathies and may provide greater insight into the pathogenesis. The urine of 28 dogs (16 with renal disease and 12 healthy) was evaluated to determine whether specific low-molecular-weight proteins or the pattern of protein excretion could also be used as a marker of tubular dysfunction in dogs. Specific proteins were assessed by immunological methods, whereas protein profiles were determined by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (MS). In particular, changes in the excretion of retinol-binding protein (RBP) and Tamm-Horsfall protein (THP) appear to be of clinical relevance in the diagnosis of canine kidney diseases. The pattern of urinary protein and peptides revealed specific changes in abundance in dogs with renal disease at molecular masses (kD) of 11.58, 12.41, 12.60, 14.58, 20.95 (RBP), 27.85, and 65.69 (albumin). In conclusion, comparable proteins as in humans might be used as urinary markers for proximal (RBP) and distal (THP) tubular dysfunction in dogs. Surface-enhanced laser desorption/ionization time-of-flight MS is a promising tool for the study of kidney physiology and pathophysiology and might aid in the discovery of new biomarkers of renal disease.     

Effects of urinary tract inflammation and sample blood contamination on urine albumin and total protein concentrations in canine urine samples

BACKGROUND: Urinary tract inflammation and hemorrhage are believed to be common causes of proteinuria in dogs based on results of studies that measured total urine protein concentration. A method to quantify urine albumin (UAlb) concentration in dogs recently has become available; however, the effect of inflammation on albuminuria is unknown. OBJECTIVES: The goals of this study were to determine the effects of urinary tract inflammation, as indicated by pyuria and sample blood contamination, on UAlb concentration and on urine protein:creatinine (UPC) ratio in dogs. METHODS: Urine samples were obtained from dogs with pyuria that were presented to a veterinary teaching hospital or were part of a laboratory colony. To mimic the effects of hematuria, canine whole blood was added to a microscopically normal canine urine sample that had baseline albumin and total protein concentrations below the limits of detection. UAlb concentration was measured using a canine albumin-specific competitive ELISA. UPC ratio was determined using routine methods. RESULTS: Of 70 samples with pyuria, 67% had negligible UAlb concentrations and 81% had normal UPC ratios. UAlb concentration but not UPC ratio was significantly higher (P < 0.05) in samples with concurrent hematuria or bacteriuria. When whole blood was added to normal urine, UAlb concentration did not exceed 1 mg/dL until the sample became visibly pink; the UPC did not exceed 0.4 at any dilution. CONCLUSIONS: Many dogs with pyuria do not have albuminuria or proteinuria; however, albuminuria may be more likely in dogs with pyuria and concurrent hematuria or bacteriuria. Hematuria may not cause an increase in UAlb concentration until it becomes macroscopic and even then may not increase the UPC ratio.     

Effect of dietary supplements containing antioxidants on attenuation of muscle damage in exercising sled dogs

OBJECTIVE: To determine whether dietary antioxidants would attenuate exercise-induced increases in plasma creatine kinase (CK) activity in sled dogs. ANIMALS: 41 trained adult sled dogs. PROCEDURE: Dogs, randomly assigned to 2 groups, received the same base diet throughout the study. After 8 weeks on that diet, 1 group (21 dogs) received a daily supplement containing vitamins E (457 U) and C (706 mg) and beta-carotene (5.1 mg), and a control group (20 dogs) received a supplement containing minimal amounts of antioxidants. After 3 weeks, both groups performed identical endurance exercise on each of 3 days. Blood samples were collected before and 3 weeks after addition of supplements and after each day of exercise. Plasma was analyzed for vitamins E and C, retinol, uric acid, triglyceride, and cholesterol concentrations, total antioxidant status (TAS), and CK activity. RESULTS: Feeding supplements containing antioxidants caused a significant increase in vitamin E concentration but did not change retinol or vitamin C concentrations orTAS. Exercise caused significantly higher CK activity, but did not cause a significant difference in CK activity between groups. Exercise was associated with significantly lower vitamin E, retinol, and cholesterol concentrations and TAS but significantly higher vitamin C, triglyceride, and uric acid concentrations in both groups. CONCLUSIONS AND CLINICAL RELEVANCE: Use of supplements containing the doses of antioxidants used here failed to attenuate exercise-induced increases in CK activity. Muscle damage in sled dogs, as measured by plasma CK activity, may be caused by a mechanism other than oxidant stress.     

Concentrations of 15F2t isoprostane in urine of dogs with intervertebral disk disease

OBJECTIVE: To measure 15F(2t) isoprostane concentrations in the urine of dogs undergoing ovariohysterectomy (OHE) and dogs undergoing surgery because of intervertebral disk disease (IVDD) and to assess relationships between urinary concentrations of 15F(2t) isoprostanes and neurologic score in dogs with IVDD. ANIMALS: 11 dogs undergoing OHE and 32 dogs with IVDD undergoing hemilaminectomy. PROCEDURES: Paired urine samples were obtained at induction of anesthesia and approximately 1 hour after OHE (controls) and were collected from dogs with IVDD at induction of anesthesia (28 samples) and approximately 1 hour after hemilaminectomy (31 samples); 26 paired urine samples were obtained from dogs with IVDD. Urinary isoprostane concentrations were measured by use of a commercial ELISA, and results were adjusted on the basis of urinary creatinine concentrations. Differences in the mean isoprostane-to-creatinine ratio were analyzed. Neurologic score was determined in dogs with IVDD by use of the modified Frankel scoring system. RESULTS: Urinary isoprostane-to-creatinine ratios were significantly higher in dogs with IVDD than in control dogs before and after surgery. There was no significant difference between values before and after surgery for either group. There was a significant correlation of neurologic score and urinary isoprostane-to-creatinine ratio because dogs that had higher neurologic scores (ie, less severely affected) generally had higher isoprostane-to-creatinine ratios. CONCLUSIONS AND CLINICAL RELEVANCE: Urinary isoprostane-to-creatinine ratios were higher in dogs with IVDD before and after surgery. Analysis of these data suggests that dogs with IVDD are in a state of oxidative stress and that preemptive treatment with antioxidants warrants further investigation.