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Background: The renin-angiotensin-aldosterone system (RAAS) regulates blood pressure, electrolyte homeostasis, and renal function. Blood pressure, serum sodium concentrations, and urinary albumin excretion are higher in Greyhounds than other purebred and mixed-breed dogs. Hypothesis: Alterations in the RAAS in Greyhounds are associated with hemodynamic and clinicopathologic differences observed in the breed. Animals: Clinically healthy Greyhound and non-Greyhound dogs consecutively enrolled as blood donors (n = 20/group). Methods: Prospective study. Standard chemical analysis was performed on serum and urine. Serum angiotensin-converting enzyme (ACE) activity was determined by fluorometric assay. All other RAAS hormones were determined by radioimmunoassay. Symmetric dimethylarginine (SDMA) was measured by immunoassay. Measurements were compared to blood pressure and urine albumin concentration. Data are presented as mean ± SD or median, range. Results: Serum creatinine (1.5 ± 0.2 vs 1.0 ± 0.1 mg/dL, P < .001), sodium (149, 147–152 vs 148, 146–150 mEq/L, P = .017), and SDMA (16.1 ± 2.9 vs 12.2 ± 1.8 μg/dL, P < .001) were significantly higher in Greyhounds versus non-Greyhounds, respectively. Plasma renin activity (0.69, 0.10–1.93 vs 0.65, 0.27–2.93 ng/mL/h, P = .60) and ACE activity (4.5, 2.1–8.5 vs 4.6, 2.1–11.4 activity/mL; P = .77) were similar between groups and did not correlate with higher systolic pressures and albuminuria in Greyhounds. Plasma aldosterone concentration was significantly lower in Greyhounds versus non-Greyhounds (11, 11–52 vs 15, 11–56 pg/mL, respectively, P = .002). Conclusions and clinical importance: Basal RAAS activation did not differ between healthy Greyhounds and non-Greyhounds. Lower aldosterone concentration in Greyhounds is an appropriate physiologic response to higher serum sodium concentration and blood pressure, suggesting that angiotensin II effects in the renal tubule predominate over those of aldosterone. [ABSTRACT FROM AUTHOR]

Background Hypertension and albuminuria often coexist in Greyhounds, suggesting generalized vascular dysfunction that could contribute to the development of a variety of diseases in this breed. Eicosanoid metabolites of arachidonic acid ( AA) mediate endothelial function, vascular reactivity, and proteinuria in humans and in rodent models. Hypothesis The eicosanoid profile of Greyhounds is shifted toward metabolites that promote vascular dysfunction, hypertension, and proteinuria. Animals Healthy Greyhounds (n = 20) and non-Greyhound (n = 20) dogs that were consecutively enrolled in a blood donor program. Methods Prospective study. Plasma eicosanoid metabolites were assayed by liquid chromatography/electrospray ionization mass spectrometry ( LC/ ESI/ MS) and compared to systolic blood pressure ( SP) measurements and urine albumin concentration. Results Isomers of hydroxyeicosatetraenoic acid ( HETE) were higher in Greyhounds than non-Greyhounds (median, range in pmol/mL: 5(S) HETE 19.82, 8.55-32.95 versus 13.54, 4.33-26.27, P = .033; 8(S) HETE 9.39, 3.28-19.84 versus 5.80, 2.25-17.66, P = .002; 9(S) HETE 9.46, 2.43-13.79 versus 5.82, 1.50-17.16, P = .026; 12(S) HETE 10.17, 3.81-40.06 versus 7.24, 2.9-16.16, P = .022). Dihydroxyeicosatrienoic acid ( DHET) isomers also were higher in Greyhounds compared to non-Greyhounds (mean ± SD in pmol/mL: 8,9 DHET 5.78 ± 2.13 versus 4.03 ± 1.36, P = .004; 11,12 DHET 11.98 ± 2.86 versus 8.90 ± 3.48, P = .004; 14,15 DHET 7.23 ± 2.19 versus 5.76 ± 1.87, P = .028). Albuminuria correlated with total DHET (rs = 0.46, P = .003). SP was positively correlated with 11,12 EET (rs = 0.42, P = .006) and 20(S) HETE (rs = 0.38, P = .017). SP and 8,9 EET were inversely correlated (rs = −0.49, P = .001). Conclusions and Clinical Importance Plasma eicosanoid profile in Greyhounds was consistent with activation of metabolic pathways known to promote vascular dysfunction and might contribute to higher blood pressures and albuminuria. Inhibition of these eicosanoid pathways should be evaluated as therapeutic targets in Greyhounds. [ABSTRACT FROM AUTHOR]

Background Greyhounds have several hematologic variables that are outside of the respective reference intervals of other dog breeds. In addition, increases in HCT, total protein and HGB concentration, and RBC and WBC counts occur immediately after exercise; these values return to resting values within a few hour after racing. Objective This study evaluated the effects of exercise on the concentration of reticulocytes in circulating blood in racing Greyhounds. We hypothesized that reticulocyte numbers are significantly increased immediately after a race, and return to baseline within one to 2 h postrace. Methods Fifty actively racing Greyhounds at the Wheeling Island Racetrack and Casino were included in the study. Samples were collected by jugular venipuncture one day prior to racing at the kennel (resting), immediately after racing, and one to 2 h after the race (recovery). Reticulocyte counts were determined with an IDEXX ProCyte Dx Hematology Analyzer ( IDEXX Laboratories, Inc., Westbrook, ME, USA). Due to a nonparametric distribution, the results were statistically compared using the Friedman test. Results Reticulocyte concentrations were significantly different among the 3 sample collection times ( P < .0001). There was a significant increase in reticulocyte concentration immediately after racing ( P < .001); one to 2 h after racing, the reticulocyte numbers decreased significantly ( P < .001) to counts comparable to resting samples. Conclusion The increase in reticulocyte concentration is probably related to splenic contraction secondary to the release of catecholamines, although premature bone marrow release could also account for these changes. Thus, it is important to consider a Greyhound's activity and degree of excitement when interpreting selected hematologic data in a clinical setting. [ABSTRACT FROM AUTHOR]

Background Despite the popularity of canine blood donor ( BD) programs, there is scarce scientific information regarding iron status in this canine population of dogs. Objective To assess iron status in dogs used in a blood donor program. Animals A total of 130 healthy dogs (75 BD, 55 controls [C]) were included. A subset of dogs (n = 12) were used to evaluate the effects of repetitive donations by having a second and more recent sample analyzed. Methods Serum iron concentration ( SI), unsaturated iron-binding capacity ( UIBC), total iron-binding capacity ( TIBC), and percentage transferrin saturation (% SAT) were obtained. Values were compared using a 2-way ANOVA (factors: BD status, breed). For the subset of BD, the first sample (less frequent donors - LD-, after a mean of 3.8 donations) was compared to a second sample (experienced donors - ED-, mean 13.6 donations) using a paired t-test. Results SI (183.7 ± 55.3 μg/dL) and % SAT (55.7 ± 17.4%) were higher and UIBC (152.6 ± 73.3 μg/dL) was lower in BD dogs than in C (153.9 ± 51.7 μg/dL, 43.8 ± 17.8%, and 224.1 ± 120.6 μg/dL, respectively). Also, UIBC and TIBC were lower, and % SAT higher in Greyhounds when compared with non-Greyhounds. ED had decreased % SAT and increased UIBC and TIBC when compared with LD. Conclusions and Clinical Importance Our canine BD population did not have iron deficiency and had higher SI concentration than C. However, ED (~14 consecutive blood donations every ~8 weeks) developed a mild iron deficiency, although values were still within canine reference intervals. Greyhounds have higher % SAT than non-Greyhounds, which might be a breed-specific peculiarity. [ABSTRACT FROM AUTHOR]

Background Physiologic peculiarities of Greyhounds as compared to other dogs make interpretation of laboratory results in this breed challenging for veterinarians. Hypertension in retired racing Greyhounds ( RRG) can contribute to microalbuminuria ( MA), overt proteinuria, and renal histologic lesions. Objectives To evaluate clinicopathologic findings, hemodynamic status, and renal histology in a population of healthy RRG. Animals RRG presented to Ohio State University College of Veterinary Medicine for inclusion in a spay and neuter program. Methods Cross-sectional study. RRG were classified as normotensive (<160 mmHg) or hypertensive (>160 mmHg) based on blood pressure ( BP) determinations using Doppler and oscillometric methods. Of the dogs evaluated, 62% (n = 29) were hypertensive and 38% (n = 18) were normotensive. Health status was evaluated using routine clinicopathologic tests ( CBC, serum biochemistry, urinalysis) as well as evaluation of fractional excretion of electrolytes and MA determinations. Adequate renal biopsy specimens (n = 15) were evaluated using light, immunofluoresence, and electron microscopy. Results All serum biochemistry results were normal in 45/49 dogs, but MA was more common in hypertensive (84% positive for MA) as compared with normotensive (18% positive for MA) RRG. Observed renal lesions were mild and renal biopsy scores were low in this sample of RRG. Conclusions Hypertension is common in RRG and might be breed-related. It is associated with MA, but observed renal lesions are mild. Whether or not hypertension and MA in RRG leads to progressive renal damage requires longitudinal study. [ABSTRACT FROM AUTHOR]

Owing to the development of Greyhounds as racing sighthounds, these dogs have acquired unique physiologic adaptations that distinguish them from other breeds. Reference intervals for many analytes in retired racing Greyhounds ( RRGs) differ from those of other breeds; most of the hematologic differences have also been described in other sighthounds. In this review, we provide a survey of the literature on clinical pathology of Greyhounds and other sighthounds and results of laboratory testing, including analysis of CBCs, biochemical profiles, coagulation tests, and blood gases, in RRGs at The Ohio State University. Major clinicopathologic differences in this breed include higher RBC mass, creatinine concentration, glomerular filtration rate, activities of hepatic enzymes, and concentration of cardiac troponin, as well as lower WBC, neutrophil, and platelet counts, thromboelastographic values, and concentrations of serum haptoglobin, total globulins, and T4. [ABSTRACT FROM AUTHOR]

The article presents information on a study which determined whether the white coat effect causes the high systemic blood pressure (BP) in retired racing greyhound (RRG) dogs. Information on their cardiovascular features is provided as well as on white-coat hypertension. The characteristics of the RRG are presented together with BP measurements, taken in three environments, of systolic arterial pressure (SAP), mean arterial pressure (MAP), diastolic arterial pressure (DAP) and heart rate (HR). Results are discussed.