The Renin‐Angiotensin‐Aldosterone System in Greyhounds and Non‐Greyhound Dogs

Abstract

BackgroundThe 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.HypothesisAlterations in the RAAS in Greyhounds are associated with hemodynamic and clinicopathologic differences observed in the breed.AnimalsClinically healthy Greyhound and non‐Greyhound dogs consecutively enrolled as blood donors (n = 20/group).MethodsProspective 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.ResultsSerum 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 importanceBasal 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.

Hyperkalemia during general anesthesia in two Greyhounds

“…20 However, the few articles that describe exercise-associated hyperkalemia also report proportional increases in sodium and chloride concentrations, suggesting this change is likely the result of intravascular fluid translocation or dehydration. [20][21][22][23][24][25] A recent study 26 by one of the authors found that Greyhounds have significantly lower basal aldosterone concentrations than non-Greyhound dogs, despite having similar plasma renin-and angiotensin-converting enzyme activities. It is possible that this contributes to the development of hyperkalemia or the inability of Greyhounds to rapidly or effectively respond to increases in serum potassium concentrations when they occur.…”

Serum Symmetric Dimethylarginine as an Early Marker of Excretory Dysfunction in Canine Leishmaniosis(L. infantum)Induced Nephropathy

“…In our study, we found a Greyhound with a mild increase in creatinine without elevated SDMA concentration. This result can be attributed to the idiosyncrasy of this breed, which presents higher creatinine concentrations [ 34 ] and probably SDMA levels when compared with dogs from other breeds [ 35 ].…”

Establishment of reference intervals for serum symmetric dimethylarginine in adult nonracing Greyhounds

“…Compared with other breeds, Greyhounds possess a number of unique hematologic, biochemical, and drug metabolism characteristics and some of these factors could indicate differences in cellular production and metabolism. Indeed, increased SDMA production due to an increased cell turnover rate has been a proposed mechanism for higher SDMA concentrations in juvenile dogs, and could be a potential mechanism in Greyhounds.…”

“…Indeed, a study comparing SDMA concentrations between 3 different breeds (Pointers, Cairn Terriers, and Cavalier King Charles Spaniels) found no significant differences . In contrast, SDMA concentrations were significantly higher in Greyhounds (n = 20) compared with other breeds (n = 20), and 68% of Greyhounds had an SDMA concentration greater than the upper limit of the previously established canine RI . Larger studies are required to confirm this latter finding, particularly since Greyhound pet ownership has become increasingly popular, and with this comes greater owner expectations for veterinarians to have breed‐specific knowledge .…”

“…11 In contrast, SDMA concentrations were significantly higher in Greyhounds (n = 20) compared with other breeds (n = 20), and 68% of Greyhounds had an SDMA concentration greater than the upper limit of the previously established canine RI. 12 Larger studies are required to confirm this latter finding, particularly since Greyhound pet ownership has become increasingly popular, and with this comes greater owner expectations for veterinarians to have breed-specific knowledge. 13 In addition, Greyhounds appear predisposed to hypertension, proteinuria, and renal dysfunction, and thus there is a need for early detection of renal disease in this breed.…”