Page 1392 - Small Animal Internal Medicine, 6th Edition

1364 PART XIII Hematology

et al., 2017). The serum angiotensin-converting enzyme of the 423 serum samples; however, it was significantly more
(ACE) activity was determined by fluorometric assay. All common in Greyhounds with hypocobalaminemia and
VetBooks.ir other RAAS hormones were determined by radioimmuno- hypofolatemia (92%) than in those with normal concentra-
tions of cobalamine and folate (61%, P = 0.0806). Serum
assay. Symmetric dimethylarginine (SDMA) was measured
by immunoassay. Measurements were compared with blood
healthy Greyhounds than in those with diarrhea or throm-
pressure and urine albumin concentration. homocysteine concentrations were significantly higher in
Serum creatinine (1.5±0.2 versus 1.0±0.1 mg/dL, P bosis; however, there were no differences in folate or cobala-
< 0.001), sodium (149, range 147-152 versus 148, range mine concentrations among these three groups.
146-150 mEq/L, P = 0.017), and SDMA (16.1±2.9 versus The low cobalamin and folate concentrations commonly
12.2±1.8 µg/dL, P < 0.001) concentrations were significantly seen in the breed should be taken into consideration when
higher in Greyhounds than in non-Greyhounds. Plasma interpreting “diarrhea panels,” because hypocobalaminemia
renin activity (0.69, range 0.10-1.93 versus 0.65, range and hypofolatemia are typically associated with several
0.27-2.93 ng/mL/h, P = 0.60) and ACE activity (4.5, range enteropathies, leading to unnecessary additional diagnostics
2.1-8.5 versus 4.6, range 2.1-11.4 activity/mL; P = 0.77) were in Greyhounds with diarrhea.
similar between groups and did not correlate with higher
systolic pressures and albuminuria in Greyhounds. Plasma
aldosterone concentration was significantly lower in Grey- CLINICAL PATHOLOGY
hounds versus non-Greyhounds (11, range 11-52 versus 15, IN GREYHOUNDS: THE
range 11-56 pg/mL, respectively; P = 0.002). The lower aldos- AUTHOR’S EXPERIENCE
terone concentration in Greyhounds is likely an appropriate
physiologic response to higher serum sodium concentration Because of the well-known clinicopathologic peculiarities of
and blood pressure, suggesting that angiotensin II effects in this breed, the establishment of Greyhound-specific RIs has
the renal tubule predominate over those of aldosterone. been of great interest to me for a long time. Several studies
have been done involving different physiologic parameters
Cobalamine, Folate, and Homocysteine (hematology, chemistry, coagulation, and blood gases) to
Two decades ago, we made the observation that most normal help characterize these differences and establish RIs valid
RRGs had lower serum cobalamine concentreations than and specific for the breed.
non-Greyhound dogs (Fig. 83.1). Recently, Grützner et al. The dogs used for the generation of these RIs are from two
(2012) documented that Greyhounds are the breed with the different populations. The first group is from the Greyhound
highest probability of having hypocobalaminemia. In subse- Spay-Neuter-Dental Clinic at The Ohio State University for
quent studies, we evaluated the serum concentration of third- or fourth-year veterinary students in which Grey-
homocysteine, because in humans hypocobalaminemia and hounds from an adoption group (Greyhound Adoption of
hypofolatemia have been associated with hyperhomocyste- Ohio, Chagrin Falls, OH; www.greyhoundadoptionofoh.org)
inemia. High serum homocysteine concentrations frequently are spayed or neutered before being placed in adoptive homes.
result in cardiovascular disease and in thrombosis (Heilman This program has a current animal use protocol (IACUC).
et al., 2016). Hyperhomocysteinemia was identified in 41% Samples were collected over a 5-year span. The second group
is the Greyhound blood donor population, which is a homo-
geneous population of healthy RRGs. Animals from both
groups were considered healthy based on a normal physical
examination and negative serology for Ehrlichia canis, Ana-
plasma phagocytophilum, Borrelia burgdorferi, and Dirofi-
laria immitis (Canine SNAP 4Dx Test, IDEXX Laboratories,
Westbrook, ME).
Jugular or cephalic venous samples were collected in
tubes containing sodium EDTA (for complete blood count
[CBC]) and sodium citrate (for hemostasis assays), and
without anticoagulant (for biochemical profiles). All CBC
and hemostasis samples were analyzed within 4 hours of
collection; the nonanticoagulated blood was immediately
centrifuged and the serum was analyzed within 4 hours of
sample collection. Samples for CBC were evaluated with
LaserCyte or ProCyte Dx (IDEXX Laboratories) using the
appropriate software settings. Samples with flags were not
reevaluated because of a lack of additional blood samples. In
FIG 83.1 a subset of dogs, CBCs were evaluated using a Cell-Dyn 3500
Serum cobalamin concentrations in Greyhounds and (Abbott Diagnostics, Santa Clara, CA). Differential WBC
non-Greyhound dogs. counts were performed manually by the staff at the Clinical