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SUMMARY

Analysis of hepatic enzyme activities in serum samples from 1- to 3-day-old pups revealed alkaline phosphatase (alp) activities that were 30 times higher and γ-glutamyltransferase (ggt) activities that were 100 times higher than activities in clinically normal adult dogs. A study was conducted to investigate high enzyme activity in pups and to determine whether there is any association between serum enzyme activity and colostrum ingestion, passive transfer of maternal serum enzyme (in colostrum or in utero), or excessive renal or hepatic tissue enzymes. Serum enzyme activity was quantified in 15 neonatal pups before and after ingestion of colostrum and in 3 colostrum-deprived neonates fed a milk substitute. Serum samples were collected on postpartum days 0, 1, 10, 15, and 30. Enzyme activity was also quantified in serum from pregnant and lactating bitches (collected on days -2, 0, 1, 10, 30), hepatic and renal tissue from clinically normal adult dogs and 1-day-old pups, colostrum, milk (collected on days 10 and 30), and milk replacer.

Significant (P < 0.01) differences in serum ggt and alp activities between colostrum-deprived and suckling pups did not exist before initial feeding. Significant (P < 0.001) increases in serum ggt and alp activities developed within 24 hours in suckling pups, but not in the colostrum-deprived pups. At 10 and 30 days after birth, serum ggt and alp activities were less than values before suckling in all pups.

Enzyme activities in bitches’ serum remained within the normal range for adult dogs throughout whelping and lactation. Renal ggt and alp activities were substantially greater than hepatic enzyme activities in neonates and adults. Renal tissue from adults contained 3 times greater ggt and 2 times greater alp activities than that from neonates. Hepatic tissue from neonates contained 5 times more ggt activity than did hepatic tissues from clinically normal adults; however, hepatic alp activity was similar in adults and neonates.

Colostrum and milk had substantially higher enzyme activities than did bitches’ serum. Activities of ggt and alp in milk were 100 times and 10 times greater, respectively, than activities in serum through day 10. By day 30, ggt and alp activities in milk were less than before suckling. Enzyme activity was not detected in the milk substitute.

These studies reveal an association between colostrum ingestion by suckling and acute, profound increases in serum ggt and alp in 1- to 3-day-old pups. Although this phenomenon might be useful as an indicator of colostrum ingestion, it precludes the diagnostic use of either enzyme as an indicator of hepatobiliary disease in 3-day-old pups.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the influence of treatment with ultralow-dose aspirin (ULDAsp) on platelet aggregation, P-selectin (CD62P) expression, and formation of platelet-leukocyte aggregates in clinically normal dogs.

Animals—18 clinically normal dogs.

Procedures—Studies were conducted before and 24 hours after ULDAsp administration (0.5 mg/kg, PO, q 24 h, for 2 days). Whole blood impedance aggregometry for the assessment of platelet function was performed with sodium citrate–anticoagulated blood and aggregation agonists (ADP at 20, 10, and 5 μmol/L; collagen at 10, 5, and 2 μg/mL). Onset, maximum response, and rate of platelet aggregation were recorded. Flow cytometric assays were configured to detect thrombin-induced CD62P expression and platelet-leukocyte aggregates in EDTA-anticoagulated whole blood. Externalized platelet CD62P and constitutive CD61 (GPIIIa) were labeled with antibodies conjugated to phycoerythrin (PE) and fluorescein isothiocyanate (FITC), respectively. Red blood cell–lysed paraformaldehyde-fixed EDTA-anticoagulated whole blood was dual labeled with CD61-FITC and a panleukocyte antibody (CD18-PE) to characterize platelet-leukocyte aggregates.

Results—ULDAsp significantly delayed platelet aggregation onset with ADP at 20 μmol/L by 54% to 104%, attenuated maximum aggregation with various concentrations of ADP and collagen by ≥ 41%, and slowed aggregation rate with the highest ADP and collagen concentrations by ≥ 39%. Depending on the parameter tested, up to 30% of dogs failed to have an ULDAsp effect. Thrombin stimulation significantly increased CD62P expression in platelets and platelet-leukocyte aggregates, but ULDAsp did not alter basal or thrombin-stimulated CD62P expression.

Conclusions and Clinical Relevance—ULDAsp treatment of clinically normal dogs impaired platelet aggregation in most dogs, but did not influence CD62P platelet membrane expression. (Am J Vet Res 2010;71:1294–1304)

Full access
in American Journal of Veterinary Research