The objective of this study was to develop prediction models for the serum IgG concentration in critically ill calves based on indirect assays and to assess if the predictive ability of the models could be improved by inclusion of age, clinical covariates, and/or laboratory covariates. Seventy-eight critically ill calves between 1 and 13 days old were selected from 1 farm. Statistical models to predict IgG concentration from the results of the radial immunodiffusion test, the gold standard, were built as a function of indirect assays of serum and plasma protein concentrations, zinc sulfate (ZnSO4) turbidity and transmittance, and serum γ-glutamyl transferase (GGT) activity. For each assay 4 models were built: without covariates, with age, with age and clinical covariates (infection and dehydration status), and with age and laboratory covariates (fibrinogen concentration and packed cell volume). For the protein models, dehydration status (clinical model) and fibrinogen concentration (laboratory model) were selected for inclusion owing to their statistical significance. These variables increased the coefficient of determination (R2) of the models by ≥ 7% but did not significantly improve the sensitivity or specificity of the models to predict passive transfer with a cutoff IgG concentration of 1000 mg/dL. For the GGT assay, including age as a covariate increased the R2 of the model by 3%. For the ZnSO4 turbidity test, none of the covariates were statistically significant. Overall, the R2 of the models ranged from 34% to 62%. This study has provided insight into the importance of adjusting for covariates when using indirect assays to predict IgG concentration in critically ill calves. Results also indicate that ZnSO4 transmittance and turbidity assays could be used advantageously in a field setting.

Objective—To evaluate the effects of perioperative oral administration of carprofen and meloxicam on concentrations of 3 acute-phase proteins in dogs undergoing elective ovariohysterectomy (OVH). Animals—18 healthy adult anestrous female dogs undergoing elective OVH. Procedures—Dogs were allocated to 3 groups (6 dogs/group). A placebo treatment, carprofen (2.0 mg/kg), or meloxicam (0.2 mg/kg) was orally administered to the dogs of the respective groups. The initial doses were administered 30 minutes before premedication prior to OVH; additional doses were administered once daily for 4 days after surgery. Blood samples were collected 45 minutes before premedication and 4, 8, 12, 24, 36, 48, 72, 96, and 120 hours after the end of OVH; samples were used for measurement of total WBC and neutrophil counts and concentrations of C-reactive protein (CRP), ceruloplasmin, and fibrinogen. Results—Values did not differ significantly among groups for WBC and neutrophil counts, serum concentrations of CRP and ceruloplasmin, and plasma concentrations of fibrinogen. Concentrations of all inflammatory markers, except serum ceruloplasmin, increased significantly following OVH, but in a similar manner for each group. No significant changes were detected in serum ceruloplasmin concentrations over time. Conclusions and Clinical Relevance—Perioperative administration of both carprofen and meloxicam did not significantly affect the concentrations of CRP, ceruloplasmin, and fibrinogen in dogs undergoing OVH. Thus, use of carprofen or meloxicam should not affect clinical interpretation of results for these 3 acute-phase proteins.

Objective-To evaluate the platelet activation response before and after treatment with clopidogrel in horses. Animals-12 healthy adult mares. Procedures-In a masked study, horses (6/group) were randomly allocated to alternately receive placebo or clopidogrel via nasogastric tube at a loading dose of 4 mg/kg followed by 2 mg/kg every 24 hours. Blood samples were collected before and 72 hours after initiation of treatment for ADP- and collagen-induced light transmission aggregometry; determination of closure time in collagen-ADP cartridges; modified thrombelastography for comparison of maximal amplitudes generated by kaolin, reptilase, and reptilase plus ADP activation; and flow cytometric tests to detect platelet fibrinogen binding, P-selectin expression, and phosphatidylserine externalization before and after ex vivo stimulation with thrombin, convulxin, thrombin with convulxin, and calcium ionophore. Results-Clopidogrel administration induced a significant decrease in mean aggregation response to 5μM and 10μM ADP stimulation; however, 2 horses had resistance to clopidogrel's inhibitory action. Significant differences after clopidogrel treatment were not found in any other tests of platelet function. Conclusions and Clinical Relevance-Assays using commercially available reagents were configured to measure different variables of the platelet activation response; however, clopidogrel's platelet inhibitory action was only detected by ADP-induced light transmission aggregometry. Results also suggested that horses, like humans, have interindividual variability in response to clopidogrel that may influence the drug's clinical efficacy as an antiplatelet agent.

Objective—To optimize the overall hemostasis potential (OHP) assay for use with canine platelet-poor plasma and determine reference intervals in healthy dogs. Animals—40 healthy dogs. Procedures—Blood was collected from the dogs into citrated tubes, and platlet-poor plasma was obtained. The OHP assay and standard coagulation assays (prothrombin time, activated partial thromboplastin time, and fibrinogen concentration) were performed for each sample. The OHP assay outputs were tested for correlations with results of the standard coagulation assays, age, and sex. Results—Modifications to the published methodology for the OHP assay were required for use with canine plasma, with less coagulation activator (thrombin) and more fibrinolysis activator (tissue plasminogen activator) than used with human plasma. Male dogs had a higher OHP than did females. High fibrinogen concentrations were associated with increases in maximum optical density, OHP, and overall coagulation potential, and reduced prothrombin time was associated with increases in maximum optical density, overall coagulation potential, OHP, and maximum slope. Conclusions and Clinical Relevance—Results supported the use of the OHP assay as an accessible, cost-effective global coagulation assay. Further research is required to determine its clinical application as an alternative to thromboelastography or thrombin generation assays.