An intramammary device (IMD) was adapted for use in ewes; this device was made of abraded poly. ethylene material (1.7 mm in diameter, 47 mm long) and formed a 15-mm-diameter loop in the gland cistern. The IMD was inserted in 1 gland in each of 43 ewes. A significant (P < 0.0001) increase in milk somatic cell count (SCC) was observed in glands provided with an IMD. This increase was attributable to an increase in neutrophil numbers and was observed during the first 12 weeks after insertion. The IMD had a protective effect against experimentally induced staphylococcal mastitis (Staphylococcus aureus and S epidermidis), although different milk SCC were required for protection from each bacterial species in most ewes (10(6) and 2 X 10(5) cells/ml, respectively). Histologic studies revealed that the IMD induced local squamous metaplasia in the glandular part of the lactiferous sinus. Erythrocytes were found in milk from glands provided with an IMD throughout the studied period (35 days of the 45-day lactation) and, in some cases, blood clots were observed during the first 2 weeks of lactation. Glands with IMD also had lower milk production and quality at 30 and 32 days of lactation. Eight ewes with IMD were studied throughout a subsequent lactation. Milk from the IMD-containing glands had an increase in SCC, as in the previous lactation period; did not contain blood clots or erythrocytes; and had normal composition (similar to that in glands without the IMD).

OBJECTIVE To evaluate coagulation factors in units of leukoreduced (LR) and nonleukoreduced (non-LR) canine fresh-frozen plasma (cFFP). ANIMALS 8 healthy research dogs. PROCEDURES In a crossover study, dogs were randomly assigned to 1 of 2 groups from which blood was collected and either did or did not undergo leukoreduction. After a recovery period of ≥ 28 days, the dogs were switched between protocols. After each collection, blood samples were centrifuged, and cFFP was stored frozen for later comparative analysis of coagulation factors, antithrombin, and protein C activities (reported as comparative percentages of the corresponding activities determined in a canine pooled plasma standard); prothrombin and activated partial thromboplastin times; and fibrinogen concentration. RESULTS There were no significant differences detected between results for LR cFFP, compared with those for non-LR cFFP. CONCLUSIONS AND CLINICAL RELEVANCE Although there was variation among residual activities of coagulation factors in LR and non-LR cFFP, the variations and differences were considered unlikely to impact the efficacy of LR cFFP transfused for coagulation factor replacement in dogs. However, owing to the small sample size and high variability of results in the present study, additional research with a larger sample size is required for definitive conclusions on the effects of leukoreduction on coagulation factors in cFFP and to develop treatment guidelines for LR cFFP use in dogs with congenital and acquired coagulopathies.

OBJECTIVE To assess feasibility of the use of a dynamic viscoelastic coagulometer on chicken blood and compare coagulation variables for fresh whole blood and sodium citrate–preserved whole blood as well as effects of 3 coagulation activators on blood from chickens. SAMPLE Blood samples from 30 hens. PROCEDURES Chickens were allowed to rest undisturbed for 1 hour. A blood sample was collected from an ulnar vein; 1.4 mL was analyzed immediately, and 1.8 mL was mixed with sodium citrate and subsequently recalcified and analyzed. A separate coagulation activator (glass beads, kaolin clay, or tissue factor) was in each of the 2 channels of the analyzer. Chickens were allowed a 1-hour rest period, and another blood sample was collected from the contralateral ulnar vein; it was processed in the same manner as for the first sample, except both channels of the analyzer contained the same coagulation activator. RESULTS Compared with fresh samples, citrated samples had higher values for activated clotting time and platelet function and lower clotting rates. Intra-assay coefficients of variation of coagulation profiles for citrated samples were markedly greater than the limit of 10%, whereas values for fresh samples were close to or < 10%. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that use of a dynamic viscoelastic coagulometer on chicken blood was feasible and that analysis of fresh whole blood from healthy chickens provided results with less variability than did analysis of citrated blood. Samples preserved with sodium citrate were associated with significant relative hypocoagulability, compared with results for fresh blood.

OBJECTIVE To validate that dogs become hypocoagulable following rattlesnake envenomation and to determine whether thromboelastographic abnormalities are correlated with envenomation severity for dogs bitten by rattlesnakes native to southern California. ANIMALS 14 dogs with observed or suspected rattlesnake envenomation (envenomated dogs) and 10 healthy control dogs. PROCEDURES For each dog, a citrate-anticoagulated blood sample underwent kaolin-activated thromboelastography. For each envenomated dog, a snakebite severity score was assigned on the basis of clinical findings, and prothrombin time, activated partial thromboplastin time, and platelet count were determined when the attending clinician deemed it necessary and owner finances allowed. RESULTS For 12 of 14 envenomated dogs, the thromboelastographically determined clot strength was below the 25th percentile for the clot strength of control dogs, which was indicative of a hypocoagulable state. No envenomated dog had thromboelastographic results indicative of a hypercoagulable state. One envenomated dog had a prolonged prothrombin time, but the activated partial thromboplastin time and all thromboelastographic variables were within the respective reference ranges for that dog. Seven of 13 envenomated dogs were thrombocytopenic (platelet count, ≤ 170,000 platelets/μL). Snakebite severity score was negatively correlated with platelet count but was not correlated with any thromboelastographic variable. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that dogs generally become hypocoagulable following rattlesnake envenomation. Thromboelastography might provide an objective measure of the coagulation status of envenomated dogs and aid in the identification of dogs that are in a hypocoagulable state and in need of antivenin treatment prior to the onset of progressive clinical signs.

OBJECTIVE To compare the effects of equivalent volumes of equine plasma and 6% hydroxyethyl starch (600/0.75) solution (hetastarch) administered IV on plasma colloid osmotic pressure (pCOP) and commonly monitored clinicopathologic variables in horses. ANIMALS 6 healthy mares. PROCEDURES In a randomized, crossover study, horses were administered hetastarch or plasma (both 10 mL/kg, IV) 18 months apart. The pCOP and variables of interest were measured before (baseline), immediately after, and at intervals up to 96 or 120 hours after infusion. Prothrombin and activated partial thromboplastin times were measured before and at 2 and 8 hours after each infusion. RESULTS Prior to hetastarch and plasma infusions, mean ± SEM pCOP was 19.4 ± 0.5 mm Hg and 19.4 ± 0.8 mm Hg, respectively. In general, hetastarch and plasma infusions comparably increased pCOP from baseline for 48 hours, with maximum increases of 2.0 and 2.3 mm Hg, respectively. Mean Hct and hemoglobin, total protein, and albumin concentrations were decreased for a period of 72, 96, or 120 hours after hetastarch infusion with maximum decrements of 8.8%, 3.2 g/dL, 1.2 g/dL, and 0.6 g/dL, respectively. Plasma infusion decreased (albeit not always significantly) hemoglobin concentration and Hct for 20 and 24 hours (maximum changes of 1.5 g/dL and 6.6%, respectively) and increased total solids concentration (maximum change of 0.6 g/dL) for 48 hours. Platelet count and coagulation times were minimally affected. CONCLUSIONS AND CLINICAL RELEVANCE Overall, the hetastarch and plasma infusions comparably increased pCOP in healthy horses for up to 48 hours. Hetastarch induced greater, more persistent perturbations in clinicopathologic variables.

OBJECTIVE To determine a treatment protocol for SC administration of dalteparin to cats on the basis of currently available detailed pharmacokinetic data and to assess the effect of SC administration of dalteparin to cats on coagulation variables such as activated partial thromboplastin time (aPTT), thrombin time, and results for thromboelastometry, compared with effects on anti–activated coagulation factor X (anti-Xa) activity. ANIMALS 6 healthy domestic shorthair cats. PROCEDURES Cats received 14 injections of dalteparin (75 anti-Xa U/kg, SC) at 6-hour intervals. Blood samples were collected before and 2 hours after the first and second injections on days 1, 2, and 4. Anti-Xa activity was measured by use of a chromogenic substrate assay, aPTT and thrombin time were measured by use of an automated coagulometer, and viscoelastic measurements were obtained with thromboelastrometry. RESULTS 2 hours after the second injection, the target peak anti-Xa activity range of 0.5 to 1.0 U/mL was achieved in all cats, whereas median trough values remained below this range. Peak anti-Xa activity had only minimal effects on coagulation variables; the maximum median ratio for aPTT (in relationship to the value before the first dalteparin injection) was 1.23. CONCLUSIONS AND CLINICAL RELEVANCE Results of this study indicated that this treatment protocol resulted in reproducible anti-Xa activity in cats that was mostly within the targeted peak range of anti-Xa activity recommended for humans. Treatment in accordance with this protocol may not require routine coagulation monitoring of cats, but this must be confirmed in feline patients.

The effects of heparin administration, by the oral route, were evaluated in dogs. In single and multiple dose studies (single 7.5 mg/kg, multiple 3 × 7.5 mg/kg per 48 h), plasma, urine, and fecal samples were collected at various times up to 120 h after oral administration of unfractionated heparin. Changes in plasma and urine anti-Xa activity, plasma and urine anti-IIa activity, plasma activated partial thromboplastin time (APTT) and antithrombin (ATIII), and chemical heparin in urine and feces were examined with time. There was support for heparin absorption, with significant differences in APTT, heparin in plasma as determined by anti-Xa activity (Heptest) in the single dose study and plasma anti-Xa activity, anti-IIa activity and ATIII; and chemical heparin in urine in the multiple dose study. No clinical evidence of bleeding was detected in any dog during the studies. Oral heparin therapy may be applicable for thromboembolic disease in animals. Further studies are warranted to determine the effects of oral heparin at the endothelial level in the dog.

Objective: To characterize acute inflammatory and hemostatic surgical stress responses following castration in cats and to evaluate whether the addition of local anesthesia to the anesthetic protocol attenuates these responses. Animals: 39 male cats. Procedures: Cats undergoing castration were randomly assigned to 2 groups: both groups underwent surgery with general anesthesia, and 1 group additionally received a local anesthetic (lidocaine [2.0 mg/kg in total, divided intratesticularly and SC]) prior to incision. Blood samples were collected after anesthetic induction (baseline) and 1, 5, and 24 hours later. Thromboelastography and coagulation variables (activated partial thromboplastin time [aPTT] and prothrombin time [PT]) were analyzed; fibrinolysis was assessed with plasma D-dimer concentrations. The acute-phase response was evaluated via measurement of plasma fibrinogen and serum amyloid A (last time point, 28 hours) concentrations. Hematologic variables were analyzed at baseline and 1, 5, and 24 hours later. Results: Evidence of hemostatic and inflammatory activation after surgery was detected in both groups. Maximum amplitude and G (global clot strength) were significantly increased at 24 hours, and significant, but not clinically relevant, decreases were detected in aPTT at 5 and 24 hours and in PT at 24 hours, compared with baseline values. Serum amyloid A concentrations were significantly higher at 24 and 28 hours than at baseline, and plasma fibrinogen concentration was significantly increased at 24 hours; WBC and RBC counts and Hct were significantly increased at multiple time points. No differences between groups were detected for any variables. Conclusions and Clinical Relevance: Castration appeared to induce hypercoagulability and an acute-phase inflammatory response in cats. Local anesthesia with lidocaine did not attenuate this response.

Objective-To investigate whether submaximal aerobic exercise in dogs is followed by activation of all phases of coagulation as has been reported for humans. Animals-9 healthy Beagles. Procedures-30 minutes before dogs were exercised, a 16-gauge central venous catheter was placed in a jugular vein of each dog by use of the catheter-through-the-needle technique. Samples were collected before exercise, after running on a treadmill (6 km/h for 13 minutes), and at 60 minutes. Platelet activation was evaluated with platelet morphology indices (mean platelet component, mean platelet volume, and number of large platelets) provided by a laser-based hematology system. Platelet function was assessed in hirudin-anticoagulated whole blood with an impedance-based aggregometer with collagen as the agonist (final concentrations, 0, 1.6, 3.2, 5, and 10 micrograms/mL). Prothrombin time, activated partial thromboplastin time, and concentrations of fibrinogen, factor VIII, antithrombin, protein C, protein S, and fibrin D-dimer were determined automatically. Kaolin-activated thromboelastography variables R (reaction time), K (clot formation time), angle alpha, maximal amplitude, and G (clot stability) were measured in recalcified citrated whole blood. Results-Exercise resulted in a significant decrease in mean platelet volume and the number of large platelets but did not change the mean platelet component, which reflected platelet activation as well as platelet function. Secondary and tertiary coagulation did not change significantly, nor did thromboelastography variables. Conclusions and Clinical Relevance-Aerobic exercise resulted in a decrease in the number of large and thus most likely activated platelets but otherwise had no major impact on coagulation in dogs.

OBJECTIVE To evaluate acute changes of the liver by use of shear wave elastography (SWE) and CT perfusion after radiofrequency ablation (RFA). ANIMALS 7 healthy Beagles. PROCEDURES RFA was performed on the liver (day 0). Stiffness of the ablation lesion, transitional zone, and normal parenchyma were evaluated by use of SWE, and blood flow, blood volume, and arterial liver perfusion of those regions were evaluated by use of CT perfusion on days 0 and 4. All RFA lesions were histologically examined on day 4. RESULTS Examination of the SWE color-coded map distinctly revealed stiffness of the liver tissue, which increased from the normal parenchyma to the transitional zone and then to the ablation zone. For CT perfusion, blood flow, blood volume, and arterial liver perfusion decreased from the transitional zone to the normal parenchyma and then to the ablation zone. Tissue stiffness and CT perfusion variables did not differ significantly between days 0 and 4. Histologic examination revealed central diffuse necrosis and peripheral hyperemia with infiltration of lymphoid cells and macrophages. CONCLUSIONS AND CLINICAL RELEVANCE Coagulation necrosis induced a loss of blood perfusion and caused tissue hardening (stiffness) in the ablation zone. Hyperemic and inflammatory changes of the transitional zone resulted in increased blood perfusion. Acute changes in stiffness and perfusion of liver tissue after RFA could be determined by use of SWE and CT perfusion. These results can be used to predict the clinical efficacy of RFA and to support further studies, including those involving hepatic neoplasia.