The objective of this study was to characterize the highly elevated levels of clotting factor VIII (FVIII) in camel plasma. Whole blood was collected from healthy camels and factor VIII clotting activity (FVIII:C) assays were conducted using both the clotting and the chromogenic techniques. The anticoagulant citrate phosphate dextrose adenine (CPDA) produced the highest harvest of FVIII:C, the level of plasma factor VIII, compared to heparin:saline and heparin: CPDA anticoagulants. Camel FVIII can be concentrated 2 to 3 times in cryoprecipitate. There was a significant loss of camel FVIII when comparing levels of FVIII in camel plasma after 1 h of incubation at 37°C (533%), 40°C (364%), and 50°C (223%). Thrombin generation of camel plasma is comparable to that of human plasma. It was concluded that camel plasma contains very elevated levels of FVIII:C, approaching 8 times the levels in human plasma, and that these elevated levels could not be attributed to excessive thrombin generation. Unlike human FVIII:C, camel FVIII:C is remarkably heat stable. Taken together, these unique features of camel FVIII could be part of the physiological adaptation of hemostasis of the Arabian camel in order to survive in the hot desert environment.

Objective—To determine the effect of large colon ischemia and reperfusion on concentrations of the inflammatory neutrophilic protein calprotectin and other clinicopathologic variables in jugular and colonic venous blood in horses. Animals—6 healthy horses. Procedures—Horses were anesthetized, and ischemia was induced for 1 hour followed by 4 hours of reperfusion in a segment of the pelvic flexure of the large colon. Blood samples were obtained before anesthesia, before induction of ischemia, 1 hour after the start of ischemia, and 1, 2, and 4 hours after the start of reperfusion from jugular veins and veins of the segment of the large colon that underwent ischemia and reperfusion. A sandwich ELISA was developed for detection of equine calprotectin. Serum calprotectin concentrations and values of blood gas, hematologic, and biochemical analysis variables were determined. Results—Large colon ischemia caused metabolic acidosis, a significant increase in lactate and potassium concentrations and creatine kinase activities, and a nonsignificant decrease in glucose concentrations in colonic venous blood samples. Values of these variables after reperfusion were similar to values before ischemia. Ischemia and reperfusion induced activation of an inflammatory response characterized by an increase in neutrophil cell turnover rate in jugular and colonic venous blood samples and calprotectin concentrations in colonic venous blood samples. Conclusions and Clinical Relevance—Results of this study suggested that large colon ischemia and reperfusion caused local and systemic inflammation in horses. Serum calprotectin concentration may be useful as a marker of this inflammatory response.

Objective: To measure and compare insulin secretion and sensitivity in healthy alpacas and llamas via glucose clamping techniques. Animals: 8 llamas and 8 alpacas. Procedures: Hyperinsulinemic euglycemic clamping (HEC) and hyperglycemic clamping (HGC) were performed on each camelid in a crossover design with a minimum 48-hour washout period between clamping procedures. The HEC technique was performed to measure insulin sensitivity. Insulin was infused IV at 6 mU/min/kg for 4 hours, and an IV infusion of glucose was adjusted to maintain blood glucose concentration at 150 mg/dL. Concentrations of blood glucose and plasma insulin were determined throughout. The HGC technique was performed to assess insulin secretion in response to exogenous glucose infusion. An IV infusion of glucose was administered to maintain blood glucose concentration at 320 mg/dL for 3 hours, and concentrations of blood glucose and plasma insulin were determined throughout. Results: Alpacas and llamas were not significantly different with respect to whole-body insulin sensitivity during HEC or in pancreatic β-cell response during HGC. Alpacas and llamas had markedly lower insulin sensitivity during HEC and markedly lower pancreatic β-cell response during HGC, in comparison with many other species. Conclusions and Clinical Relevance: New World camelids had lower glucose-induced insulin secretion and marked insulin resistance in comparison with other species. This likely contributes to the disorders of fat and glucose metabolism that are common to camelids.

Objective: To evaluate intraday and interday variations in glucose concentrations in cats and to test the utility of a continuous glucose monitoring system (CGMS). Animals: 6 lean and 8 long-term (> 5 years) obese cats. Procedures: Blood glucose concentrations were measured during the course of 156 hours by use of a laboratory hexokinase-based reference method and a handheld glucometer. Interstitial glucose concentrations were evaluated with a CGMS. Results: Paired measures of glucose concentrations obtained with the CGMS typically were marginally higher than concentrations for the reference method and less biased than concentrations obtained with the glucometer. This was partially confirmed by the concordance correlation coefficients of the concentration for the CGMS or glucometer versus the concentration for the reference method, although the correlation coefficients were not significantly different. Mean ± SD area under the curve for the glucose concentration (AUCG) did not differ significantly between lean (14.0 ± 0.5 g/dL•h) and obese (15.2 + 0.5 g/dL•h) cats during the 156-hour period, but one of the obese cats had a much higher AUCG. Within-day glucose variability was small in both lean and obese cats. Conclusions and Clinical Relevance: Glucose homeostasis was maintained, even in long-term obese cats, and intraday glucose fluctuations were small. One obese cat might have been classified as prediabetic on the basis of the AUCG, which was approximately 25% higher than that of the other obese and lean cats. The CGMS can be useful in the evaluation of long-term effects of drugs or diet on glucose homeostasis in cats.

Objective: To evaluate a human radioimmunoassay (RIA) and equine and high-range porcine (hrp) species-specific ELISAs for the measurement of high serum insulin concentrations in ponies. Samples: Serum samples from 12 healthy nonobese ponies (7 clinically normal and 5 laminitis prone; 13 to 26 years of age; 11 mares and 1 gelding) before and after glucose, insulin, and dexamethasone administration. Procedures: Intra-and interassay repeatability, freeze-thaw stability, dilutional parallelism, and assay agreement were assessed. Results: Assay detection limits were as follows: RIA, < 389 μU/mL; equine ELISA, < 175 μU/mL; and hrp ELISA, 293 to 8,775 μU/mL. Mean ± SD intra- and interassay repeatability were respectively as follows: RIA, 6.5 ± 5.1 % and 74 ± 3.4%; equine ELISA, 10.6 ± 11.0% and 9.0 ± 4.6%; and hrp ELISA, 19.9 ± 172% and 173 ± 16.6%. Freezing and thawing affected measured concentrations. Dilutional parallelism in the RIA was only evident when insulin-depleted equine serum was used as a diluent (percentage recovery, 95.7 ± 274%); in the ELISAs, dilutional parallelism was observed when a zero calibrator was used. Agreement between RIA and equine ELISA results was good for samples containing concentrations < 175 μU of insulin/mL (bias, −18.5 ± 25.5 μU/mL; higher in RIA). At higher concentrations, assay agreement was poor between RIA and equine ELISA results (bias, −185.3 ± 98.7 μU/mL) and between RIA and hrp ELISA results (bias, 25.3 ± 183.0 μU/mL). Conclusions and Clinical Relevance: Agreement among results of the 3 assays was variable, and dilutional parallelism was only evident with the RIA when insulin-depleted equine serum was tested. Caution is recommended when evaluating high insulin concentrations measured with the RIA or ELISAs.

The effects of 2 different 8-hour continuous rate infusions (CRIs) of medetomidine on epinephrine, norepinephrine, cortisol, glucose, and insulin levels were investigated in 6 healthy dogs. Each dog received both treatments and a control as follows: MED1 = 2 μg/kg bodyweight (BW) loading dose followed by 1 μg/kg BW per hour CRI; MED2 = 4 μg/kg BW loading dose followed by 2 μg/kg BW per hour CRI; and CONTROL = saline bolus followed by a saline CRI. Both infusion rates of medetomidine decreased norepinephrine levels throughout the infusion compared to CONTROL. While norepinephrine levels tended to be lower with the MED2 treatment compared to the MED1, this difference was not significant. No differences in epinephrine, cortisol, glucose, or insulin were documented among any of the treatments at any time point. At the low doses used in this study, both CRIs of medetomidine decreased norepinephrine levels over the 8-hour infusion period, while no effects were observed on epinephrine, cortisol, glucose, and insulin.

Objective: To examine the effect of endotoxins on metabolism and histopathologic changes of isolated perfused equine forelimbs. Sample: Forelimbs (comprising the metacarpus and digit) were collected from cadavers of 12 healthy adult horses after slaughter at an abattoir (14 limbs; 1 forelimb of 10 horses and both forelimbs of 2 horses). Procedures: Forelimbs were perfused for 10 hours with autologous blood, with and without the addition of endotoxin (80 ng of lipopolysaccharide [LPS]/L). Two limbs of the endotoxin exposure group and 2 nonperfused limbs were loaded to failure of the suspensory apparatus of the pedal bone to evaluate the effect of body weight. Metabolic and histologic variables were evaluated. Results: Blood pressure increased during the first hour and did not differ between groups. Lactate dehydrogenase activity was similar in both groups and increased significantly during the 10-hour period; glucose consumption at 5 hours and lactate concentration at 8 hours were significantly higher in limbs exposed to endotoxin. The width of secondary epidermal lamellae was greater in LPS limbs. In the primary dermal lamellae of LPS limbs, there were significantly more vessels with an open lumen and aggregates of intravascular neutrophils. Conclusions and Clinical Relevance: In the blood-perfused isolated forelimbs of equine cadavers, exposure to LPS led to significant changes in the laminar tissue as well as to metabolic changes. Therefore, endotoxin should be considered as a causative factor for laminitis and not merely as a risk factor.

Objective: To determine whether the method of lipopolysaccharide (LPS) administration (intermittent vs continuous) affects the magnitude and duration of the systemic inflammatory response in horses and whether prolonged (48 hours) endotoxemia induces laminitis. Animals: 12 healthy adult horses (10 mares and 2 geldings). Procedures: Horses were randomly assigned to receive LPS (total dose, 80 μg; n = 4) or saline (0.9% NaCl) solution (80 mL/h; 4) via constant rate infusion or 8 bolus IV injections of LPS (10 μg, q 6 h;4) during a 48-hour period. Physical examinations were performed every 4 hours, inflammatory cytokine gene expression was determined for blood samples obtained every 8 hours, and IV glucose tolerance tests were performed. Results: All LPS-treated horses had signs of depression and mild colic; those signs abated as the study progressed. Administration of LPS increased expression of interleukin-1β, interleukin-6, and interleukin-8, but results were not significantly different between LPS treatment groups. Cytokine expression was significantly higher on the first day versus the second day of LPS treatment. Interleukin-1β expression was positively correlated with rectal temperature and expression of other cytokines. Glucose and insulin dynamics for both LPS groups combined did not differ significantly from those of the saline solution group. Signs of laminitis were not detected in any of the horses. Conclusions and Clinical Relevance: Horses developed LPS tolerance within approximately 24 hours after administration was started, and the method of LPS administration did not affect the magnitude or duration of systemic inflammation. Laminitis was not induced in horses.

We investigated vascular access ports for feline blood donation. Eight cats were anesthetized for conventional blood collection by jugular venipuncture at the beginning and end of the study. In-between conventional collections, vascular access ports were used for collection with or without sedation every 6 to 8 wk for 6 mo. Ports remained functional except for one catheter breakage, but intermittent occlusions occurred. Systolic blood pressure was lower during conventional collection. Behavioral abnormalities occurred during 3 port collections. Packed red cells prepared from collected blood were stored at 4°C for 25 d and assessed for quality pre- and post-storage. With both collection methods, pH and glucose level declined, and potassium level, lactate dehydrogenase activity and osmotic fragility increased. There were no differences between methods in pre-storage albumin and HCO3− levels, and pre and post-storage hematocrit, lactate dehydrogenase activity, and glucose and potassium levels. Pre-storage pH and pCO2 were higher with conventional collection, and pre- and post-storage osmotic fragility were greater with port collection. One port became infected, but all cultures of packed red cells were negative. Tissue inflammation was evident at port removal. In a second study of conventional collection in 6 cats, use of acepromazine in premedication did not exacerbate hypotension. The use of vascular access ports for feline blood donation is feasible, is associated with less hypotension, and may simplify donation, but red cell quality may decrease, and effects on donors must be considered.

Objective: To determine the effect of Hct on blood glucose readings of dogs obtained by use of 2 point-of-care (POC) blood glucometers and a laboratory analyzer. Animals: 184 dogs, including 139 Greyhounds. Procedures: Venous blood samples collected from 184 dogs with a range of Hcts (measured in EDTA-anticoagulated blood) were immediately analyzed with a handheld glucometer specifically developed for veterinary use and a glucometer developed for use in humans. The remainder of each blood sample was placed in fluoride oxalate tubes, and plasma glucose concentration was measured with a laboratory analyzer. Agreement between results for the POC glucometers and laboratory analyzer and effect of Hct on glucometer accuracy was assessed via regression analysis. Results: Significant differences were detected between results of the glucometers and the reference laboratory analyzer. The Hct affected the correlation between results for the glucometers and the laboratory analyzer. Deviations of the glucometers from the reference interval varied with Hct. The glucometer for veterinary use more closely correlated with the glucose concentration when Hct was within or above its reference interval. The glucometer for use in humans more closely approximated laboratory reference glucose concentrations in anemic dogs. Conclusions and Clinical Relevance: Hct had a relevant impact on the correlation between whole blood and plasma glucose concentrations in dogs. Significant variations between results obtained with the 2 glucometers could be critical when interpreting blood glucose measurements or selecting a POC glucometer for an intensive care setting and precise glycemic control in critically ill dogs.