The diagnostic and prognostic value of alkaline phosphatase activity in serum and peritoneal fluid from horses with acute colic

Alkaline phosphatase (ALP) is an enzyme present in intestinal mucosa, bile, bone, and renal tubule cells. We sought to assess the diagnostic and prognostic relationships of total ALP (ALPt) activity and that of intestine-derived ALP (ALPi) in serum and peritoneal fluid of 126 horses with colic. ALPt and ALPi activities were measured in both serum and peritoneal fluid by using both standard and L-phenylalanine-based buffers, respectively. Neither ALPt nor ALPi activity were useful in classifying type or severity of intestinal damage. ALPt and ALPi activities in peritoneal fluid were lowest in horses suffering from simple medical colic (39 international units [U]/L [19-60 U/L]; versus 31 U/L [16-44 U/L], median [interquartile range], P < .001) and nonstrangulated surgical lesions (45 U/L [30-62 U/L] versus 36 U/L [23-54 U/L], P < .001), and highest in surgical cases with suspected ulceration (109 U/L [60-1,113 U/L] versus 83 U/L [52-970 U/L], P < .001), strangulation (114 U/L [69-240 U/L] versus 94 U/L [56-191 U/L], P < .001), peritonitis (313 U/L [110-2,227 U/L] versus 283 U/L [91-1,800 U/L], P < .001) or intestinal rupture (687 U/L [205-852 U/L] versus 564 U/L [166-732 U/L], P < .001). Higher ALPt and ALPi activities in peritoneal fluid were associated with greater intestinal damage, increased probability of surgery, and a worse prognosis. The use of L-phenylalanine buffer in both serum and peritoneal fluid did not improve the sensitivity of the test. Based on these results, total ALP activity in peritoneal fluid may help in identifying ischemic or inflammatory bowel lesions in horses with acute colic.     

Thromboelastography in healthy horses and horses with inflammatory gastrointestinal disorders and suspected coagulopathies

Objectives – To evaluate the use of citrated recalcified (nonactivated) thromboelastography (TEG) in healthy horses and horses with colitis and suspected coagulopathies. Design – Prospective, observational study conducted between October 2007 and June 2009. Setting – Veterinary Teaching Hospital. Animals – Forty‐five healthy adult horses and 12 sick adult horses with colitis and prolonged prothrombin time (PT) or activated partial thromboplastin time (aPTT). Interventions – None. Measurements and Main Results – Whole blood was collected on admission. Coagulation profile (PT, aPTT, platelet count, and fibrinogen concentration) and citrated recalcified whole blood TEG analysis (R‐time [R], K‐time [K], angle [α], maximum amplitude [MA], G value [G], lysis at 60 min [LY60]) were evaluated. Mean values (SD) for TEG parameters in healthy horses were: R=10.4 (3.1) minutes; K=3.5 (1.2) minutes; α=46.3 (11.0)°; MA=55.6 (5.1) mm; G=6,429 (1,341) dyn/cm², and LY60=5.1 (2.4)%. Mean coefficients of variation for intra‐assay/interindividual variability in healthy horses were: R=4.7%/30.7%, K=4.8%/35.3%, α=4.4%/23.8%, MA=1.4%/9.3%, G=3.4%/20.8%, and LY60=13.1%/47.7%, respectively. Horses with colitis and prolonged PT and/or aPTT had longer mean values for R (P<0.001) and K (P<0.001), narrower mean α (P<0.001), decreased mean MA (P=0.001), and smaller mean G (P=0.02); changes consistent with hypocoagulability. Conclusions – Citrated recalcified (nonactivated) TEG demonstrated changes consistent with hypocoagulability in horses with colitis that had preidentified coagulation abnormalities. This technique has high interindividual variability and low intra‐assay variability. TEG may be useful for detecting hypocoagulable states in horses with colitis and suspected coagulopathies.     

Serum tumor necrosis factor activity in horses with colic attributable to gastrointestinal tract disease.

Over a 24-month period, serum tumor necrosis factor (TNF) activity was determined in 289 horses with colic attributable to gastrointestinal tract disease. Serum TNF activity was quantitated by use of a modified in vitro cytotoxicity bioassay, using WEHI 164 clone-13 murine fibrosarcoma cells. Causes for colic, determined by clinical and laboratory evaluation, exploratory celiotomy, or necropsy included: gastrointestinal tract rupture (GTR); ileal impaction; small intestinal strangulating obstruction (SIO); proximal enteritis (PE); transient small intestinal distention; large-colon displacement; large-colon volvulus; large-colon impaction; colitis; small-colon obstruction; peritonitis; and unknown. Each diagnosis was placed into 1 of 3 lesion categories: inflammatory disorders (GTR, PE, colitis, peritonitis); strangulating intestinal obstruction (SIO, large-colon volvulus); and nonstrangulating intestinal obstruction (ileal impaction, transient small intestinal distension, large-colon displacement, large-colon impaction, small-colon obstruction, unknown). The prevalence of high serum TNF activity and/or mortality were evaluated. Differences were tested at significance level of P less than 0.05. Approximately 20% of the 289 horses has serum TNF activity greater than that found in clinically normal horses (greater than 2.5 U/ml). Twenty-three horses (8%) had marked increase in serum TNF activity (greater than or equal to 10 U/ml) which was more prevalent among horses with SIO and PE than in horses of other diagnostic groups, except those with GTR. Mortality and marked increase in serum TNF activity were greater in horses with intestinal inflammatory disorders or strangulating intestinal obstruction than in horses with nonstrangulating intestinal obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of peritoneal fluid lactate as a marker of intestinal ischaemia in equine colic

REASONS FOR PERFORMING STUDY: The most common cause of death as a direct result of colic is acute circulatory failure secondary to intestinal ischaemia. Early and accurate recognition of ischaemic bowel is essential to decrease complications and increase survival. Blood to peritoneal lactate values have been evaluated as a prognostic indicator, but lactate values characterised by type of lesion have not been reported. HYPOTHESIS: Plasma and peritoneal lactate values are higher in horses with intestinal ischaemia secondary to a strangulating obstruction (ISSO). METHODS: Venous blood and peritoneal fluid were collected sequentially from 20 clinically healthy horses and 189 horses admitted for colic during a one-year period. Blood gas, pH, electrolyte (K+, Na+, Ca++, Cl-), glucose and lactate values were determined for blood and peritoneal fluid samples; other values recorded for peritoneal fluid included gross appearance, total protein and nucleated cell count. Information regarding diagnosis, treatment and outcome was retrieved from the medical records. RESULTS: Peritoneal and plasma levels of lactate were lower in control compared to clinical cases. Horses with ISSO had a higher peritoneal lactate value (8.45 mmol/l) than those with nonstrangulating obstruction (2.09 mmo/l). Factors with the strongest correlations with the presence of ISSO were changes in the gross appearance of the peritoneal fluid and values of peritoneal fluid chloride, pH and log10 lactate. CONCLUSIONS: Analysis of peritoneal fluid gross appearance, pH, lactate and chloride can be used for diagnosis of ISSO. POTENTIAL RELEVANCE: Peritoneal fluid lactate is a better predictor of ISSO than blood lactate and may aid in early detection of catastrophic peritoneal lesions such as intestinal strangulation and rupture.     

Effects of submaximal exercise on adenine nucleotide concentrations in skeletal muscle fibers of horses with polysaccharide storage myopathy

OBJECTIVE: To determine whether disruption of adenine triphosphate (ATP) regeneration and subsequent adenine nucleotide degradation are potential mechanisms for rhabdomyolysis in horses with polysaccharide storage myopathy (PSSM) performing submaximal exercise. ANIMALS: 7 horses with PSSM and 4 control horses. PROCEDURES: Horses with PSSM performed 2-minute intervals of a walk and trot exercise on a treadmill until muscle cramping developed. Control horses exercised similarly for 20 minutes. Serum creatine kinase (CK) activity was measured 4 hours after exercise. Citrate synthase (CS), 3-OH-acylCoA dehydrogenase, and lactate dehydrogenase activities prior to exercise and glucose-6-phosphate (G-6-P) and lactate concentrations before and after exercise were measured in gluteal muscle specimens. Adenine triphosphate, diphosphate (ADP), monophosphate (AMP), and inosine monophosphate (IMP) concentrations were measured before and after exercise in whole muscle, single muscle fibers, and pooled single muscle fibers. RESULTS: Serum CK activity ranged from 255 to 22,265 U/L in horses with PSSM and 133 to 278 U/L in control horses. Muscle CS activity was lower in horses with PSSM, compared with control horses. Muscle G-6-P lactate, ATP, ADP, and AMP concentrations in whole muscle did not change with exercise in any horses. Concentration of IMP increased with exercise in whole muscle, pooled muscle fibers, and single muscle fibers in horses with PSSM. Large variations in ATP and IMP concentrations were observed within single muscle fibers. CONCLUSIONS AND CLINICAL RELEVANCE: Increased IMP concentration without depletion of ATP in individual muscle fibers of horses with PSSM during submaximal exercise indicates an energy imbalance that may contribute to the development of exercise intolerance and rhabdomyolysis.     

Mesenteric rents as a source of small intestinal strangulation in horses: 15 cases (1990-1997)

OBJECTIVE: To describe the clinical findings in horses with small intestinal strangulation through mesenteric rents, and to determine the recurrence and survival rates after surgery. DESIGN: Retrospective study. ANIMALS: 15 horses with small intestinal obstruction via a mesenteric rent. PROCEDURE: Medical records of horses with obstruction of the small intestine via a mesenteric rent between January 1990 and December 1997 were reviewed. The signalment, history, initial physical examination findings, results of abdominocentesis, and clinical laboratory values were recorded. Surgical findings, including location of the mesenteric rent and surgical procedure performed, were recorded. Short- and long-term survival rates were calculated. RESULTS: Most mesenteric rents were located in the mesentery of the small intestine (13 horses). Two horses had multiple mesenteric defects. Seven horses were euthanatized at surgery because of an inability to reduce the entrapped intestine (3 horses), uncontrollable hemorrhage (2), inability to close the rent (1), and the amount of compromised intestine involved (1). Seven horses required intestinal resection and anastomosis. The median length of intestine resected was 2.6 m (range, 0.6 to 4.5 m). The mesenteric rents created during resection were not closed in 2 horses. One of these 2 horses subsequently developed a strangulating obstruction through the open rent. Seven of 15 horses in our study were discharged from the hospital (i.e., short-term survival rate of 47% [7/15]). Long-term follow-up information was available for 5 of the 7 horses (follow-up duration of 5 months to 9 years), of which 2 died as a result of colic, and 1 horse was euthanatized because of severe arthritis (i.e., long-term survival rate of 40% [2/5]). CONCLUSIONS AND CLINICAL RELEVANCE: Inability to reduce the intestinal obstruction, severe hemorrhage from the mesentery, and the length of intestine involved are the main factors that decrease survival rates in horses with small intestinal strangulation caused by mesenteric rents.     

Factors for prognostic use in equine obstructive small intestinal disease

Twenty horses with small intestinal obstructions requiring surgery were evaluated prospectively. Ten horses lived (group 1) and 10 died (group 2). Eight of the horses in group 1 had simple obstruction and 7 of the horses in group 2 had strangulation obstruction. There was a significant difference (P less than 0.001) between the mean intraluminal hydrostatic pressure in horses of groups 1 and 2 (6.3 cm H2O and 15 cm H2O, respectively). The mean peritoneal fluid protein concentration in horses of groups 1 and 2 (2.8 mg/dl and 5.4 mg/dl, respectively) also differed significantly between groups (P less than 0.01). Histologic evaluation of the intestinal specimens from horses of group 1 (n = 3) and group 2 (n = 6) revealed more severe mucosal lesions in group 2. The measured values that were not significantly different between the 2 groups included PCV, total serum protein content, WBC count, anion gap, and duration of colic before admission. It was concluded that peritoneal fluid protein concentration and intraluminal hydrostatic pressure in small intestinal obstruction may be used as adjuncts to diagnosis and as prognostic indicators.     

Detection and comparison of nitric oxide in clinically normal horses and those with naturally acquired small intestinal strangulation obstruction.

The purpose of this study was to determine whether nitric oxide (NO) is present in clinically normal horses under basal conditions and if it increases secondary to naturally acquired small intestinal strangulation obstruction. Thirty-one horses were used; 20 horses with naturally acquired small intestinal strangulation obstruction and 11 clinically normal horses with no signs of gastrointestinal tract disease. Jugular venous blood, abdominal fluid, and urine were collected for NO quantification. Plasma, abdominal fluid, and urine were stored at -70 degrees C until analyzed for NO using a chemiluminescent method. Biopsy specimens collected from the affected jejunal segment, during anesthesia or after immediately after euthanasia, or from the midjejunum of control horses, were divided into subsections for fixation in zinc formalin and cryopreservation in OCT gel. Nicotinamide adenine dinucleotide phosphate (reduced) (NADPH) diaphorase histochemical stains were performed on cryopreserved tissues and inducible nitric oxide synthase (iNOS) and nitrotyrosine immunohistochemical stains were performed on formalin-fixed, paraffin-embedded tissues. There were significantly greater plasma and abdominal fluid NO concentrations in affected horses as compared with controls, but there were no significant differences between horses for urine NO concentrations. There was a significant decrease in NADPH diaphorase stain in mucosal epithelium, vasculature, and leukocytes, and in submucosal plexi in affected horses compared with control horses. There was a significant increase in iNOS staining in mucosal and submucosal leukocytes and in mucosal leukocyte nitrotyrosine staining of the affected compared with control horses. Endothelial NOS and neuronal NOS are present under basal conditions in the jejunum of horses and probably mediate physiologic or cytoprotective effects. Plasma and abdominal fluid, but not urine, NO concentrations increase subsequent to small intestinal strangulation obstruction; this may be associated with increased mucosal and submucosal iNOS staining in leukocytes, which was likely due to increased expression subsequent to stimuli associated with ischemia. The increased nitrotyrosine staining in mucosal leukocytes of affected horses likely reflects the presence of peroxynitrite subsequent to increased NO and superoxide production and may reflect a cytotoxic role of NO in small intestinal strangulation obstruction in horses.     

Pancreatic injury in equine acute abdomen evaluated by plasma trypsin activity and histopathology of pancreatic tissue

In cases of equine acute abdominal disease, where pancreatic damage is suspected, pancreatic damage can be assessed by measuring increased trypsin activity in the plasma of horses suffering intestinal obstruction and severe shock. The pancreas is particularly vulnerable to splanchnic hypoperfusion because it is a highly active tissue. In this study, 10 horses undergoing abdominal surgery for intestinal obstruction were assayed for trypsin activity on admission and, because of extensive intestinal lesions that were not amenable to surgery, euthanasia was selected; the pancreas was removed before euthanasia. Trypsin activity in the plasma of these horses was significantly higher than in healthy horses (196 ng/ml +/- 128.2 versus 28.5 ng/ml +/- 19.2; P = 0.0026). Light and transmission electron microscopy revealed slight to severe lesions of vacuolar degeneration, a few zymogen granules, dilation of the endoplasmic reticulum, and swelling of mitochondria in the exocrine pancreas. The activation of an inflammatory cascade occurring during strangulating intestinal obstruction could increase pancreatic anoxic lesions caused by severe shock and hypoperfusion in the horse. Further studies will show the significance of pancreatic lesions and the ensuing damage in equine acute intestinal obstruction and shock.     

Validation of the Lactate Plus Lactate Meter in the Horse and Its Use in a Conditioning Program

The equine industry has a need for a convenient, rapid, and reliable method of measuring blood lactate concentrations ([LA]). We hypothesized that the handheld Lactate Plus lactate meter (LPlus), developed and tested for use in humans, would provide dependable results when used in horses undergoing an exercise conditioning program and that horse's fitness would improve following individualized conditioning based on each horse's velocity at which [LA] = 4 mmol/L (V_LA4) was reached. Five adult horses underwent a 4-week training program that consisted of 3 exercise bouts/wk. Horses were subjected to an incremental step standardized exercise test (SET) before starting (SET-1) and after the completion of the program (SET-2). Blood samples were collected before each increase in speed until [LA] reached ≥4 mmol/L, and then the SET was terminated. The [LA] sample range in our study was 0–8 mmol/L. Blood was analyzed at the time of collection using a calibrated LPlus, and plasma was collected for [LA] determination using the lactate dehydrogenase–based enzymatic colorimetric method. Although the LPlus tended to significantly underestimate [LA] by 0.39 mmol/L (P < .001), the LPlus proved to be a dependable device for use in horses based on good correlation with the biochemical analysis (r = 0.978) and Bland–Altman limits of agreement and 95% confidence intervals. All horses showed an increase in V_LA4 from SET-1 to SET-2, consistent with improved fitness following our 3 exercise bout/wk training protocol. The LPlus can reliably be used in horses to determine [LA] ranging from 0–8 mmol/L. When determining serial [LA], analytical techniques should not be used interchangeably.     

Equine trypsin: purification and development of a radio-immunoassay

Shock is accompanied by generalised splanchnic hypoperfusion, and splanchnic organs like the pancreas can be damaged, as shown in animal experimental models and in humans, by the presence of high plasma concentrations of trypsin and other pancreatic enzymes. In order to design a radioimmunoassay technique (RIA) for the measurement of equine trypsin-like immunoreactivity (TLI) in biological fluids, trypsin was purified (with purity > or = 96%) from the equine pancreas by extraction in an acid medium, ammonium sulfate precipitations, gel filtration chromatography and, after activation of trypsinogen into trypsin, affinity chromatography. Gel polyacrylamide electrophoresis showed a monomeric enzyme with a molecular weight of 27 kDa. The purified equine trypsin served for the immunisation of rabbits in order to obtain a specific antiserum, and the labelled antigen was prepared by iodination of equine trypsin with 125I. The RIA was based on the binding of the antigen to the antibody followed by the separation of the antigen-antibody complex by immunoprecipitation in the presence of sheep anti-rabbit gammaglobulins and the assay of the radioactivity in the precipitate. The RIA showed good sensitivity, specificity, precision, accuracy and reproducibility. The reference mean value of TLI in the plasma of healthy horses (n = 20) was 30.01+/-6.84 ng/mL (upper confidence limit 50.52 ng/mL; p < 0.01). Three horses with non strangulating intestinal obstruction without shock showed TLI values within normal limits whereas 5 of 7 horses with strangulation obstruction showed TLI levels above the upper confidence limit. Further studies using the RIA and the enzymatic assay should be performed in order to confirm the role of the pancreas in equine intestinal obstruction.     

Correlation Between Serum Creatine Kinase Activities And Anorexia in Cats

There are no available biochemical analyses that will reliably identify malnourished cats or enable monitoring them during supportive alimentation. Studies in people indicate that creatine kinase (CK) activity is high in malnourished patients and may decrease in response to nutritional intervention. The purpose of this study was to determine the value of quantifying serum CK activities in anorectic cats and to assess the usefulness of this test in monitoring nutritional support in these patients. Serum CK activity was evaluated in nonanorectic cats (Group 1, n = 25), and in hospitalized, anorectic cats that received nutritional support through a nasoesophageal tube (Group 2, n = 25). Anorectic cats had a significantly higher serum CK activity (median = 2,529 U/L, range 88 to 153,000 U/L) than the control group (median = 175 U/L, range 81 to 363 U/L, P < .001). There were significant positive correlations between serum CK and both aspartate transaminase (AST) ( P < .05; r = .59) and lactate dehydrogenase (LDH) (P < .05; r = .41) activities. Serum CK activity was significantly lower in anorectic cats after 48 hours of nutritional support than at time 0 ( P < .001) and eventually returned to normal with continued support. Serum CK activity may serve as a useful marker in assessing and monitoring nutritional status in cats.     

Non-strangulating intestinal infarction in horses in the UK: A review of 15 cases

The clinicopathological features of 15 horses diagnosed with non-strangulating intestinal infarction (NSII) based on identification of focal areas of intestinal necrosis without mesenteric strangulation were reviewed. The mean age at presentation was 16.3 years, median 13 years, and there was no age, sex, or breed predilection. The major presenting clinical signs included: acute colic ≤ 24 h duration in nine horses; diarrhoea, depression, and inappetence in four horses; and low-grade chronic or recurrent colic, depression, and inappetence in two horses. One horse presented with both acute colic and diarrhoea. Predisposing diseases included colitis or typhlocolitis in five horses and an initial strangulating small intestinal obstruction in three horses, but in seven horses no underlying or predisposing disease was identified. Four cases were managed medically and 11/15 were managed surgically. The most useful diagnostic test was exploratory celiotomy and the only successful treatment was complete resection of the necrotic intestine. Prognosis for survival was poor with a survival rate of only 1/15 (7%). Among the 15 horses, both single and multiple NSII lesions were seen, and they occurred in both the small intestine and large intestines. There was no evidence of Strongylus vulgaris infestation in any of the affected horses.     

Retrospective Study: The association of blood lactate concentration with outcome in dogs with idiopathic immune‐mediated hemolytic anemia: 173 cases (2003–2006)

Objective – To determine the association of blood lactate with outcome and response to transfusion therapy in dogs with idiopathic immune‐mediated hemolytic anemia (IMHA). Design – Retrospective study. Setting – Urban veterinary small animal emergency hospital. Animals – One hundred and seventy‐three client‐owned dogs with IMHA. Interventions – None. Measurements and Main Results – Serial blood lactate concentration, therapeutic interventions, and outcome were recorded. Nonsurvivors were defined as those that died or were euthanized. One hundred and thirty‐three dogs (77%) survived, 35 (20%) were euthanized, and 5 (3%) died. One hundred forty‐five dogs (84%; 145/173) had a lactate concentration above the laboratory reference interval [0.46–2.31 mmol/L] on presentation. Blood lactate at presentation was higher in the nonsurvivors (median 4.8 mmol/L; 0.5–13.6) compared with survivors (median 2.9 mmol/L; 0.3–13.2) (P<0.01). All dogs presenting with hyperlactatemia that normalized (<2.0 mmol/L) within 6 hours of admission survived, whereas, 71% of dogs that had a persistent hyperlactatemia at 6 hours survived (P=0.034). Lactate was positively correlated with age, BUN, and alkaline phosphatase, and inversely correlated with PCV. Receiver operating curve analysis for lactate concentration at admission as a test for outcome had an area under the curve of 0.69 with an optimal lactate cutoff concentration of 4.4 mmol/L correctly predicting outcome 73% of the time (sensitivity 60%, specificity 77%). Conclusions – Lactate concentration at presentation was significantly higher in nonsurvivors than survivors. Lactate was significantly correlated with previously reported outcome variables but lactate concentration at admission, as a predictor for outcome was less than optimal. However, serial lactate concentration measurements may be more predictive as patients with persistent hyperlactatemia 6 hours after admission were less likely to survive. Prospective studies evaluating serial lactate concentration while controlling for other variables may provide further insight into lactate measurement as a prognostic indicator in animals with IMHA.     

Pulmonary gas exchange and plasma lactate in horses with gastrointestinal disease undergoing emergency exploratory laparotomy: a comparison with an elective surgery horse population

Objective: To characterize pulmonary gas exchange and arterial lactate in horses with gastrointestinal disease undergoing anesthesia, compared with elective surgical horses, and to correlate these variables with postoperative complications and mortality. Study Design: Prospective clinical study. Animals: Horses undergoing emergency laparotomy for acute intestinal disease (n=50) and healthy horses undergoing elective surgery in dorsal recumbency (n=20). Methods: Arterial blood gas analysis was performed at predetermined intervals on horses undergoing a standardized anesthetic protocol. Alveolar–arterial oxygen gradient was calculated. Predictive factors for postoperative complications and death in colic horses were determined. Results: Arterial oxygen tension (P_aO₂) varied widely among horses in both groups. P_aO₂ significantly increased in the colic group after exteriorization of the ascending colon. P_aO₂ and alveolar–arterial oxygen gradient were not significantly different between groups, and neither were correlated with horse outcome. Arterial lactate in recovery ≥5 mmol/L was associated with a 2.25 times greater relative risk of complications and lactate ≥7 mmol/L was associated with a 10.5 times higher relative risk of death. Conclusion: Colic horses in this population were not more likely to be hypoxemic than elective horses, nor was gas exchange impaired to a greater degree in colic horses relative to controls. Arterial lactate sampled immediately after anesthetic recovery was predictive for postoperative complications and death.     

Effect of oral administration of dantrolene sodium on serum creatine kinase activity after exercise in horses with recurrent exertional rhabdomyolysis

OBJECTIVE: To determine the effect of oral administration of dantrolene sodium on serum creatine kinase (CK) activity after exercise in horses with recurrent exertional rhabdomyolysis (RER). ANIMALS: 2 healthy horses and 5 Thoroughbreds with RER. PROCEDURE: 3 horses received 2 doses of dantrolene (4, 6, or 8 mg/kg, p.o., with and without withdrawal of food) 2 days apart; 90 minutes after dosing, plasma dantrolene concentration was measured spectrofluorometrically. On the basis of these results, 5 Thoroughbreds with RER from which food was withheld received dantrolene (4 mg/kg) or an inert treatment (water [20 mL]) orally 90 minutes before treadmill exercise (30 minutes, 5 d/wk) during two 3-week periods. Serum CK activity was determined 4 hours after exercise. Plasma dantrolene concentration was measured before and 90 minutes after dosing on the first and last days of dantrolene treatment and before dosing on the first day of the inert treatment period, RESULTS: 90 minutes after dosing, mean +/- SEM plasma dantrolene concentration was 0.62 +/- 0.13 and 0 microg/mL in the dantrolene and inert treatment groups, respectively. Serum CK activity was lower in dantrolene-treated horses (264 +/- 13 U/L), compared with activity in water-treated horses (1,088 +/- 264 U/L). Two horses displayed marked muscle stiffness on the inert treatment. CONCLUSIONS AND CLINICAL RELEVANCE: In 5 horses with RER from which food had been withheld, 4 mg of dantrolene/kg administered orally provided measurable, though variable, plasma concentrations and significantly decreased serum CK activity after exercise in 4 of those horses.     

Serum chemistry reference values in free‐ranging North Atlantic male walruses (Odobenus rosmarus rosmarus) from the Svalbard archipelago

Background: Information regarding health and disease is limited for walruses, a keystone species in arctic marine ecosystems. Serum chemistry analysis is a useful clinical tool for the health assessment of walruses, but only a few captive Pacific walruses have been evaluated. Objectives: The aim of this study was to determine serum chemistry reference values for free‐ranging male Atlantic walruses (Odobenus rosmarus rosmarus) on Svalbard and to assess potential differences in animals with low and high tissue levels of organic pollutants. Methods: Blood samples were collected from 17 wild, adult, male Atlantic walruses chemically immobilized with etorphine at eastern Svalbard (Norway). Serum was obtained for routine biochemical analysis as well as nonesterified free fatty acids (NEFA) and cortisol tests. Serum protein concentration was also measured by agarose gel electrophoresis. Results: Reference values (ranges) included alanine aminotransferase (12–51 U/L), aspartate aminotransferase (54–137 U/L), alkaline phosphatase (42–243 U/L), creatine kinase (32–506 U/L), lactate dehydrogenase (480–1322 U/L), amylase (0–23 U/L), lipase (68–298 U/L), total protein (68–91 g/L), albumin (25.3–34.8 g/L), creatinine (84–137 μmol/L), urea (8.2–19.9 mmol/L), bilirubin (0–4 μmol/L), cholesterol (4.4–7.3 mmol/L), NEFA (0.1–0.4 mmol/L), triglycerides (0.6–2.2 mmol/L), calcium (2.0–2.7 mmol/L), phosphorus (1.7–2.8 mmol/L), sodium (147–162 mmol/L), potassium (4.7–7.4 mmol/L), chloride (102–115 mmol/L), and cortisol (<28–214 nmol/L). Walruses exposed to high levels of organic pollutants (n=6) had significantly lower (P=.022) phosphorus concentration than those with low levels of pollutants (n=6). Conclusions: The clinical chemistry reference values determined in this study can serve as baseline data for future health‐related studies of walruses in a changing Arctic and may also be helpful for health evaluations of walruses in captivity. Impacts of the exposure of marine mammals to organic pollutants should be further investigated.     

Evaluation of peritoneal fluid pH, glucose concentration, and lactate dehydrogenase activity for detection of septic peritonitis in horses

OBJECTIVE: To determine whether peritoneal fluid pH, glucose concentration, and lactate dehydrogenase activity can be used to differentiate horses with septic peritonitis from those with nonseptic peritonitis. DESIGN: Prospective study. ANIMALS: 46 horses, including 10 healthy horses, 15 horses with septic peritonitis, and 21 horses with nonseptic peritonitis. PROCEDURE: Peritoneal fluid and blood samples were analyzed for pH, glucose concentration, and lactate dehydrogenase activity. Complete blood cell counts were performed, and peritoneal fluid samples were submitted for bacterial culture. RESULTS: Horses with septic peritonitis had significantly lower peritoneal fluid pH and glucose concentrations than horses with nonseptic peritonitis and healthy horses. Compared with other tests, serum-to-peritoneal fluid glucose concentration differences > 50 mg/dl had the highest diagnostic use for detection of septic peritonitis. Peritoneal fluid pH < 7.3, glucose concentration < 30 mg/dl, and fibrinogen concentration > 200 mg/dl were also highly indicative of septic peritonitis. CLINICAL IMPLICATIONS: Peritoneal fluid pH and glucose concentration can be used to assist in the identification of horses with septic peritonitis. These measurements can provide an early indication of sepsis, especially if cytologic evaluation of peritoneal fluid is unavailable or results are equivocal and peritoneal fluid bacterial culture results are pending.     

Age distributions of horses with strangulation of the small intestine by a lipoma or in the epiploic foramen: 46 cases (1994-2000).

OBJECTIVE: To test the hypothesis that strangulation of the small intestine by a lipoma or in the epiploic foramen is more common in older horses. DESIGN: Retrospective study. ANIMALS: 46 horses. PROCEDURE: Ages of horses with strangulation of the small intestine by a lipoma (n = 29) or in the epiploic foramen (17) were compared with ages of 79 horses with miscellaneous small intestinal lesions. Effects of increasing age on risk of the diseases of interest were examined by use of logistic regression and a 1-sided trend test for binomial proportions. RESULTS: Mean age of the horses with strangulation in the epiploic foramen (9.6 years) was the same as that for the horses with miscellaneous small intestinal lesions (7.7), but mean age of the horses with strangulation by a lipoma (19.2) was significantly greater than that for the other groups. The proportion of horses with lipoma increased significantly with increasing age, but the proportion with strangulation in the epiploic foramen did not. CONCLUSIONS AND CLINICAL RELEVANCE: Results refute the current suggestion that increasing age predisposes horses for strangulation of the small intestine in the epiploic foramen but support the suggestion that the risk of strangulation of the small intestine by a lipoma increases with age.     

Lactate Dehydrogenase Activity in Abdominal Fluid From Horses With Colic

The purpose of this study was to determine whether lactate dehydrogenase (LDH) activity in abdominal fluid could be used as a prognostic indicator in horses with colic. Lactate dehydrogenase activity was measured in 27 abdominal effusions from horses with colic presented to Murdoch University Veterinary Teaching Hospital using three different LDH test methods. Lactate in effusions was also measured in 11 of the horses. Lactate dehydrogenase activity was significantly different for each test method used—the ratio of Randox wet chemistry LDH lactate to pyruvate:Randox wet LDH pyruvate to lactate (P-L):IDEXX dry chemistry P-L was approximately 1:2:4. Lactate dehydrogenase activity in the abdominal effusions was significantly higher with all methods in the horses that died or were euthanized because of abdominal sepsis or advanced neoplasia than in those that survived after treatment for colic signs because of mechanical obstructions or nonseptic abdominal inflammation. Lactate dehydrogenase activity showed moderate-to-good correlation (r = 0.73 to 0.86) with lactate concentration of the fluid. In conclusion, LDH activity in abdominal fluid may be a useful prognostic test in horses with colic. The test method for LDH measurement must be known and remain constant for meaningful interpretation. Significantly higher levels of LDH activity may be present in horses with colic because of sepsis or advanced neoplasia than in those with colic because of nonseptic inflammation or mechanical obstructions that may respond to treatment.