Prevalence of intra-abdominal hypertension in horses with colic.

OBJECTIVE: To determine an abdominal pressure cutoff value for intra-abdominal hypertension (IAH) in the horse and characterize IAH in horses with acute colic. DESIGN: Prospective clinical cohort. SETTING: University teaching hospital. ANIMALS: Nine healthy adult horses and 56 horses with acute colic. INTERVENTIONS: Ventral intra-abdominal pressure (IAP) was measured in triplicate at end expiration and averaged. Each colic case was classified as medical or surgical and large intestine (LI) or small intestine (SI). Management and final outcome (alive, euthanized, or died) were recorded. IAH was defined as ≥32 mm Hg (mean + 2 SDs of ventral IAP in control horses). Proportions of horses with and without IAH for different lesions were expressed as fractions and percentages. Differences in IAP between groups were determined using ANOVA with post-testing or t-tests. Odds ratio for management strategy (ie, need for medical or surgical) in horses with IAH was performed using Fisher's exact test. P < 0.05 was considered significant. MEASUREMENTS AND MAIN RESULTS: IAP was higher in horses with colic compared to controls (P = 0.025). Over 18 months, 30.4% of horses with colic had IAH (n = 10 LI lesions, n = 7 SI lesions). Horses with LI medical lesions had the highest IAP of all lesions (mean 36.5 mm Hg). IAH horses with medical lesions were 15 times more likely to survive than IAH horses requiring surgery (P = 0.03). CONCLUSIONS: Acute colic in horses is associated with an increased ventral IAP compared with healthy controls. IAH does exist in horses with colic, notably LI medical lesions, and is associated with nonsurvival in horses that require surgery.

Equine renal hemangiosarcoma: clinical presentation, pathologic features, and pSTAT3 expression.

Hemangiosarcoma is an uncommon tumor in horses. We characterized 3 cases of equine renal hemangiosarcoma, focusing on clinical and pathologic features, and describe occurrence of the epithelioid variant of hemangiosarcoma in one of these cases. Nuclear expression of phosphorylated STAT3 (pSTAT3) was assessed to analyze potential inappropriate STAT3 activation as a component of tumor pathogenesis. Clinical signs in the 3 horses included insidious weight loss, followed in one case by serosanguineous nasal discharge and terminal epistaxis, and nonspecific signs of abdominal pain. Two of the hemangiosarcomas had a classical histopathologic appearance; in the other, neoplastic cells were polygonal and were arranged in densely packed sheets, resembling the epithelioid variant. Cross-reactivity of a pSTAT3 antibody was established by demonstration of pSTAT3 expression in the epithelium of glabrous skin by immunoblotting and immunohistochemistry. In the epithelioid hemangiosarcoma, ~40% of neoplastic cells exhibited nuclear pSTAT3 expression, but in the other 2 cases, expression was weak and variable in the neoplastic population, although stromal cell pSTAT3 activity was evident in pulmonary metastases in one case.

Effect of body position on intra-abdominal pressures and abdominal perfusion pressures measured at three sites in horses anesthetized with short-term total intravenous anesthesia.

OBJECTIVE: To assess effects of body position on direct measurements of intra-abdominal pressure (IAP) and abdominal perfusion pressure (APP) in horses anesthetized with total intravenous anesthesia (TIVA). ANIMALS: 9 healthy adult horses. PROCEDURES: Instrumentation in unsedated standing horses involved insertion of an arterial catheter for blood pressure measurements and 3 intraperitoneal cannulas (left flank, right flank, and ventral abdomen) for IAP measurements. Baseline values were measured for heart rate, respiratory rate, systolic arterial blood pressure, mean arterial blood pressure (MAP), diastolic arterial blood pressure, and IAP. Horses were medicated with xylazine, and pressures were measured again. Anesthesia was induced with ketamine-diazepam and maintained with a ketamine-guaifenesin infusion. Horses were positioned twice into left lateral recumbency, right lateral recumbency, or dorsal recumbency. Hemodynamic pressures and accessible abdominal pressures were measured for each recumbency position. The APP was calculated as MAP - IAP. Differences in IAP, MAP, APP and sedation (standing horses) or body position (anesthetized horses) were compared by means of repeated-measures ANOVA or paired t tests. RESULTS: Baseline hemodynamic and IAPs were not different after xylazine administration. Ventral abdomen IAP and MAP were lower for horses in dorsal recumbency than in right or left lateral recumbency. Ventral abdomen APP remained unchanged. For lateral recumbencies, flank IAP was lower and APP was higher than pressure measurements at the same sites during dorsal recumbency. CONCLUSIONS AND CLINICAL RELEVANCE: Body position affected IAP and APP in healthy anesthetized horses. These effects should be considered when developing IAP acquisition methods for use in horses with abdominal disease.

Serum protein concentrations as predictors of serum immunoglobulin G concentration in neonatal foals.

OBJECTIVE: To determine the predictive value of serum concentrations of total protein (sTP), albumin (sAlb), and globulin (sGlob) measured by automated calorimetric assays to estimate serum immunoglobulin G (sIgG) concentrations in neonatal foals and identify failure of transfer of passive immunity when compared to turbidoimmunometric assay determinations of sIgG. DESIGN: Retrospective and prospective analysis of laboratory data. SETTING: University tertiary care facility. ANIMALS: Group 1 (retrospective): foals (n = 45) ≤7 days of age in which sIgG, sGlob, sAlb, and sTP concentrations were measured on an automated chemistry analyzer. Group 2 (prospective): foals (n = 31) ≤7 days of age with same laboratory data collected used to validate equations generated from group 1 foals. INTERVENTIONS: Spearman rank correlations between measured sIgG and serum protein concentrations were performed. When significant correlation was found, sIgG was estimated using an sGlob simple linear regression and estimated using a sGlob, sTP, and sAlb multiple linear regression. Comparisons between estimated and measured sIgG was performed using Kruskal-Wallis testing. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated to identify foals with sIgG < 8.0 g/L [<800 mg/dL]. MEASUREMENTS AND MAIN RESULTS: sIgG was correlated with sGlob, sTP, and sAlb (ρ = 0.8, 0.6, and -0.3, respectively; P < 0.05). Estimated sIgG and measured sIgG were not different (P > 0.9). In group 1 foals, the sensitivity, specificity, positive predictive value, and negative predictive value were 73%, 76%, 73%, and 83%, respectively, for sGlob, and 90%, 76%, 75%, and 90%, respectively, for multiple proteins estimated sIgG identification of failure of transfer of passive immunity. Test qualities were improved in group 2 foals. CONCLUSIONS: Serum protein concentrations may be used to estimate sIgG concentrations in newborn foals. Further investigation using a larger sample size is needed to validate this methodology of assessing humoral immunity in neonatal foals.

Direct intra-abdominal pressures and abdominal perfusion pressures in unsedated normal horses.

OBJECTIVES: To determine whether direct intra-abdominal pressures (IAP) and calculated direct abdominal perfusion pressures (APP) are location dependent within the abdomen of standing horses. We hypothesize that IAP will be increased and calculated APP will be decreased at a ventral abdominal location (V) when compared to values obtained from the left (LFl) or right flank (RFl). DESIGN: Prospective experimental design. SETTING: University-based equine research facility. ANIMALS: Seven healthy adult horses, 4 geldings and 3 mares. INTERVENTIONS: Measurements of direct IAP obtained from the RFl, LFl, and V locations via abdominal cannulation and direct arterial blood pressures obtained via catheterization of the transverse facial artery were obtained in fasted, standing, unsedated horses. APP was calculated for each location by the subtraction of IAP from the mean arterial pressure. Differences between sites of measurement for IAP, APP, and their gradients were calculated and compared by ANOVA and t-tests. MEASUREMENTS AND MAIN RESULTS: Mean flank IAP measurements were subatmospheric and negative compared to ventral IAP values (LFl = -3 mm Hg, RFl = -5 mm Hg, V = 25 mm Hg; P < 0.001 between each flank and the ventral location). Ventrum APP was lower than flank APP (V = 82 mm Hg; LFl = 106 mm Hg; RFl = 108 mm Hg; P = 0.029 between each flank and the ventral location). Gradient calculations between sites showed the IAP increased and APP decreased from dorsal to ventral (P < 0.05) and from right to left (P = 0.004) within the abdomen. CONCLUSIONS: IAP and calculated APP are location dependent. These data provide new information regarding abdominal pressure profiles in standing healthy adult horses.