Background: Septicemia is associated with a systemic inflammatory response, hemostatic activation, and disseminated intravascular coagulopathy (DIC).Hypothesis: Increased plasma D-dimer concentration occurs in septic neonates and can reliably detect sepsis or DIC, and predict death in ill neonatal foals.Animals: 40 septic, 41 nonseptic hospitalized foals, and 22 healthy neonates. Methods: Prospective observational clinical study. Blood samples were collected on admission, at 24-48 hours after admission, and at the time of discharge or euthanasia. Plasma D-dimer concentration, clotting times, antithrombin activity, and fibrinogen concentration were determined.Results: On admission, D-dimer concentration values were significantly higher in septic foals (median, 25-75th percentiles; 568, 245-2013 ng/mL) compared with the nonseptic and healthy groups (386, 175-559 and 313, 152-495 ng/mL, respectively), and in septic foals at the age of 2-7 days compared with similar-age nonseptic foals. By means of samples taken at 24-48 hours of hospitalization and a cut-off value of 4 2000 ng/mL, D dimer concentration was significantly associated with the diagnosis of septicemia (odds ratio [OR] 5 19.6, 95% confidence interval [95% CI] 1.9-203) and death (OR 5 8.7, 95% CI 1.8-43). Owing to a high false-positive prediction rate (71%), a normal D-dimer concentration is better at eliminating the diagnosis of sepsis than an increased D-dimer concentration at predicting sepsis. Fifty percent of septic foals had a diagnosis of DIC, but D-dimer concentration was not significantly associated with the diagnosis of DIC.Conclusions and clinical importance: Septic foals showed a marked activation of coagulation and fibrinolytic systems and a high prevalence of DIC. Increased plasma D-dimer concentration is significantly associated with the diagnosis of sepsis.

Peritoneal D-dimer concentration is markedly higher in severe GI disorders, and it can be used to assess peritoneal fibrinolytic activity in horses with colic.

Background: Septicemia in human neonates frequently is complicated by activation of the coagulation system, disseminated intravascular coagulation (DIC) and multiple organ failure syndrome, which may contribute to high mortality. In adult horses with DIC, the lung has been the organ most frequently affected by fibrin deposits. In addition, in vivo studies suggest that hemostatic mechanisms may be immature in foals o1-day old.Hypothesis: Newborn foals with severe septicemia have fibrin deposits in their tissues independently of their age, and these fibrin deposits are associated with organ failure.Animals: Thirty-two septic and 4 nonseptic newborn foals euthanized for poor prognosis. Methods: Tissue samples (kidney, lung, and liver) collected on postmortem examination were stained with phosphotungstic acid hematoxylin (PTAH) and immunohistochemistry (IHC) for blind histologic examination. A fibrin score (grades 0-4) was established for each tissue sample and for each foal. Medical records were reviewed for assessing clinical evidence of organ failure during hospitalization.Results: Fibrin deposits were found in most septic foals (28/32 when using IHC and 21/32 when using PTAH), independently of the age of the foal. The lung was the most affected tissue (97% of the septic foals). Additionally, organ failure was diagnosed in 18/32 septic foals (8 with respiratory failure, 14 with renal failure), although a statistical association with severe fibrin deposition was not identified.Conclusions and Clinical Importance: Nonsurviving septic foals have fibrin deposits in their tissues, a finding consistent with capillary microthrombosis and DIC.

We studied equine platelet function and activation using ultrastructural examination, flow cytometry, and perfusion. The main aim of the study was to evaluate hemostatic mechanisms in horses using these techniques. Ultrastructural observations were done on resting and activated platelets. Flow cytometry was used to evaluate binding of antibodies to major platelet glycoproteins (GPIIb-IIIa, GPIV, and GPIb) and activation-dependent antigens (P-selectin and lysosomal integral membrane protein [LIMP]). Perfusion techniques were used to evaluate the interaction between platelets and damaged subendothelium. Aggregation experiments were done to identify the best agonists for flow cytometry. Ultrastructural observations confirmed that equine platelets lack a developed open canalicular system and that release of granule contents occurs by fusion of adjacent granule membranes that ultimately connect with external membranes. Flow cytometry identified a 2-fold increase in binding of antibodies against GPIIb-IIIa and GPIV after activation. Binding of antibodies against P-selectin and LIMP increased from 2.12 and 1.74% to 15.5 and 11.6%, respectively, in response to thrombin and to 21.86 and 10.50%, respectively, in response to collagen. Annexin V binding increased moderately after activation. Perfusion experiments with citrated blood indicated that equine platelets react more strongly to subendothelium than do human platelets. When blood was anticoagulated with low molecular weight heparin, a marked impairment of platelet interactions was observed. In conclusion, although some differences were observed between human and equine platelet function, some techniques currently used to assess human platelet function may be useful to assess equine platelets.

The purpose of this study was to compare traditional and quantitative approaches in analysis of the acid-base and electrolyte imbalances in horses with acute gastrointestinal disorders. Venous blood samples were collected from 115 colic horses, and from 45 control animals. Horses with colic were grouped according to the clinical diagnosis into 4 categories: obstructive, ischemic, inflammatory, and diarrheic problems. Plasma electrolytes, total protein, albumin, pH, pCO 2 , tCO 2 , HCO 3 Ϫ , base excess, anion gap, measured strong ion difference (SIDm), nonvolatile weak buffers (A tot ), and strong ion gap were determined in all samples. All colic horses revealed a mild but statistically significant decrease in iCa 2ϩ concentration. Potassium levels were mildly but significantly decreased in horses with colic, except in those within the inflammatory group. Additionally, the diarrheic group revealed a mild but significant decrease in Na ϩ , tCa, tMg, total protein, albumin, SIDm, and A tot . Although pH was not severely altered in any colic group, 26% of the horses in the obstructive group, 74% in the ischemic group, 87% in the inflammatory group, and 22% in the diarrheic group had a metabolic imbalance. In contrast, when using the quantitative approach, 78% of the diarrheic horses revealed a metabolic imbalance consisting mainly of a strong ion acidosis and nonvolatile buffer ion alkalosis. In conclusion, mild acid-base and electrolyte disturbances were observed in horses with gastrointestinal disorders. However, the quantitative approach should be used in these animals, especially when strong ion imbalances and hypoproteinemia are detected, so that abnormalities in acid-base status are evident.Key words: Acid-base imbalance; Colic; Electrolyte; Horse; Quantitative approach.A cid-base and electrolyte imbalances have been reported in horses with gastrointestinal (GI) disorders 1,2 and after exercise. [3][4][5][6][7][8][9] In other species, such as dogs and cattle, digestive problems are also associated with acid-base and electrolyte alterations.10,11 However, there are few references about acid-base imbalances in horses with different forms of GI disturbances. The clinical relevance of acidbase imbalance in horses with GI disorders is also controversial. A previous study demonstrated that metabolic acidosis was observed in 83.3% of horses with acute diarrhea and in 66.7% of horses with severe forms of GI disorders, 12 while Nappert and Johnson documented that most horses with colic of different origin did not have metabolic acidosis. 13Two different methods have been used since 1997 to describe the acid-base and electrolyte imbalances in horse plasma: the traditional method and the simplified strong ion model.14 The traditional approach uses the Henderson-Hasselbalch equation and is clinically adequate to describe acid-base imbalances. However, it is more descriptive than mechanistic and can only be accurately applied to plasma with approximately normal protein, albumin, and hemoglobin concentrations. 15,16 On the...