Evaluation of an oral direct factor Xa inhibitor anticoagulant in healthy adult horses.

OBJECTIVE: To assess whether an oral direct factor Xa inhibitor (DiXaI) anticoagulant drug used at the low end of the recommended dose in people achieves presumed prophylactic plasma concentrations and does not induce bleeding in horses. DESIGN: Experimental study. SETTING: Field study. ANIMALS: Ten healthy adult horses. INTERVENTIONS: A DiXaI was administered at a dose of 0.125 mg/kg every 24 h orally for 4 days. Following a wash-out period of 2 weeks, 8 of 10 horses received daily subcutaneous doses of a low molecular weight heparin (dalteparin) for 4 consecutive days at 50 IU/kg. In both trials, antifactor Xa activity was measured at baseline time and 3 hours after each dose administration. Activated partial thromboplastin time, prothrombin time, hematocrit, erythrocyte agglutination, and platelet aggregation were monitored throughout the study. In addition, an in vitro spiking experiment was performed to demonstrate anticoagulant activity of this DiXaI in horse plasma. MAIN RESULTS: When treated with the DiXaI, this group of horses did not achieve the suggested thromboprophylactic plasma range of antifactor Xa activity (0.1-0.2 IU/mL), except for 1 horse after the first administration of the drug. In contrast, median values of plasma antifactor Xa activity 3 hours after receiving dalteparin were within the prophylactic range (0.16 IU/mL). No hemorrhagic events or erythrocyte agglutination were observed. In vitro addition of this DiXaI caused a concentration-dependent effect in antifactor Xa activity. CONCLUSIONS: At the low end of the recommended dose in people this oral formulation of DiXaI did not reach prophylactic plasma antifactor Xa activity in this group of healthy adult horses. Further studies are warranted in order to establish the prophylactic dose for horses.

Progression of plasma D-dimer concentration and coagulopathies during hospitalization in horses with colic.

OBJECTIVE: To assess the progression of plasma D-dimer concentrations and coagulation status in horses with different types of colic. DESIGN: Prospective clinical observational study performed between March 2004 and September 2008. SETTING: Veterinary university teaching hospital. ANIMALS: Horses admitted and treated for colic and hospitalized for >48 hours were considered. Animals were classified by diagnosis into medical obstructive conditions (MO), surgical obstructive conditions (SO), inflammatory conditions, and ischemic lesions (IS). INTERVENTIONS: Three blood samples were obtained from each horse (admission, at 24-48 h [or after surgery] and upon discharge). For each sample, plasma D-dimer concentration, prothrombin time, activated partial thromboplastin time, antithrombin activity, and the presence of subclinical disseminated intravascular coagulation were determined. MEASUREMENTS AND MAIN RESULTS: When median plasma D-dimer concentration values at admission and after 24-48 hours were compared, they were different but stable in horses with MO (1.29-1.95 nmol/L) and inflammatory conditions (5.70-6.69 nmol/L). However, 10-fold and 5-fold increases were observed, respectively, in SO (2.08 to 16.38 nmol/L) and IS (3.08 to 15.91 nmol/L) in the postoperative period. By 24-48 hours, the percentage of horses with coagulopathy increased in most groups (MO, 43 to 58%; SO, 50 to 96%, IS, 53 to 90%). By the time of discharge, 87% of horses with SO problems and 89% of horses with IS still had some form of coagulopathy documented. CONCLUSIONS: Throughout hospitalization, horses with MO problems had less severe coagulopathy and lower plasmatic D-dimer concentrations compared to other groups of horses. On admission, most horses with inflammatory conditions presented with coagulopathy. At 24-48 hours of hospitalization and following surgery, the hemostatic profile can differ markedly when compared to admission values.

Aqueous humor fibrinolytic activity in dogs with cataracts.

OBJECTIVE: To investigate fibrinolytic activity in aqueous humor (AH) of healthy and sick dogs, with and without cataracts. PROCEDURE: Prospective observational clinical study. A total of 45 dogs were included in the study. Physical and ophthalmic examinations, complete blood cell count (CBC) and serum biochemistry panel were performed in all animals. According to the ocular and systemic diagnoses, animals were classified into three groups: sick dogs without cataracts (20 dogs; 40 eyes), diabetic dogs with cataracts (11 dogs; 22 eyes), and healthy dogs with cataracts (14 dogs; 25 eyes). Bilateral AH and blood samples were collected during intraocular surgery (25 dogs; 47 eyes), or immediately after euthanasia (20 dogs; 40 eyes). Citrated samples were centrifuged and stored at -81 °C until analysis. Plasma and AH D-dimer concentration were determined using a quantitative immunoturbidimetric latex agglutination assay. RESULTS: A total of 108 canine samples (45 plasma and 87 AH samples) were obtained. D-dimer concentration in log-scale, in AH of eyes with diabetic cataract was significantly higher than AH of eyes with nondiabetic cataract, with a difference of 0.9 ng/mL 95% confidence interval (CI) (0.2; 1.6) P = 0.0116 and higher than that of sick animals with healthy eyes, with a estimated difference of -0.89 ng/mL 95% CI (-1.52; -0.25) P = 0.0061. Plasma D-dimer concentration was significantly higher in the group of animals with systemic disease [median 606 ng/mL, Interquartil Range (IQR) 145-1956 ng/mL] than in healthy dogs (median 47.5 ng/mL, IQR 4-250 ng/mL) (P = 0.002) and diabetic dogs (median 60.5 ng/mL, IQR 0-147.5 ng/mL) (P < 0.001). CONCLUSION: AH fibrinolysis is present in dogs, being significantly higher in animals with diabetic cataracts than in those without cataracts, and those with nondiabetic cataracts.

Neutrophilic myeloperoxidase index and mean light absorbance in neonatal septic and nonseptic foals.

BACKGROUND: Two neutrophilic indices reported by the ADVIA 120 Hematology Analyzer, neutrophilic myeloperoxidase index (MPXI), and mean light absorbance (neutrophil X mean [NXM]) have been proposed as indicators of systemic inflammatory disease in horses and of neutrophil activation in coronary ischemic syndromes in people. OBJECTIVE: The aim of this study was to evaluate NXM and MPXI in healthy, sick nonseptic, and sick septic foals to determine whether conditions likely associated with neutrophil activation result in decreases in these variables. METHODS: In this retrospective study, CBC data from 61 neonatal foals presented to the Equine Teaching Hospital of Barcelona were evaluated for correlations between MPXI, NXM, percentage of large unstained cells, neutrophil count, and percentage of band neutrophils. Results obtained in septic (n=32), sick nonseptic (n=22), and healthy foals (n=7) were compared. In addition, results recorded in septic/neutropenic (n=12), septic/non-neutropenic (n=20), nonseptic/neutropenic (n=8), nonseptic/non-neutropenic (n=14), and healthy foals (n=7) were also compared. RESULTS: A weak negative correlation was found between MPXI and neutrophil count and between NXM and percentage of band neutrophils. Septic/neutropenic foals had significantly higher MPXI values (median 17.9, minimum-maximum 4.7-42.5) than did septic/non-neutropenic (1.5, -24.4 to 22.3), nonseptic/neutropenic (6.6, 0.6-17.9), and nonseptic/non-neutropenic foals (8.8, -10.1 to 16.8) but did not differ significantly from controls (12.8, -8.5 to 20.4). CONCLUSIONS: Significant differences in NXM or MPXI were not found when disease groups were compared with controls; however, septic/neutropenic foals had significantly higher median MPXI than other groups of sick foals. Further prospective studies are needed to clarify if this finding is related to decreased neutrophil function or activation in septic/neutropenic foals.

Coagulopathies in horses with colic.

The most common coagulopathy in horses with colic is a hypercoagulable state associated with disseminated intravascular coagulation. The intensity of this coagulopathy depends on the severity and duration of the gastrointestinal lesion, with the ischemic and inflammatory problems and peritonitis being the most frequently affected by coagulopathies. Early initiation of prophylactic therapy significantly reduces the severe hypercoagulable state in horses with intestinal conditions which are recognized to be at high risk for disseminated intravascular coagulation. In addition to the systemic coagulopathy observed in horses with colic, a peritoneal coagulopathy independent from that occurring in blood has been observed, and its recognition and assessment may have clinical usefulness in the diagnosis of the gastrointestinal diseases and outcome.

Detection of fibrin deposits in horse tissues by immunohistochemistry.

BACKGROUND: Histochemical and immunohistochemical techniques have been used to detect fibrin deposits in different tissues in humans and experimental animal models with disseminated intravascular coagulation (DIC). Fibrin deposits also have been observed in horses with severe ischemic and inflammatory disorders by histochemical stainings (phosphotungstic acid hematoxylin [PTAH]). HYPOTHESIS: Immunohistochemical (IHC) methods can be used to accurately detect fibrin deposits in horses at risk of DIC. ANIMALS: Tissue-organ samples collected on postmortem examination from 87 horses with severe inflammatory and ischemic gastrointestinal disorders. In addition, tissue samples from 13 horses with colic and colonic obstructions or displacements and from 13 slaughter horses were used as controls. METHODS: Tissue samples (kidney, lung, and liver) were stained with PTAH and IHC for blinded histologic examination and comparison. A fibrin score (grades 0 to 4) was established for each tissue sample and for each horse for both techniques. RESULTS: When the IHC method was used, fibrin deposition was observed in 47.1% of the horses with colic with a poor prognosis, compared with 41.4% with PTAH. An agreement of 70% was achieved when both methods were compared, and the lung was confirmed as the most affected organ. Almost none of the colic and slaughter control horses had fibrin deposits in their tissues. CONCLUSIONS AND CLINICAL IMPORTANCE: IHC technique for fibrin antigens was very effective in the detection and identification of fibrin deposits in equine tissues and may be a reliable technique for the postmortem diagnosis of DIC.

Mean platelet component as an indicator of platelet activation in foals and adult horses.

BACKGROUND: Mean platelet component (MPC) is a new platelet variable, measured by modern commercial complete blood count analyzers, that is reduced during platelet activation in humans and small animals. HYPOTHESIS: MPC decreases in horses with clinical conditions that cause platelet activation and disseminated intravascular coagulation (DIC). ANIMALS: We obtained 418 CBCs from 100 sick and 20 healthy neonates and 178 sick and 45 sound adult horses. Sick neonates were classified into septic and nonseptic, and DIC and non-DIC groups. Adults were grouped by diagnoses (systemic inflammatory disorders, gastrointestinal problems, and thrombocytopenia). METHODS: MPC together with platelet count, mean platelet volume, platelet distribution width, and platelet component distribution width were measured with a commercial analyzer and compared between the different disease and control groups in neonates and in adults. RESULTS: MPC values were significantly lower in the septic and nonseptic neonates (24.0 +/- 3.5 g/dL and 26.6 +/- 2.6 g/dL, respectively) than in the control group (28.1 +/- 1.7 g/dL). Neonates with DIC had the lowest MPC values (23.8 +/- 6.3 g/dL). MPC values in adult horses were significantly lower in the inflammatory (23.5 +/- 4.7 g/dL), gastrointestinal obstruction (23.0 +/- 5.0 g/dL), enteritis (23.6 +/- 4.6 g/dL), ischemic (23.9 +/- 5.1 g/dL), and thrombocytopenia (20.2 +/- 5.7 g/dL) groups when compared with control horses (26.2 +/- 3.5 g/dL). Other platelet variables were not different between the control and the disease groups. CONCLUSION AND CLINICAL IMPORTANCE: MPC might be a useful variable for quickly and easily detecting platelet activation in sick neonates and adult horses.

Detection of fibrin deposits in tissues from horses with severe gastrointestinal disorders.

BACKGROUND: In humans and experimental animals, disseminated intravascular coagulation (DIC) causes fibrin deposition in several organs, which eventually leads to ischemia and multiorgan failure. HYPOTHESIS: Horses who died or were euthanized for severe gastrointestinal disorders could have fibrin deposits in different tissues. ANIMALS: Tissue-organ samples collected during postmortem examinations on 66 colic horses with poor prognoses (eg, severe intestinal ischemia, enteritis, peritonitis), from 11 colic horses with good prognoses (eg, large-colon obstruction or displacement), and from 16 slaughter horses. METHODS: Tissue samples (kidney, lung, liver) were stained with hematoxylin and eosin, and phosphotungstic acid hematoxylin for a blinded histologic examination. A fibrin score (grades 0 to 4) was established for each tissue sample and for each horse. RESULTS: Fibrin deposits were found in tissue specimens of 11 of 27 of horses (40.7%) in the ischemic group, 8 of 21 in the enteritis group (38.1%), and 7 of 18 in the peritonitis group (39.0%), whereas none of the horses in the obstructive group (n = 11) and only 1 horse in the slaughter group (n = 16) had fibrin deposits in their tissues. In addition, the mean fibrin score values for the ischemic, enteritis, and peritonitis groups (1.3 +/- 1.7, 1.1 +/- 1.6, and 0.9 +/- 1.3, respectively) were statistically higher than those for the obstructive and slaughter groups (0.0 +/- 0.0 and 0.1 +/- 0.5, respectively). The largest fibrin deposits were found in the lungs. CONCLUSIONS AND CLINICAL IMPORTANCE: Horses with severe gastrointestinal disorders have fibrin deposits that are consistent with capillary microthrombosis, multiorgan failure, and DIC.

Effects of etamsylate on equine platelets: in vitro and in vivo studies.

The aim of this study was to investigate whether etamsylate produces equine platelet activation. In vitro and in vivo studies were designed in which seven and eight adult healthy horses were included, respectively. In the in vitro study, citrated blood was incubated with different concentrations of etamsylate, and P-selectin expression and annexin V binding were determined by flow cytometry. In the in vivo study, blood was collected before and 1 and 2h after IV administration of etamsylate, and P-selectin expression was evaluated. In the in vitro study, a significant increase in P-selectin expression, leukocyte-platelet aggregate formation and annexin V binding were observed. In the in vivo study, a marked increase in P-selectin expression and heterotypic aggregate formation was seen in two and five horses, respectively, although no significant differences were detected when analyzing results from all the animals together. The results of the in vitro study indicate that etamsylate produces a pre-activation state in equine platelets, but this fact could be confirmed by the in vivo study.

Assessment of platelet function in horses: ultrastructure, flow cytometry, and perfusion techniques.

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.

A comparison of traditional and quantitative analysis of acid-base and electrolyte imbalances in horses with gastrointestinal disorders.

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, pCO2, tCO2, HCO3-, 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 iCa2+ 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+, 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.

[Guttural pouch mycosis by Emericella nidulans in a horse]. / Micosis de las bolsas guturales causada por Emericella nidulans en un caballo.

A case of guttural pouch mycosis in a horse caused by Emericella nidulans is reported for the first time in Spain. The high incidence of E. nidulans in this special kind of mycoses is discussed.