Occurrence of Theileria equi in horses raised in the Jaboticabal microregion, São Paulo State, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phosphorus bioavailability in diets for growing horses

A study of phosphorus (P) metabolism was carried out using 12 month old Brasileiro de Hipismo breed of horses to determine the P bioavailability available from feeds commonly fed to horses in Brazil. Five different diets were formulated to contain approximately equivalent levels of crude protein and digestible energy, as well as to supply at least 22 g P/horse/day (NRC, 1989). All 5 diets contained 40% Bermuda coastal hay plus 60% concentrate. The 5 different concentrates contained: C1 (corn+ cottonseed meal) C2 (corn grain+soybean meal) C3 (corn+sugarcane yeast), C4 (oat+cottonseed meal), and C5 (oat+soybean meal). The radioisotope (32)p was injected with 30 NIB. Blood, feces and urine were collected for 7 days to evaluate endogenous fecal P and true absorption. Analysis of variance of P intake showed differences due to dietary effects (P < 0.05). Concentrate C3 had the lowest intake (79.68 mg/ kg BW). All of the diets produced positive P retention. Absolute values for P concentrations in plasma, urine, feces and endogenous feces did not vary between diets. Values for endogenous fecal P were independent of the level of P intake, so the correlation between P intake and P endogenous was not significant. P bioavailability values were 50.75; 40.98; 43.50; 51.03 and 57.68% for diets C1 through C5, respectively. However, differences in P bioavailability were found (P < 0.05) between diets. Diets C2 and C3 had lower P bioavailability than the other diets. The P bioavailability of all dietary treatments in this study exceeded NRC (1989) postulations of 35% true P absorption in diets not supplemented with inorganic P. The results of this study indicate that inorganic P supplementation is not needed for growing yearlings fed common Brazilian feeds. Considering the high cost of P supplementation and the risk of environmental P contamination, inorganic phosphorus supplementation for growing yearlings may not be required. (c) 2007 Elsevier B.V. All rights reserved.

Dried yeast (Saccharomyces cerevisae) as a protein source for horses

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Serological detection of West Nile virus in horses and chicken from Pantanal, Brazil

In an effort to detect West Nile virus (WNV) in Brazil, we sampled serum from horses and chickens from the Pantanal region of the state of Mato Grosso and tested for flavivirus-reactive antibodies by blocking ELISA. The positive samples were further confirmed for serological evidence of WNV infection in three (8%) of the 38 horses and one (3.2%) of the 31 chickens using an 80% plaque-reduction neutralisation test (PRNT80). These results provide evidence of the circulation of WNV in chickens and horses in Pantanal.

Effects of a muscarinic type-2 antagonist on cardiorespiratory function and intestinal transit in horses anesthetized with halothane and xylazine

Objective-To evaluate the cardiorespiratory and intestinal effects of the muscarinic type-2 (M-2) antagonist, methoctramine, in anesthetized horses.Animals-6 horses.Procedure-Horses were allocated to 2 treatments in a randomized complete block design. Anesthesia was maintained with halothane (1% end-tidal concentration) combined with a constant-rate infusion of xylazine hydrochloride (1 mg/kg/h, IV) and mechanical ventilation. Hemodynamic variables were monitored after induction of anesthesia and for 120 minutes after administration of methoctramine or saline (0.9% NaCl) solution (control treatment). Methoctramine was given at 10-minute intervals (10 mug/kg, IV) until heart rate (HR) increased at least 30% above baseline values or until a maximum cumulative dose of 30 mug/kg had been administered. Recovery characteristics, intestinal auscultation scores, and intestinal transit determined by use of chromium oxide were assessed during the postanesthetic period.Results-Methoctramine was given at a total cumulative dose of 30 mug/kg to 4 horses, whereas 2 horses received 10 mug/kg. Administration of methoctramine resulted in increases in HR, cardiac output, arterial blood pressure, and tissue oxygen delivery. Intestinal auscultation scores and intestinal transit time (interval to first and last detection of chromium oxide in the feces) did not differ between treatment groups.Conclusions and Clinical Relevance-Methoctramine improved hemodynamic function in horses anesthetized by use of halothane and xylazine without causing a clinically detectable delay in the return to normal intestinal motility during the postanesthetic period. Because of their selective positive chronotropic effects, M-2 antagonists may represent a safe alternative for treatment of horses with intraoperative bracycardia.

Effects of glycopyrrolate on cardiorespiratory function in horses anesthetized with halothane and xylazine

Objective-To evaluate cardiopulmonary effects of glycopyrrolate in horses anesthetized with halothane and xylazine.Animals-6 horses.Procedure-Horses were allocated to 2 treatment groups in a randomized complete block design. Anesthesia was maintained in mechanically ventilated horses by administration of halothane (1% end-tidal concentration) combined with a constant-rate infusion of xylazine hydrochloride (1 mg/kg/h, IV). Hemodynamic variables were monitored after induction of anesthesia and for 120 minutes after administration of glycopyrrolate or saline (0.9% NaCl) solution. Glycopyrrolate (2.5 mug/kg, IV) was administered at 10-minute intervals until heart rate (HR) increased at least 30% above baseline or a maximum cumulative dose of 75 mug/kg had been injected. Recovery characteristics and intestinal auscultation scores were evaluated for 24 hours after the end of anesthesia.Results-Cumulative dose of glycopyrrolate administered to 5 horses was 5 mug/kg, whereas 1 horse received 75 mug/kg. The positive chronotropic effects of glycopyrrolate were accompanied by an increase in cardiac output, arterial blood pressure, and tissue oxygen delivery. Whereas HR increased by 53% above baseline values at 20 minutes after the last glycopyrrolate injection, cardiac output and mean arterial pressure increased by 38% and 31%, respectively. Glycopyrrolate administration was associated with impaction of the large colon in I horse and low intestinal auscultation scores lasting 24 hours in 3 horses.Conclusions and Clinical Relevance-The positive chronotropic effects of glycopyrrolate resulted in improvement of hemodynamic function in horses anesthetized with halothane and xylazine. However, prolonged intestinal stasis and colic may limit its use during anesthesia.

Platelet activation: ultrastructure and morphometry in platelet-rich plasma of horses

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Triple bothropic envenomation in horses caused by a single snake

In the present study, snakebites caused by a single Bothrops pauloensis simultaneously affecting three male adult horses are described. Whereas the first two affected horses were six years old, the third was 16 years old; they weighed respectively 555, 550 and 500 kg. All horses presented swollen muzzles. The first animal received an initial antivenom dose of 19 vials and adjuvant medication, it was also subjected to tracheostomy due to the progression of acute respiratory failure. The second and third horses respectively received 15 vials of antivenom each, in addition to adjuvant medication. Due to continuous changes in blood coagulation observed during hospitalization, the first and the second horses received five more vials of antivenom, respectively, in the second and third days of treatment. The first animal was discharged on 15(th) day and the other on the 8(th) day of hospitalization. Several factors including the main actions of Bothrops venom (coagulation, proteolytic and vasculotoxic activities), the importance of early diagnosis based on clinical history and clinical examination suggesting the diagnosis of Bothrops snakebite, the adequate doses of antivenom, and finally the immediate tracheostomy are herein discussed. The tracheostomy, required to save the life of the first horse, should only occur after the administration of antivenom and control measures for changes in blood coagulation.

Clinical and histopathological aspects of the insect bite hypersensitivity in horses

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effects of muscarinic receptor antagonists on acetylcholine-induced contractions of jejunal smooth muscle in horses

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effects of chronic acetazolamide administration on gas exchange and acid-base control in pulmonary circulation in exercising horses

P>Reasons for performing study:Carbonic anhydrase (CA) catalyses the hydration/dehydration reaction of CO(2) and increases the rate of Cl- and HCO(3)- exchange between the erythrocytes and plasma. Therefore, chronic inhibition of CA has a potential to attenuate CO(2) output and induce greater metabolic and respiratory acidosis in exercising horses.Objectives:To determine the effects of Carbonic anhydrase inhibition on CO(2) output and ionic exchange between erythrocytes and plasma and their influence on acid-base balance in the pulmonary circulation (across the lung) in exercising horses with and without CA inhibition.Methods:Six horses were exercised to exhaustion on a treadmill without (Con) and with CA inhibition (AczTr). CA inhibition was achieved with administration of acetazolamide (10 mg/kg bwt t.i.d. for 3 days and 30 mg/kg bwt before exercise). Arterial, mixed venous blood and CO(2) output were sampled at rest and during exercise. An integrated physicochemical systems approach was used to describe acid base changes.Results:AczTr decreased the duration of exercise by 45% (P < 0.0001). During the transition from rest to exercise CO(2) output was lower in AczTr (P < 0.0001). Arterial PCO(2) (P < 0.0001; mean +/- s.e. 71 +/- 2 mmHg AczTr, 46 +/- 2 mmHg Con) was higher, whereas hydrogen ion (P = 0.01; 12.8 +/- 0.6 nEq/l AczTr, 15.5 +/- 0.6 nEq/l Con) and bicarbonate (P = 0.007; 5.5 +/- 0.7 mEq/l AczTr, 10.1 +/- 1.3 mEq/l Con) differences across the lung were lower in AczTr compared to Con. No difference was observed in weak electrolytes across the lung. Strong ion difference across the lung was lower in AczTr (P = 0.0003; 4.9 +/- 0.8 mEq AczTr, 7.5 +/- 1.2 mEq Con), which was affected by strong ion changes across the lung with exception of lactate.Conclusions:CO(2) and chloride changes in erythrocytes across the lung seem to be the major contributors to acid-base and ions balance in pulmonary circulation in exercising horses.

Influence of chromium supplementation on energy metabolism in horses used in policing activity

O presente trabalho avaliou a influência da suplementação com cromo em algumas variáveis sanguíneas em 11 equinos machos, adultos, usados em atividade de policiamento. Cada animal recebeu 11mg de cromo/400kg de peso corpóreo, via oral, durante 30 dias. Nos dias 0 (antes) e 30 (após), os animais foram avaliados e amostras de sangue foram obtidas antes e após o exercício. Glicose e lactato plasmáticos e cortisol e insulina séricas foram determinados. No dia 0, as concentrações de glicose plasmática foram 68,4±5,6mg/dL e 78,7±6,5mg/dL; de lactato plasmático, 6,2±0,6mg/dL e 13,1±7,6mg/dL; de cortisol sérico, 48,5±7,9ng/mL e 42,6±19,7ng/mL; e de insulina sérica, 3,0±6,4µUI/m L e 1,9±1,7µUI/mL, respectivamente, antes e após o exercício. No dia 30, as concentrações de glicose plasmática foram 73,3±5,7mg/dL e 78,4±6,7mg/dL; de lactato plasmático, 7,3±0,9mg/dL e 7,6±1,2mg/dL; de cortisol sérico, 62,9±21,8ng/mL e 40,3±17,0ng/mL; e de insulina sérica, 1,4±1,3µUI/mL e 1,7±1,4µUI/mL, respectivamente, antes e após o exercício. Como efeito do exercício, foi demonstrado redução na concentração sérica de insulina e aumento no lactato e glicose plasmáticas. A suplementação com cromo resulto u em redução dos valores de lactato após a atividade física, possivelmente indicando que o cromo contribuiu para a melhor utilização da glicose plasmática e melhor adaptação ao exercício físico realizado.

Slaframine toxicosis in Brazilian horses causing excessive salivation

Ingestion of food contaminated with slaframine, an alkaloid produced by Rhizoctonia leguminicola, causes a mycotoxicosis, characterised by excessive salivation. Twenty-eight horses demonstrated this clinical sign after the consumption of alfalfa hay which on inspection showed dark patches on many of the stems. The presence of slaframine (1.5 ppm) in this hay was confirmed by gas chromatography and mass spectroscopy. This is the first equine slaframine toxicosis case reported in Brazil.

Serum Iron Parameters and Acute Experimental EHV-1 Infection in Horses

Background Research in humans has demonstrated that high serum iron (sFe) concentration can predispose to infection, and many infections subsequently result in alterations of host sFe. A decrease in sFe concentration is an early and sensitive indicator of systemic inflammation caused by tissue necrosis, bacterial infections, or endotoxemia in horses. Serum iron parameters in acute equine herpesvirus type 1 (EHV-1) infection have not been evaluated previously. Objectives To document the sFe response to EHV-1 infection and to determine whether or not significant differences in sFe concentration exist between EHV-1 infected horses that develop neurologic disease and those that do not. Animals A total of 14 horses experimentally infected with EHV-1. Methods Data were collected as an ancillary data set during a blinded experimental EHV-1 infection. Horses were infected with the rAb4 strain of EHV-1. Temperature, neurologic score, packed cell volume (PCV), and sFe parameters (sFe concentration, % saturation, and total iron-binding capacity) were recorded daily for 2weeks. Data were evaluated using Wilcoxon signed rank tests and Wilcoxon rank sum tests with Bonferroni corrections. Conclusions and Clinical Relevance Serum iron concentration decreases significantly in a biphasic pattern after EHV-1 infection. There was no significant difference in sFe concentration in horses that developed neurologic disease and those that did not in these experimentally infected animals. Serum iron parameters may be useful in monitoring the clinical course of viral infections such as EHV-1.