A pharmacokinetic/clinical approach to postulate a local action of intra-articular xylazine administration in the horse: a preliminary study.

The study aims to evaluate whether the analgesic effect of intra-articular (IA) route of xylazine administered to horses following arthroscopic surgery is due to a local or a systemic action. Two connected studies were performed. In the first, 1 mg/kg b.w. of xylazine was injected IA, and blood samples were taken to assess drug systemic absorption. In addition, systemic effects of the drug (sedation, ataxia or reduction of respiratory and cardiac rate) were registered. Control horses injected with saline IA were included in the study to exclude the influence of anaesthesia in the occurrence of these manifestations. In the second study, 1 mg/kg b.w. of xylazine was administered intravenously (i.v.) in healthy horses. Blood samples were collected to determine the concentrations of xylazine, and the same signs of systemic effects of the drug were recorded. By correlating these parameters, a systemic 'no effect' concentration was defined. Pharmacokinetic data after IA administration resulted in some xylazine absorption (bioavailability equal to 58.12%) with values above the systemic 'no effect' concentration. The occurrence of some signs related to systemic effects in horses receiving IA xylazine was significant compared with horses receiving saline. In conclusion, a systemic action of the drug after IA administration cannot be excluded.

Evaluation of transabdominal ultrasound as a tool for predicting the success of abdominocentesis in horses.

The aim of this study was to evaluate the transabdominal ultrasonography as a tool for predicting the success of abdominocentesis in horses. Patients were included in the study if a complete transabdominal ultrasonography examination and abdominocentesis were performed as part of the clinical work-up. Ultrasonographically, the amount of peritoneal fluid was assessed using a 4-point grading system, as well as the amount of peritoneal fluid collected. A χ(2) or Fischer exact test was performed to test for an association between the ultrasonography findings and fluid retrieved, and between the two grading scales. Interobserver and intraobserver agreement values were calculated using k statistics. Values of P<0.05 were considered significant; 109 horses met the inclusion criteria. Peritoneal fluid was identified ultrasonographically in 72 per cent of horses, and it was collected from 93 per cent of these cases. In horses with no peritoneal fluid identified at ultrasonography (28 per cent), fluid was collected in 70 per cent of cases. There is a significant association between transabdominal ultrasonography detection of peritoneal fluid and the likelihood to obtain a diagnostic amount of peritoneal fluid at abdominocentesis; however, even when peritoneal fluid is not detected during abdominal ultrasonography examination, an amount of peritoneal fluid useful for gross, clinicopathological and cytological evaluation can frequently be obtained.

Is there a statistical correlation between ultrasonographic findings and definitive diagnosis in horses with acute abdominal pain?

REASON FOR PERFORMING STUDY: Abdominal ultrasonography has become a part of the diagnostic investigation for the acute abdomen in many equine clinics. There is limited information on the correlation between abnormalities detected on abdominal ultrasonography and the specific category of small intestine (SI) and large intestine (LI) diseases. OBJECTIVES: To investigate the relationship between abdominal ultrasonographic findings and disease categories that cause abdominal pain requiring surgery. METHODS: Medical records were reviewed for horses undergoing surgery or post mortem examination for colic. The ultrasound examination was performed to assess free peritoneal fluid, the left kidney, stomach, appearance and motility of the duodenum, identification, appearance, motility and thickness of small intestine loops, and the appearance and motility of the colon. Logistic regression analysis was used to identify associations between disease categories and ultrasonographic findings; a Chi-squared test was used to test for associations between each variable and disease categories. RESULTS: The study included 158 horses. Distended and nonmotile SI loops were associated with strangulated obstruction (n = 45); increased free peritoneal fluid, completely distended SI loops with abnormal motility and thickened loops were associated with definitive diagnosis involving SI (n = 58). Failure to visualise the left kidney was associated with renosplenic entrapment (n = 16); thickened large colon (LC) was associated with LC strangulating volvulus (n = 9). CONCLUSION: The use of abdominal ultrasonography can be used for the accurate definitive diagnosis involving SI and LI diseases. POTENTIAL RELEVANCE: This retrospective study may be used as a basis for prospective studies to assess the ultrasonographic findings in horses with medical colic and to compare these with surgical findings.