Macarena G. Sanz

Summary Background Analgesic protocols related to orchiectomy or castration of young horses vary widely depending on geographic location, educational background of the veterinarian, and other demographic factors. Specific practices of equine veterinarians in the United States (US) have not been reported. Objectives To determine perioperative pain management practices of equine veterinarians in the United States as they relate to castration of healthy yearling colts. Study design Cross‐sectional survey. Methods An internet‐based questionnaire included items related to analgesic drugs used in association with castration of healthy yearling colts. Demographic, educational, and experiential factors associated with routine recommendation of analgesic medications after castration were analysed with calculation of odds ratios (OR) with 95% confidence intervals (CI) and multivariable logistic regression. Results Responses from 146 equine veterinarians in the United States revealed that 112/146 (76.7%) administered a nonsteroidal anti‐inflammatory drug (NSAID) at the time of castration, and 107/143 respondents (73.3%) recommended administration of NSAIDs for a median of 3 days (IQR = 3–5) after surgery. Veterinarians who recommended NSAID analgesia after castration provided a higher pain severity score for horses at 24 h after a routine castration. Routine recommendation of post‐castration NSAID analgesia was associated with veterinarians who were employed in a multi‐veterinarian practice (OR = 2.7, 95% CI = 1.2–6.1) and completed their veterinary education in the year 2000 or more recently (OR = 2.6, 95% CI = 1.1–5.9). Main limitations Possible distribution, self‐selection, and response biases as a result of convenience sampling methodology and possible recall bias of respondents. Conclusions Perioperative pain management practices vary widely among US veterinarians but the majority of veterinarians, especially more recent graduates and those in multi‐veterinarian practices, recommend administration of an NSAID at the time of castration and for a median of 3 days after surgery.

Background Foals that develop pulmonary ultrasonographic lesions on Rhodococcus equi ( R. equi ) endemic farms are treated with antibiotics because those at risk of developing clinical pneumonia (~20%) cannot be recognised early. Candidate biomarkers identified using metabolomics may aid targeted treatment strategies against R. equi . Objectives (1) To describe how foal ageing affects their plasma metabolome (birth to 8 weeks) and (2) to establish the effects that experimental infection with Rhodococcus equi ( R. equi ) has on foal metabolome. Study design Experimental study. Methods Nine healthy newborn foals were experimentally infected with R. equi as described in a previous study. Foals were treated with oral antibiotics if they developed clinical pneumonia ( n = 4, clinical group) or remained untreated if they showed no signs of disease ( n = 5, subclinical group). A group of unchallenged foals ( n = 4) was also included in the study. By the end of the study period (8 weeks), all foals were free of disease. This status was confirmed with transtracheal wash fluid evaluation and culture as well as thoracic ultrasonography. Plasma metabolomics was determined by GC–MS weekly for the study duration (8 weeks). Results Foals' plasma metabolome was altered by ageing (birth to 8 weeks) and experimental infection with R. equi as demonstrated using multivariate statistical analysis. The intensities of 25 and 28 metabolites were altered by ageing and infection ( p < 0.05) respectively. Furthermore, 20 metabolites changed by more than 2‐fold between clinical and subclinical groups. Main limitations The number of foals is limited. Foals were experimentally infected with R. equi . Conclusions Ageing and R. equi infection induced changes in the plasma metabolome of foals. These results provide an initial description of foal's plasma metabolome and serve as background for future identification of R. equi pneumonia biomarkers.