Plasma metabolome of healthy and Rhodococcus equi-infected foals over time.

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.

INTRODUCTION/CONTEXTE: Les poulains qui développent des lésions pulmonaires échographiques dans les fermes d'élevage où Rhodococcus equi (R. equi) est endémique sont traités avec antibiotiques car ceux à risque de développer des lésions cliniques (~20%) ne peuvent être identifiés précocement. Certains biomarqueurs identifiés par le biais de la métabolomique pourraient aider à orienter les stratégies de traitement pour R. equi. OBJECTIFS: (1) Décrire les changements de métabolome plasmatique qui surviennent chez les poulains en lien avec l'âge (naissance jusqu'à 8 semaines d'âge) et (2) Établir les effets d'une infection expérimentale à Rhodococcus Equi sur le métabolome des poulains. TYPE D'ÉTUDE: Étude expérimentale. MÉTHODES: Neufs poulains nouveaux-nés en santé ont été infectés de façon expérimentale par R. equi tel que décrit précédemment. Ils ont été traités avec des antibiotiques s'ils ont développé une pneumonie clinique (n = 4, groupe clinique) ou ont simplement été suivi dans le temps s'ils n'ont pas montré de signes de la maladie (n = 5, groupe sous-clinique). Un groupe de poulains sains (n = 4) était aussi inclus dans l'étude. À la fin de l'étude (8 semaines), tous les poulains étaient sains tel que confirmé par l'évaluation et la culture de leur fluide de lavage transtrachéal de même qu'à l'échographie thoracique. Les métabolomiques plasmastiques ont été déterminées par GC-MS de façon hebdomadaire pour la durée de l'étude (8 semaines). RÉSULTATS: À la fois l'âge et l'infection expérimentale ont altéré le métabolome plasmatique des poulains tel que démontré par l'analyse statistique multivariée. L'âge a altéré l'intensité de 25 métabolites et l'infection a modifié l'intensité de 28 métabolites (p < 0.05). De plus, 20 métabolites ont changé de plus de 2 fois leur valeur initiale, entre les groupes cliniques et sous-cliniques. LIMITES PRINCIPALES: Le nombre de poulains reste limité. Les poulains ont été infecté par R. equi de façon expérimentale. CONCLUSIONS: Le vieillissement et l'infection par R. equi induisent des changements dans le métabolome plasmatique des poulains. Ces résultats représentent une description initiale du métabolome plasmatique chez le poulain et peuvent servir de base pour l'identification future de biomarqueurs pour la détection de pneumonie à Rhodococcus equi.

Plasma lipidome of healthy and Rhodococcus equi-infected foals over time.

BACKGROUND: Many foals that develop thoracic ultrasonographic lesions as a result of Rhodococcus equi infection heal on their own. However, most of these foals receive antimicrobials because foals at risk of developing clinical pneumonia cannot be identified. Untargeted lipidomics is useful to identify candidate biomarkers. OBJECTIVES: (a) To describe the changes that occur in foal lipidomics as a result of ageing (birth to 8 weeks) and (b) To compare these results with those observed in foals after experimental infection with R. equi. STUDY DESIGN: Experimental study. METHODS: Healthy newborn foals (n = 9) were challenged with R. equi intratracheally the first week of life. Foals were treated with antimicrobials if they developed clinical pneumonia (n = 4, "clinical group") or were closely monitored if they showed no signs of disease (n = 5 "subclinical group"). An unchallenged group (n = 4) was also included. All foals were free of disease (transtracheal wash fluid evaluation and culture as well as thoracic ultrasonography) by 8 weeks of life. Plasma lipidomics was determined by LC-MS weekly for the study duration (8 weeks). RESULTS: Both ageing and experimental infection altered the foal's plasma lipidome as demonstrated by multivariate statistical analysis. The intensities of 31 lipids were altered by ageing and 12 by infection (P < .05). Furthermore, nine lipids changed by more than twofold between clinical and subclinical groups. MAIN LIMITATIONS: The number of foals is limited. Foals were experimentally challenged with R. equi. CONCLUSIONS: Ageing and R. equi infection induced changes in the plasma lipidome of foals. These experimental results provide the background for future work in the discovery of earlier biomarkers of R. equi pneumonia. Early identification of foals at risk of developing clinical pneumonia is key in order to decrease antimicrobial use and development of antimicrobial resistance.

Treatment of temporohyoid osteoarthropathy in horses with a basihyoid-ceratohyoid disarticulation technique: 6 cases (2018-2019).

OBJECTIVE: To describe a technique for basihyoid-ceratohyoid disarticulation (BCD) in standing sedated horses affected by temporohyoid osteoarthropathy (THO) and report outcomes for horses that underwent the procedure. ANIMALS: 6 client-owned horses. PROCEDURES: Electronic medical records of a veterinary teaching hospital were searched to identify horses that underwent BCD for treatment of THO from 2018 to 2019. Signalment, clinical data, use of the horse, and complications were recorded. Follow-up data obtained by telephone interview with owners included the clinical outcome and time to improvement after surgery, any persistent clinical signs, horse's activity level before onset of clinical signs and after BCD, subsequent use of the horse, and whether they would pursue the same treatment again. RESULTS: All horses tolerated the procedure well, with no complications and improved neurologic function after BCD. Five of 6 horses had a reported activity level equal to or greater than that prior to having signs of THO. Three of 3 horses with acute ataxia prior to BCD reportedly had full resolution of this sign; 3 of 4 horses with facial nerve deficits prior to BCD had mild residual facial nerve deficits at follow-up. All owners indicated they would pursue BCD again. CONCLUSIONS AND CLINICAL RELEVANCE: The BCD procedure was performed safely in this sample of THO-affected horses that were sedated while standing, avoiding risks associated with general anesthesia and resulting in no adverse effects such as iatrogenic injury to neurovascular structures.

Midbody penile urethrocutaneous fistula repaired by fistulectomy and urethral anastomosis in a stallion.

CASE DESCRIPTION: A 12-year-old Friesian stallion was examined because of a 1-year history of preputial injury and urination through a urethrocutaneous fistula located at the midbody of the ventral aspect of the penis. CLINICAL FINDINGS: Physical examination revealed an opening with a clearly apparent mucocutaneous junction 12 cm from the distal opening of the urethra on the ventral left side of the penis. Endoscopic examination of the distal portion of the urethra confirmed a blind pouch with no communication with the fistula or proximal portion of the urethra. TREATMENT AND OUTCOME: A temporary perineal urethrostomy was performed with sedation and local anesthesia, with the stallion standing, to divert urine from the urethral reconstruction site. Fistulectomy and urethral resection and anastomosis were performed under general anesthesia with the stallion in dorsal recumbency. At 15 days after surgery, endoscopic examination of the urethra revealed distortion of the urethral lumen at the fistulectomy site. Under sedation, the urethra was dilated for 5 minutes every 12 hours for 3 days. At 22 days after surgery, endoscopic examination of the urethra revealed a healed anastomosis site and a large urethral luminal diameter. At 36 months after surgery, the owner reported that the stallion had normal micturition and had sired multiple foals by live cover matings. CLINICAL RELEVANCE: Severe preputial or penile trauma in horses is most commonly treated with amputation because of concerns of postoperative urethral stricture and occlusion. To the authors' knowledge, this case represented the first time that a successful end-to-end anastomosis of the distal portion of the urethra has been performed in a stallion.