Risk factors associated with development of colitis in horses post-exploratory laparotomy.

BACKGROUND: Diagnosis of colitis has been shown to impact morbidity and mortality in hospitalised horses. There are no studies to date that describe the incidence of infectious colitis after exploratory laparotomy. OBJECTIVES: To investigate risk factors associated with the development of colitis and infectious colitis post-exploratory laparotomy. STUDY DESIGN: Retrospective case-control. METHODS: Medical records of equids admitted from 2011 to 2020 were reviewed. The primary outcome was a diagnosis of colitis following exploratory laparotomy. Bivariable associations between colitis and risk factors were assessed using the 2-sample t-test and Fisher's exact test. All risk factors were subjected to a backward elimination variable reduction algorithm within a logistic regression framework (p-value set to 0.05). Odds ratios and 95% confidence intervals were computed for the final model. RESULTS: A total of 504 equids were included in the study. Forty-two patients (8.3%) were diagnosed with postoperative colitis. Five patients were diagnosed with Salmonella spp. and two with Clostridioides difficile. The odds of postoperative colitis were higher among patients that had pelvic flexure enterotomy (OR = 3.7, 95% CI = 1.7-7.9, p = 0.001), postoperative leukopenia or leukocytosis (OR = 21.2, 95% CI = 9.7-46.7, p < 0.001), or plasma lactate 2.0-4.0 mmol/L (OR = 3.0, 95% CI = 1.3-6.7, p < 0.008). Patients diagnosed with colitis had a longer median length of hospitalisation (9 days; range 2-21) compared with patients without colitis (7 days; range 2-25). Patients with colitis had a survival to discharge rate similar to patients without colitis (95% compared to 93%). MAIN LIMITATIONS: Risk factors for infectious colitis could not be determined due to variation in testing protocols in this retrospective study and the low number of positive cases. CONCLUSIONS: Colitis as a postoperative complication does not negatively impact survival to discharge but is associated with longer hospitalisation. Pelvic flexure enterotomy, postoperative leukopenia or leukocytosis, and increased plasma lactate were identified as significant risk factors associated with colitis.

INTRODUCTION/CONTEXTE: Il a été démontré qu'un diagnostic de colite a un impact sur la morbidité et la mortalité des chevaux hospitalisés. Il n'y a aucune étude décrivant l'incidence de colites infectieuses suivant une laparotomie exploratrice. OBJECTIFS: Investiguer les facteurs de risque associés au développement de colites et de colites infectieuses en période post-opératoire suivant une laparotomie exploratrice. TYPE D'ÉTUDE: Étude de type rétrospective avec cas témoins. MÉTHODES: Les dossiers médicaux de chevaux admis entre 2011 et 2020 ont été utilisés. La résultante primaire était un diagnostic de colite suivant une laparotomie exploratrice. Les analyses bivariées entre colites et facteurs de risque ont été évalués par le biais d'un test de Fisher exact et un test de T à deux échantillons. Tous les facteurs de risque ont été sujet à un algorithme de réduction par élimination régressive des variables dans le cadre d'une régression logistique (valeur de p à 0.05). Les probabilités (odds ratio) et les intervalles de confiance à 95% ont été inclus dans le modèle final. RÉSULTATS: Au total, 504 chevaux ont été inclus dans l'étude. Quarante-deux patients (8.3%) ont reçu un diagnostic de colite post-opératoire. Cinq patients ont reçu un diagnostic de Salmonella spp. et deux, de Clostridioides difficile. Les chances de colites post-opératoires étaient plus élevées chez les patients ayant subi une entérotomie de la courbure pelvienne (OR = 3.7, 95% CI = 1.7-7.9, p = 0.0008), ayant souffert d'une leucopénie ou leucocytose (OR = 21.2, 95% CI = 9.7-46.7, p < 0.0001), ou ayant eu une valeur de lactate plasmatique de 2.0-4.0 mmol/L (OR = 3.0, 95% CI = 1.3-6.7, p < 0.0084). Les patients diagnostiqués avec une colite ont eu une durée d'hospitalisation médiane supérieure (9 jours; étendu 2-21) comparativement aux patients sans colite (7 jours; étendu 2-25). Il n'y avait pas de différence entre les patients avec et ceux sans colite, en ce qui a trait au taux de survie de congé hospitalier (95% comparé à 93%). LIMITES PRINCIPALES: Les facteurs de risque pour les colites infectieuses n'ont pas pu être identifié en raison de variations des protocoles de tests employés dans cette étude rétrospective et du faible nombre de cas positifs. CONCLUSIONS: Les colites en tant que complication post-opératoire n'ont pas d'impact négatif sur le taux de survie hospitaliser mais sont associées à une période d'hospitalisation de plus longue durée. Une entérotomie de la courbure pelvienne, une leucopénie ou leucocytose post-opératoire et une valeur élevée de plasma sanguin ont été identifiés comme facteurs de risque associés au développement de colite.

Horses affected by EPM have increased sCD14 compared to healthy horses.

Equine protozoal myeloencephalitis (EPM) is a debilitating neurologic disease affecting horses across the Americas. Gaps in understanding the inflammatory immune response in EPM-affected horses create difficulties with diagnosis and treatment, subsequently negatively impacting the prognosis of affected horses. The purpose of the current study was to evaluate circulating levels of the inflammatory immune marker soluble CD14 (sCD14), in horses with EPM (n = 7) and determine if they differed from healthy neurologically normal horses (n = 6). Paired sera and cerebrospinal fluid (CSF) samples were analyzed for sCD14. Inclusion criteria for EPM horses consisted of the presence of neurologic signs consistent with EPM, Sarcocystis neurona surface antigens 2, 4/3 (SnSAG 2, 4/3) ELISA serum: CSF antibody ratio ≤ 100, and a postmortem diagnosis of EPM. Control horses were neurologically normal, healthy horses with SnSAG 2, 4/3 ELISA serum: CSF antibody ratios of > 100. Serum anti-Sarcocystis neurona antibodies indicate that healthy control horses were exposed to S. neurona but resistant to developing clinical EPM. EPM cases had significantly greater concentrations of sCD14 in CSF samples compared to control horses and increased serum sCD14 concentrations. A positive correlation between sCD14 serum and CSF concentrations was observed in EPM-affected horses but not healthy horses. Soluble CD14 is an inflammatory marker, and the study results suggest it is elevated in EPM patients. When performed in conjunction with clinical evaluation and standard antibody testing, there may be potential for sCD14 to be utilized as a correlate for EPM.

Immune-mediated haemolytic anaemia and thrombocytopenia in 25 adult equids: 1997-2016.

BACKGROUND: Information concerning clinical presentation, conditions associated with immune-mediated haemolytic anaemia (IMHA) and thrombocytopenia (IMTP) and outcome in equids is lacking. Previous case reports suggest that immune-mediated disease and neoplasia are associated. OBJECTIVES: Characterise the clinical presentation, clinicopathologic data, underlying conditions, treatment and outcome of IMHA and IMTP cases in equids. We hypothesise that IMHA with concurrent thrombocytopenia occurs more often than IMHA or IMTP alone, and that neoplasia is commonly associated with these immune diseases and cases frequently have a poor prognosis. STUDY DESIGN: Retrospective case-control study. METHODS: Medical records were reviewed from 1997 to 2016. Twenty-five equids were diagnosed with IMHA, IMTP or IMHA with thrombocytopenia by Coombs test or flow cytometry. Controls were equids presented for nonimmune-mediated disease immediately prior to and after study animals. Fisher's exact test was used to compare between groups for categorical variables (P < .05). Results reported as odds ratios (OR) and 95% confidence intervals (CI). Unpaired t test and Mann-Whitney test were used to compare between groups for continuous variables (P < .05). RESULTS: Neoplasia incidence was significantly higher in the study population (28%) versus controls (8%) (P = .04). Equids with primary disease were more likely to survive to discharge than equids with secondary disease (8/9 vs 7/16; P = .03; OR = 13.3; 95% CI: 1.3-134.7). Survivors had a significantly lower blood urea nitrogen (BUN) than those that died or were subjected to euthanasia (survivors, 6.1 ± 2.5 mmol/L vs nonsurvivors, 9.9 ± 3.1 mmol/L P = .003). The odds of short-term mortality were higher in horses presenting with increased BUN (OR = 19.5; 95% CI, 1.8-214.1; P = .009). MAIN LIMITATIONS: Retrospective nature of the study, small case numbers and limited long-term follow-up. CONCLUSIONS: Primary IMHA/IMTP cases have a reasonable prognosis and warrant treatment. Secondary cases have a poor prognosis, and are frequently associated with cancer. BUN may have utility as a prognostic indicator for IMHA/IMTP cases.

Pharmacokinetics of chloramphenicol base in horses and comparison to compounded formulations.

Chloramphenicol is commonly used in horses; however, there are no studies evaluating the pharmacokinetics of veterinary canine-approved tablets. Studies using different formulations and earlier analytical techniques led to concerns over low bioavailability in horses. Safety concerns about human health have led many veterinarians to prescribe compounded formulations that are already in suspension or paste form. The objective of this study was to evaluate the pharmacokinetics of approved chloramphenicol tablets in horses, along with compounded preparations. The hypothesis was that chloramphenicol has low absorption and a short half-life in horses leading to low serum concentrations and that compounded preparations have lower relative bioavailability. Seven horses were administered chloramphenicol tablets (50 mg/kg orally). In a crossover design, they were administered two compounded preparations to compare all three formulations at the same dose (50 mg/kg). Cmax was 5.25 ± 4.07 µg/ml at 4.89 hr, 4.96 ± 3.31 µg/ml at 4.14 hr, and 3.84 ± 2.96 µg/ml at 4.39 hr for the tablets, paste, and suspension, respectively. Elimination half-life was 2.65 ± 0.75, 3.47 ± 1.47, and 4.36 ± 4.54 hr for tablets, paste, and suspension, respectively. The AUC0→∞ was 17.93 ± 7.69, 16.25 ± 1.85, and 14.00 ± 5.47 hr*µg/ml for the tablets, compounded paste, and compounded suspension, respectively. Relative bioavailability of compounded suspension and paste was 78.1% and 90.6%. Cmax after administration of all formulations did not reach the recommended MIC target of 8 µg/ml set by the Clinical Laboratory Standards Institute (CLSI) for most bacteria. Multidose studies are warranted, but the low serum concentrations suggest that bacteria with MIC values lower than CLSI recommendations should be targeted in adult horses.

The prevalence of temporal bone fractures is high in horses with severe temporohyoid osteoarthropathy.

Temporohyoid osteoarthropathy is a well-recognized cause of equine neurologic disease. Temporal bone fractures associated with temporohyoid osteoarthropathy have been recognized with CT, however, little information is available regarding these fractures. The aims of this retrospective analytical study were to assess the prevalence of these fractures and to describe the specific configurations and associated imaging and clinical features. Fracture of the temporal bone was identified with CT in 16 of 39 included horses. All fractures were unilateral, minimally displaced and extended through the temporal bone in a rostrodorsal to caudoventral orientation. Two fracture configurations were identified: in nine cases, the fracture extended the full width of the petrous pyramid into the cranial vault and in seven cases, the fracture only extended through the lateral part of the petrous temporal bone, not involving the cranial vault. Fusion of the temporohyoid joint was present in 13 of the 16 fracture cases. Quarter Horses were over-represented in the fractured population (14/16). All horses with fractures had ipsilateral neurologic deficits. Patient outcomes were not significantly different between temporohyoid osteoarthropathy horses with and without temporal bone fractures (P = 0.68). However, six of the nine patients with cranial vault involvement did not return to their previous use. Findings support previous studies indicating that temporal bones should be carefully assessed for concurrent fractures when temporohyoid osteoarthropathy is identified in CT images, especially when there is fusion of the temporohyoid joint. An improved awareness of specific fracture configurations will help with detection of these fractures.

Lipid peroxidation biomarkers for evaluating oxidative stress in equine neuroaxonal dystrophy.

BACKGROUND: Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) is a neurodegenerative disorder affecting genetically predisposed foals maintained on an α-tocopherol (α-TOH) deficient diet. Currently no antemortem diagnostic test for eNAD/EDM is available. HYPOTHESIS: Because α-TOH deficiency is associated with increased lipid peroxidation, it was hypothesized that F2 -isoprostanes (F2 IsoP), F4 -neuroprostanes (F4 NP) and oxysterols derived from free radical oxidation would be increased in the cerebrospinal fluid (CSF) and neural tissue of eNAD/EDM affected horses and could serve as potential biomarkers for disease. ANIMALS: Isoprostane Study A: 14 Quarter horse foals (10 healthy foals and 4 eNAD/EDM affected foals) at 1 and 6 months of age. Isoprostane Study B: 17 eNAD/EDM affected and 10 unaffected horses ≥ 1-4 years of age. Oxysterol study: eNAD/EDM affected (n = 14, serum; n = 11, CSF; n = 10, spinal cord [SC]) and unaffected horses 1-4 years of age (n = 12, serum; n = 10, CSF; n = 7, SC). PROCEDURES: Cerebrospinal fluid [F2 IsoP] and [F4 NP] were assessed using gas chromatography-negative ion chemical ionization mass spectrometry. Serum, CSF, and cervical SC [oxysterols] were quantified using high performance liquid chromatography mass spectrometry. Results were compared with respective α-TOH concentrations. RESULTS: Spinal cord [7-ketocholesterol], [7-hydroxycholesterol], and [7-keto-27-hydrocholesterol] were higher in eNAD/EDM horses whereas [24-ketocholesterol] was lower. No significant difference was found in CSF [F2 IsoP] and [F4 NP], serum [oxysterols] and CSF [oxysterols] between eNAD/EDM affected and unaffected horses. No correlation was found between [F2 IsoP], [F4 NP], or [oxysterols] and respective [α-TOH]. CONCLUSIONS AND CLINICAL IMPORTANCE: In the SC, targeted markers of cholesterol oxidation were significantly increased in horses with eNAD/EDM.

Sialoendoscopy as a treatment for an obstructed mandibular salivary duct in a horse.

A 14-year-old Quarter Horse was examined for a draining tract of 8 months' duration on the right mandible that was non-responsive to antibiotic therapy and surgical therapy. Further investigation and subsequent treatment with sialoendoscopy and ultrasonography were performed to relieve an obstruction of plant awns in the mandibular salivary duct.

Sialo-endoscopie comme traitement pour un canal salivaire mandibulaire bloqué chez un cheval. Un cheval Quarter Horse âgé de 14 ans a été examiné pour une fistule purulente d'une durée de 8 mois à la mandibule droite qui ne répondait pas à la thérapie antibiotique et à la thérapie chirurgicale. De nouvelles investigations et le traitement subséquent à l'aide de la sialo-endoscopie et de l'échographie ont été réalisés pour éliminer un blocage du canal salivaire mandibulaire par des barbes de plantes.(Traduit par Isabelle Vallières).