Temporal patterns of bovine leukemia virus infection in dairy herds in Atlantic Canada.

Objective: The primary objective was to determine the youngest age group where bovine leukemia virus (BLV)-infected dairy animals were identified. The secondary objective was to investigate associations between age-specific management practices and BLV infection status of different age groups of dairy calves and heifers. Procedure: For enrolled herds, BLV status was determined using blood samples from pre-weaned calves, weaned calves, and breeding-age heifers; and bulk tank milk from the adult herd. A questionnaire investigating age-specific management factors was administered for each herd. Ordinal logistic regression was performed to identify management factors associated with the youngest age range in which BLV was identified. Results: Fifty-three dairy herds from the 4 provinces in Atlantic Canada were enrolled. Bovine leukemia virus was most commonly earliest identified in pre-weaned heifers (18 herds, 32.1%) and the adult herd (18 herds, 32.1%). Ordinal logistic regression revealed that BLV was first identified in older age groups more often than in younger age groups when herds regrouped weaned heifers at least once, when fly control was used for breeding-age heifers, when herds practiced foot trimming on breeding-age heifers, and when bred heifers were brought in. Conclusion: Producers can use results to identify the youngest age group(s) in which BLV is identified and to tailor management strategies to prevent new infections.

Tendances temporelles de l'infection par le virus de la leucémie bovine dans les troupeaux laitiers des provinces atlantiques canadiennes. Objectif: L'objectif principal était de déterminer le groupe d'âge le plus jeune dans lequel les animaux laitiers infectés par le virus de la leucémie bovine (BLV) ont été identifiés. L'objectif secondaire était d'étudier les associations entre les pratiques de gestion spécifiques à l'âge et le statut d'infection par le BLV de différents groupes d'âge de veaux et de génisses laitiers. Procédure: Pour les troupeaux inscrits, le statut BLV a été déterminé à l'aide d'échantillons de sang provenant de veaux présevrés, de veaux sevrés et de génisses en âge de se reproduire; et de lait de réservoir en vrac du troupeau adulte. Un questionnaire portant sur les facteurs de gestion spécifiques à l'âge a été administré pour chaque troupeau. Une régression logistique ordinale a été réalisée pour identifier les facteurs de gestion associés à la tranche d'âge la plus jeune dans laquelle le BLV a été identifié. Résultats: Cinquante-trois troupeaux laitiers des quatre provinces atlantiques canadiennes ont été inscrits. Le virus de la leucémie bovine a été le plus souvent identifié le plus tôt chez les génisses pré-sevrées (18 troupeaux, 32,1 %) et dans le troupeau adulte (18 troupeaux, 32,1 %). La régression logistique ordinale a révélé que le BLV a été identifié pour la première fois plus souvent dans les groupes d'âge plus âgés que dans les groupes d'âge plus jeunes lorsque les troupeaux regroupaient au moins une fois les génisses sevrées, lorsque le contrôle des mouches était utilisé pour les génisses en âge de se reproduire, lorsque les troupeaux pratiquaient le parage des pattes des génisses en âge de se reproduire., et quand les taures saillies étaient intégrées au troupeau. Conclusion: Les producteurs peuvent utiliser les résultats pour identifier le(s) groupe(s) d'âge le plus jeune dans lequel le BLV est identifié et pour adapter les stratégies de gestion afin de prévenir de nouvelles infections.(Traduit par Dr Serge Messier).

Listeria monocytogenes cholangiohepatitis in a lactating Holstein cow.

OBJECTIVE: To describe a unique presentation of systemic Listeria monocytogenes infection in a lactating adult Holstein cow. ANIMAL: 3-year-old second-parity female Holstein, 200 days in milk. CLINICAL PRESENTATION, PROGRESSION, AND PROCEDURES: A 3-year-old Holstein dairy cow was presented for decreased appetite, decreased milk production, and pyrexia. Blood work displayed marked abnormalities in liver-associated parameters. A diagnosis of L monocytogenes cholangiohepatitis was made following liver biopsy, histopathology, and bacterial culture. TREATMENT AND OUTCOME: The cow was treated with systemic antimicrobial and antipyretic therapy. The cow was discharged to continue treatment on farm, and at time of last communication with the owner, the cow was doing very well, with full resolution of clinical signs. CLINICAL RELEVANCE: This case report describes a novel presentation of L monocytogenes infection in an adult bovine. L monocytogenes cholangiohepatitis should be considered a rare differential diagnosis in cattle presenting with evidence of pyrexia and liver disease.

Retrospective review of atrial fibrillation in Standardbred racehorses at a tertiary care facility in Atlantic Canada.

Atrial fibrillation (AF) is the most clinically relevant cardiac arrhythmia identified in the Standardbred racehorse. However, there is limited literature regarding athletic ability in Standardbred racehorses following AF conversion. To investigate this issue, the objectives of this review were to: i) determine the success rate in using quinidine sulphate to treat AF in a population of hospitalized equine patients in Atlantic Canada between January 2008 and December 2019; and ii) measure return to athletic ability (using racetrack earnings and top-3 finishes) following cardioversion with quinidine sulphate in a population of Standardbred racehorses. Overall, 73% (16/22) of AF instances in this study were successfully treated with enteral quinidine sulphate. No significant difference was detected in racetrack earnings or number of top-3 finishes for each horse that raced at least 5 times pre- and post-conversion. Key clinical message: To the authors' knowledge, this is the first published review to assess the athletic ability of Standardbred racehorses following cardioversion with enteral quinidine sulphate. Based on the current information, it does not appear that treatment of AF with quinidine sulphate affects future athletic performance in horses that achieved cardioversion.

Examen rétrospectif de la fibrillation auriculaire chez des chevaux de course Standardbred dans un établissement de soins tertiaires au Canada Atlantique. La fibrillation auriculaire (FA) est l'arythmie cardiaque la plus cliniquement pertinente identifiée chez le cheval de course Standardbred. Cependant, il existe peu de littérature concernant la capacité athlétique des chevaux de course Standardbred après la conversion de l'FA. Pour étudier cette question, les objectifs de cette revue étaient de : i) déterminer le taux de réussite de l'utilisation du sulfate de quinidine pour traiter la FA dans une population de patients équins hospitalisés au Canada Atlantique entre janvier 2008 et décembre 2019; et ii) mesurer le retour à la capacité athlétique (en utilisant les gains en hippodrome et les trois premiers résultats) après une cardioversion avec du sulfate de quinidine dans une population de chevaux de course Standardbred. Dans l'ensemble, 73 % (16/22) des cas de FA dans cette étude ont été traités avec succès avec du sulfate de quinidine entérale. Aucune différence significative n'a été détectée dans les revenus de l'hippodrome ou le nombre de classements parmi les trois premiers pour chaque cheval ayant couru au moins cinq fois avant et après la conversion.Message clinique clé :À la connaissance des auteurs, il s'agit de la première revue publiée évaluant la capacité athlétique des chevaux de course Standardbred après une cardioversion avec sulfate de quinidine entérale. Sur la base des informations actuelles, il ne semble pas que le traitement de la FA avec du sulfate de quinidine affecte les performances sportives futures des chevaux ayant cardioversion réussie.(Traduit par Dr Serge Messier).

Development of a predictive model for bovine leukemia virus proviral load.

BACKGROUND: There is currently no commercially available method in Canada to identify bovine leukemia virus (BLV)-positive cows with high proviral load (PVL). OBJECTIVES: First, develop a model to predict PVL using common, commercially available, cost-effective diagnostic tests. Second, investigate the relationship between lymphocyte count and PVL in BLV-positive cows. ANIMALS: A total of 339 BLV-positive and 62 BLV-seronegative cows on 15 dairy farms. METHODS: Cross-sectional study. Blood and milk samples were collected from all lactating BLV-positive cows on each farm and 5 to 10 BLV-seronegative cows depending on herd size. Blood and milk samples were tested for anti-BLV antibodies using enzyme-linked immunosorbent assay (ELISA). Complete blood counts were performed on blood samples, and standard components analyses were obtained for milk samples. Proviral load was determined by quantitative polymerase chain reaction for each cow. RESULTS: The inverse of lymphocyte count, the square of the inverse of lymphocyte count, and milk ELISA percent positivity were positively associated with increasing PVL in BLV-positive cows. For BLV-positive cows, lymphocyte count >5.2 × 109 /L predicted a high PVL (BLV:Bovine DNA of >1 in blood) with a sensitivity of 92.4% and a specificity of 79.8%. For BLV-positive cows, white blood cell count >10.8 × 109 /L predicted a high PVL, with a sensitivity of 85.5% and a specificity of 83.6%. CONCLUSIONS AND CLINICAL IMPORTANCE: Based on these results, producers can implement commonly available diagnostic tests to identify cows with high probability of having high PVL, which may help in designing effective disease control strategies for BLV-positive herds.

Spontaneous resolution of bilateral congenital patellar luxation in an alpaca cria.

An 8-day-old alpaca was presented for suspected meconium impaction and abnormal gait and posture. Physical examination revealed bilateral medial patellar luxation. In previous reports, medical treatment of patellar luxation in crias has been associated with a poor to grave prognosis; here we report a case of successful resolution.

Résolution spontanée d'une luxation patellaire bilatérale congénitale chez un bébé alpaga. Un alpaga âgé de 8 jours a été présenté pour une impaction soupçonnée du méconium et une démarche et une posture anormales. L'examen physique a révélé une luxation patellaire médiale bilatérale. Dans des rapports antérieurs, le traitement médical de la luxation patellaire chez les bébés alpaga a été associé à un pronostic sombre ou grave; nous avons ici un rapport de cas d'une résolution réussie.(Traduit par Isabelle Vallières).

Investigation of within- and between-herd variability of bovine leukaemia virus bulk tank milk antibody levels over different sampling intervals in the Canadian Maritimes.

Bulk tank milk (BTM) samples are used to determine the infection status and estimate dairy herd prevalence for bovine leukaemia virus (BLV) using an antibody ELISA assay. BLV ELISA variability between samples from the same herd or from different herds has not been investigated over long time periods. The main objective of this study was to determine the within-herd and between-herd variability of a BTM BLV ELISA assay over 1-month, 3-month, and 3-year sampling intervals. All of the Canadian Maritime region dairy herds (n = 523) that were active in 2013 and 2016 were included (83.9% and 86.9% of total herds in 2013 and 2016, respectively). BLV antibody levels were measured in three BTM samples collected at 1-month intervals in early 2013 as well as two BTM samples collected over a 3-month interval in early 2016. Random-effects models, with fixed effects for sample replicate and province and random effects for herd, were used to estimate the variability between BTM samples from the same herd and between herds for 1-month, 3-month, and 3-year sampling intervals. The majority of variability of BTM BLV ELISA results was seen between herds (1-month, 6.792 ±â€¯0.533; 3-month, 7.806 ±â€¯0.652; 3-year, 6.222 ±â€¯0.528). Unexplained variance between samples from the same herd, on square-root scale, was greatest for the 3-year (0.976 ±â€¯0.104), followed by the 1-month (0.611 ±â€¯0.035) then the 3-month (0.557 ±â€¯0.071) intervals. Variability of BTM antibody levels within the same herd was present but was much smaller than the variability between herds, and was greatest for the 3-year sampling interval. The 3-month sampling interval resulted in the least variability and is appropriate to use for estimating the baseline level of within-herd prevalence for BLV control programs. Knowledge of the baseline variability and within-herd prevalence can help to determine effectiveness of control programs when BTM sampling is repeated at longer intervals.

Redundant contribution of a Transient Receptor Potential cation channel Member 1 exon 11 single nucleotide polymorphism to equine congenital stationary night blindness.

BACKGROUND: Congenital stationary night-blindness (CSNB) is a recessive autosomal defect in low-light vision in Appaloosa and other horse breeds. This condition has been mapped by linkage analysis to a gene coding for the Transient Receptor Potential cation channel Member 1 (TRPM1). TRPM1 is normally expressed in the ON-bipolar cells of the inner nuclear layer of the retina. Down-regulation of TRPM1 expression in CSNB results from a transposon-like insertion in intron 1 of the TRPM1 gene. Stop transcription signals in this transposon significantly reduce TRPM1 primary transcript levels in CSNB horses. This study describes additional contributions by a second mutation of the TRPM1 gene, the ECA1 108,249,293 C > T SNP, to down-regulation of transcription of the TRPM1 gene in night-blind horses. This TRPM1 SNP introduces a consensus binding site for neuro-oncological ventral antigen 1 (Nova-1) protein in the primary transcript. Nova-1 binding disrupts normal splicing signals, producing unstable, non-functional mRNA transcripts. RESULTS: Retinal bipolar cells express both TRPM1 and Nova-1 proteins. In vitro addition of Nova-1 protein retards electrophoretic migration of TRPM1 RNA containing the ECA1 108,249,293 C > T SNP. Up-regulating Nova-1 expression in primary cultures of choroidal melanocytes carrying the intron 11 SNP caused an average log 2-fold reduction of ~6 (64-fold) of TRPM1 mRNA expression. CONCLUSIONS: These finding suggest that the equine TRPM1 SNP can act independently to reduce survival of TRPM1 mRNA escaping the intron 1 transcriptional stop signals in CSNB horses. Coexistence and co-inheritance of two independent TRPM1 mutations across 1000 equine generations suggests a selective advantage for the apparently deleterious CSNB trait.