Monoclonal antibodies for equine CD25 improve detection of regulatory T cells in horses.

CD25, the interleukin-2 receptor α-chain, is expressed on cell surfaces of different immune cells and is commonly used for phenotyping of regulatory T cells (Tregs). CD25 has essential roles in the maintenance of hemostasis and immune tolerance and Treg cell involvement has been shown in human diseases and murine models for allergy, autoimmunity, cancer, chronic inflammation, and many others. In horses, a cross-reactive anti-human CD25 antibody has previously been used for characterizing Tregs. Here, we developed monoclonal antibodies (mAbs) to equine CD25 and compared their staining pattern with the anti-human CD25 antibody by flow cytometry. The comparison of the two reagents was performed by two separate analyses in independent laboratories. Overall, similar staining patterns for equine peripheral blood lymphocytes were obtained with the anti-human CD25 antibody and equine CD25 mAb 15-1 in both laboratories. Both reagents identified comparable CD4+CD25+ and CD4+CD25+FOXP3+ percentages after stimulation of peripheral blood mononuclear cells (PBMC) with pokeweed mitogen. However, when compared to the anti-human CD25 antibody, the equine CD25 mAb 15-1 resulted in a better staining intensity of the equine CD25+ cells and increased the percentages of Tregs and other CD25+ cells ex vivo and after culturing of PBMC without stimulation. In summary, the equine CD25 mAbs provide new, improved reagents for Tregs and CD25+ cell phenotyping in horses.

Retrospective Analysis of the Use of Tiludronate in Equine Practice: Safety on 1804 Horses, Efficacy on 343 Horses.

The objective of this retrospective study was to assess the safety and efficacy of a slow IV administration of 1mg/kg tiludronate in a large number of horses. Each horse that received at least one tiludronate-based treatment between 2006 and August 2019 at Virginia Equine Imaging or Fairfield Equine was included in the study. Concomitant medical treatments, preliminary nonsteroidal anti-inflammatory drug injection and potential side effects were recorded after each administration. Horses for which follow-up was available over 1 year were subject to clinical evolution assessment via lameness grade evolution and performance data when available. Collected data suggest excellent tolerance to tiludronate with only 0.9% of the 2,497 injections (1,804 horses) inducing potential side effects, mild colics being the most frequent. Clinical follow-up was available over more than 1 year for 343 horses. Most horses (>80%) presented an initial lameness score over 1.5/5, approximately half of the population was sound by 30 days and remained so after a year. Mean lameness score improved by more than one grade during the follow-up period compared to initial examination. Performance data were available for 129 horses. One year after treatment, 89 (69%) horses were still competing, 73 (82%) of them at a better or similar level. These data suggest good efficacy of tiludronate over a year after treatment. Despite limitations inherent to any field study, this is the first retrospective study of the use of bisphosphonates in horses combining a large group with long-term follow-ups.

Owners' perception of the efficacy of Newmarket bloodroot ointment in treating equine sarcoids.

A retrospective questionnaire-based survey was used to determine the perceived efficacy of Newmarket bloodroot ointment in treating equine sarcoids. In 49 horses with 74 sarcoids, 64 sarcoids responded either completely (n = 49) or partially (n = 15) while 10 did not respond or worsened. Sarcoids < 2 cm responded better to treatment (P < 0.001) than did larger sarcoids.

Perception des propriétaires sur l'efficacité de l'onguent à la sanguinaire de Newmarket pour traiter les sarcoïdes équines. Un sondage rétrospectif réalisé par questionnaire a été utilisé pour déterminer l'efficacité perçue de l'onguent à la sanguinaire de Newmarket pour traiter les sarcoïdes équines. Chez 49 chevaux atteints de 74 sarcoïdes, 64 sarcoïdes ont soit répondu complètement (n = 49) ou partiellement (n = 15) tandis que 10 n'ont pas répondu ou se sont aggravées. Les sarcoïdes de < 2 cm ont mieux répondu au traitement (P < 0,001) que les sarcoïdes plus grandes.(Traduit par Isabelle Vallières).