Towards a postural indicator of back pain in horses (<i>Equus caballus</i>)

Postures have long been used and proved useful to describe animals' behaviours and emotional states, but remains difficult to assess objectively in field conditions. A recent study performed on horses using geometric morphometrics revealed important postural differences between 2 horse populations differing in management conditions (leisure horses living in social groups used for occasional "relaxed" riding/riding school horses living in individual boxes used in daily riding lessons with more constraining techniques). It was suggested that these postural differences may reflect chronic effects of riding techniques on the horses' kinematics and muscular development. In the present study, we tried to evaluate the interest of postural measures to assess welfare in horses. This study was separated into 2 parts. First, 18 horses coming from these 2 types of populations (leisure/riding school horses) were submitted to 2 back evaluations by 1) manual examination (experienced practitioner) and 2) sEMG measures along the spine. We then measured neck roundness on 16 of these 18 horses. The results highlighted high correlations between manual and sEMG examinations over the spine. sEMG measures at the different locations were strongly correlated all over the spine. Moreover, neck postures and muscular activities were strongly correlated, horses with concave necks having higher sEMG measures both at precise locations (i.e. cervical sites) but also when comparing neck postures to the whole spine muscular activity highlighting the functioning of horses' back as a whole. Lastly, strong differences appeared between the populations, leisure horses being evaluated as having sounder spines, exhibiting lower sEMG measures and rounder neck than the riding school horses. sEMG measures and neck "roundness" seemed therefore to be reliable indicators of back disorders, easy to evaluate in field conditions. This highlights the accuracy of using postural elements to evaluate the animals' general state and has important implications for animals' welfare evaluations

Optimization of a Type III Secretion System-Based Pseudomonas aeruginosa Live Vector for Antigen Delivery▿

During the last few years, the use of type III secretion system-based bacterial vectors for immunotherapy purposes has been assessed in various applications. We showed that a type III secretion-based Pseudomonas aeruginosa vector delivering the ovalbumin (OVA) antigen induced an efficient specific CD8+ T-lymphocyte immune response against OVA-expressing cells. Because of the intrinsic toxicity of the vector, further virulence attenuation was needed. Therefore, we explored the effects of the deletion of quorum-sensing genes and the aroA gene toward toxicity and efficiency of the vector strain. The aroA mutation in our strain (making the strain auxotrophic for aromatic amino acids) conferred a strikingly reduced toxicity, with the bacterial lethal dose being more than 100 times higher than that of the parental strain. The quorum-sensing gene mutation alone was associated with a slightly reduced toxicity. In a prophylactic OVA-expressing melanoma mouse model, an OVA-delivering aroA-deficient mutant was the most efficient at a low dose (105), but dose enhancement was not associated with a greater immune response. The quorum-sensing-deficient strain was the most efficient at a mild dose (106), but this dose was close to the toxic dose. Combination of both mutations conferred the highest efficiency at an elevated dose (107), in agreement with the known negative effects of quorum-sensing molecules upon T-cell activation. In conclusion, we have obtained a promising immunotherapy vector regarding toxicity and efficiency for further developments in both antitumor and anti-infectious strategies