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Nevertheless, [SAA] did not correlate with the intensity of the antibody responses (VN-T) stimulated by the vaccine. EHV-1/-4 vaccination caused a prominent APR, higher in
horses than in mules, but [SAA] did not correlate with antibody responses. Measuring [SAA] after vaccination could help identify severe APRs that may require longer resting intervals before training or competition.
Dysbiosis in faecal water syndrome
In this study Angelika Schoster and colleagues in Switzerland and Canada evaluated whether dysbiosis is present in horses with faecal water syndrome (FWS) when compared to stable- matched control horses in spring and autumn. Faecal samples were collected from 16 horses with FWS (9
mares and 7 geldings) and 15 controls (8 mares and 7 geldings). The bacterial microbiome of samples collected in spring and autumn of 2016 was analysed using high- throughput sequencing. Differences in relative abundance of bacterial taxa, alpha diversity, and beta diversity indices were assessed between horses with FWS and controls based on season.
Differences in microbial community composition based on
time point and health status were not observed on any taxonomic level. Limited differences were seen on linear discriminant analysis effect size analysis. No difference in alpha diversity indices was observed including richness, diversity based on health status, or time point. No effect of health status on microbial community membership structure was observed. Limited differences were found in the bacterial microbiota
of horses with and without FWS, regardless of season. Further research is needed to elucidate the role of microbiota in the development of FWS.
Congenital stationary night blindness
This case report by Yael Hack and colleagues in the USA detailed a whole genome sequencing approach to identify a causal variant of congenital stationary night blindness (CSNB) in a Tennessee Walking Horse. Prior to this, the only known reported genetic cause of CSNB in horses was a 1378 bp insertion in the transient receptor potential cation channel subfamily M member 1 (TRPM1) gene. A male, 13-year-old Tennessee Walking Horse with clinical
signs and examination findings (including dark-adapted electroretinography) consistent with CSNB underwent whole genome sequencing. Results were compared to data from 29 horses of seven other breeds. A list of 100 candidate genes was compiled based on a literature review of mutations causal for CSNB in other species, and coding variants homozygous in the case and absent in the other horses were further evaluated. DNA from 90 randomly selected Tennessee Walking Horses and 273 horses of three other breeds was used to estimate the allele frequency of the causal mutation. The horse was not found to have any copies of the TRPM1
mutation but had a missense variant in the metabotropic glutamate receptor 6 (GRM6) gene; a G-protein coupled receptor vital for night vision. The allele frequency in Tennessee Walking Horses was estimated to be 10%. Congenital stationary night blindness can be associated with a recessive missense variant in GRM6.
Measurement of the equine diaphragm
In this study Laura Fitzharris and colleagues in the UK developed a repeatable method to measure the diaphragm thickness using ultrasonography in Thoroughbred racehorses. The diaphragm is an important respiratory muscle, playing
a key role during exercise. Measurement of diaphragm thickness, in a non-invasive and repeatable manner, is a possible approach to assess respiratory strength in the horse. A standardised technique was developed whereby the
ultrasound transducer was positioned 1 cm below a line between the cranioventral aspect of the tuber coxae and olecranon. The diaphragm thickness was measured on three occasions 1 week apart, by a single observer to determine the intraobserver repeatability, and once by a second observer to assess interobserver reproducibility. The diaphragm was observed in all intercostal spaces (ICS) from 7 to 17 on the left side, and 6–17 on the right side in a single horse. The thickest measurement (1.42 cm), obtained from 11 horses, was at ICS 11 on the left-side during inspiration. The narrowest measurement (0.56 cm) was obtained at ICS 16 on the right-side during expiration. This study provides a detailed description of
ultrasonographic imaging and measurement of the equine diaphragm. The novel technique developed to position the ultrasound transducer allowed examination and measurement of the diaphragm with good repeatability.
S. WRIGHT EVE Editorial Office References
de Oliveira, M.G.C., Luna, S.P.L., Nunes, T.L., Firmino, P.R., de Lima, A.G.A., Ferreira, J., Trindade, P.H.E., Barr^
eto J unior, R.A. and de
Paula, V.V. (2020) Post-operative pain behaviour associated with surgical castration in donkeys (Equus asinus). Equine Vet. J. Epub ahead of print;
https://doi.org/10.1111/evj.13306
Duran, M.C., Dumrath, C.A.C., Bartmann, C.P., Medina Torres, C.E., Moschos, A. and Goehring, L.S. (2020) Serum amyloid A (SAA) concentration after vaccination in horses and mules. J. Equine Vet. Sci. 92, 103165.
Fitzharris, L.E., Meehan, L.J., Hezzell, M.J. and Allen, K.J. (2020) The equine diaphragm: a novel technique for repeatable ultrasound measurement. Vet. Radiol. Ultrasound Epub ahead of print;
https://doi.org/10.1111/vru.12903
Gardner, A.K., Santschi, E.M., Mudge, M.C., Belknap, J.K. and Metzler, A.G. (2020) Intrasinus bolstering of traumatic maxillary sinus fractures by using Foley catheter balloons in two foals. Vet. Surg. 49, 1255-1261.
Hack, Y.L., Crabtree, E.E., Avila, F., Sutton, R.B., Grahn, R.A., Oh, A., Gilger, B. and Bellone, R.R. (2020) Whole genome sequencing identifies missense mutation in GRM6 as the likely cause of congenital stationary night blindness in a Tennessee Walking Horse. Equine Vet. J. Epub ahead of print;
https://doi.org/10.1111/evj. 13318
Schoster, A., Weese, J.S., Gerber, V. and Graubner, C.N. (2020) Dysbiosis is not present in horses with fecal water syndrome when compared to controls in spring and autumn. J. Vet. Intern. Med. 34, 1614-1621.
Steinmann, M., Bezugley, R.J., Bond, S.L., Pomrantz, J.S. and L eguillette,
R. (2020) A wireless endoscopy capsule suitable for imaging of the equine stomach and small intestine. J. Vet. Intern. Med. 34, 1622- 1630.
© 2020 EVJ Ltd
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