Pododermatitis in group housed rabbit does in Switzerland-Prevalence, severity and risk factors.

In rabbits (Oryctolagus cuniculus L.), pododermatitis is a chronic multifactorial skin disease that appears mainly on the plantar surface of the hind legs. In later stages, it causes pain leading to poor welfare of affected animals. Pododermatitis is commonly observed in commercial rabbit production in breeding does housed with wire mesh flooring. However, the prevalence in breeding does that are housed in groups on litter and plastic slats is not known. The aim of this cross-sectional study was to investigate the frequency, the severity and possible risk factors of pododermatitis in group housed breeding does in Switzerland on litter and plastic slats. Between June and September 2016 about 30% of all adult female breeding rabbits (1090 animals in total) were evaluated for the presence and the severity of pododermatitis on 17 commercial rabbit farms with group housing. The latter was done with a tagged visual-analogue-scale. Additionally, various animal-related (e.g. hybrid, age or body weight) and environmental risk factors (e.g. temperature, relative humidity or wet area per pen) known from the literature were recorded. The risk factors were analysed with generalized linear models, additive Bayesian network (ABN) models resulting in directed acyclic graphs (DAGs) and random forests with variable importance plots. On average, 25% of the rabbits displayed ulcerative pododermatitis likely to be painful on at least one hind leg, while the prevalence varied between farms from 4 to 49%. The age, body weight and claw-length of the animals were positively associated with pododermatitis as the most important risk factors. The best model explained 37.4% of the observed variance in the primary outcome measure for pododermatitis. These findings demonstrate that pododermatitis is prevalent in female breeding does even in group housing systems with litter and plastic slats. However, the results of this cross-sectional study also indicate that important risk factors may have been missed or were not recorded precisely enough. Thus, more in-depth research is needed to assess risk factors of pododermatitis in view of effectively preventing the occurrence of this painful disease.

Convergence of macroscopic tongue anatomy in ruminants and scaling relationships with body mass or tongue length.

Various morphological measures demonstrate convergent evolution in ruminants with their natural diet, in particular with respect to the browser/grazer dichotomy. Here, we report quantitative macroanatomical measures of the tongue (length and width of specific parts) of 65 ruminant species and relate them to either body mass (BM) or total tongue length, and to the percentage of grass in the natural diet (%grass). Models without and with accounting for the phylogenetic structures of the dataset were used, and models were ranked using Akaike's Information Criterion. Scaling relationships followed geometric principles, that is, length measures scaled with BM to the power of 0.33. Models that used tongue length rather than BM as a body size proxy were consistently ranked better, indicating that using size proxies that are less susceptible to a wider variety of factors (such as BM that fluctuates with body condition) should be attempted whenever possible. The proportion of the freely mobile tongue tip of the total tongue (and hence also the corpus length) was negatively correlated to %grass, in accordance with concepts that the feeding mechanism of browsers requires more mobile tongues. It should be noted that some nonbrowsers, such as cattle, use a peculiar mechanism for grazing that also requires long, mobile tongues, but they appear to be exceptions. A larger corpus width with increasing %grass corresponds to differences in snout shape with broader snouts in grazers. The Torus linguae is longer with increasing %grass, a finding that still warrants functional interpretation. This study shows that tongue measures covary with diet in ruminants. In contrast, the shape of the tongue (straight or "hourglass-shaped" as measured by the ratio of the widest and smallest corpus width) is unrelated to diet and is influenced strongly by phylogeny.