The EU Directive 2010/63/EU changed the requirements regarding the use of laboratory animals and raised important issues related to assessing the severity of all procedures undertaken on laboratory animals. However, quantifiable parameters to assess severity are rare, and improved assessment strategies need to be developed. Hence, a Sheep Grimace Scale (SGS) was herein established by observing and interpreting sheep facial expressions as a consequence of pain and distress following unilateral tibia osteotomy. The animals were clinically investigated and scored five days before surgery and at 1, 3, 7, 10, 14 and 17 days afterwards. Additionally, cortisol levels in the saliva of the sheep were determined at the respective time points. For the SGS, video recording was performed, and pictures of the sheep were randomized and scored by blinded observers. Osteotomy in sheep resulted in an increased clinical severity score from days 1 to 17 post-surgery and elevated salivary cortisol levels one day post-surgery. An analysis of facial expressions revealed a significantly increased SGS on the day of surgery until day 3 post-surgery; this elevated level was sustained until day 17. Clinical severity and SGS scores correlated positively with a Pearson´s correlation coefficient of 0.47. Further investigations regarding the applicability of the SGS revealed a high inter-observer reliability with an intraclass correlation coefficient of 0.92 and an accuracy of 68.2%. In conclusion, the SGS represents a valuable approach for severity assessment that may help support and refine a widely used welfare assessment for sheep during experimental procedures, thereby meeting legislation requirements and minimizing the occurrence of unrecognized distress in animal experimentation.

Objectives The aim of the present study was to establish a rodent peri‐implantitis model induced by a mixed bacterial infection characterized by bone loss and semi‐quantitative graduation of peri‐implant inflammation in histological sections. Materials and Methods Two titanium implants were implanted in Sprague‐Dawley rats, bilaterally in each maxilla. After 3 weeks healing, the rats were randomized into three groups according to different treatments over the next 3 months: Antibiotic‐Group with oral lavage of antibiotics; Bacteria‐Group with oral lavage of Streptococcus oralis and Aggregatibacter actinomycetemcomitans; and Untreated Group with standard housing and no additional treatment. Maxillae were dissected to perform microscopic and histological analysis of bone height and peri‐implant tissues. Results The bone level, measured at one implant site per animal, in the Bacteria‐Group (2.60 ± 0.39 mm) was significantly reduced compared to the Antibiotic‐Group (2.29 ± 0.32 mm) after 3 months. The differences of bone height in the Bacteria‐Group and the Untreated Group (2.46 ± 0.27 mm) did not reach statistical significance. The inflammatory response with respect to the number of inflammatory cells and fibrous tissue compartments of the peri‐implant tissues in the Bacteria‐Group was significantly increased compared with the Antibiotic‐Group (p < .05). S. oralis and A. actinomycetemcomitans DNAs were detected in the Bacteria‐Group. Conclusions This rat model of peri‐implantitis used oral bacterial lavage for the induction of an inflammatory host response and bone loss. Additional bacterial treatment enhances the peri‐implant phenotype, so that significant differences to a reduced bacterial load similar to the human peri‐implantitis disease can be identified.

Despite decreasing prevalence, rotavirus infections still rank among the most important viral infections in colonies of laboratory mice. Although the disease is characterized by low mortality and a relatively short and mild clinical period, the infection has the potential to alter the outcome of experiments substantially. For animal facilities, it is therefore essential to eradicate the virus. Here we report a successful sanitation of a rotavirus-infected mouse colony in an animal facility. Despite a high ratio of transgenic and partially immunodeficient strains, a permanent eradication of the virus was achieved by euthanasia of highly susceptible mice, a prolonged breeding cessation in areas containing immunocompromised mice and a strict hygienic management. The management of a rotavirus infection reported here is a feasible and inexpensive opportunity for sanitation that benefits from maintaining most of the animal population, even in today's mouse colonies comprising mainly transgenic mice with unknown or compromised immune status.

The LEW/Ztm-ci2 rat is an animal model for syndromal deafness that arose from a spontaneous mutation. Homozygous animals show locomotor abnormalities like lateralized circling behavior. Additionally, an impaired vision can be observed in some animals through behavioral studies. Syndromal deafness as well as retinal degeneration are features of the Usher syndrome in humans. In the present study, the mutation was identified as a base substitution (T->C) in exon 56 of Myo15, leading to an amino acid exchange from leucine (Leu) to proline (Pro) within the carboxy-terminal MyTH4 domain in the proteins' tail region. Myo15 mRNA was expressed in the retina as demonstrated for the first time with the help of in-situ hybridization and PCR. To characterize the visual phenotype, rats were examined by scotopic and photopic electroretinography and, additionally, histological analyses of the retinas were conducted. The complete loss of sight was detected along with a severe degeneration of photoreceptor cells. Interestingly, the manifestation of the disease does not solely depend on the mutation, but also on environmental factors. Since the LEW/Ztm-ci2 rat features the entire range of symptoms of the human Usher syndrome we think that this strain is an appropriate model for this disease. Our findings display that mutations in binding domains of myosin XV do not only cause non-syndromic hearing loss but can also lead to syndromic disorders including retinal dysfunction.

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