Survey on the Presence of Malassezia spp. in Healthy Rabbit Ear Canals

Malassezia spp. have rarely been reported in rodents and lagomorphs. In 2011, Malassezia cuniculi was described in two rabbits. Further microscopic studies showed M. cuniculi-like yeasts in more than 50% of samples from rabbits’ ear canals, but no isolation was made. The present study details the presence of Malassezia spp. and tries to typify it from ear canals of healthy rabbits. Seventy-eight half-breed rabbits from rural farms and 98 companion dwarf rabbits from northern Italy were considered. A first attempt to screen ear swabs was performed by microscopic and cultural examination on Sabouraud Glucose Agar (SGA), modified Dixon Agar (mDA) and Leeming and Notman Agar (LNA). Additionally, ear swabs from eight further microscopically positive rabbits for M. cuniculi-like cells, were used for both isolation on LNA medium and nine of its variants and for DNA extraction, PCR and sequencing. The microscopic observation of the swabs of the screened 168 rabbits highlighted the presence of yeasts in one or both of the external ear canals of 98 rabbits (58.3%). Rabbits used for meat production were more frequently diagnosed positive than pet rabbits (P = 0.001), and young ones were more often positive compared to rabbits older than 3 months (P = 0.027). No yeast growth was observed in culture. From the eight selected rabbits, Malassezia isolation failed both on LNA and on the modified mediums. Sequences of ~300 bp fragments of 18s rDNA, obtained by PCR from swabs, showed 99.9% identity with Malassezia phylotype 131 described from human ear canals. As Malassezia-like yeasts have been observed in more than half of the examined population, its colonization of ear meatus can be considered as physiological in rabbits. The results outline how much remains to be discovered on Malassezia as a component of the skin mycobiota of rabbits and that the use of the culture examination alone is not the best choice to detect Malassezia-like yeasts in rabbits.

The technique of articular rabbit cartilage roughness measurement and analysis of the effect of PRP in knee osteoarthritis therapy using atomic force microscopy

Hyaline cartilage undergoes degenerative-dystrophic changes with subsequent involvement of the subchondral bone. The purpose of this study was developing a new AFM-based method to articular rabbit cartilage roughness measurement, followed by an investigation of whether platelet-rich plasma therapy of knee osteoarthritis has a positive impact on mechanical properties of rabbit cartilage. The rabbits were randomly divided into two groups: the control group (N=6) and the patients (N=12). Saline (0.5 ml) and 10% surgical talc solution were injected into the right knee of 12 rabbits to induce osteoarthritis. Six rabbits underwent PRP therapy, while the other six did not receive treatment. The mechanical properties and the submicron surface morphology rabbit hyaline cartilage were investigated using atomic force microscopy (AFM). In the group of specimens worn out by induced osteoarthritis, the maximum arithmetic average of absolute values (Ra) change was a 23% increase; the maximum peak height (Rp) increased by over 100%, while the mean spacing between local peaks (S) increased by 26%, compared to healthy rabbit cartilage (p<0.05). In the group of specimens worn out by induced osteoarthritis and cured with PRP therapy, Ra increased by 13%; Rp increased by 33%, while S decreased by 77%, compared to healthy rabbit cartilage (p<0.05). It was found that the mechanical properties of hyaline cartilage deteriorate under the influence of simulated osteoarthritis. The results of PRP treatment in rabbits may constitute a step forward to further relevant studies involving OA patients.

Effect of supplementation with two combinations of alternative to antimicrobials by stages on cecal fermentation in rabbits

Antimicrobials inhibit cecal fermentation when preventing rabbit from infection. This study aimed to evaluate the effect of supplementation with two combinations of alternative to antimicrobial (combination I: 1 × 10⁹cfu/kg Bacillus subtilis + 2 g/kg fructooligosaccharide; combination II: 2 g/kg acidifier and 0.6 g/kg essential oil) by stages on rabbit’s growth performance and cecal fermentation. Two hundred and forty 15-day-old male kits with similar body weight were distributed randomly to five groups, which were control (basal diet), ZnB (addition of 0.1 g/kg bacitracin zinc in basal diet), II (addition of combination II), I-II (addition of combination I during days 15–35, addition of combination II during days 36–77), and I-II-I (supplemented with combination I during days 15–35 and 57–77, supplemented with combination II during days 36–56). Each group had 6 replicates. One healthy rabbit from each replicate was slaughtered at day 35 and day 77. The results showed: (1) at day 35, the two combinations and bacitracin zinc all inhibited ileal Escherichia coli (P &lt; 0.05), decreased cecal pH, and increased total volatile fatty acid concentration (P &lt; 0.05). Combination І decreased duodenal crypt depth and increased duodenal villi height to crypt depth ratio (VCR) (P &lt; 0.05); (2) at day 77, I-II-I group had more cecal total bacteria than control (P &lt; 0.05). Mode I-II or I-II-I increased cecal Bacteroides-Prevotella (P &lt; 0.05) compared with ZnB. Mode I-II-I shortened duodenal crypt depth and increased VCR compared with control or ZnB (P &lt; 0.05); (3) after weaning, modes I-II-I and I-II had better or similar effect on decreasing diarrhoea and mortality rate compared with ZnB. In conclusion, both modes had better or similar effect on decreasing diarrhoea and mortality rate compared with inclusion of antimicrobial or combination II alone during the whole trial, and mode I-II-I showed better effect than mode I-II.