Efficacy study of soluble bacitracin (Bacivet S®) in a chronically infected epizootic rabbit enteropathy environment.

Abstract

ABSTRACT:The present study evaluated under field conditions the efficacy of bacitracin zinc soluble powder (Bacivet S ® ) for the treatment of Epizootic Rabbit Enteropathy (ERE). A blinded study was conducted in compliance with the "Good Clinical Practice" guidance. The trial site was known to be chronically infected with ERE. A total of 384 weaned rabbits (30 days of age) were enrolled in the study. They were randomly distributed over 6 rows of cages located in the same experimental room. Two rows of cages remained untreated (control group), another 2 rows were treated with Bacivet S ® for 14 days (T14) and 2 rows were treated with Bacivet S ® for 21 days (T21). The medication was administered per row via the drinking water and initiated when at least one animal, showing clinical signs of ERE, died. The dose was adjusted daily according to the weight of the rabbits to achieve the target dose of 420 IU/kg body weight in the two treatment groups. Animals were observed daily for mortality, diarrhoea, tympany, or any other abnormal sign for 42 days post enrollment. Weights of the animals and feed intake were recorded on a weekly base. On the second day after the set-up of the trial, mortality already occurred with clear signs of ERE and the medication was initiated. On the primary evaluation parameter, mortality, both treated groups showed significant (P<0.01) better results than the control group with an overall mortality reaching 13.5%, 12.6% and 26.6% in T14, T21 and control groups, respectively. Considering only ERE confirmed mortality, differences were even more pronounced; 4.0% (T14), 6.3% (T21) and 14.1% (control), respectively. The occurrence of clinical signs (tympany and diarrhoea) was also reduced in medicated rabbits but this reduction was markedly higher for T21 treated rabbits (P<0.001 compared to control) than in the T14 group. A few days after the termination of the medication period, moderate mortality and clinical symptoms were observed in both medicated groups. These isolated cases were probably due to a recontamination through the untreated groups. Data of daily weight gain and feed intake showed a good agreement with the observed mortality and clinical symptoms. In conclusion, Bacivet S ® proved its efficacy against ERE in a chronically infected environment for both tested treatment regimens.

Characterisation of Clostridium perfringens presence and concentration of its α-toxin in the caecal contents of fattening rabbits suffering from digestive diseases

“…In agreement with previous descriptions of ERE symptoms Maertens et al, 2005;Licois, 2010), no visible inflammation of the walls of the intestinal tract was detected in ERE-affected animals. It was also observed that the distal colon was often empty or just contained mucus.…”

“…Even if this percentage could be in keeping with that (52.9%) found by Maertens et al (2005), the ERE morbidity seems very low. ERE is characterised by spreading very quickly and morbidity can rise to 100% after experimental inoculation .…”

“…On average, the live weight was lower by 49.2% (P<0.001) in the diseased rabbits as compared with the corresponding weight of healthy rabbits of the same age. Growth depression in rabbits affected by ERE has consistently been mentioned in previous reports (Boucher and Nouaille, 2002;Coudert and Licois, 2005;Maertens et al, 2005;Licois et al, 2006;Licois, 2007;Romero et al, 2009a). Coudert and Licois (2005) were even unable to avoid the fall in the growth rate of rabbits treated with bacitracin.…”

“…ERE is characterised by spreading very quickly and morbidity can rise to 100% after experimental inoculation . Nonetheless, it is true that the overall morbidity in the current trials was rather low (9.70%), especially taking into account that no antibiotics were provided in the feed or drinking water Maertens et al, 2005;Romero et al, 2010). This good health status is likely due to the hygienic and zootechnical practices applied at the farm (Garrido et al, 2009;Romero et al, 2009a).…”

“…However, it should be pointed out that it is sometimes difficult to diagnose ERE with absolute certainty in the field. ERE is indeed a non-specific enteropathy (Maertens et al, 2005) and the criteria used to distinguish it from other intestinal disorders lack specificity . In fact, the distension of stomach and small intestine by a very liquid and gaseous content that entails the abdominal bloating is probably the only distinctive feature of ERE along with the absence of macroscopic signs of inflammation Licois, 2010).…”