Identifying the major routes of disease transmission and reservoirs of infection are needed to increase our understanding of disease dynamics and improve disease control. Despite this, transmission events are rarely observed directly. Here we had the unique opportunity to study natural transmission of Bordetella bronchiseptica – a directly transmitted respiratory pathogen with a wide mammalian host range, including sporadic infection of humans – within a commercial rabbitry to evaluate the relative effects of sex and age on the transmission dynamics therein. We did this by developing an a priori set of hypotheses outlining how natural B. bronchiseptica infections may be transmitted between rabbits. We discriminated between these hypotheses by using force-of-infection estimates coupled with random effects binomial regression analysis of B. bronchiseptica age-prevalence data from within our rabbit population. Force-of-infection analysis allowed us to quantify the apparent prevalence of B. bronchiseptica while correcting for age structure. To determine whether transmission is largely within social groups (in this case litter), or from an external group, we used random-effect binomial regression to evaluate the importance of social mixing in disease spread. Between these two approaches our results support young weanlings – as opposed to, for example, breeder or maternal cohorts – as the age cohort primarily responsible for B. bronchiseptica transmission. Thus age-prevalence data, which is relatively easy to gather in clinical or agricultural settings, can be used to evaluate contact patterns and infer the likely age-cohort responsible for transmission of directly transmitted infections. These insights shed light on the dynamics of disease spread and allow an assessment to be made of the best methods for effective long-term disease control.

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Recent literature has indicated that animals seropositive for Clostridium piliforme may have negative findings on polymerase chain reaction (PCR) testing. This study examines and reports on the results of serology, PCR and histopathology tests performed on a group of 20 laboratory rabbits seropositive for C. piliforme using the latest available diagnostic methodologies. The presence of the organism was not confirmed by either PCR or histopathology in this group of 20 for C. piliforme seropositive rabbits. This presents challenges for laboratory animal veterinarians and scientists wishing to establish the presence of the organism with commonly available diagnostic methods and means that clinical signs of disease in addition to diagnostic results must be interpreted together.

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With the ever-increasing call to reduce self-imposed regulatory and administrative burden in the animal research oversight process, knowledge of the regulations and a desire to streamline policies and procedures are needed to affect a change in culture. In this opinion piece, we provide details on why institutionally imposed regulatory burden can arise.