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RWAF response to Vetcompass dental disease frequency and risk factors May 2024

RWAF Response to Dental disease in companion rabbits under UK primary veterinary care: Frequency and risk factors, Charlotte C. Burn, Joanna Hedley, Dave C. Brodbelt, Dan G. O’Neill.

We have been asked what our thoughts are on the recent study by Maria Jackson and other researchers from the Royal Veterinary College, published in the Veterinary Record (VR) at the beginning of this month. (Jackson et al., 2024, below).

RWAF Response to Dental disease
RWAF Response to Dental Disease

The RWAF has enormous respect for the VetCompass team and the authors of this paper. We welcome all research into rabbit health and welfare as rabbits are often a forgotten species, and sadly, their welfare can sometimes be seen as of lesser importance compared to dogs and cats.

The dominant message from this new VetCompass study is that it overwhelmingly confirms dental disease as a major health and welfare issue in pet rabbits in the UK. Dental disease in pet rabbits is a complex, multi-factorial disease, with poor and inappropriate diet universally recognised as by far the most important cause. Working to ensure pet rabbits are provided with the correct diet is a goal we all clearly need to continue to address, both through education and working with the companies that produce and sell rabbit food.

However, the altered conformation (body shape) in almost all pet rabbits is also recognised to play a major role in dental disease and, whilst not all studies so far have found a link, the absence of a statistically significant link does not refute there being a connection, and several existing studies are listed below for people to look at them for themselves.

Therefore, we would like to share some concerns about the way some parties are interpreting the new VetCompass study with regard to conformational factors such as brachycephaly. In summary, these concerns are;

  • The study looked at the huge amount of data collected by veterinary practices throughout the UK. This is brilliant for accessing large amounts of data, but it will always be at the mercy of those originally supplying the data and entering it. This is highlighted in the fact that almost half of the rabbits were not recorded with a formal breed or type, meaning we simply don’t know whether they were brachycephalic, lop-eared or anything else. With that unavoidable gap in the data, the conclusion has to be that while the statistics don’t confirm the connection found in the other studies that the authors reference, they also don’t prove a lack of connection either and that more work (and more detailed breed recording) is needed.

    However, the study DOES show that Rex rabbits, not the commonest breeds, but ones where the breed is likely to have been very accurately recorded and with head shapes more closely resembling their wild cousins than probably any other breed except Belgian Hares, are at significantly lower risk of dental disease.
  • By far, the main cause of dental disease in rabbits is diet, with all other factors having much less of an impact. Not all brachycephalic rabbits develop dental disease, certainly, but particular strains of Netherland Dwarfs (and breeds derived from them, such as Lionheads) have the genetic makeup to have an undershot jaw, a Class 3 facial malocclusion, which means that the front teeth will never meet. But both that and any increased tendency for other brachycephalic rabbits to show dental disease is simply swamped by the much more significant effects of diet. As the authors of the study also explain, looking at the pet rabbit population, practically ALL those rabbits are more brachycephalic than their wild ancestors, and so, picking out those which are a bit more brachycephalic than the average is a judgment call.
  • The study looked at the primary care records of rabbits presented for any and all reasons. As more detailed examinations were not performed to look for dental disease, we can’t be sure that the true number of rabbits with dental issues wasn’t greater.
  • Indeed, the study highlights the fact that many rabbits still have their teeth clipped, which can lead to fractures of the roots, and many rabbits do not have radiographs taken – the most accurate way to diagnose dental disease.

Dental issues are not the only potential health concern of brachycephalism. Brachycephaly may also have an impact on ear disease and blocked tear ducts and these issues were not looked at in this study.

It is our view that this is an excellent piece of work highlighting dental disease as a major health and welfare concern in the pet rabbit population. However, as with every piece of veterinary and other forms of research, there are several limitations to how the results can be interpreted.

It is clear that much more research is still needed in this area. To fully assess the impact of conformation (RWAF) would welcome further studies looking at rabbits at exotic/rabbit referral centres where all rabbits presented could be properly categorised by conformation and breed, examined for the presence of dental disease, including radiographs where appropriate, and diet taken into account (although we acknowledge that this would carry its own biases) (Bartlett et al, 2010).

Until a wider range of studies are performed, looking at all aspects of rabbit dental (and other health and welfare) issues, RWAF plans to retain our current precautionary view, supported by the several other studies cited in this study, that brachycephaly is detrimental to the health and welfare of rabbits. We will happily review this stance with time and further research.

And, in any case, rabbit breeders have altered the natural conformation of the domestic rabbit so far from that of their wild ancestors that nearly all domestic rabbits are, to some extent or another, brachycephalic and we are simply distinguishing between slightly and very brachycephalic in our breed definitions. (BRC Rabbit Breed Standards 2021-2025).

In summary :

  • The results rely on the breed and conformation of the rabbit being correctly entered at reception.
  • The results do not take into account ear disease and blocked tear ducts.
  • Most domestic rabbits can be considered to be brachycephalic in some form.
  • The take-home message is that diet is of the utmost importance in ensuring dental health.

For anyone who wants to read the study for themselves, it is available as a full, free, Open Access download from the VR website.

Jackson MA, Burn CC, Hedley J, Brodbelt DC, O’Neill DG. Dental disease in companion rabbits under UK primary veterinary care: Frequency and risk factors. Vet Rec. 2024;e3993. https://doi.org/10.1002/vetr.3993

Other references:

Fiorello CV, German RZ. Heterochrony within species: craniofacial growth in giant, standard, and dwarf rabbits. Evolution. 1997; 51(1): 250–261.

Geiger M, Schoenebeck JJ, Schneider RA, Schmidt MJ, Fischer MS, Sánchez-Villagra MR. Exceptional changes in skeletal anatomy under domestication: the case of brachycephaly. Integr Org Biol. 2021; 3(1): 1–31.

Siriporn B, Weerakhun S. A study of risk factors, clinical signs and radiographic findings in relation to dental diseases of domestic rabbits. KKU Vet J. 2014; 24(2): 201–213.

Capello V, Gracis M. Anatomy of the skull and teeth. In: AM Lennox, editor. Rabbit and rodent dentistry handbook. 1st ed. Lake Worth: Zoological Education Network; 2005. p. 3–42.

Mosallanejad B, Moarrabi A, Avizeh R, Ghadiri A. Prevalence of dental malocclusion and root elongation in pet rabbits of Ahvaz, Iran. Iran J Vet Sci Technol. 2010; 2(2): 109–116.

Palma-Medel, T., Marcone, D. and Alegría-Morán, R. (2023) ‘Dental Disease in Rabbits (Oryctolagus cuniculus) and Its Risk Factors—A Private Practice Study in the Metropolitan Region of Chile’, Animals, 13(4), 676.

Johnson JC, Burn CC. Lop-eared rabbits have more aural and dental problems than erect-eared rabbits: a rescue population study. Vet Rec. 2019 Dec 21;185(24):758. doi: 10.1136/vr.105163. Epub 2019 Oct 1. PMID: 31575760.

Bartlett, P.C., Van Buren, J.W., Neterer, M. and Zhou, C. (2010) ‘Disease surveillance and referral bias in the veterinary medical database’, Preventive Veterinary Medicine, 94(3-4), 264-271, available: http://dx.doi.org/DOI: 10.1016/j.prevetmed.2010.01.007.

BRC Rabbit Breed Standards 2021-2025.

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