Dental disease in donkeys: frequency and association with colic and body condition

Research award
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Four part project including surveys, case control study, and retrospective analysis of database.

  1. To describe and estimate the prevalence of abnormal dentition in the donkeys housed at The Donkey Sanctuary.
  2. To identify and quantify risk factors for colic, in particular impaction colic, in donkeys at The Donkey Sanctuary and on foster in the UK.
  3. To describe and quantify the association between dental disease and impaction colic in donkeys.
  4. To describe and quantify the association between dental disease and body condition score in donkeys in the UK.
  1. Dental examination records from Jan 2003 to Mar 2005 found 43.6% of donkeys had dental disease, of these 12% had more than one abnormality. Disease included missing teeth (34.1%), step mouth (4.7%), shear mouth (4.3%), wave mouth (1.5%), diastema (1.3%), undershot jaw (1%), overshot jaw (0.3%). There was a positive correlation between age and dental disease. Results of the 2006 prospective study found a much higher incidence rate of dental disease,92.1% of the sample had at least one dental abnormality/disease.
  2. Results obtained from retrospective database analysis from Jan 2000 to Mar 2005 found incidence rates for colic and impaction colic were 5.9 and 3.2 episodes per 100 donkeys per year respectively. Peaks were seen in late autumn and troughs in spring/summer. 51% of impaction colics resulted in death or euthanasia. Dental disease, musculoskeletal problems, previous history of colic and farm location were all identified as risk factors. Donkeys that were older, on extra feeds or underweight were also at an increased risk of suffering colic. Donkeys in foster homes between Sept 2004 and Aug 2005 had a lower incidence rate at 1.4 cases per 100 donkeys per year. Of these animals those fed 2 concentrate meals per day, or those bedded on rubber were more at risk of colic. Results from the prospective study Jan to Dec 2006 multivariable analysis which was performed in response to questions raised in the first part of the study found that a number of donkey and management variables were associated with the risk of impaction colic. The greater the number of carers responsible for the donkey, the greater the increase in risk with donkeys with 1 or 2 carers at the lowest risk. Donkeys that were fed extra rations as concentrate feed were at a 5 fold increased risk of impaction. In addition animals with no access to pasture were at increased risk (odds ratio 3.4) compared to those with 24 hour access. Donkeys bedded on paper were at increased risk of colic, however this has wide confidence intervals due to the small number of cases and controls that were bedded on paper. These animals were in the hospital and at 2 other farms. Animals that were vaccinated in the previous 2 weeks were also at increased risk of colic. Animals that had weight loss in the previous 4 weeks were at increased risk of colic although few animals had this health problem. Other variables relating to body condition did not remain in the multivariable model. A number of dental pathologies remained in the multivariable model; these included missing cheek teeth, ulcers, diastema and worn teeth which all increased the risk of colic. The presence of hooks was still associated with decreased risk of colic. After allowing for the above variables age was no longer significant (P=0.9) and forcing age into the model did not changed the effect of the other variables. Forcing of month (or season) into the final model showed that this was not significant, demonstrating that this model explains some of the seasonality. The farm level variation was zero after the inclusion of fixed effects suggesting that these fixed effects explained differences in farm.
  3. There was a significant increase in the frequency of dental disease in donkeys that died from colic (80/94) than in those that recovered from colic (34/53) between Jan 2003 and March 2005. Results of the 2006 prospective study also confirmed an association between dental disease and colic, 92.1% of the sample had at least one dental abnormality/disease. Number of missing teeth and diastemata are positively correlated with impaction colic. There pathologies were also associated with ageing, whereas hooks and sharp edges were found in younger animals and not associated with increased risk of impaction colic.
  4. Initial results from the retrospective analysis found donkeys with dental disease had a marginally significant (p=0.05) lower body condition score of 4/10 compared to 4.7/10 in those without dental disease. These results were supported by the prospective study which also found lighter/lower condition animals more at risk of impaction colic.

The incidence of colic in donkeys appears similar to that reported in horses. Age, weight, dental disease and supplementary feeding are known to be risk factors in other equines.