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Do dogs bite more during a full moon?

The power of the moon is often used to explain a wide range of events - from human insanity to traffic accidents - but do animals feel more inclined to bite humans during the full moon than at other times? Two new studies have come up with different answers.

This week's British Medical Journal (BMJ) carries two studies - one from the UK which finds that you are more likely to be bitten by a dog when the moon is full, and a study from Australia which finds that you're not.

Chapman et al. (Pic: <i>BMJ</i>)A study by Professor Simon Chapan and Stehen Morrell of The University of Sydney showed no positive relation between the full moon and dog bites requiring hospital treatment. They compared dates of admission for dog bites to public hospitals throughout Australia with dates of the full moon, over a 12-month period.

Overall, full moon days were associated with slightly lower admissions (4.6 compared with 4.8 per day). Of 18 peak days (more than 10 admissions per day) the maximum peak centred on the New Year break. Full moons coincided with none of these peaks.

A study by a team in Bradford, UK on the other hand, has found that animals do have an increased propensity to bite humans during the full moon periods. During 1997 to 1999, they identified 1,621 patients attending the accident and emergency department at Bradford Royal Infirmary after being bitten by an animal.

The chance of being bitten was twice as high on or around full moon days, indicating that an association exists between the lunar cycles and changes in animal behaviour. However, the authors suggest that further experiments are needed to verify these results.

So why the difference between the UK and Australia? Are dogs in the UK more aggressive?

"The only explanation I have is that maybe because of a general drabness in England more people take pleasant walks under the full moon and are therefore more available to be bitten by dogs," speculates Professor Chapman who submitted his article to the BMJ without any idea that the other paper was being submitted.

He decided to do the study after a comment from a farmer on a randomised controlled trial he had done on the use of school programs to prevent dogs biting children.

"Don't you scientists know anything?," the farmer said to him. "You should be looking at why they bite - it's because of the full moon!"
