Canine Lunacy: Is my dog really more prone to bite because of the Full Moon?

(This is an article my Mum wrote back in August 2008. ~ Shelby)

My interest in observing animal behaviour has been rekindled since we bought a beautiful 7 week old Border Collie puppy last September, who we named Shelby.

My baby at 7 weeks old, snoozing after a long day.
My baby at 7 weeks old, snoozing after a long day.

I’ve been observing Shelby’s behaviour over the last few months since we’ve had him and I’ve become aware of an interesting, but slightly disturbing trend. My darling puppy gets a special ‘crazy-eyed’ look and is much more excitable, snappy and potentially dangerous around the time of the full moon, starting a couple of days before the moon reaches its fullest and calming down again a few days later. His play becomes far more aggressive and impulsive and he is more prone to ‘bitey’, snappy behaviour – never serious rip-your-arm-off biting but overly aggressive play biting, which still hurts a LOT when he makes contact – ouch!

My "little" puppy sprawled out on a 2-seater lounge.
My little puppy sprawled out across a 2-seater lounge.

While still being basically well behaved there’s definitely a noticeable change in him – he’s generally just that little bit harder to control. He’s only just turned 1 year old so he’s still very much a puppy in his behaviour and outlook on life – trouble is he’s a very BIG puppy …with very BIG teeth! And, because he’s a Border Collie, I’ve been told by many people – and read the same in many different sources – that he’ll maintain his youthful exuberance and puppyish outlook for much longer than many other breeds of dogs – probably another 2 or 3 years!

Naturally I turned to Google for further information on this intriguing topic and came across lots of articles both for and against belief in the full moon having any effect on human and animal behaviour.

But first, a bit of background info…

‘The word lunacy derives from the Latin for moon, ‘luna’. History is littered with references of madness being linked to cycles of the Earth’s closest celestial neighbour. Several studies have tried to get to the bottom of this age-old belief. A 1976 report compared 34,318 crimes against the lunar cycles. It found offences occurred more frequently during a full moon. However, most research has failed to find any firm link between the cycles of the Moon and irrational behaviour. In the United States, a 1983 survey of 361,580 calls for police assistance showed no relationship to the phase of the Moon. English law has not always agreed. The link between the Moon and madness was acknowledged in the 1600s by Sir William Hale – who was later to become chief justice.

He wrote: ‘The Moon has great influence in all diseases of the brain, especially dementia.’ The Lunacy Act of 1842 built on this ‘logic’, and as recently as 1940 a soldier who was charged with murder pleaded ‘moon madness’. Some notable murder cases have been tied to the lunar phases. Of the eight murders committed by New York’s infamous ‘Son of Sam’, David Berkowitz, five were during a full moon. A series of chilling murders by Charles Hyde in the late 1880s – the inspiration for Robert Louis Stevenson’s Dr Jekyll and Mr Hyde – were committed under a full moon. However, it is not always a full moon that is blamed for murder and mayhem – lunar eclipses can prove more hazardous. In 1974, 16 residents of Phnom Penh, Cambodia, died when soldiers decided a hail of bullets would frighten away the ‘monkey’ eating up the Moon.

Those who advocate a link between madness and the Moon will often cite the ‘biological tides’ theory as the basis of their belief. The theory states that since the Moon’s gravity pulls on huge bodies of water, causing ocean tides, then it will have an effect on the human body, which is, after all, 80% water. However, scientists point out that any biological tide is swamped by the effect of the beating of our hearts and the heaving of our lungs. Theories about the Moon’s influence on animal behaviour are more widely accepted in the scientific world. Researchers in Bradford correlated 1,621 dog attacks reported between 1997 and 1999 with lunar phases. The results suggested people were twice as likely to be bitten around the time of a full moon.

On a lighter note, many gardeners still work to the phases of the Moon, believing that it is best to sow seeds and transplant seedlings only with a waxing, never a waning moon. The Old Farmer’s Almanac says: ‘Plant flowers and vegetables during the height of the Moon.’ The theory is said to take advantage of gravity, light and magnetism.’ (1)

Now, back to the animal behaviour topic…

Some studies on animal behaviour cited changes in behaviour that could be attributed to the increase in light at night during a full moon. Prey animals tended to be less active, which in turn affected the behaviour of the predators (2).

‘An intriguing July 2007 study by the Journal of the American Veterinary Medical Association found that full moon emergency room visits for pets were increased compared to the rest of the month, to the tune of 23% higher for cats and 28% higher for dogs. Why? Nobody has a clue. Could it be that people and their pets tend to spend more time outdoors in the brightness of a full moon, and hence get into more trouble? A 2001 study that appeared in the British Medical Journal was based on admissions to a human emergency department and concluded that there are more animal bites of humans in and around the time of the full moon than in any other lunar phase. The biters included dogs, cats, rats and horses.’ (3)

I found lots of other articles claiming that the moon does indeed affect the behaviour of pets (4) and after some more Googling I found the British Medical Journal article referred to above (5)…

‘The word ‘lunacy’ is derived from Luna, the Roman goddess of the moon, and from the belief that the power of the moon can cause disorders of the mind. The effect of the phases of the moon on human nature and behaviour is well documented; some studies show positive aspects of the association and some show negative aspects. Crime, crisis incidence, human aggression, human births, and traffic accidents are all positively correlated with the phases of the moon. Some articles have suggested that the full moon has no influence on human insanity, alcohol intake, drug overdose, trauma, or the volume of patients in emergency departments.

We are not aware, however, of any correlation between the full moon and injury to humans by animals. In ancient mythology the day of the full moon was a day for driving away misfortune and evil. We aimed to determine if any pattern exists of animal attacks on humans during a full moon.

In our study we showed that an association exists between the lunar cycles and changes in animal behaviour and that animals’ propensity to bite humans accelerates sharply at the time of a full moon. Further experiments are needed to verify our hypothesis. Few other studies have correlated the influence of the full moon with behaviour of animals or insects. One article has suggested that the predatory activity of mites is significantly depressed during a full moon.

The moon, ever present, will continue to influence different aspects of nature and humans. More studies are therefore needed to explore lunar effects on animals, especially their propensity to bite humans.’ (4)

Beware! ...the crazy-eyed dog!
Beware! …the crazy-eyed dog!

Hmm… well, in my opinion it certainly appears to be the case that there are lunar effects on animals, causing them to bite more – at least in the case of my darling doggie.

Now, changes in behaviour due to the level of light at night time are quite understandable and easily explained, but what would cause the behaviour changes that are observed during the daytime hours when the level of moonlight is not an issue? Maybe they’re all just grumpy with “short fuses” due to lack of sleep after staying up all night to play in all that extra moonlight? LOL!

Or perhaps the animals are somehow sensing and reacting to the subtle changes in gravitational pull of the moon and the sun on the earth, which increases at the time of a new moon and a full moon. (6) Hmm… must try to see if Shelby’s behaviour changes at the new moon as well now.

Unfortunately none of the articles I’ve come across so far offer any ‘scientific’ explanations, only observations that this behaviour change does happen. Regarding the study above, I’m also curious to know what time of day the people were bitten – was it only at night when the moon was visible or were the bite times randomly scattered throughout the daytime hours as well, indicating that something other than the light itself is influencing their behaviour (unless the animals are all just grumpy, as I suggested above)? Shelby’s snappiness is during daytime hours when we’re interacting with him a lot. I haven’t played with him outside in the moonlight – too cold and I’d rather be in bed! Although occasionally my sleep is disturbed by Shelby barking at possums in the trees beside the verandah where he sleeps as the possums seem to be more active during a full moon …annoying little buggers! LOL

Well at least I know now to be more careful of my dog’s ‘moods’ when approaching the full moon and to supervise my youngest son (11years old) more carefully when he plays with the dog at these times, as he is most vulnerable to the dog’s attitude change.

...just so you can see his gorgeous brown eyes without the flash.
…just so you can see his gorgeous brown eyes without the flash.

Well, whatever the cause, its an interesting observation and one worth keeping in mind, especially where children and pets are concerned. I’m interested to hear if anyone else has noticed any changes in their pets around full moon time.

1. Mad on the Moon
2. A note on the effect of the full moon on the activity of wild maned wolves, Chrysocyon brachyurus
3. Animals and the Full Moon Effect – Does the Earth’s Favorite Satellite Cause Behavior Changes?
4. The effect of the full moon on pets
5. Do animals bite more during a full moon? Retrospective observational analysis
6. The Moon and Tides

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