Does the Moon Really Affect Your Pet's Behavior?

By Linda Cole

In the horror movies, a full moon can bring out unnatural creatures of the night and send them wandering across the land. The moon plays a role in the ocean tides and gives us an awesome sight in the night sky when it's full. Rumors and legends claiming that people and animals act strange during a full moon persist even today, but can the moon really affect your pet’s behavior?

For centuries, people have used a full moon to explain odd behavior and the common belief is it can have an effect on both people and animals, including pets. Dogs are supposed to howl more during a full moon, and cats yowl their mating calls with more passion. There have been attempts to study whether a full moon really can affect people abnormally and cause some people to become more aggressive or commit more crimes just before or right after a full moon. Some studies have shown increased visits to emergency rooms on days prior to and after a full moon, but there is no study that can absolutely say a full moon is the cause. It's possible emergency rooms see more patients a few days before and after a full moon because it's lighter outside at night and there's a higher percentage of people out and about which could create increased chances of more accidents.

A study on pets was done in 2007 by a researcher at Colorado State University College of Veterinary Medicine and Biomedical Sciences. Raegan Wells, DVM, wanted to find out if pets were affected by a full moon. She wanted to know if, like people, pets experienced more injuries or got into more trouble during periods when the moon was full. She discovered a correlation between more emergency visits for both cats and dogs during the period just before or after a full moon. The study, “Canine and Feline Emergency Room Visits and the Lunar Cycle,” was the first of its kind and was published in the Journal of the American Veterinary Medical Association.

Wells went back over an 11 year period and charted emergency visits at the clinic and noted when full moons had occurred within that time frame. During the 11 year period, 11,940 pets were seen at the university's veterinary medical center. The visits consisted of animal bites, epilepsy seizures, cardiac arrest, gastric problems, trauma, and other emergencies. The vets saw 9,407 dogs and 2,533 cats. According to Wells, there was a 28 percent greater chance for dogs and a 21 percent increased chance for cats to be seen by emergency personnel during periods of full moons.

This is the only “full moon” study that’s been done on pets, and researchers are still trying to understand if the increase was actually due to the phases of the moon or if there were other explanations that might increase a pet's chances of having to visit an emergency vet. Wells said of the study, “It is difficult to interpret the clinical significance of these findings.”

However, in the wild, there is some evidence that animals are affected by the moon. For a couple of nights each year, there are hundreds of corals called reef builders that release their eggs and sperm into the water at precisely the same time. It's considered to be the largest moonlight sex event on Earth. In another species of coral called Acropora millepora, scientists have discovered a light sensitive gene that seems to be more active during full moons.

Azara's owl monkeys that live in Argentina forests are more active at night during full moons, and because they spend more time roaming around, they sleep in the next morning. Scientists also learned that the monkeys would stay put and not move about when there's no moon.

A study done in 2006 discovered that prey is more apt to hunker down during full moons because there's more light and it makes them easier to be seen by a predator. Researchers wanted to see if a full moon made a difference in a predator’s behavior as well. Over a period of four lunar cycles, they tracked three wild wolves during full moons and new moons and found that predators, like their prey, are less active during a full moon.

As far as our pets being affected by a full moon, the jury is still out. However, during periods when it's lighter outside, we should remain vigilant and keep a close eye on our pets overall health, and be mindful of their environment to keep them safe and out of the emergency room.

Photo by Pieter Vanhaecke

Read more articles by Linda Cole