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Can your pet be moonstruck?

Original Publication Date: September 21, 2015
By C. Sue Furman, Ph.D.

A full moon is rising next week. Legend has it that werewolves come out to howl and prowl at the full moon.

Many believe that dogs bay more during a full moon and cats yowl their mating calls with extra fervor.

People have long conjectured that there is a lunar effect that triggers strange behaviors in animals and people. The term lunatic derives from luna, the Greek word for moon.

The Greek philosopher Aristotle suggested that because the brain is the moistest organ in the body, it is vulnerable to the influences of the moon, which triggers the tides. The idea persisted for many years because of the fact that about 80 percent of the body is water. It was even thought that the moon could somehow disrupt the alignment of water molecules in the nervous system. However, the moon's gravitational force only affects large open bodies of water like lakes and oceans not the small amounts of water found in the brain.

Some speculate that animals are especially active at the full moon because of the increased amount of light so they tend to prowl more and get into mischief and potential trouble. Until recently, all explanations were only suppositions.

Reagan Wells, DVM and colleagues in the College of Veterinary Medicine and Biomedical Sciences at Colorado State University, wished to evaluate the number of dogs and cats that showed up for emergency medical care in relation to the cycle of the moon. The findings were published in the Journal of the American Veterinary Medical Association.

The study, "Canine and Feline Emergency Room Visits and the Lunar Cycle," was the first of its kind and provided thought-provoking results. The researchers evaluated the medical records of 11,940 animals - 9,407 dogs and 2,533 cats- during an 11-year period.

Dog howling at the moon Dog howling at the moon
(click image to enlarge)

They categorized the emergency visits into several types including animal bite, cardiac arrest, epilepsy, gastric dilatation-volvulus (bloat), trauma and poisoning and calculated the phase of the moon for each pet visit.

The investigators found a significant increase in the number of dogs and cats seen for emergency medical care when the moon was full or was waxing and waning (more than half full). There was a 28 percent greater chance that dogs and a 21 percent increased probability that cats would show up to see an emergency room veterinarian.

This is the first study of its kind, so more research is necessary to determine if the increase in emergency room care was because of the phases of the moon or if other factors were in play.

Early legends explaining why dogs bark and cats yowl at the full moon are no longer convincing, but recent scientific investigation indicates that animal behavior correlates with the phase of the moon. Pending more research, we are left to speculate just why our pets bark or yowl when the moon is full.

Sue Furman, Ph.D, has published two books and a DVD on canine massage and teaches classes in pet massage, acupressure, first aid and CPR. See her schedule and submit questions at