Lunar cycle may be linked to more veterinary visits

FORT COLLINS, COLO. — There may be a link between an increase in emergency-room visits for dogs and cats and lunar-cycle days when the moon is near or at its fullest, according to a study by colleagues at Colorado State University's College of Veterinary Medicine and Biomedical Sciences.

Led by Raegan Wells, DVM, the data were compiled from 10 years and 12,000 case histories of dogs and cats treated at the CVM Veterinary Medical Center. The risk of emergencies — ranging from cardiac arrest to epileptic seizures and trauma — on fuller-moon days was 23 percent greater in cats and 28 percent greater in dogs than other days. The first-of-its-kind study shows the increase was most pronounced during the moon's three fullest stages: waxing gibbous, full and waning gibbous.

The cause of the correlation found in the study, titled "Canine and feline emergency room visits and the lunar cycle: 11,940 cases (1992-2002)," remains unclear.

"It is difficult to interpret the clinical significance of these findings," says Wells. One theory is that full moons provide increased luminosity, which may tie to an expected increase in nocturnal hunting rates among cats.

While the percentage of increase in emergencies during fuller-moon days is large, the correlation to an actual number of animals is quite low. Data show an increase by about one cat or dog during fuller-moon days, Wells says. Additionally, data did not indicate that there was an increase in aggressive behavior in pets during a full moon.