The Deepest Blood Moon Until 2028 Was Overnight. A 10-Year Vet ER Study Found 28% More Dog Visits Around the Full Moon.

A deep partial lunar eclipse crossed the sky overnight, running from 9:23 p.m. EDT Thursday to 3:01 a.m. EDT Friday and reaching its maximum at 12:12 a.m. EDT.[1] Just over 96% of the moon slid into Earth's shadow — enough to turn nearly all of it a rusty red without quite qualifying as totality — and it was the best lunar eclipse anywhere on Earth until New Year's Eve 2028.[1][2] Something like 987 million people were positioned to see every phase of it.[1]

Which makes this a reasonable morning for the question that surfaces whenever the moon does something dramatic: does any of it reach the dog?

The study everyone cites

There is one real piece of veterinary research behind the folklore, and it is better than the folklore deserves.

Researchers at Colorado State University's veterinary teaching hospital went back through nearly 12,000 emergency case histories for dogs and cats spanning 1992 to 2002, and compared visit volume against the lunar calendar.[3] On the days around a fuller moon, the risk of an emergency visit was 23% higher for cats and 28% higher for dogs.[3] The work was published in the Journal of the American Veterinary Medical Association in July 2007.[4]

Then comes the part that rarely travels with the headline. Lead author Dr. Raegan Wells put the finding in plain terms: "While the results of our retrospective study indicate that there is an increased likelihood of emergency room visits on the days surrounding a full moon, it is difficult to interpret the clinical significance of these findings."[3]

In absolute numbers, the effect worked out to roughly one extra cat or dog per full-moon night.[3] And the obvious explanation — that animals get scrappier under a bright moon — did not hold up: the data showed no increase in injuries related to aggressive behavior.[3]

So the honest summary is that a busy emergency clinic may see one more patient than usual, for reasons nobody has pinned down, and that the reasons may have as much to do with people being outside longer as with anything happening inside the animal.

Two studies, opposite answers

The bite research lands in the same ambiguous place, which is itself informative.

A team at Bradford Royal Infirmary in England reviewed 1,621 patients treated for animal bites between 1997 and 1999 and reported that incidents were roughly twice as high on and around full-moon days.[5]

In the same period, Professor Simon Chapman and Stephen Morrell at the University of Sydney ran the equivalent analysis on a year of Australian dog-bite hospital admissions and found nothing — 4.6 admissions on full-moon days versus 4.8 on other days, with the real spike clustered around New Year rather than any lunar phase.[5]

Chapman's proposed explanation for the discrepancy was less about dogs than about people: more pleasant evening walks under a bright moon means more humans within reach of a dog that was going to bite someone eventually.[5]

Two competent studies, two opposite conclusions, and a plausible mechanism that has nothing to do with lunar influence on animal behavior. That is roughly where the science sits.

What definitely does change animal behavior

There is an astronomical event with a well-documented effect on animals, and it is the other kind of eclipse.

During the total solar eclipse of August 2017, researchers observed 17 species at Riverbanks Zoo in South Carolina. About 75% of the mammals, birds and reptiles showed a behavioral response.[6] The most common reaction was simply the evening routine arriving early — gorillas, elephants and giraffes heading toward their enclosures, birds shifting activity — apparently because the light and temperature drop told their internal clocks it was dusk.[6] The second most common response was anxiety: pacing, coordinated running, more vocalizing.[6]

A lunar eclipse does not do that, and the reason is straightforward. It happens at night, and what changes is the brightness of the moon rather than the presence of the sun. There is no false dusk for a circadian clock to react to. The moon dimming from full to a dull copper is a smaller change, in the middle of the night, than a cloud passing over at noon.

The part of eclipse night that actually involves your pet

On a night like last night, the variable that shifts most is human behavior. People are outdoors at midnight who are normally asleep, front doors are propped open, neighbors are gathered in yards, and dogs and cats are out at hours they usually are not.

That is the part worth planning around, and it applies to the next meteor shower just as well:

• Leash, even in the yard. A dog that is reliable off-leash at 7 p.m. in daylight is a different animal in the dark, among unfamiliar people, with wildlife moving around.
• Check that the microchip registration is current before the night you need it, not after. A chip with a disconnected phone number on it is the most common way a recoverable pet stays lost.
• Keep cats in. Dawn and dusk are peak hunting hours for most of the predators that share suburban neighborhoods, and a late-night gathering with an open door is a good way to lose track of a cat.
• Don't force the viewing. If your dog would rather be inside, inside is a fine place to be. There is nothing for a pet to gain from watching an eclipse.
• No eye protection needed. Lunar eclipses, unlike solar ones, are entirely safe to look at with bare eyes — for you and for anyone standing next to you on four legs.[2] The eclipse-glasses guidance that circulates every August applies to the sun, not the moon.

For daytime solar eclipses, veterinary guidance is more specific: keep pets indoors and away from crowds and traffic, hold to normal routines, stay calm yourself since animals read human emotion, and make sure ID tags and microchip records are current in case something bolts.[6] Notably, the same guidance says not to bother with eclipse glasses for pets — animals don't stare at the sun.[6]

Where this leaves the folklore

The moon is not doing much to your dog. There is a real, repeatedly-cited study showing slightly busier emergency nights around a full moon, and the researcher who ran it was careful to say she could not explain it and could not vouch for its clinical significance. The bite literature contradicts itself. The one astronomical event with a solid, measured effect on animal behavior is the kind that turns midday into twilight, which is not what happened last night.

What did happen last night is that a lot of people were outside in the dark with their pets, several hours past everyone's usual bedtime. If something goes sideways on an eclipse night, that is the likelier reason — and it is the one you can actually do something about.

Sources

1. Space.com, "Partial lunar eclipse August 27-28 — A complete guide to the 96% 'blood moon.'" https://www.space.com/stargazing/lunar-eclipses/august-2026-lunar-eclipse-everything-you-need-to-know-about-the-96-percent-blood-moon
2. NASA Scientific Visualization Studio, "August 27-28, 2026 Deep Partial Lunar Eclipse." https://svs.gsfc.nasa.gov/5672/
3. Colorado State University, "Bad Moon Rising? Lunar Cycle May be Linked to More Veterinary Visits, According to Colorado State University Study," July 16, 2007. https://newsmediarelations.colostate.edu/2007/07/16/bad-moon-rising-lunar-cycle-may-be-linked-to-more-veterinary-visits-according-to-colorado-state-university-study/
4. Wells RJ, et al., "Canine and feline emergency room visits and the lunar cycle: 11,940 cases (1992-2002)," JAVMA, July 15, 2007. https://pubmed.ncbi.nlm.nih.gov/17630892/
5. ABC Science, "Do dogs bite more during a full moon?" December 22, 2000 (covering the two BMJ analyses). https://www.abc.net.au/science/articles/2000/12/22/226987.htm
6. dvm360, "Understanding animal reactions to a solar eclipse." https://www.dvm360.com/view/understanding-animal-reactions-to-a-solar-eclipse