Looking at records from 229 United Kingdom veterinary practices between 2012 and 2017, the researchers discovered that Christmas is when dogs are most at risk, when they're four times as likely to go to the vet due to chocolate exposure than at other times of year.
Dogs don't react well to certain chemicals in cocoa beans and eating chocolate can lead to vomiting, irregular heartbeat, signs of agitation or seizures.
Not all dogs are equally at risk. Valentine's Day and Halloween were not risky times for theobromine dog poisonings, perhaps because the study was not done in the U.S.
Vets are preparing for a spike in cases of chocolate poisoning over the next week - with advent calendars, chocolate Santas and Christmas decorations all seen as a tasty targets by your dog.
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The team found that around Easter, dogs were twice as likely to have chocolate exposure than on non-holidays.
In all, the investigators found 386 cases from 375 dogs, meaning that some dogs had been taken to the vet for eating chocolate a couple of times. Agitation and restlessness occurred, but were less common, only appearing in 12 cases, while seizures were not reported at all.
None of the cases seen by vets were considered to be life-threatening, researchers at the University of Liverpool said.
The researchers suggest while considering the findings, dog owners should be aware of the increased risk around Christmas and Easter and they should keep chocolate away from their dogs.
Pet owners are told to call the vet immediately if their dog ingests chocolate - some affects won't appear until a few hours after consumption and catching it early helps the dog recover faster.
If you are anxious your dog may have eaten a toxic amount of chocolate, call your vet immediately and be prepared to describe the type of chocolate and the amount consumed.