SNOHOMISH — An investigation by Snohomish County Parks &Recreation has determined that a dog most likely was poisoned at Willis Tucker Park on Thanksgiving Day. The dog later died.

There have been numerous reports on social media over the past several months of alleged poisonings, starting in November, but the Thanksgiving Day incident is the only one the county has been able to confirm.

Even then, the only confirmation is that the poisoning happened, not where or why.

“The vet determined it was indeed poisoned with rat poison,” said Park Ranger David Green in Willis Tucker Park on Friday. “They couldn’t confirm if the dog consumed it here or somewhere else.”

Another incident described on social media involved three dogs that fell ill after playing in the off-leash area of the park on Jan. 8. It has not been confirmed.

Officials have not been able to locate and contact the owner of those three dogs, and Green said he visited five veterinary clinics nearby. One clinic reported receiving three calls on Saturday, Jan. 9, and referred the owner over the phone to the 24-hour emergency animal hospital in Lynnwood.

None of the vets, including the emergency hospital, reported treating any cases of poisoning, however.

Green said that county officials didn’t even learn of the poisonings until messages started appearing on Facebook. One post from Jan. 12 seemed to refer to the Thanksgiving Day incident, suggesting the dog ate a poisoned meatball while in the off-leash area of Willis Tucker Park.

The post was second-hand, however, referring to the pet owner as “one of my clients.”

A message sent to the poster of that message by The Daily Herald was not returned Friday. The identity of the dog’s owner is unknown.

In investigating the incidents, park officials identified the Thanksgiving Day incident, plus two more poisonings in private yards in Marysville and one in a private yard in Lake Stevens. Those cases were believed to be related to neighbor disputes and referred to police and Animal Control officers.

No poisonings were found to have occurred at other county operated off-leash areas in the Tambark Creek, Lake Stickney and Cavelero parks, Green said, and the county has increased monitoring of the parks since they became aware of the first instance. Warning notices have been posted at off-leash areas.

“The safety of people and the dogs is the number one priority for the Parks Department,” Green said.

Chris Winters: 425-374-4165; cwinters@heraldnet.com. Twitter: @Chris_At_Herald.

Report suspected poisoning

If your pets fall ill after an outing in Snohomish County parks and poisoning is suspected, the Parks Department requests that the owners contact them directly at 425-388-6600.