Dog walkers are being urged to take extra care after police received reports of poison on the ground in Parkhurst Forest.
A number of pets are understood to have fallen ill in recent days after being walked in the area, on the outskirts of Newport.
Now, police have confirmed the Cowes Neighbourhood Patrol Team (NPT) are stepping up patrols - and are urging the public to report any suspicious activity.
A Hampshire and Isle of Wight Constabulary spokesperson said:
"Please be vigilant and if you think your dog may have eaten poison, seek veterinary advice immediately.
"We are also urging members of the public to report suspicious incidents to the police including if you find poison.
"If you have gloves and a plastic bag with you, it will be safe for you to pick up and store in a plastic bag, in which case we recommend calling us on 101 and we can arrange to come and collect this from you, so we can make further enquiries relating to the substance.
"But as above, please avoid handling with bare hands, and if you think your pet has ingested the substance, please seek help from your vet immediately."
You can report it by calling 101 or online here - https://www.hampshire.police.uk/ro/report/