The owner of a rest home near Otamatea Reserve says his organisation has never used rat bait because of the danger it would cause pets.
Last week several dogs that had walked at the reserve became unwell and there were concerns unwell rats had been seen drinking from a trough at Otamatea.
The Whanganui District Council said one of the sick dogs was taken to Massey University for tests but it's yet to hear back on the results.
One woman who walked her dogs at Otamatea Reserve was concerned a nearby rest home had possibly laid down rat bait.
The Chronicle understands that concern has been repeated among others in the dog-walking community.
Philip Tebbutt, who owns the Virginia Lodge Rest Home next door to Otamatea Reserve, denied he would have ever used rat bait.
"That is just absolute rubbish," he said.
"We've got dogs and cats here as well. If anyone's going to get poisoned it would be mine.
"To be fair I'm here all the time ... I haven't seen a rat running around my place. We do have mice traps out and we do get the odd mouse but the cats keep them down fairly well."
Tebbutt said he'd never had contractors or anyone from outside his rest home that could have used rat bait.
"I do it all myself. I do all the trimming, the mowing, the hedges, general maintenance. It's not possible it could have come from this place - not at all.
"I spoke with my nurse manager and she and her partner had run it here for the last 25 years and they'd never put rat baits out. She was horrified."
Tebbutt said it was more likely that if rat bait had made its way to Otamatea Reserve it would have come from one of the households surrounding the park.