"We had a lot of rain and some decent floods in the time the signs were up," Mr Smith said.
"We weren't aware of the date of the drop and thought the risk of poisoning would be low."
His partner returned with their dog, which started showing signs of 1080 poisoning several hours later including vomiting, disorientation, frenzied hysteria, and maniacal behaviour.
"The actual mechanism of the poisoning is pretty convoluted and quite complicated.
"It works at a cellular level and most animals die of heart failure very quickly. They're usually dead within a matter of minutes.
"We heard of one dog that went in to the stage of frenzied hysteria, took off out the door and was dead before it got to the wool shed.
"It can happen very quickly."
Mr Smith and his partner live near the Featherston clinic of South Wairarapa Veterinary Services where he works, to where the couple dashed their pet, calling for support while travelling.
Fellow vet Richard Kirton had been first to respond after duty vet that day, Jane Ough, initially medicated Tess and gave her anesthetic to make her sleep.
Another vet joined the team that day along with two clinic nurses and Masterton vet John McLaren, who provided a vital component of treatment called acetamide, and his receptionist as well.
Other nursing staff from the practice also helped with the emergency treatment, Mr Smith said, and Tess was kept in an induced coma with round-the-clock monitoring until Monday night.
He and his partner barely slept in the immediate wake of the poisoning although after Tess survived the first two nights in an induced coma, their hopes grew that she would survive.
She was at one point fitted with three intravenous drips running simultaneously and her recovery from the anesthetic "was long and slow and quite nasty and rough on her", he said.
"She loves to chase tennis balls and by the middle of the week, by Wednesday, when she finally managed to catch the ball, we knew she'd be okay," Mr Smith said.
"I don't know if I'd go as far as calling her a miracle dog but she's lucky a whole lot of things fell in to place.
"If just one of those steps had not worked, she would have died.
"We certainly recommend a lead and a muzzle and urge owners to take precautions whenever the signs are out.
"Prevention and caution is far better than trying to pull them back from the brink."
