The contaminated pet food withdrawn from the market last week has killed up to 35 dogs countrywide, the manufacturer has announced.
At least 10 dogs died at a single Paarl veterinary clinic.
The pet food maker, Aquanutro, warned last week that a small number of dog food batches had been contaminated by ethylene glycol. The substance is a type of coolant, popularly known as anti-freeze.
The company said it had been alerted late in 2006 by dog owners and a veterinary surgeon who said the products caused renal failure.
On Tuesday Aquanutro chief Dirk van der Linde said: "There are so many rumours flying around, but I don't think it was more than 30 to 35 (dead) - somewhere around there."
One breeder in Paarl, who asked not to be named, said he had lost three boerboels. And a Gordon's Bay animal rescue centre owned by sisters Wendylle and Lynne Fuller reported losing five dogs.
Emile du Plessis of the Market Street Animal Hospital in Paarl said on Tuesday that he knew of at least 10 dogs that had died after eating the pet food.
"Some had permanent kidney damage - we conducted blood tests and it confirmed kidney problems - and we had to euthanise them."
He said dogs usually suffered from liver problems, and the kidney problems were "quite unique".
He had treated the first sick dog in late December and a post-mortem and subsequent tests had proven the presence of ethylene glycol. Yet the products were not withdrawn until this month.
"We were quite shocked. I don't know why it took so long for the penny to drop," Du Plessis said.
One of the dogs that died was "Flekkies", a Jack Russell belonging to Lana Carstens, who lives on a smallholding outside Paarl.
"He started losing weight. Two days later he started vomiting. I took him to the vet, they gave him an injection, put him on a drip.
"From the beginning (the vet) said there were signs of poisoning. They operated on him.
"Eventually his kidneys gave in and we had to put him down."
Carstens said she had not deliberately changed her pet food brand, but a new product had been given to her husband.
Her other dog, a German Shepherd, "didn't like the food, so she didn't eat it, so she didn't get sick".
But her Jack Russell's death was "very traumatic".