Last year two dogs died after consuming the toxic cyanobacteria algae from the Cardrona River. The Otago Regional Council is warning dog owners to watch where their animals go as temperatures increase and river levels drop.
The algae occurs naturally in waterways but becomes a problem in summer when it forms thick mats on river beds, especially during low flows.
Regional council director of engineering, hazards and science Dr Gavin Palmer said the council was unable to monitor all waterways in Otago for the algae so people needed to be aware of the risk wherever they were.
The algae was found in the Cardrona and Manuherikia rivers last summer but would have also been present in other streams and waterways in the region, he said. Last year the council warned people to keep dogs away from the Cardrona River after two dogs died in February.
People could be affected by ingesting algae or skin contact.
Dog owners spoken to on the Upper Clutha River Track next to the Cardrona River said they were aware of the algae and would be cautious about it.
Signs of a dog having consumed the algae included lethargy, muscle tremors, fast breathing, salivation, twitches, paralysis or uncontrolled shaking, convulsions and frothing at the mouth.
Anyone concerned a pet had consumed the toxic algae should immediately contact a vet.
