Dog owners should be careful around Nelson rivers after one animal died and others have become sick, victims of possible poisoning by toxic algae.
Town and Country veterinarian Mark McGinley said a dead dog had been brought in and there had been other cases of dogs with vomiting and diarrhoea over the past few days.
With warm days and little rain, conditions were right for toxic algae to bloom.
His comments come after a Facebook message was circulated among Nelson people saying that a dog died after returning from a swim in the Appleby River.
It had begun having seizures within 30 minutes, the message said, and died before the family could get it to a vet.
Mr McGinley said owners should be "pretty wary" if they saw algae floating or forming mats on the side of any river in the district.
However, as far as he knew algae was only suspected as the cause of the problems. Even mouldy food could be a serious danger, depending on the toxins that developed.
"At this time of year dogs get into all sorts of things."
Nelson City Council warned a month ago that dog owners should keep their dogs away from parts of Nelson's Maitai River which were infested with blue-green cyanobacteria algae.
- The Nelson Mail
Does Nelson deserve to be classed as a city?Related story: (See story)