On Sunday, Te Anau woman Terrin Hansen took her family and her dog Tora to enjoy the day at the Upukerora River.
However, within 20-30 minutes of being there, Tora started showing signs something was wrong, she said.
"She [Tora] came out with her eyes tightly closed and acting like she wanted to vomit. When we opened her mouth, she had froth coming up her throat.
"We induced vomiting and her front legs collapsed under her and then she began groaning."
Mrs Hansen said they immediately called the emergency veterinarian, who was 15 minutes away from the clinic.
"Within that 15 minutes she declined so quickly. We lost her a few times but she was fighting hard for us.
"We got her in just in time to get her on some oxygen and some meds and fluids ... [but] she was still excessively drooling, groaning. The bladder was leaking and within two hours we got the call that our baby had passed."
The news had devastated the family.
Mrs Hansen recalled that in the previous week, her son also became incredibly ill after swimming in the river and started vomiting.
The veterinarian indicated to the family the potential cause was toxic algae poisoning.
Toxic algae (benthic cyanobacteria) can be recognised at rivers and streams as a green-brown slime on rocks, or dark brown/black mats at the water’s edge.
These algae can produce toxins that are harmful to people and animals if swallowed, or through contact with skin.
At the time of the incident there was no toxic algae alert in the area, Mrs Hansen said.
"We feel angry. Angry that there was a lack of knowledge on our behalf ... but more than anything we are feeling broken.
"We have lost an amazing, beautiful, sweet-natured fur baby and all we want is to have her back."
Environment Southland chief scientist Karen Wilson said yesterday the incident was very upsetting, and her thoughts were with the Hansen family.
She confirmed no alert had been issued for the area on the day of the incident.
The Upukerora River at Te Anau-Milford Rd was monitored monthly and, even before the incident, staff had scheduled a monitoring visit for the river on Monday.
"As part of the regular, monthly monitoring programme, Environment Southland staff have undertaken a visual survey of the site and wider area. An alert has now been issued for this site.
"Samples were collected from toxic algae mats, and these will be tested for toxin production."
No toxic algae was present last month — but the site previously had one alert issued in January 2022, she said.
She urged dog owners and people to take extra care.
“River users should keep their dogs on a lead until they have checked the river for algal growth or mats of algae floating in the water.
"Dogs can be attracted to the musty smell of the toxic algae on riverbanks and in the water, and can be poisoned from eating a small amount of the slime or dried slime mats.”
If anyone was concerned an animal had consumed toxic algae or contaminated water, it should be taken to a vet immediately, she said.
