Mystery remains over source of poison that killed three dogs

by Kim Bowden - Dec 19, 2023

A visit to a riverside spot by Otago Regional Council staff has shed no light on the source of a poison that killed three dogs there over the weekend.

A walk with his beloved pets along a stretch of the Manuherekia River close to Alexandra took a disastrous turn for a holidaymaker from Riversdale on Saturday.

The animals ended up dead, presumably poisoned after consuming something on the banks of the Central Otago river.

However a visit by regional council staff yesterday revealed no signs of toxic algae, which both the vet involved with the case and council staff suspected to be the culprit.

As a result, no warning signs have been erected.

ORC scientist Helen Trotter, an expert on water quality, says a thorough assessment Monday morning of the site, as well as another popular river access point downstream of it, uncovered none of the algae.

"These observations are consistent with recent results of our routine monitoring at Shaky Bridge and at Galloway which have also not found potentially toxic algae to be present."

Council staff have been testing known hotspots across the region since the start of December, as the algae is potentially deadly to both humans and animals and is more likely to be present during periods of warm weather and low water flows.

Warning signs are already in place in Ophir, upstream from the Galloway Road location where the deadly dog walk took place.

Ms Trotter says the ORC was notified of the incident on Sunday afternoon. But a response team has been unable to solve the mystery.

"With no toxic algae visible at Galloway Road it is unlikely that toxic algae at this site caused the dogs’ deaths.

"My thoughts are with the dogs’ owner as, whatever the cause, this will be very upsetting for them."

The Riversdale man says the fact that council staff found no trace of the toxic algae "seems strange" as, according to the vet, that was the cause of the dogs' deaths.

He says blood tests taken from his three English springer spaniels confirmed they suffered liver, lung and kidney failure.

He is heartbroken by the loss.

Despite warning signs elsewhere on the Manuherekia River and nearby Butchers Dam, regional council staff yesterday found no sign of toxic algae at a site where three dogs were poisoned on the weekend.

"I came up (to Central Otago) to visit my friends and came home with three dead family members."

He wants to get the message out to other dog owners to be wary of waterways over summer.

"If I had any idea of what was going in the rivers there I would have never gone near them. My dogs were my life.

"I hope this helps other dog owners because I know how much my dogs meant to me and don't wish that hurt on anyone."

Despite the mystery around what caused this weekend's deaths, Ms Trotter is still warning anyone walking dogs on Central Otago waterways to know how to spot potentially dangerous algae to try and keep their animals safe.

"While toxic algae was not found in or around the Manuherekia near Galloway Road (yesterday), it is commonly found in and around waterways over summer and it’s important people, dog owners in particular, are vigilant.

"Dogs should be kept on a leash to steer them away from the water and riverbanks. One teaspoon can be enough to be fatal."

Learn how to identify potentially toxic algae by visiting LAWA, and report any suspected sightings to the ORC pollution hotline on 0800 800 033.

Known hotspots for it in Central Otago include Butchers Dam, Cardrona River, and Hāwea River, in addition to the Manuherekia River.

Main image: Pixabay/zoegammon

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