Pet owners warned over ‘deadly’ algae in lakes after death of four dogs

Fermanagh vet says her practice has dealt with a number of cases in which dogs died after swimming in stagnant water in Lough Melvin on border of Leitrim and Fermanagh

A Fermanagh vet is warning pet owners to keep animals away from lakes or ponds with stagnant water following the deaths of four dogs who had been swimming in a lake on the border of Leitrim and Fermanagh. Aoife Ferris of Lakeland Veterinary Services in Belleek, Co Fermanagh told RTÉ radio’s News at One that her practice has dealt with a number of cases recently in which animals died after swimming in a nearby lake, Lough Melvin.

“We’ve been seeing a couple of cases of dogs that have been swimming or have been playing along the shores of one of the lakes nearby. Immediately, after they’ve come out of the water, some of them have started to present with signs such as drooling from their mouth, frothing at their mouth, seizures. And ultimately, unfortunately, these dogs have passed away pretty quickly after being down there.

“We do see these kinds of cases after periods of very hot weather. So we would encourage all dog owners, not just around here, to keep their pets away from any lakes or ponds where there is stagnant water.”

While an investigation is under way, including water sampling, Ms Ferris said that all the clinical signs indicated that the deaths had been caused by algae in the water.


“It is an algae called blue green algae. And it is very, very toxic to pets. They don’t necessarily have to ingest the water. It can be something as simple as having a little bit of this on their paws and licking their paws afterwards. It can cause acute organ failure.”

The vet added that unless the animals were treated immediately, in most cases they died.

“Usually it works on the body very fast. It’s very, very toxic. So it’s really important for pet owners to be aware of this,” she said.

The algae can appear in the form of scum on top of the water, it can also be brown in colour and can be present in foam that appears on the shoreline and can have an earthy or musty smell. The algae could also be harmful to humans, she said.

“From the research that we have done over the last number of days, we can see that it can cause illness in humans. So it would be important for people to maybe avoid swimming in those areas as well.”

Last year warning signs for algal bloom were erected on Lough Leane in Killarney, Co Kerry, after the death of a number of dogs in recent years. Blue-green and brown algal scum, caused by the build up of phosphates, has been visible on occasion in the lake since the 1980s. A study in the 1990s identified agricultural waste as the chief cause.

Meanwhile, Inland Fisheries Ireland has urged the public to report any sightings of fish in distress, or that have died, over the bank holiday weekend.

The State agency said it was concerned due to reduced oxygen levels in lakes, rivers and streams during the fine weather.

“Air and water temperatures are approaching dangerous and potentially lethal levels for salmonids in parts of the country,” said its head of operations, Barry Fox. “The risk to fish mortality may be unavoidable due to low oxygen levels and thermal stress.”

Thermal stress affects many fish types once water temperatures rise above 20 degrees.

IFI has also appealed to boat owners to help stop invasive species spreading in rivers, lakes and canals by checking, cleaning and drying their boats and equipment when travelling from one waterway to another.

The appeal is especially aimed at those using the River Shannon and tributaries.

“This will greatly contribute to slowing the spread of very harmful organisms such as the bloody red Shrimp, Zebra mussel - and the Quagga mussel, which was first detected on the Shannon’s lakes in 2021,” Mr Fox said.

“We are asking boat owners and anglers not to move any watercraft between waterbodies due to the risks involved in carrying invasive species with them. However, if they must do so, then we urge them to make time to disinfect their boats and fishing equipment afterwards as per Check, Clean, Dry guidelines”.

Vivienne Clarke

Vivienne Clarke is a reporter