Blue-green algae in local parks: A Hidden Risk to Dogs in Summer
If you enjoy walking your dog in local open areas, always check that the pond water is safe to drink or swim in, writes Pippa Duncan
As the weather warms up and we enjoy long days outdoors, local dog walkers should be aware of a serious seasonal hazard in freshwater ponds and lakes: blue-green algae. This naturally occurring organism – actually a type of bacteria called cyanobacteria – can rapidly multiply in slow-moving or stagnant water during hot, calm weather, forming dense ‘blooms’ that produce potent toxins. These cyanotoxins can cause severe illness or even be fatal to dogs if ingested or swallowed while swimming.
The worst risks tend to appear in the hotter summer months, when sunlight and nutrient-rich water fuel explosive algal growth. In Richmond Park, blue-green algae is most commonly associated with the Pen Ponds, particularly during prolonged warm spells. However, other ponds and water bodies – whether in parks, commons or local green spaces – can also harbour blooms. Locally, blue-green algae has been reported in ponds on Wimbledon and Putney Commons, such as Kingsmere, Scio and Hookhamslade. It’s better to be safe than sorry around all pond water or in still or slow-moving waters including park lakes, reservoirs and ornamental ponds, so always check for signs stating it is present.
One of the dangers is that it is not always obvious. While blooms can resemble pea soup, green flakes, surface scum or foam at the water’s edge, it can also look like normal water. Symptoms can include vomiting, diarrhoea, drooling, weakness, breathing difficulties, seizures and collapse. These can develop rapidly and there is no specific antidote. If you suspect your dog has been exposed, seek emergency veterinary help immediately.