Blue-Green Algae: The Summer Water Hazard That Kills Dogs Fast

What it is

'Blue-green algae' (cyanobacteria) blooms in warm, still, nutrient-rich water — lakes, ponds, even backyard fountains — especially in late summer. Some blooms produce toxins that attack the liver or nervous system, and dogs die from it in the US every year.

What risky water looks like

Pea-soup green, blue-green paint streaks, foam or scum along the shoreline, or mats of material in the shallows. But toxic blooms aren't always visible — heed posted advisories and local news, and when in doubt, keep dogs out.

Exposure is an emergency

Dogs are poisoned by swimming, drinking, or licking algae off their coat. Signs — vomiting, drooling, weakness, stumbling, seizures, collapse — can start within minutes to hours. Rinse the dog with clean water and get to a vet immediately; do not wait.

Safer summer swims

Choose flowing rivers or maintained dog pools over stagnant ponds in hot months, bring drinking water so they're not tempted, and rinse your dog after any natural-water swim.