Dog exposed to blue-green algae
Blue-green algae blooms can kill dogs within hours — if your dog has swum in or drunk from a scummy pond or lake, head to the vet now even if they seem fine.
In the next 60 seconds
- Get the dog out of the water immediately.
- Rinse the dog thoroughly with clean water — do not let them lick fur.
- Phone the vet immediately.
- Drive to the practice without delay.
Recognise the signs
- Vomiting, diarrhoea (often bloody)
- Drooling, weakness
- Disorientation, seizures
- Difficulty breathing
- Collapse
- Onset within 15 minutes to hours of exposure
First aid steps
- Get the dog out of the water immediately.
- Rinse the dog thoroughly with clean water — do not let them lick fur.
- Phone the vet immediately.
- Drive to the practice without delay.
Do NOT
- Do not let the dog lick wet fur.
- Do not wait for symptoms.
- Do not assume short exposure is safe.
While transporting to the vet
- Bring a photo of the water if possible.
- Phone ahead.
When to phone the vet immediately
- Any known exposure, with or without symptoms
- Any neurological or vomiting signs after pond exposure
Common causes
- Stagnant or slow-moving freshwater with algal blooms — typically ponds, lakes, reservoirs in warm weather
- Common UK summer hazard, especially July–September
What the vet will need to know
- Location of water (was it a known bloom area)
- Length of exposure
- Whether the dog drank, swam, or licked
- Photo of water if taken
Aftercare
- Decontamination, IV fluids, anti-seizure medication, liver support.
- No specific antidote; supportive care.
- Outcome varies — some dogs deteriorate rapidly, others recover with treatment.
Prevention
- Avoid still or scummy ponds in summer — assume any green/blue scum is potential bloom.
- Check Environment Agency or local council alerts in summer.
- Carry water on walks for the dog, do not let them drink from suspect sources.
- If you see warning signs at a water body, take them seriously.
Frequently asked questions
What does blue-green algae look like?
Blue-green or pea-soup-coloured scum on water surface, sometimes with a paint-like sheen. Often forms in warm, still water in summer.
How quickly do dogs die from it?
Some toxins act within 15–60 minutes. Survival depends on exposure and prompt treatment — but it is one of the deadliest UK summer hazards for dogs.
Is salt water safer?
Different risks. Sea water has its own concerns (salt poisoning, jellyfish), but blue-green algae is freshwater. Either can be dangerous in different ways.