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Blue-green Algae Poisoning in Pets

Blue-green algae can be found in any stagnant water sources including garden ponds, garden pots, bird baths and fountains!

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Blue-green algae are not technically algae, but the name used to describe a group of bacteria called cyanobacteria. These bacteria can’t be seen with the naked eye but when they clump together on the surface of the water they can look like green, blue-green or brown algae. They’re appearance is sometimes describes as a blue-green scum or foam and often accumulates at the edges non-flowing fresh water such as ponds, lakes and reservoirs. They are most abundant during periods of hot, sunny weather and low rainfall in mid-to late summer months.

Not all types of blue-green algae are dangerous, but some can produce toxins which are very harmful to a dog’s liver. Unfortunately, it’s not possible to tell which blue-green algae are toxic and which aren’t, without laboratory testing. These algae are poisonous to other animals too when swallowed, including to humans.

If you think your dog may be suffering with blue-green algae poisoning, contact your vet immediately. 

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Signs of blue-green algae poisoning


  • Vomiting
  • Diarrhoea/dark, tarry stools
  • Lack of appetite
  • Excessive drooling
  • Confusion/disorientation 
  • Weakness/collapse or even coma
  • Muscle tremors/seizures
  • Breathing difficulties

If left untreated, blue-green algae poisoning can cause liver failure and quickly be fatal. Always contact your vet if you are worried about any of these signs. Even though many of them are seen with other (less serious) conditions, early aggressive treatment is key for the best chance of success.

Treatment of blue-green algae poisoning


There is no specific antidote for blue-green algae poisoning and depending on the signs, your vet will use supportive treatments such as oxygen therapy and a drip.

More intensive care may be required if your dog has more severe signs such as collapse and seizures. Your vet may also induce vomiting to remove the algae from your dog’s stomach or give activated charcoal to absorb the toxins.

Prevention of blue-green algae poisoning


  1. Never ignore blue-green algae warning signs or news reports
  2. Don’t let your dog drink from or swim in water you suspect might be contaminated
  3. If you see blue-green algae, assume they are toxic and keep your dog away from the water
  4. Always rinse your dog thoroughly after they’ve been swimming

Remember blue-green algae can be found in any stagnant water sources including garden ponds, garden pots, bird baths and fountains!