There are apparently many different types of blue-green algae which are found in water and which play an important part in its bio-diversity.  Usually they are there in small quantities which are harmless but in still, warm, sunny weather the algae multiply very quickly and become excessive.  They can be seen as a blue-green scum or bloom on the surface of ponds and lakes and even at the edge of the sea in some places.

About 50% of the different types of algae are poisonous, and it is very difficult to tell them apart from those which are harmless, so it is safer to assume they are all poisonous.  Don’t let your dog drink from, or swim in water with algae floating on it.  Some authorities put up warning signs if they know it is there.

If your dog does come into contact with the algae and becomes sick then see your vet as an emergency as it can be very serious and dogs have been known to die, although this is rare.

Symptoms of poisoning can be seen within minutes or maybe take a few hours to show.

They include:

  • Lethargy
  • Panting
  • Excessive salivating
  • Vomiting –possibly with blood
  • Diarrhoea
  • Muscle weakness
  • Difficulty in breathing
  • Seizures
  • Black, tarry stools

If your dog gets the algae on his coat then wash or hose him down and don’t allow him to lick himself clean as he will be ingesting more.  Also don’t let other dogs in the house clean him either.

These algae have been found as far north as The Shetland Isles in the UK, and also in other parts of the world as well and can vary in colour to red or black.