Dog owners are being warned to take extra care when walking their pets near to water because of a rise in a dangerous form of algae.
The British Veterinary Association (BVA) has said blue green algae contain toxins which can be harmful to dogs if ingested.
The algae blooms, which can appear as green or greenish-brown scum on the water surface, has been found in water bodies in Southampton and Fleet, as well as other locations across the UK including Edinburgh, Cornwall and Derbyshire.
Symptoms include vomiting, diarrhoea, drooling, disorientation, trouble breathing, seizures and blood in faeces. These can appear within a few minutes or hours depending on the toxin ingested.
If the symptoms are left untreated they can cause liver damage and be potentially fatal.
The warning comes after three dogs died in North Caroline, in the US, after swimming in an affected pond.
Daniella Dos Santos, BVA junior vice president, said: ‘While not all blue green algae are poisonous, it is impossible to tell the difference visually, so it is better to be safe than sorry.
‘There is currently no known antidote for the toxins, so prompt veterinary treatment is essential to tackle their effects and ensure a good chance of recovery.
‘If you suspect your dog has been exposed to blue green algae, rush it to your local vet without delay.’
The BVA has urged dog owners to look out for Environment Agency warning signs near water, and to wash dogs thoroughly if they have been swimming outside.