Blue-green algae, which poses a health risk to humans and animals, flourishes during warm spells. Hot and dry weather across the UK in the spring and summer often leads to UK environment agencies confirming reports of blue green algae nationwide.  Dogs are at risk because they enjoy drinking and playing in lakes and ponds, and may lick their fur after swimming. With the summer rapidly approaching, it’s time to make sure that you know how to keep your pets safe.


What are blue-green algae?

Blue-green algae has certain characteristics of an algae, but is technically classified as a bacterium, called cyanobacteria. It can be found in freshwater lakes, streams, ponds and brackish water ecosystems. Some species produce toxins that can pose a risk to human health, and be life threatening to animals that swim in and drink from contaminated water.


Why are blue-green algae an issue in the summer?

Heavy blooms are most abundant during periods of sunny, dry weather. Some suggest global warming may increase its prevalence. The algae are most likely to be found in nutrient-rich water; agricultural runoff of fertilizers and animal waste may increase the phosphorus and nitrogen levels, intensifying blooms.


How would I know blue-green algae was there?

In the right environment the algae “blooms”, undergoing a population explosion which gives a pea soup appearance, or look like blue or green paint, or sometimes brown foam, on the surface of the water. Because the blooms can float, they may be blown by the wind into thick layers near the shore, easily accessible to livestock, pets and people. The toxic bacteria use up oxygen in the water so you may see dead fish.

Even if there is no foam on the surface of the water, it doesn’t mean blue green algae isn’t present. It can be suspended at various depths, depending on the conditions.

Throughout the summer months UK environment agencies test water samples for the algae. They then inform landowners so they can take steps to warn the public of any potential dangers. This could may be the local authority, or a private landowner. They are encouraged to inform users of the water, by way of posters, notices or other means.


Are algae always harmful?

No, not all species produce harmful toxins. However it is not possible to determine the presence of toxins without testing, so all blooms should be considered potentially toxic. Very small exposures, such a few mouthfuls of certain algae-contaminated water, may result in fatal poisoning.


How can my pet be affected by blue-green algae?

Symptoms depend on the toxin involved. There are two broad categories of toxins: toxins that affect the liver (hepatotoxins), and those that affect the nervous system (neurotoxins).

Exposure to the hepatotoxins can lead to liver damage and failure. Signs of liver injury include vomiting, diarrhoea, bloody or tarry stools, weakness, pale gums, yellowing of the gums or skin (jaundice), and seizures. These signs normally occur within 1-24 hours of exposure. Long term damage or even death from liver failure can occur within hours or a few days.

Neurotoxins may cause excessive secretions (salivation, tears), muscle tremors, muscle rigidity, paralysis, blue discoloration of the skin and gums, and difficulty breathing. These signs can occur within minutes, and may cause death quickly due to respiratory paralysis. Livestock may be found dead near an infected water source.


How is poisoning diagnosed?

Often we make a tentative diagnosis using a history of exposure and the symptoms alone.

Blood samples would show elevated liver enzymes, a low blood sugar, a low protein, and possibly abnormal clotting.

Blood samples, urine samples, and water samples (including any foam) can be tested for toxins. These tests are not routine, and may take time. Treatment must be initiated immediately and cannot be delayed pending these results. As there is no antidote, a positive result will not actually affect your pets treatment, but may be useful in order to warn others of potential dangers in the area.


How is algae poisoning treated?

Although there is no antidote for the toxins produced by blue-green algae, immediate veterinary care is still imperative. Your pet may need oxygen and is likely to need intravenous fluids to help flush the toxins from the body. Treatment depends on the symptoms. Your dog may require intensive care and medication for seizures, respiratory distress or liver failure. Surviving pets have a good chance for recovery.


Can the algae harm people?

People exposed to the algae when swimming or taking part in water-sports can suffer skin rashes, nausea, vomiting, stomach pains, fever and headaches. Occasionally they can cause more serious illness such as liver and brain damage. Children are at greater risk because of their comparatively lower body weight.


Is there anything I can do to prevent algae poisoning?

If you suspect algal blooms or see dead fish or animals near the water, do not let your dog drink or swim in it. If your dog has been swimming, always wash them afterwards. Look for warning posters when walking your dog. If there are warnings, keep your dog by your side or avoid the area all together.

If you think an area may be contaminated, report it to your local authority or local environment agency. To report algal blooms in England call the Environment Agency 24-hours-a-day on 0800 80 70 60. More details can be found here.

People can now record the presence of harmful algal blooms with an app called “Bloomin’ Algae”. Details of this app can be found here. This app has been created in collaboration with the Environment Agency, Scottish Environment Protection Agency, Public Health England and Health Protection Scotland. It enables users to submit a photo of the bloom and state what activity takes place at the location, so that the potential risks to people and animals can be gauged.


What do I do if I think my pet has been affected?

If you suspect your dog was exposed to blue-green algae, contact us immediately for guidance. Although there is no antidote, aggressive and early therapy gives your pet the best chance.