CONTRIBUTOR(S): Elizabeth Youens, Vetstream Ltd, Fear Free,
Blue-green algae poisoning
Blue-green algae poisoning
Many dogs enjoy a swim or paddle on a hot day, but care must be taken to avoid areas with blue-green algae. Blue-green algae appear in many bodies of water, and its blooms appear as green or greeny-brown scum on the water surface. These blooms contain organisms which can produce toxins under certain conditions. These toxins can cause severe illness and even death in dogs, and so care must be taken to prevent dogs swimming or ingesting water in affected areas.
What is blue-green algae?
Blue-green algae is present in many areas of water (mostly fresh but also in stagnant ponds) and can be harmless. In fact it is a group of bacteria and not an algae at all. Some of the bacteria in the group can produce a toxin which is very harmful to animals. However, in certain conditions – usually in late spring or summer – ‘blue-green algal blooms’ form which are clumps of the bacteria on the surface of water. These can appear as scum on the surface or dots or flakes in the water. They are usually blue-green in colour but can also be reddish brown. The scum may accumulate near the shore due to the wind and wave movement. These blooms usually appear in summer when there is plentiful sunshine, and the water is rich in nutrients, and so this is when the danger is highest.
How do dogs get poisoned?
Signs of toxicity can occur very quickly, but this will depend on the specific type of bacterium, and therefore toxin, ingested.
Some types produce neurotoxins which can cause dramatic effects within 15-30 minutes of exposure: excess salivation, muscle tremors, staggering, weakness/collapse, seizures, difficulty breathing and even sudden death. Signs may be more delayed (hours to a few days) with toxins that mostly affect the liver and kidneys. Signs of organ damage include weakness, loss of appetite, muscle tremors, pale or yellow gums, vomiting and diarrhea (which can be bloody) and collapse.
If your dog develops any of these signs or appears generally unwell, and has recently been near water (even if only briefly), blue-green algae poisoning should be considered, and quick action must be taken.
How will my veterinarian diagnose blue-green algae poisoning?
Definitive diagnosis of toxicity depends on finding the cyanobacterium in water samples or on the dog’s coat or in their vomit. However the bacteria can’t be seen with the naked eye and, if there are suggestive clinical signs and your dog has been near water, your veterinarian may just act on the suspicion that your dog has been poisoned, especially if it is the right time of year. Your vet will take a blood sample to check how the liver and kidneys are functioning. Sadly, many dogs do not survive, even with treatment, and diagnosis might be confirmed at post-mortem.
How will my veterinarian treat my dog?
There is no specific antidote for blue-green algae toxicity, but your veterinarian will focus on managing the specific signs your dog is displaying. Basic treatment includes making the dog sick to bring up any toxins not yet absorbed from the stomach, gastric lavage to help wash out toxins before absorption, and an intravenous drip to counter the effects or shock, maintain blood volume and support liver and kidney function.
If your dog is convulsing, or showing severe muscle tremors, medications such as sedatives, muscle relaxants or even full general anesthesia may be used to control this. Artificial respiration under anesthesia may be needed if your dog is struggling to breathe due to the effect of the toxins on the respiratory system. If the liver is affected, medication to protect the liver, stop blood clotting and maintain correct electrolyte balance may be needed, as well as intravenous fluid therapy. In some cases, blood transfusion is indicated.
Will my dog recover?
The prognosis is unfortunately quite poor. Dogs that have ingested only small amounts of toxin, and who receive exceedingly prompt treatment may recover, but some are left with chronic organ damage.
What can I do to protect my dog from blue-green algae poisoning?
Not all blue-green algae are poisonous, but it is impossible to tell from looking at them which ones produce toxins so never let your dog near water with algal scum on, especially during the spring and summer months. The local council or Environment Agency will often erect signs to warn of blue-green algae in known problem areas, so watch out for these. Keep your dog on a lead around areas with confirmed toxic blue-green algal blooms and do not let them swim or drink in these areas. If your dog has been swimming, wash them off thoroughly with clean water as soon as possible. If you think your dog may have ingested blue-green algae, take them straight to your local veterinarian.
If you see any signs of blue-green algae when you are out and about with your dog always report it to the Environment Agency so that they can test the water and put up signs to warn other dog owners.