Blue-Green Algae Toxicity Average Cost

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What is Blue-Green Algae Toxicity?

Blue-green algae toxicity in horses, known as cyanobacteria, is a poisoning that occurs in horses from coming into contact with infected water. The blue-green algae is found in water on farms and in stagnant ponds that are contaminated with urine, manure, fertilizer, or other unclean substance that encourages this toxic algae to form.

There are over 2,000 species of this algae known and approximately 80 are confirmed poisonous. These are also poisonous to other animals besides horses, and to humans as well. When horses ingest this water, they can become very ill. The influx of phosphorus and nitrogen within the algae growth occurs when the temperature is hot and the air is dry. 

Horse owners are unable to see with the naked eye whether a pond or other water source contains this toxic algae. The only way of knowing if blue-green algae are present is by having the water tested in the laboratory. Water that is infected with the algae may have a tint of blue-green or blue-green blooms that give a sheen within the water, and this may or may not be the actual algae that is toxic. It is important for horse owners to have pond water that the horse grazes around tested for this algae. Horses that drink affected water succumb to the toxicity. Often, animals are found extremely ill or dead close to the source of water.

Animals can be severely poisoned after drinking just a few ounces of infected water. If the water bloom is not very dense and has a lower content of the cyanotoxins, your horse may survive unless he drinks several gallons of the water. Whether or not the water is deathly toxic depends on the concentration in your pond or water supply.

Blue-green algae toxicity in horses occurs when horses ingest stagnant water, or affected pond water, with concentrations of a specific type of blue-green algae. Blue-green algae toxicity in horses can be fatal.

Symptoms of Blue-Green Algae Toxicity in Horses

Treatment of blue-green algae poisoning is symptomatic. Symptoms of toxicity in horses may include:

  • Difficulty breathing
  • Decreased movement
  • Muscle tremors
  • Pale gums
  • Collapse
  • Convulsions
  • Diarrhea
  • Blood in the stools

There are several types of blue-green algae on the continent of North America. Not every strain of each genera produce toxins. The environmental situations, including amount of sunlight, pH of the water, temperature, and the concentration of nutrients all play a role if toxins are present. It is important to know the types for laboratory testing purposes. Blue-green algae that may have toxins are poisonous are: 

  • Microcystis
  • Anabaena
  • Oscillatoria
  • Aphanizomenon

Causes of Blue-Green Algae Toxicity in Horses

Causes of blue-green algae toxicity begin with the ingestion of an infected water source. The cells of the algae die in the water and then release the toxins.  Specific causes include:

  • Blue-green algae affects the nervous system
  • Algae produces severe toxins
  • Neurotoxins are present
  • Toxins may affect the liver
  • Photosensitization from the toxic algae can occur

Diagnosis of Blue-Green Algae Toxicity in Horses

If your horse is showing any signs of toxicity and has been exposed to different water types, contact your veterinarian immediately. Often, horses are found too late, after they have succumbed to the poisoning. Your veterinarian will immediately assess your horse’s symptoms and perform blood work and other laboratory tests, if needed. He will ask you questions about his environment, namely about any water supply your horse may drink from.

Your medical professional may perform a complete blood count, biochemistry profile, and urinalysis to test for any increases in microcystins, bile acids, and to also test for hyperkalemia and hypoglycemia. He will also be looking for any depressed activity of blood cholinesterase.

Your veterinarian may want to perform testing on the water your horse drinks from. The water sample will be taken from an area of the water in which the algae is present. Typically, one gallon of water is used for testing. Your horse may also exhibit signs of stains on his coat of blue-green color. 

If your horse has already passed, necropsy testing will be done on the tissues of his stomach, brain, and liver. This will lead the veterinarian to a definitive diagnosis and will alert you to take measures to remove your animals or other horses away from the infected water.

Treatment of Blue-Green Algae Toxicity in Horses

Unfortunately, there is no antidote for blue-green algae poisoning. Typically, if the horse has ingested the water, he will not survive. If your horse is surviving, treatment methods may include:


Your veterinarian may administer activated charcoal to your horse to absorb any of the toxins in his stomach contents. The effectiveness of this treatment is very questionable, as it usually does not prove to be helpful in horses who are experiencing a moderate to severe level of poisoning.

Supportive Therapy

Your medical professional will treat your horse’s symptoms, namely hypovolemia and decreased electrolytes, with fluid therapy. IV fluids can rehydrate your horse and help the body flush any urine through the kidneys.


Medications may be given if your horse is having seizures from the neurotoxins. Drugs such as diazepam or atropine may be given intravenously to control muscle tremors, anatoxin, and seizures.


Once your horse is stabilized, he will need to be constantly monitored by your veterinarian. Fluid therapy and any drug administration will need to be repeated until your horse is showing signs of recovery.

Recovery of Blue-Green Algae Toxicity in Horses

Once your horse is able to go home, he will also need to be very closely monitored according to your veterinarian’s instructions. Your medical professional will want to have repeated visits with your companion to be sure he is becoming well again.

Horses should be placed in an area away from the affected water supply. Fresh water and high-quality feed should be always available for your horse. Horses that have responded to any treatment methods have a very good chance of recovering from blue-green algae toxicity. Because the toxins have a steep dose-response curve, surviving animals have a good chance for recovery. 

If there is no other water supply that is available to your horse, you can consult with your veterinarian and he can help you with options to keep your horse safe. Horses should only be allowed to ingest water from any shore areas that are free of any surface scum. You may also want to ask your professional about adding treatments to the water, such as copper sulfate or other copper treatments. Phosphorus treatments may also be an option; once again it is important to gain the advice from a professional who is very knowledgeable about your water content and what can be done to possibly eliminate the toxins. Testing the water frequently is very important, as it is very difficult to completely remove the toxins from any water; however, this depends on the level of toxicity in your pond or water source, and what technologies are available in your area.