Taking Care Sourcing Drinking Water For Horses

Summer may seem months and months way, but when the warmer months approach, there is nothing more refreshing for yourself or your companion animal than a cool drink of water. You would never expect that a water source could actually cause health problems in your pet. You may have heard of the growth of blue green algae in water sources. Algae blooms often occur in lakes, rivers and reservoirs and are a source of toxins which could be potentially fatal. So what are these toxins? Can they be treated and how can I ensure my horse avoids them?

Algal Blooms

Blue Green Algae is toxic to horses*

During the later summer months of 2014, cyanobacteria, commonly known as blue-green algae, was found, amongst other algaes, in numerous lakes throughout Kentucky. Blue-green algae naturally exist in damp environments but will become fast growing in warm, stagnant, nutrient-rich water. Algae blooms occur when vast populations of algae group together and thrive in freshwater and marine water environments. Due to their expansive nature, their presence can reduce water quality. This leads animals which rely on the water source to drink less water during the hot, dry summer, which can cause dehydration and illness. There are more than 2,000 species of blue-green algae with at least 80 known to produce cyanotoxins (poisons).

Toxic water

Although algae blooms can happen anytime throughout the year, they are most likely to occur between March and September when the weather is warmer. Although not all algae are harmful, contaminated water sources where there has been a run off of fertilizer or manure and urine, provide the ideal environment for toxic blue-green algae. Hot, dry weather causes the algae to grow rapidly (the “bloom” which is seen as a green, blue-green, white, or brown coloring on the surface of the water.) From a distance, it can look as though paint is floating on the surface. During windy weather, or over time, the blooms concentrate along the water’s edge where livestock are more likely to drink.

Toxic Effects

Animals that drink water containing cyanotoxins can die suddenly or progressively suffer from weakness, staggering, or photosensitization, depending on the type of toxin and how much they ingest. These Cyanotoxins affect the liver and nervous system. It has been established that blue green algae is implicated in illness and human and livestock death in at least 35 states and in more than 50 countries worldwide. Taking some simple steps to protect your horse and other livestock can prevent illness and even death.

How to Protect Your Horse’s Water Sources.

If you suspect that a water source contains any algae, it is advisable to keep your horse away from the water completely. Always assume it is toxic!

  • To keep existing water safe, provide clean, fresh water which is fenced off and cannot be contaminated with feces or urine.
  • Keep the horse away from natural water sources which are considered unsafe.
  • If a water source is treated with an algaecide, prevent animal access for at least a week to allow any toxins released in the water to degrade.
  • Creating and maintaining natural buffers. Use trees and shrubs to help filter out excess nitrogen and phosphorus before they reach the water.
  • For humans, don't swim in water with scum layers or blooms and avoid jet skiing, windsurfing, tubing, or water skiing over scum or blooms. Don’t use untreated water for drinking, cleaning food, or washing camping gear. Boiling water will not remove algae toxins. Thoroughly wash any skin that comes into contact with a bloom. Don’t eat shellfish caught or harvested from a bloom area.
  • Farmers who notice algae blooms in ponds intended for livestock use should have the water tested, as not all algae blooms produce toxins.


Blue green algae presents an issue for livestock such as cattle and horses as well as for pets such as cats and dogs. During summer months, it is regularly found in water sources throughout the U.S., so keeping abreast of local news and warnings regarding local water bodies, you should be able to effectively prevent your pet from ingesting these harmful toxins.

 *Image courtesy of Dollar Photo Club