Animals, particularly dogs, are at the greatest risk of becoming sick and even dying from the blue-green algae thriving in Kansas lakes and ponds this summer.

Each year, the diagnostic laboratory at Kansas State University’s College of Veterinary Medicine tests water from around the state that is suspected to have made animals sick, said Deon van der Merwe, who directs the toxicology section of the lab. The culprit is often blue-green algae.

“When we see the problem it’s typically during the summer months when we have elevated temperatures. Most of them are in ponds or lakes that are highly fertilized and often associated with agriculture runoff,” van der Merwe said.

A few years ago, several dogs died after drinking water from Marion Reservoir in central Kansas. The water was never tested, but blue-green algae were suspected to be the cause.

“Dogs seems to be somewhat sensitive to it,” said Steve Adams, who is a natural resource coordinator for the Kansas Department of Wildlife and Parks.

Heavy rains this spring followed by hot and calm days over the summer created prime conditions for algae growth in many of the state’s water bodies.

With such good growing conditions, algae blooms started to occur with plants multiplying exponentially. It’s at that point that blue-green algae produces toxins that are poisonous to a number of species, most notably dogs and cattle.

Humans are also susceptible to the toxin; they just aren’t as prone to drink out of scum-covered ponds, van der Merwe said.

The toxins released from the plant can cause liver failure and less frequently cause problems in the nervous system, van der Merwe said. The end result can be fatal.

Common warning signs are when an animal stops eating, becomes lethargic, vomits or has diarrhea. Animals will behave abnormally if there is damage to the nervous system.

Symptoms can occur within a day and be present within minutes or a couple of hours after the animal drinks from the tainted water.

Van der Merwe advises pet owners to take their animal to the vet immediately if they notice early warning signs.

“A significant portion of animals will die,” van der Merwe said.

He also recommends for pet owners to keep animals out of ponds or lakes on hot, calm days when conditions are ripe for algae blooms or when they see pound scum.

The poisonous toxin isn’t the only negative effect that large algae blooms have. While fish aren’t vulnerable to the toxins the plants produce, large amounts of algae can deplete oxygen in the water, resulting in many fish dying at once.

On hot, still nights when photosynthesis stops and little air is exchanged, the plants suck up all the oxygen and leave little for the fish, Adams said.

In the past six weeks, a number of fish kills have been reported across the state. Usually, though, during dry years when water levels are low, fish kills are more common.

“It hasn’t been a bad year at all,” Adams said.