April 2020

Blue-green Algae Season is Approaching

By Drs. Steve Ensley and Scott Fritz

Summer is quickly approaching, and with it comes long days, warm weather and the blue-green algae (cyanobacteria) bloom season.

Blue-green algae can be blue, bright green, brown or red. It can look like scum, foam or a mat on the surface. Or it may look like paint floating on the water. (Figure 1) Do not confuse with plants like moss, duck weed, etc.

Blue-green algae bloom

Figure 1. Blue-green algae bloom

Not all types of blue-green algae blooms produce toxins, but if blooms are present it is best to assume that the water could be dangerous if used for livestock drinking water.

Cyanobacteria produce neurotoxins and hepatotoxins that can affect livestock, pets and humans when exposed. They live in surface waters in low concentrations and normally cause no problems. During certain weather conditions, these bacteria can be concentrated to a level where toxicity is possible. These weather conditions include: high rainfall events, municipal and agriculture fertilizer run-offs, warm temperatures, and low wind speeds.

Clinical Signs:

Clinical signs of toxicity in all animal species can range from ataxia, dyspnea, weakness, diarrhea, and death. Necropsy findings may be unremarkable or the liver may have a nutmeg appearance.


A presumptive diagnosis can be made from clinical signs and recent suspected exposure to cyanobacteria blooms. Microscopy of water or rumen samples and histopathology performed on liver samples can be an aid in diagnosis.

Diagnostic Samples

Appropriate samples are a water sample of at least 100 ml. collected an inch below the water surface, and 200 ml of rumen fluid. Both samples should be refrigerated before and during shipping. Do not freeze the sample as this may lyse the cyanobacteria. When collecting water, gloves should be worn, as some cyanobacteria produce dermatotoxins. If KSVDL identifies cyanobacteria in the sample, a test for the amount of the most common toxin (microcystin) can be performed. Below is a short video on blue-green algae sampling. You can also watch on our YouTube channel.

A formalin fixed liver sample 4” X 4” and < ½” thick is adequate for histopathology.

For more information please contact KSVDL Client Care at 866-512-5650-5650 for more information on these tests.

If algae blooms are observed at a publicly accessible lake, please contact the Harmful Algal Blooms (HAB) Hotline (785-296-1664) established by the Kansas Department of Health and Environment (KDHE), or file a report on their website: http://www.kdheks.gov/algae-illness.

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