Dear Daisy Dog:  I hike with my dogs, and often they play in a pond along one of the wooded trails. Sometimes the pond water is green, and occasionally a green scum floats on top. Is it safe for my dogs to wade in the water when it’s green?

Daisy Responds: It sounds like blue-green algae, also called cyanobacteria, may be taking over the pond. Some species of cyanobacteria produce potent toxins, so it’s best to keep your dogs away from the water when it’s discolored.

Cyanobacteria overgrowth occurs in warm, calm water, particularly after heavy rains wash fertilizer and other nutrients into the water.

These bacteria produce a variety of toxins, collectively called cyanotoxins, that sicken and kill wildlife, domestic animals and humans.

Dogs are particularly susceptible because they usually drink the water they’re playing in and sometimes eat the floating mats of algae. Dogs also can be poisoned through skin contact, by inhaling airborne water droplets and by eating fish from the contaminated waters.

So when the pond water looks murky or discolored, keep your dogs away from it.