{"id":44980,"date":"2025-07-02T15:30:06","date_gmt":"2025-07-02T19:30:06","guid":{"rendered":"https:\/\/news.maryland.gov\/dnr\/?p=44980"},"modified":"2025-07-02T15:30:06","modified_gmt":"2025-07-02T19:30:06","slug":"protect-your-dogs-health-harmful-algae-mats-can-pose-danger-to-pets","status":"publish","type":"post","link":"https:\/\/news.maryland.gov\/dnr\/2025\/07\/02\/protect-your-dogs-health-harmful-algae-mats-can-pose-danger-to-pets\/","title":{"rendered":"Protect Your Dogs\u2019 Health: Harmful Algae Mats Can Pose Danger to Pets"},"content":{"rendered":"
\"Mats<\/a>

Wye Mills Lake 2024 boat ramp. Accumulation of Microseira mats (floating and within vegetation) that contained saxitoxin.The bright green color on top of mats are small floating plants (duckweed and watermeal). Also note the green colored water which was due to a planktonic algae, Microcystis, bloom that produced microcystin and led to a no-contact advisory being placed on the waterbody. DNR photo<\/p><\/div>\n

As summer has begun, Maryland Department of Natural Resources scientists caution the public to be vigilant about freshwater algae mats that can sometimes be a health hazard for dogs and other animals.<\/span><\/p>\n

Benthic algae mats are accumulations of algae that can vary in structure and appearance, but are often dense, green, and fibrous. Benthic cyanobacteria mats grow in both flowing and standing water such as rivers, creeks, reservoirs, lakes, and ponds, where they adhere to submerged rocks, plants, sand, shells, wood, and banks. Mats can also detach and float on the water surface, accumulate in eddies, or wash up on shore.<\/span><\/p>\n

Not all benthic algae mats are toxic, but mats containing toxins have been found in Maryland waters over the past two years. Mats containing toxins are harmful when ingested, therefore scientists urge dog owners to keep their dogs out of the water when potentially harmful mats are present. Mats can be green, yellow, brown, or black. There is no way to determine if a mat is toxic just by looking at it; lab analysis is required.\u00a0<\/span><\/p>\n

Some benthic algae mats (those containing cyanobacteria) can produce potent neurotoxins including saxitoxin and anatoxin-a. Deaths from anatoxin-a exposure have been reported in dogs, cattle, bats, flamingos, waterfowl, and carp. Dog deaths from anatoxin-a have occurred in over 20 states. Some algal mats can also produce a liver toxin, microcystin, that has resulted in canine mortalities in Maryland. Dogs are most susceptible and can be exposed by drinking from natural waterbodies, eating algae mats, and grooming their fur and paws after swimming.\u00a0<\/span><\/p>\n

Exposure to cyanotoxins generally comes when an individual or pet comes into direct contact with a mat through skin contact or ingestion. Since adults are not likely to eat algae mats, the risk is low. On the other hand, dogs and children are more likely to come in contact with mat material. Dogs and other animals may be attracted to the musty smell and purposefully seek out and eat mats.<\/span><\/p>\n

If ingested, neurotoxins can harm the nervous system. At low to moderate exposure levels, anatoxin causes neurological symptoms including muscle twitching, tingling, numbness, salivation, and loss of balance. At high doses, anatoxin may cause rapid death from respiratory system paralysis. Currently there are no national thresholds for either of these toxins in recreational waters in the U.S.\u00a0<\/span><\/p>\n

Protect Your Pets<\/b><\/p>\n

Concentrations of blue-green algae will vary throughout the course of the year, but the blooms are most abundant during the mid to late summer when the weather is hottest. To protect pets, owners should:\u00a0<\/span><\/p>\n