Reports of dogs getting sick last year after eating dark false mussels have prompted a renewed warning from the Maryland Department of Natural Resources.

Be safe: Keep your canine pals away from anything encrusted with the mussels, whether the mussels are in the water or on land.

Many speculate that the problem may be most acute if mussels are near areas where boat bottoms have been cleaned and where remains of the bottom cleaning are improperly disposed of on land — where dogs can get at them.

Click here to get details from DNR.

DNR also reports that for reasons unclear just yet, the Severn and Magothy Rivers are hots spots of the dark false mussel toxicity reports.

Boat owners: When cleaning and scraping your boats, DNR’s Catherine Wazniak urges you to collect all the debris, securely wrap it up and dispose of it in trash cans with tight lids.

Dog owners: Don’t let Rover wander off. Keep your dogs on a leash, especially if you’re near the riverside and most especially, keep your dog away from areas where boats are launched and/or cleaned.

Sadly, most of the reports of canine toxicity in the past two years are coming from the Magothy and Severn Rivers. Wazniak says it’s not clear why the two rivers are generating a lot of dog toxicity reports. 

It’s not clear what’s in the mussel that causes the toxicity. It might be the copper in bottom paint. It might be the mussel itself.

Click here to read the abstract of a 2004-2015 ingestion study about the dark false mussel toxicity in dogs.

The toxicity problem has been reported since at least 2004. The DNR map to the right indicates hot spots of dark false mussel populations. Most of the hot spots are in low-salinity areas.

One possible reason the Severn and Magothy are hot spots is that rivers are not easily flushed by the brackish waters of the Chesapeake Bay.

For a larger version of the map, click here.

In any case, it’s best to keep your dog away from the dark false mussels in or out of the water.