Monsoon season has arrived right on schedule this year. As I listen to the rain coming down outside the window I can’t help but wonder what crop of mushrooms is going to pop up in my yard tomorrow as a result. It is amazing how a previously completely clear area can sprout clumps of large mushrooms overnight, or even from the morning to the evening.

August is the height of mushroom season in Colorado. There are many edible and even positively delicious varieties of mushrooms that come up this time of year, and experienced mushroom hunters gather them with much glee. Our dogs often harvest the mushrooms in our yards with equal glee, but usually without as much differentiation between the edible and toxic varieties, which unfortunately tend to spring up right alongside each other. Last year while strolling around the East Library I noticed that the grassy park was full of pink bottoms, a very tasty and common type of edible mushroom. As I approached the front door there was a dramatic group of green spored parasols--tall white mushrooms with a ring like a hula hoop around the stem. The green color to their gills was the final clue that identified them as a species that would likely cause some violent vomiting and diarrhea if eaten.

The chemical compounds found in "poisonous" mushrooms are an extremely varied and in large part incompletely understood group of toxins. Many cause gastrointestinal irritation which may range from mild to very violent. Some can cause liver and kidney damage. Some have neurologic effects that may present as extreme drooling or as an altered mental state. Although there are mushrooms that are toxic enough to be fatal, they do not tend to appear in this area, so in spite of the fact that some symptoms can be quite dramatic, dying from mushroom toxicity would be an unlikely event. There is no laboratory test that can positively identify a patient that is suffering the effects of indiscreet mushroom ingestion, but the history, clinical signs, time of year, and lack of evidence for other problems can help point in that direction.

As with any potential poisoning, the critical window for preventing problems is immediately after the toxin has been ingested. If vomiting can be induced before the poison can be absorbed then the problem can be averted. If the toxins have already been absorbed then supportive care to help with the symptoms until the problem runs its course is the only treatment really available. Of course any dog with an ounce of sense will be scarfing mushrooms on the sly so nobody will come along and expect them to share, so you have to be pretty lucky to actually witness the mushroom ingestion.

When you do see the dog eating a mushroom the first logical question is whether it is poisonous or not. We would hate to make the dog suffer the unpleasantness of a trip to the vet to spend the next few hours vomiting if he was just snacking on some perfectly edible boletes. Unfortunately mushroom identification can be tricky, and veterinarians don’t receive any training for this sort of thing, so it is unlikely your regular vet will know any more than you do whether that particular mushroom is a problem. By the time an expert could be chased down to make an identification it will be too late, so it is usually better to be safe than sorry and induce vomiting when in doubt.

It doesn’t hurt to sweep the yard on a daily basis and remove any mushrooms you see growing there. There will always be some sneaky ones that you don’t see that the dog will find anyway, and some that spring up immediately after you finish your sweep, but at least you can do something to reduce the exposure.