Mushroom poisoning

Photo used with permission by Dr. Tina Miller

While the mushrooms in the grocery store are safe to eat and help make delicious meals, other types of mushrooms such as the wild ones along hiking trails or even in our own backyards are a completely different story. There are many types of mushrooms containing different toxins that can make not only ourselves sick but also our dogs and cats. Moreover, it’s difficult for people to distinguish between a safe, edible mushroom and one that can send their pet to the emergency room or even lead to death. Similarly, our furry companions do not have a built-in sense of what is safe to eat and what is not. A pet, especially a dog, will happily chow down on a toxic mushroom without a care in the world. That is, until you find them sick on the ground minutes to hours, and in some cases days, later. It’s important to note that most mushroom poisonings occur in dogs as many dogs will put almost anything into their mouth. As a result, most of what is known about mushroom toxicosis (or poisoning) is based on dogs. However, cats also eat toxic mushrooms and get sick too.  

Depending on the type of mushroom, a number of symptoms can be seen from milder vomiting and diarrhea to seizures and death. Besides being toxic in and of themselves, wild mushrooms can also contain bacteria, pesticides and heavy metals that can make your pet sick. It is essential you closely monitor your pet and restrict any access to mushrooms whenever you may be around an area with them, as they can grow almost anywhere. While mushrooms can grow in many different environments from woods to rocky terrains, their primary growing seasons are spring and early fall. However, in warmer climates mushrooms can grow year-round and it’s not impossible to find some in the colder winter months. When it comes to mushrooms and your pet, you do not want to take any chances so it’s a good idea to be wary year-round.

Wild mushrooms are not the only source of mushroom toxins that can make your pets sick. Recreational drugs or ‘magic mushrooms’ contain several toxins that can make your pet ill. As a general rule, it’s a good idea to be vigilant when it comes to what your pet puts in their mouth; that is especially true in regards to mushrooms.

How to Recognize Signs of Mushroom Ingestion

Oftentimes when a pet eats a mushroom, you may not be around to witness it or may not have noticed. After all, it only takes a few seconds to take a bite. In these cases, there are some clues you can look for. If you are with your dog at the time, signs of chewing, especially when they don’t have access to their food or treats, could indicate they have something in their mouth they shouldn’t. Moreover, pieces of the mushroom may be lingering around their lips or there’s a mushroom near where your dog was with some chunks missing.

Later signs of potential mushroom ingestion include vomiting and diarrhea. Some pets vomit up parts of the mushroom which may not be easily recognizable depending on how long ago they ingested it. Sometimes, though, you may be able to recognize mushroom chunks in your pet’s vomit. If this is the case, taking pictures as well as collecting the sample is a good idea so your veterinarian can look at it later.

Others signs of mushroom poisonings include depression or excitation, abdominal pain, excessive salivation, muscle tremors, seizures, and coma. How your pet will be affected depends on the specific mushroom they ate and how much of it they had. Your pet can show signs as relatively mild as vomiting once or have dramatic seizures. Some mushroom poisonings will affect your pet within minutes to a few hours while others may take days before signs of illness begin. In the case of very poisonous mushrooms, initial signs may be so mild they are missed while later signs are life-threatening emergencies. All of the signs listed are not specific for mushroom poisonings and thus can also be due to another issue. The wide variability of non-specific signs makes recognizing mushroom poisonings in animals particularly difficult.

Immediate Steps when Suspecting Mushroom Poisoning

If you are lucky enough to be with your pet at the time of possible mushroom ingestion and your pet is still chewing, the first thing to do is get them to spit out whatever is in their mouth. Only do so through safe means such as a command in a trained dog. Depending on your individual pet and their relationship with you, it may not be safe to try and pry their mouth open to stop them from swallowing the mushroom. If you are able to get your pet to spit it out, you should proceed as if they had swallowed it. You may not know if your pet ingested some of the mushroom so they may still be at risk of a poisoning.

The next step to take is contacting a professional immediately. This may be your pet’s veterinarian, an animal poison control center, or an emergency veterinary hospital. Depending on your individual situation you may be asked to bring your cat or dog in to be seen as soon as possible. Additionally, they may want you to obtain a sample of the mushroom your pet ate and record details about its environment, if possible. Put the sample on a white sheet of paper, wrap it in wax paper and place in an airtight paper bag with a dry paper towel. Refrigerate until it can be examined. Take note of the location the mushroom was found, including the terrain, location and if possible whether the area is potentially exposed to pesticides or other chemicals. Make sure to follow the directions provided by the professional you contacted.

If you did not witness your pet eating a mushroom, you will likely notice when they start feeling sick. Remember this can look different depending on the mushroom type. Charts 1 and 2 summarize the effects different mushrooms can have on your pet. Some of these symptoms are general. For example, a dog can vomit for a huge number of reasons. Keeping track of where you pet roams and whether they have access to mushrooms will help raise or lower your suspicion of a poisoning. Do not rule out a poisoning just because you don’t see mushrooms, though. Some mushrooms can be difficult to spot and can spring up within days so unless you are checking the area carefully, it’s possible your pet had access to them without you realizing it. If you do notice any of the signs associated with mushroom poisonings, it’s a good idea to let your veterinarian know. Your pet could be experiencing the effects of a toxic mushroom or something else could be wrong that needs to be addressed.

Mushroom poisoning top and side

Photo used with permission by Dr. Tina Miller

Common Types of Toxic Mushrooms

There are many different types of toxic mushrooms. One way they can be grouped together is by the body system they affect. For example, there are mushrooms they affect primarily the central nervous system and cause related symptoms such as excitation, depression and seizures. There are also mushrooms that mainly affect the gastrointestinal system of your pets, causing vomiting and diarrhea. These are summarized in Chart 1. One thing to note is that while some mushrooms only affect one body system, there are many that have effects on multiple and thus a combination of symptoms can be seen in your pet.

Another useful way to group toxic mushrooms is by their primary toxin (see Chart 2). There you will find the typical symptoms associated with each mushroom toxin and how they develop in your pet. It’s important to note that different mushrooms will affect your pet at different times. For example, mushrooms with isoxazole derivatives can affect your pet within minutes while mushrooms with cyclic peptides may take 10-12 hours after eating to take effect. Moreover, how long your pet’s symptoms last also depends on the mushroom and its specific toxin as well as how much your pet ingested. While each mushroom toxin is different, the most toxic ones do not cause acute signs. Cyclic peptides, for one, are among the deadliest toxins but your pet may not show signs until about 10-12 hours after ingestion.

Diagnosis

Oftentimes, it is difficult to confirm a diagnosis of mushroom poisoning. If you were able to obtain a sample of it, species identification is tricky and your veterinarian may need to send the sample to a trained mycologist for evaluation. Correct evaluation and identification depend greatly on good preservation of the mushroom. Ways to ensure this are to quickly give the sample to your veterinarian for evaluation. Other useful steps to take are getting pictures of the mushroom as soon as you collect it, making sure to take different angles and include all the different parts because many mushrooms can look similar from the top. Taking these steps helps whoever is evaluating the mushroom sample make an accurate identification.

If you do not have a mushroom sample or did not notice your pet ingesting one, other ways your veterinarian can diagnose your pet is by examining your pet’s vomit and feces, and checking which symptoms your pet has. Your veterinarian may look for spores in your pet’s stomach contents under a microscope. The history you report to your veterinarian may also increase their suspicion of a poisoning. It’s critical to provide a thorough picture of the situation. For instance, it may be useful for them to know you and your pet went on a hike through a new area recently, especially if your pet was off-leash at any point. Oftentimes, however, your veterinarian may not be able to confirm a diagnosis of mushroom poisoning and instead treat them without it.

Treatment and Prognosis

Unless a confirmed diagnosis of mushroom poisoning and correct identification were made promptly, your veterinarian will likely treat your pet on a worst-case scenario basis. Usually this involves decontaminating your pet which includes inducing vomiting if appropriate, administering activated charcoal to bind the poison from the stomach and small intestines, and using a drug to speed defecation. In addition, your veterinarian will likely give your pet supportive treatments such as intravenous fluids, oxygen and other medications to address their specific symptoms. Usually cats and dogs will receive basic supportive care regardless of whether they are symptomatic or not as this can help prevent signs from developing. If the mushroom species is identified or highly suspected, there are specific medications that can be given. These include liver support medications for cyclic peptides or the drug atropine in the case of muscarinic mushrooms. Your pet’s treatment will be largely based on the symptoms they are displaying and what your veterinarian suspects most.

Depending on how your pet is affected, they may need to be hospitalized for a period of time. This allows your veterinarian to monitor and respond quickly new symptoms or worsening of their current condition. It may not be necessary, however, especially with less severe toxins. Your pet might be stable enough for you to monitor at home.

How well the treatment works out depends heavily on the type of mushroom ingested as well as how much your pet consumed, your pet’s health, and how quickly they were able to receive treatment. Many mushrooms are not fatal although your pet could suffer serious complications if not treated appropriately; other mushrooms live up to their common names such as the death cap mushroom. Recognizing symptoms early and seeking immediate care are good ways to help potential life-threatening consequences.

Prevention

It is always better and oftentimes easier to prevent your pet from ingesting a toxic mushroom than treating them for mushroom toxicosis, not to mention more economic. Regularly check your backyard for mushrooms before letting your pet out. While not all mushrooms that grow in your yard will be toxic, it is difficult to differentiate between safe and toxic Better no mushrooms and safe than a mushroom that may be poisonous.

Another way to prevent mushroom poisonings in your pet is to keep them on a leash whenever you are out with them. This way you can better monitor them and make sure they don’t get into any trouble with mushrooms.

Recreational mushrooms or ‘magic mushrooms’ are also toxic to your dogs and cats. While use of these substances may be legal in some places, you should still be careful around them. If there are any magic mushrooms in your home, be absolutely sure they are locked away from pets. While usually not lethal, symptoms associated with these mushrooms can be less than pleasant for both you and your pet.

There are thousands of species of mushrooms in North America, the majority of which are not poisonous. Not every mushroom you see growing will cause your pet to get sick, but you should treat each one as if they could. Better safe than sorry.

Chart 1: General Body Systems Affected

Note: The same mushroom species may affect multiple body systems. Mushrooms are categorized here by their primary effect; if a mushroom is listed as hepatotoxic it may still affect other body systems but to a lesser degree relative to its effect on the liver.

Chart 2: Important Specific Toxins and Mushrooms