Mushroom Poisoning in Dogs

What Is Mushroom Poisoning in Dogs?

There are over 10,000 species of mushrooms in the United States, but only about 100 are toxic. However, it can be very difficult to accurately identify mushrooms to determine which are safe and which are poisonous. Depending on the specific mushroom ingested, mushroom poisoning in dogs can cause vomiting, diarrhea, tremors, and seizures, as well as liver and kidney failure. 

Because highly toxic mushrooms can be deadly to pets, any mushroom ingestion should be treated as a medical emergency. If your dog ingested any wild mushrooms, seek immediate veterinary care. 

Symptoms of Mushroom Poisoning in Dogs

Clinical signs of mushroom poisoning in dogs may affect pets quickly (within 15-30 minutes after ingestion), but they can also be delayed up to 24 hours. It may take 2-3 days to see evidence of liver and kidney failure. 

Common clinical signs of mushroom poisoning include:

• Drooling

• Vomiting

• Diarrhea

• Abdominal pain

• Weakness/lethargy

• Abnormal heartbeat

• Trouble breathing

• Uncoordinated movements/stumbling

• Disorientation

• Increased drinking and urinating

• Yellow discoloration to gums and eyes

• Tremors/seizures

There is no simple test to differentiate a poisonous mushroom from a non-poisonous one. Therefore, unless a specialist can quickly identify a mushroom as non-toxic, all mushroom ingestions by pets should be considered potentially toxic, and a veterinarian should see the pet immediately. Mushroom poisoning in dogs can be fatal, so do not wait until clinical signs are noted. 

Causes of Mushroom Poisoning in Dogs

In the U.S., there are approximately 100 toxic species of mushrooms, but most fatal species are Amanita, Galerina, or Lepiota. Mushroom poisoning in dogs can occur any time throughout the year, but it’s most commonly reported in September and October, when many mushrooms grow.

The mechanism of poisoning can vary depending on the species of mushroom, but the deadliest is the Amanita species, which is absorbed by the stomach when ingested. The toxins (amanitins) travel to the liver, where they can kill liver cells and cause liver failure. The amanitins are then excreted by the kidneys, which can result in subsequent kidney failure. The amount needed to make a dog sick varies depending on the mushroom species, but in the deadly Amanita species, a single mushroom may contain enough toxin to be lethal. 

Other species of toxic mushrooms are often grouped based on the clinical reactions they cause. For example, a relatively large group of mushrooms can cause gastrointestinal issues such as vomiting and diarrhea, which can be severe and lead to significant dehydration and decreased heart rate. There are also mushrooms that cause neurologic and hallucinogenic effects when ingested, resulting in stumbling, tremors, and even seizures. And then there are poisonous mushrooms that primarily target the kidneys, causing illness through kidney failure. 

It's important to remember that accurately identifying mushrooms can be very difficult and should not be attempted unless you are a mushroom specialist (mycologist). If your dog eats any wild mushrooms, take them to the veterinarian immediately.

How Veterinarians Diagnose Mushroom Poisoning in Dogs

Your veterinarian will start with a thorough history of any possible toxins your pet may have been exposed to. It’s always helpful to tell your vet if your pet was recently hiking, traveling, or out of your sight when they got sick, even if you did not see them eat a mushroom. If you know your pet ingested mushrooms, try to bring a sample of the mushroom to your vet for examination. It’s best to store the mushrooms in a damp paper towel or paper bag, because plastic bags can cause mushrooms to spoil faster. It may also be helpful to photograph the mushroom in nature—and be sure to get shots from all angles.

Your veterinarian will perform a physical examination to assess your pet for abdominal pain, assess their heart rate, check their neurologic status, and assess for dehydration. A complete blood count, serum blood chemistry, and urinalysis will all likely be recommended for a baseline evaluation.

While there are laboratory tests to screen for mushroom toxins in blood, urine, and vomit, these tests are not readily available and cannot usually be completed quickly enough to be of clinical assistance.  They are also limited in that not every species of mushroom has a corresponding laboratory test. That means a complete history of any possible mushroom ingestion is crucial.   

Treatment of Mushroom Poisoning in Dogs

Decreasing the stomach’s mushroom absorption is the top priority, so identifying what mushroom your dog ate may actually have to wait. Even veterinarians are not mushroom experts, so once your pet is stable, your vet may need to research the mushroom based on your sample and photos. 

If your pet ate mushrooms within the past two hours, your veterinarian may induce vomiting at the hospital as a means of decontamination. If your dog is already showing clinical signs, it may be too late to induce vomiting, as there is a risk of aspiration pneumonia. The vet may also give your dog activated charcoal to bind any additional toxin in the stomach.   

Unfortunately, there is no specific antidote for mushroom poisoning in dogs. Treatment varies depending on the type and amount of mushroom ingested. Some dogs may be treated outpatient, with symptomatic care for vomiting and diarrhea. However, if the mushroom cannot be identified or is identified as highly toxic, your dog will need to be hospitalized and started on IV fluids for hydration and supportive care. Generally, therapy will be started to try to prevent signs from developing, even if the dog is not showing any immediate signs of illness.

Medications will be given to treat the symptoms of vomiting and diarrhea, as well as treatment for muscle twitching and seizures. Additional therapy may include liver-support medications.   

Recovery and Management of Mushroom Poisoning in Dogs

Early diagnosis and aggressive treatment are crucial for a successful outcome. Mushroom poisoning can be fatal for many reasons, from neurologic symptoms like seizures to liver and kidney failure. Overall, the prognosis is very good for dogs that are treated quickly. 

Most dogs will remain hospitalized for 3-5 hours, but will need more bloodwork to monitor their liver and kidney values daily for 72 hours following the ingestion. If the liver and kidney values are normal at that time and the dog is neurologically okay, no long-term consequences are anticipated. However, dogs with elevated liver and kidney values may end up with chronic liver and kidney disease. Although many mushrooms are not fatal, some dogs may still die from mushroom poisoning despite receiving therapy. 

Prevention of Mushroom Poisoning in Dogs

Prevention is key when it comes to toxicities in dogs. Even though there are many non-toxic mushrooms, it’s safest to assume all mushrooms are toxic until proven otherwise.

Check your backyard regularly and remove any mushrooms you find. When taking your dog on a walk or hike, keep them on a leash anywhere mushrooms may be growing. The best way to prevent mushroom poisoning in your furry friend is to prevent them from having access to mushrooms in the first place!