You can trust this content. Vet-Approved Content

Beware: Understanding Mold Poisoning in Dogs – Symptoms, Treatment, and Prevention

Beware of mold poisoning in dogs! Learn symptoms, treatment, and prevention to protect your furry friend from toxic mold. Read our vet-approved guide now.


This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed on July 4, 2024

mold poisoning in dogs image
Mold poisoning in dogs is a serious problem. Pets can develop skin rashes and sores when faced with black mold in their living quarters. By: larrison

Is Black Mold Making Your Dog (and You) Unwell?

Black mold is seriously unpleasant. It lurks in your home, in a poorly ventilated bathroom or along a damp window frame. Wherever there’s condensation or a damp wall, black mold is never far behind.

But what many people do not realize is just how bad black mold is for the health of your pets—and you.

Key Points to Consider:

  • Common Locations: Black mold thrives in places with poor ventilation and high humidity.
  • Health Risks: Both pets and humans can suffer from serious health issues due to black mold exposure.

What Is Black Mold?

Black mold belongs to the fungal family. Fungi make up 25% of our planet’s biomass, and they are very diverse, including mushrooms, toadstools, molds, and mildews. What unites them all is a lack of chlorophyll.

Although many fungi are harmless, there are also some extremely unpleasant family members, such as aspergillus, which cause serious infections.

Black mold loves to grow on cellulose, which includes substances such as straw, grains, paper (including wallpaper), and wood. It thrives when that substrate has a relative humidity of 15% and the ambient environment is around 90% (hello, bathrooms). But basically, it will take advantage of anywhere that water has got in, so a leaky roof, faulty damp-proof course, or a cracked drain are all open invitations to black mold.

Black Mold Facts:

  • Scientific Name: It is a fungus called Stachybotrys chartarum.
  • Health Impact: Black mold poisoning is called stachybotryotoxicosis (literally “poisoned by Stachybotrys”).
  • Sick Building Syndrome: Black mold is partly responsible for “sick building syndrome,” where people develop respiratory difficulties, chest tightness, and headaches.

A Short History of Black Mold and Its Impact

Black mold has long caused problems in farm animals, but only recently has awareness increased about ill health in our domestic pets.

This fungus thrives in damp straw, causing symptoms from sudden death in horses to diarrhea in cattle and tremors in pigs.

In the 1930s, black mold was found to cause skin problems in Russian farm workers, resulting in rashes and sores. The mold’s toxin, trichothecene mycotoxin, can damage any body tissue it contacts, including the liver and lungs.

Key Points to Remember:

  • Historical Impact: Issues in farm animals and recent awareness for pets.
  • Symptoms in Animals: Sudden death, diarrhea, and tremors.
  • Human Impact: Skin rashes, ulcers, and sores.
Bathrooms are a common breeding ground for black mold. By: apardavila

Black Mold Poisoning in Dogs and Pets

Black mold gained attention in 2007 when a veterinarian linked it to the deaths of 2 cats after routine dental work, causing fatal lung hemorrhages.

Black mold produces mycotoxins, toxic chemicals that, when circulated in the bloodstream, cause cell death and liver damage. These toxins impair the liver’s ability to produce blood clotting factors, leading to symptoms like nosebleeds, blood in waste, and fatal lung hemorrhages.

Key Points on Mold Poisoning in Dogs:

  • Toxin Production: Black mold produces harmful mycotoxins.
  • Blood Clotting Issues: Mycotoxins damage the liver’s blood clotting function.
  • Symptoms in Pets: Nosebleeds, blood in waste, and lung hemorrhages.

Symptoms of Mold Poisoning in Dogs

The symptoms of mold poisoning in dogs range from allergic reactions to serious health issues.

  • Runny nose
  • Sneezing
  • Nosebleeds
  • Lameness (due to bleeding in the joints)
  • Skin rashes and sores (on thin-furred areas such as the belly or armpits)
  • Loss of appetite
  • Lethargy
  • Trembling

For more information on mold allergy symptoms in dogs, visit VetInfo.

Long-Term Effects of Mold Exposure in Dogs

Prolonged exposure to mold can have severe long-term effects on dogs. Chronic respiratory issues, such as persistent coughing and difficulty breathing, are common. Additionally, mold exposure can lead to long-term liver damage and compromised immune function, making dogs more susceptible to other illnesses. The continuous presence of mold toxins in the body can also cause ongoing skin problems and gastrointestinal issues, affecting the overall health and well-being of your pet.

Key Long-Term Effects:

  • Chronic Respiratory Issues: Persistent coughing and difficulty breathing.
  • Liver Damage: Long-term exposure can harm liver function.
  • Compromised Immune System: Increased susceptibility to other illnesses.
  • Ongoing Skin Problems: Persistent rashes and sores.
  • Gastrointestinal Issues: Chronic digestive problems.
An extreme case of dangerous black mold overtaking a home. By: satemkemet

Treatment for Mold Poisoning in Dogs

Treatment for mold poisoning in dogs may involve a blood transfusion (if the pet bleeds unduly) and antibiotics to fight secondary infections. Your vet will repeat blood tests to monitor liver function. The pet must rest to reduce the risk of knocks and bumps, which could cause bleeding.

It is crucial to eliminate the black mold or stay away from it. Remember, this condition affects both pets and people, so if your dog is unwell, leave that environment and seek urgent medical help for yourself as well.

Common Myths About Mold Poisoning in Dogs

There are several myths surrounding mold poisoning in dogs that can lead to misinformation and inadequate care. One common myth is that only old or weak pets are affected by mold; however, mold can impact pets of all ages and health conditions. Another misconception is that mold is only a problem in visibly damp or water-damaged homes. In reality, mold can thrive in hidden areas and still pose a significant health risk. It is also falsely believed that regular cleaning alone can prevent mold growth, but without addressing underlying moisture issues, mold can quickly return.

Debunking Common Myths:

  • Myth 1: Only old or weak pets are affected by mold.
    • Fact: Mold can impact pets of all ages and health conditions.
  • Myth 2: Mold is only a problem in visibly damp homes.
    • Fact: Mold can thrive in hidden areas.
  • Myth 3: Regular cleaning can prevent mold growth.
    • Fact: Without addressing moisture issues, mold can return.

Final Thoughts on Mold Poisoning in Dogs

The chilling conclusion is that black mold in the home is potentially very dangerous. Not only could your pets be at risk, but it also poses a threat to human health.

If you have black mold in your home, be alert to the risks and get rid of the mold. If you or your pet have allergy-type symptoms or feel unwell in any way, see a physician or veterinarian immediately.

Key Points on Treatment and Precautions:

  • Medical Intervention: Blood transfusions and antibiotics may be needed.
  • Environmental Action: Eliminate or avoid black mold.
  • Health Vigilance: Seek medical help if you or your pet show symptoms.

Frequently Asked Questions (FAQ)

How to treat mold poisoning in dogs?

To treat mold poisoning in dogs, consult a veterinarian immediately for appropriate medical intervention, which may include blood transfusions, antibiotics, and removing the source of mold.