Garden Amendments and Pets: Dangerous Mulch, Moldy Compost, and Other Garden Hazards

I have had at least one pet in my household since I was five years old. It started with a cat, then a dog, and as an adult with many children we’ve had everything from hermit crabs to hamsters, bunnies to budgies, and a myriad of cats and dogs over the years. We live in a rural area on acreage, which means those cats and dogs have had the run of the place. Pretty good life, in most cases.

What’s not good is when one of those beloved pets gets into something they’re not supposed to, and it makes them sick. What we might find repulsive, like old rotting food, our pets find appealing and sometimes downright tempting. And there are times when we use things in our gardens that might pose a threat to our furry friends.

Let’s go over some of the things we might want to keep an eye on when we have our four-legged family members in the garden with us.

Compost. Composting at home can be a very passive activity, especially for those of us who take the easy way of just throwing things in a heap and letting it sit there for a few years without really paying much attention to it. While this works fine for use in the garden, the problem comes when we have pets that might be attracted to what’s in that compost. Essentially, the foods from our kitchens are molding in the middle of that pile. Molds start growing on moist, porous surfaces within 24 to 48 hours and grows best in warm temperatures, between 77°F to 88°F. And it doesn’t need light to grow. The outer edge of a newly formed compost pile matches these exact conditions. And while we may have enough brown materials like dried leaves and shredded paper to keep us from being able to smell that molding and decomposition, our canine and feline companions can still detect it and it’s attractive to them. (Listen to an episode about home composting here.)

Unfortunately, mold can be very dangerous for our pets to consume and they can contain tremorgenic mycotoxins. These are toxins that, when ingested, can lead to muscle tremors, vomiting, drooling, elevated heart rate and seizures, among other things. Most of the time these types of mycotoxins will develop in the molds found on pastas, breads, dairy foods and grains. If you’re adding any of these to your compost pile, be aware and build a barrier so your pets can’t access your fresh compost pile.

This also means that mushroom compost can be a danger, as well. The mycotoxins that can form in mushroom compost actually come from the mushrooms themselves. (Learn more about mushroom compost here.) So, unless we’re purchasing a mushroom compost that has been sterilized before being sold, we have the possibility of exposing our pets to other types of neurotoxins present in varying amounts in different mushroom types. Ingesting these neurotoxins can lead to weakness, lack of coordination, hallucinations, strange vocalizations, and, again, seizures. And, as a side note, this also applies to some of the wild mushrooms that may appear in our yards and gardens.

So, if you’re creating your own compost or if you are using large amounts of mushroom compost in your garden, take care to keep your pets out of it for their own safety.

Mulch. I am a huge proponent of mulch in the garden and most mulches are going to be just fine. But in areas where cocoa mulch is readily available, that can cause a problem with our dogs. Most everybody knows chocolate is toxic to dogs and cocoa mulch contains cocoa bean shells that are roasted and sterilized. Even after sterilization they still contain the two things that are toxic to dogs: caffeine and theobromine. Unfortunately, it also has a lovely smell which can make it attractive to our canine companions, further tempting them to taste it. Cocoa mulch ingestion can lead to symptoms as benign as gastrointestinal irritation to vomiting and diarrhea all the way to seizures and death. So, unless you can guarantee your dog doesn’t have access to the area, I would skip the cocoa mulch.

Fertilizers and amendments. I think it’s pretty obvious that any synthetic fertilizer is going to have hazards if our pets are exposed, and this can come in the form of digestion but also in the form of exposure to their skin or fur. Not only can the chemicals be toxic to pets if ingested through eating or if inhaled, they can also be absorbed through the skin or ingested when the pet is cleaning themselves. Any of these can cause digestive problems, respiratory issues, and skin irritation. Fertilizers may also contain other toxic substances, such as pesticides, herbicides, and fungicides, especially ones used on lawns, which can be even more dangerous than the fertilizers themselves.

But it’s not just the chemically derived fertilizers we have to worry about. Even our natural and organic amendments can cause problems if our pets get into them. These are typically leftover byproducts from the meatpacking industry, and they are usually meals of some sort. Bone meal, blood meal, feather meal, and fish meal are the most common. And while these meals are often included in our pets dry kibble they are also widely used as soil amendment products and fertilizer components. These are highly palatable to our pets, especially our dogs. These amendments may smell gross to us, but dogs have a different idea of the definition of gross.

This means if they gain access to a large amount of these amendments, they may gorge themselves. A little ingestion isn’t a problem. But when it’s over ingested, it can lead to gastrointestinal problems like vomiting and diarrhea. Excessive consumption can even lead to a foreign body obstruction, specifically from bone meal congealing into a large solid mass internally, or even severe pancreatitis. So, even if it’s an organic amendment it doesn’t mean it’s safe for our pets. Keep your furry friends out of the garden for at least 24 hours after applying any amendment and be sure to keep the bags out of their reach when not in use.

Having pets around our gardens can be a pleasant experience, but we need to be careful as their caretakers to ensure what we're using in the garden is harmful or dangerous for them.

Your Friend in the Garden,


Mushroom Toxicity | VCA Animal Hospitals (

Tremorgenic Mycotoxins - Moldy Food Strikes Back - CriticalCareDVM

Common Garden Dangers for Dogs - BluePearl Pet Hospital (

Dangers of Fertilizers to Pets (

Garden Amendments and Pets: Dangerous Mulch, Moldy Compost, Mycotoxins and More - Focal Point Friday 

Search Results: Compost | Just Grow Something with Karin Velez