Mouldy food is a fast-acting yard hazard that is easy to overlook. Certain moulds growing on compost, fallen fruit and forgotten leftovers produce compounds that cause muscle tremors and seizures, sometimes within half an hour. If your dog has raided a compost heap, phone us straight away rather than waiting to see.

Why the autumn yard is different

Through the summer a compost bin is mostly grass clippings and vegetable peelings, and it dries out between additions. From late September the balance changes. Windfall apples and plums sit in wet grass, the bin stops drying, and kitchen waste goes in faster because people are cooking more. Warm, wet, undisturbed organic matter is exactly what moulds want.

The result is that a bin a dog has ignored since May becomes interesting in October, and what is in it has changed character. This is not about a dog eating a few vegetable peelings. It is about what grows on the pile once the weather turns.

The fast one: mouldy food and tremors

Some moulds that grow on bread, cheese, pasta, nuts, grain and fallen fruit produce compounds called tremorgenic mycotoxins. They act on the nervous system, and they act quickly. Signs usually begin within thirty minutes to two hours, occasionally a little longer, and they look alarming because they are.

• Fine muscle tremors, often starting in the head and legs
• Wobbliness and an unsteady, drunken gait
• Restlessness, pacing, an inability to settle
• Twitching that builds into whole-body shaking
• A raised body temperature, because sustained tremors generate heat
• Vomiting, often before the tremors appear
• In a bad case, seizures

Two things make this worth knowing in advance. First, it does not need much, and a visibly small amount of mouldy material can produce signs in a medium-sized dog. Second, the tremors themselves cause a secondary problem: an animal shaking hard for an extended period overheats, and the high temperature does damage of its own. That is why this is a go-now situation rather than a watch-and-see one.

Dogs who have had tremors from mouldy food generally do well when they are seen early and given supportive care, including help settling the tremors and cooling if the temperature has climbed. The outcome is much better before the shaking has been going on for hours.

What else is in a compost bin

The mould is the fast hazard. The bin holds several slower ones at the same time, and a dog who has been in it has usually eaten more than one thing.

Coffee grounds. Used grounds still contain a useful amount of caffeine. A dog who eats a filter’s worth can become restless, develop a fast heart rate, pant and vomit. How much it matters depends heavily on your dog’s size, so phone us with the weight and roughly how much went down rather than working it out at home. Grounds also go into the bin daily, so they are near the surface.

Onion and garlic scraps. Skins, ends and the papery outer layers accumulate, and they are concentrated rather than diluted. The effect on red blood cells is cumulative and it shows up several days later, not the same evening, which is why it gets missed.

Grapes, raisins and currants. A handful of shrivelled grapes off a vine, or the dregs of a fruit loaf, both go in the compost. Any amount is worth a phone call because the kidney risk does not scale predictably with quantity.

Stone fruit pits. Plum, peach and cherry pits do not break down quickly and are the right size to lodge in a dog’s gut. Windfall season fills the bin with them.

Avocado skins and stones. The stone is the obstruction risk and it is smooth and heavy, so it travels.

Corn cobs. The classic autumn blockage. They do not soften, they do not break up, and they are almost always a surgical problem once they are stuck.

Cocoa mulch. Not compost, but it lives in the same part of the yard. It is made from cocoa bean shells, so it carries the same compounds that make chocolate a problem, and it smells like chocolate to a dog. Dogs eat it deliberately. If yours has, phone us with the bag or the brand name and roughly how much is gone, because the amount and your dog’s weight both matter here.

If your dog has been in the compost

1. Look at your dog before you look at the bin. If there are tremors, wobbliness, twitching or a dog who cannot settle, get in the car now. Phone us before you set off, or have a passenger call on the way. If we are closed, go straight to a 24-hour emergency veterinary hospital instead.
2. If your dog seems well, phone us anyway and describe what is in the bin. The onion and grape risks do not announce themselves on day one.
3. Photograph the bin and what is spilled around it. Mould colour and what it is growing on both help.
4. Bag a sample of anything obviously mouldy if you can do it without delaying the journey.
5. Note the time as closely as you can, and roughly how long the dog was unsupervised.
6. Do not try to make your dog sick. Doing it at home, with anything, can cause a second problem on top of the first. Whether it is the right step at all depends on what was eaten and how your dog is doing, which is a decision for us to make here.
7. Do not give anything by mouth, including milk, bread or anything from a cupboard or a cabinet.
8. If a pit, a stone or a corn cob may have gone down, keep watching for three days. Repeated vomiting, going off food, straining with nothing passing, or a tense or painful belly all mean phone us, even if your dog was fine when we saw them.
9. Keep your dog cool and quiet on the way in. A tremoring dog is already generating heat, so leave the car heater low and the windows cracked rather than wrapping them up.

Come in through our urgent care. Our diagnostics team checks kidney values, liver values and electrolytes where the history calls for it, and with onion or grape exposure it is the repeat samples two and three days out that actually answer the question. Our medical services team manages the stretch in between.

We are open 8:00 AM to 10:00 PM Monday to Friday, 9:00 AM to 10:00 PM on Saturday, 10:00 AM to 10:00 PM on Sunday, and 8:00 AM to 10:00 PM on statutory holidays. That covers most of the day, so there is a good chance we are open when it happens. The gap to plan around is overnight and the early morning on a weekend. If your dog starts tremoring at two in the morning, go to a 24-hour emergency veterinary hospital in the Lower Mainland and have someone phone ahead, because tremors do not wait for opening time.

Setting the yard up so it does not happen

• Get a lid that latches, not one that rests. A tumbler or a bin with a clip removes the easiest way in. A dog can nose a loose lid off in seconds.
• Site the bin outside the dog’s area if you can, behind a gate or a fence line rather than in the middle of the lawn.
• Keep cooked food, dairy, bread and nuts out of an accessible bin. These are the things the tremor-causing moulds grow on best. Vegetable peelings and garden waste are a much lower-risk pile.
• Pick up windfall fruit twice a week through October and November. Fallen apples and plums go mouldy where they lie, and they are the version of this that is not in a bin at all.
• Turn the pile when you add to it. A well-aerated heap runs hotter and grows less of the surface mould that causes the problem.
• Check behind the shed and under the deck. Bags of garden waste waiting for a trip to the depot are a common second site.
• Watch the green bin on collection day. A full bin wheeled to the curb and left overnight is the most accessible it will ever be.
• Choose a different mulch. If you are topping up beds this autumn, use bark rather than cocoa shell.

Our guide to fall coat care and matting covers the other job the wet season creates, which is keeping a long coat in order once the yard stays damp.

Questions we are asked

My dog ate mouldy bread and seems completely fine. Do I still need to phone?

Yes, today. Tremors from mouldy food usually begin within half an hour to two hours, so a dog who is genuinely well three hours later has probably avoided the worst of it. But that window is not a guarantee, and bread in a compost bin rarely comes alone. Phone us, describe what was in there, and we will tell you whether to come in or what to watch for.

How much mouldy food does it take?

Less than people expect, and there is no safe amount to work out at home. The amount of toxin in a given piece of mouldy food varies enormously depending on which mould is growing and how long it has been there, so two similar-looking mouthfuls can behave completely differently. That is the reason we ask rather than calculate.

Is a compost bin dangerous to cats too?

Much less so, because cats are far more selective about what they eat and rarely scavenge a heap. The compost risk to a cat is mostly indirect: bins attract mice and rats, and a cat who hunts around one may catch prey that has eaten bait put down elsewhere. If you use any rodent control near the bin, or know a neighbour does, phone us with the product name as soon as you think your cat may have caught a poisoned mouse, not after they look unwell. With this one the useful window is before there is anything to see.

Can my dog eat windfall apples?

Not the ones that have been lying in wet grass. Those are a mould source, and a dog who grazes under a fruit tree every day through October is the dog who gets into trouble with this. A sound apple picked off the tree is fine beyond a possible upset stomach, and the seeds are only an issue in large quantities.

What about the smell? My dog is obsessed with the bin.

That interest is the warning, not a quirk. Decomposing food smells strongly of protein and fat to a dog, and a bin that has become a daily fixation will eventually get opened. Take persistent interest as a reason to secure the lid now rather than to supervise more closely.

My dog vomited after being in the compost and now seems better. Is that enough?

Not on its own. Vomiting clears some of what was swallowed but you have no way of knowing how much, and with mouldy food the vomiting often comes before the tremors rather than instead of them. It also does nothing about the onion or grape component, which works on a different timescale entirely. Phone us and tell us what came back up.

Is grass clippings-only compost safe?

Much safer, and it is a reasonable way to keep a bin without the risk. Grass, leaves, vegetable peelings and coffee-free garden waste grow far less of the mould that causes tremors. A latching lid is still worth having, because a dog who digs will find the warm middle of any pile.

Speak to the team at Langley Meadows Animal Hospital

If your dog has been in the compost, or is tremoring, wobbly or unable to settle after time in the yard, phone us and come in. Outside our hours, go to a 24-hour emergency veterinary hospital in the Lower Mainland and have a passenger call ahead on the way.

Published by the team at Langley Meadows Animal Hospital.

This article is educational in nature and is not a replacement for hands-on assessment of your own pet by a veterinarian.

Langley Meadows Animal Hospital
6233 200 St #7, Langley, BC V2Y 1A2
Phone: (236) 706-0019
Hours: Monday to Friday 8:00 AM to 10:00 PM; Saturday 9:00 AM to 10:00 PM; Sunday 10:00 AM to 10:00 PM; statutory holidays 8:00 AM to 10:00 PM