Autumn Hazards for Dogs: Conkers, Acorns & Harvest Mites
Autumn walks are some of my favourites, all crunchy leaves and muddy paws and dogs having the time of their lives. It's also the time of year a handful of things start turning up on the ground, in the grass and in the dark that are well worth knowing about. None of them need to stop you getting out, they just need a bit of awareness. Here's what to look out for, and what the vets say to do about each one.
- Conkers & acorns
- Harvest mites, July–November
- Darker evenings
TL;DR — key points
- Conkers and acorns are toxic and can cause vomiting, stomach upset and blockages, so don’t let your dog eat them
- Some wild mushrooms and fungi are very toxic, so keep your dog away from all of them
- Harvest mites are tiny orange mites that make feet, legs and tummies itchy between July and November
- Seasonal canine illness can be serious, so call your vet straight away if your dog is unwell a few days after a woodland walk
- Reflective gear, a torch and a charged phone make darker evenings safer
- Avoid stagnant puddles, and anything with a blue-green layer on the water
Quick reference only — this is a shortened summary, not medical advice. For anything urgent, read the full guide below and contact your vet.
Conkers and acorns
Both are everywhere on autumn walks, and both are toxic to dogs. PDSA says serious poisoning is rare, but they can cause stomach problems, vomiting and blockages in the intestines. Acorns contain tannic acid, which affects the liver and kidneys, and the unripe green ones are more toxic than the rest. A horse chestnut tree has several poisonous parts, including the bark, leaves and flowers as well as the conkers, and a swallowed conker can block the intestines, which could be fatal.
Plenty of dogs pick them up simply because they're there and they're fun to carry, so it's worth keeping an eye on what your dog has in their mouth and swapping it for a treat. For dogs who scavenge a lot, PDSA suggests a basket muzzle and training classes if coming back when called is a struggle.
Signs of poisoning can include sickness, diarrhoea, drooling, tummy pain, shaking and breathing problems. If you think your dog has swallowed a conker or acorn, ring your vet for advice straight away.
A conker is only a worry if my dog eats loads of them.
Large amounts can cause harm, but a swallowed conker can also block the intestines, which can be serious. It’s best not to let them eat any, and to ring your vet if one has gone down.
Mushrooms and fungi
The damp weather brings fungi popping up in grass and woodland. Not every species is dangerous, but some are very toxic, and it isn't something you can judge by eye, so PDSA's advice is to keep your dog away from all of them. Watch for your dog sniffing at or eating anything growing in the grass or at the foot of trees.
If your dog does eat one, ring your vet straight away. If you can do it safely, take a quick photo of the mushroom first as it can help with identifying it, but don't hang about. My dog first aid guide covers what to do if you think a dog has eaten something poisonous, including the Animal PoisonLine.
Harvest mites
Harvest mites are tiny, bright orange mites that live in the soil. They're common in woodland and grassy areas, and they're most active between July and November. They'll attach to any animal that brushes past, dogs included, and some dogs are very sensitive to their saliva. You can often see them as tiny red or orange dots on the skin and fur, most commonly between the toes and on the feet and legs, but also in the armpits, on the tummy and sometimes in the ears.
The skin becomes itchy, red and inflamed, and you might notice your dog licking and chewing at their feet constantly, which can stain the fur. Checking between the toes after a woodland or long-grass walk only takes a minute and is the easiest way to spot them early.
If you think your dog has harvest mites, contact your vet, as they'll probably need treatment. There's no product made specifically to kill them, but some flea treatments work, and your vet may add an anti-inflammatory to calm very itchy skin. PDSA says dogs on regular flea treatment are unlikely to catch them, and once they're cured the outlook is excellent. My guide to fleas has more on that side of things.
Seasonal canine illness
There's also something called seasonal canine illness. Nobody is sure what causes it, but it's suspected it could be linked to harvest mites. It typically starts a few days after a walk in woodland, with vomiting, diarrhoea, low energy, a high temperature and muscle tremors, and left untreated it can be fatal. If your dog shows these signs, especially if they've been in woodland recently, contact your vet immediately.
Not veterinary advice: this guide is general information, not a diagnosis or treatment plan. If your dog seems unwell after a walk, or you think they've eaten something they shouldn't, please speak to your vet straight away.
Mud, puddles and blue-green algae
Muddy walks are half the fun, but leaves can hide sharp stones and rubbish that can cut a paw, so it's worth carrying a basic first aid kit. Bring a towel for mucky paws too, so your dog isn't tempted to lick anything harmful off their fur.
Early autumn can still bring blue-green algae. It's highly toxic and can quickly become fatal, so if you see a blue-green layer on any water, avoid it entirely. Muddy, stagnant puddles and ponds can also cause a stomach upset, and clean fresh water in your bag helps stop your dog drinking from them. There's more in my water safety guide.
Darker evenings
With the clocks going back, your usual evening walk can suddenly be in the dark. PDSA suggests reflective lights on your dog's collar, harness or lead so you can both be seen, and it's sensible to take a torch and a fully charged phone with you as well.
Halloween and the central heating
Halloween brings its own hazards. Chocolate is highly toxic to dogs, so keep the trick-or-treat sweets well out of reach, and keep lit pumpkins away from them too, as mouldy pumpkins can make a dog sick if eaten. A walk before it gets dark means fewer costumes to startle your dog, and a quiet den away from the front door helps if the doorbell keeps going. If it's fireworks you're worried about, my Bonfire Night guide has plenty on keeping dogs calm.
Autumn is also when the central heating goes on, which PDSA says can wake up dormant flea eggs in the house, so it's a good time to check your flea treatment is up to date.
Autumn really is a lovely time to be out with a dog, and a bit of awareness is all it takes. If you've got any questions, or you're not sure whether something is a worry, message me, I'm always happy to help.
Where this advice comes from
If you'd like to read the vets' own advice in full:
- PDSA on caring for your pet in autumn and toxic autumn plants
- PDSA on harvest mites in dogs
- PDSA on poisons and hazards for your pets
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