What should I watch out for on autumn dog walks?
Conkers, acorns, toadstools, harvest mites and blue-green algae. Which autumn hazards are worth worrying about, which aren't, and the one that can kill a dog in hours.
Conkers and acorns are the two that fill vets' phone lines in September, and both are worth avoiding rather than panicking about. The one that genuinely kills is blue-green algae in standing water, and it can do it within hours. Everything else on this page is manageable if you know what you're looking at.
Got a cat as well? The autumn list for cats is almost entirely different, and antifreeze is the one that matters. See autumn dangers for cats.
Are conkers and acorns poisonous to dogs?
Yes, both, and they're the most common autumn problem by a distance.
Conkers fall from horse chestnut trees and contain a toxin called aesculin. Dogs Trust say a dog who eats or chews one can become seriously unwell, with vomiting, diarrhoea, stomach pain, restlessness, swelling around the eyes and mouth, and in bad cases collapse. Symptoms can appear anywhere from an hour to two days later.
Acorns come from oaks and contain tannins. Same picture: drooling, vomiting, diarrhoea, stomach pain and lethargy, with kidney and liver damage possible if a dog eats a lot.
Both are also the wrong size and shape. A conker is a choking risk for a small dog and a blockage risk for a big one that swallows it whole.
Dogs Trust advise walking on the lead where conkers are thick on the ground, and ringing your vet straight away if you think your dog has had one. Don't wait for symptoms.
The practical version: if your usual route goes under horse chestnuts or oaks, September and October are lead months. If your dog is a hoover, that's not negotiable.
What about toadstools and mushrooms?
Assume the worst and move them on.
The Kennel Club's position is the sensible one. Some are harmless, some are lethal, and telling them apart is difficult even for people who study fungi for a living. Nobody is identifying a toadstool correctly on a phone screen in a wet field.
So there's no useful list to give you. If your dog picks one up, take it off them, and if they've swallowed any of it, ring your vet and take a photo of what's left.
Which one should I actually worry about?
Blue-green algae. This is the one that turns into an emergency.
It isn't algae, it's cyanobacteria, and it forms in standing water: ponds, lakes, flooded fields, and the still edges of slow rivers. It can look like green scum, a pea-soup film, or paint spilled across the surface.
PDSA's advice is blunt and worth following exactly. Carry water for your dog rather than letting them drink from open water. Be extra careful around stagnant water in summer and autumn. Never let a dog swim in or drink from water with dead fish in it. Check local council websites and look for warning signs when you're somewhere new.
Not every bloom is toxic, but you cannot tell by looking, so all of it gets treated as toxic. If your dog has been in water you're unsure about, don't wait to see how they get on. Ring your vet.
This is the one hazard on the page where speed genuinely changes the outcome.
Why is my dog suddenly itching?
Probably harvest mites, if it's started in the last few weeks.
They're tiny bright orange mites that live in soil and long grass, and PDSA put their active season at July to November. They cluster on the parts of a dog closest to the ground: feet, legs, tummy, and sometimes inside the ears. They look like orange dust or a sprinkle of paprika on the skin.
The itch is out of proportion to the size of the thing causing it. Some dogs barely react and others chew their feet raw.
Worth knowing: PDSA say ordinary flea and tick spot-ons don't appear to shift them, so this is a vet conversation rather than something to treat off the shelf.
And one thing most autumn articles leave out. PDSA describe seasonal canine illness, a condition that turns up in autumn, typically a few days after a walk in woodland. Signs are vomiting, diarrhoea, low energy, a high temperature and muscle tremors. Nobody is certain what causes it and harvest mites are one suspect. Left untreated it can be fatal.
If your dog walked in woods this week and is now unwell in that pattern, say so when you ring the vet. It matters.
Is there anything in the leaf piles?
Less than the internet suggests, but two things are real.
Wet leaf piles grow mould, and a dog who eats a mouthful can get an upset stomach. And piles hide things: broken glass, sharp sticks, whatever was dropped there in August. Paw injuries in autumn usually come from what was under the leaves rather than the leaves themselves.
Check paws when you get home. That's the whole precaution.
What changes about walking in the dark?
Everything about being seen, and it creeps up on you. The walk that was in daylight last week isn't any more.
That's a big enough subject that it gets its own article. The short version for now: if your dog is off the lead near roads in the dark and you can't see them from thirty paces, neither can a driver.
Quick reference
| What | How bad | What to do |
|---|---|---|
| Conkers | Common, occasionally serious | Lead under horse chestnuts. Ring the vet if eaten, don't wait |
| Acorns | Common, occasionally serious | Same. Watch for drooling and vomiting |
| Toadstools | Rare but can be lethal | Take it off them, photograph it, ring the vet |
| Blue-green algae | Rare and can kill fast | Avoid all standing water. Carry your own water. Vet immediately |
| Harvest mites | Common, miserable, not dangerous | Vet appointment. Spot-ons don't work on them |
| Seasonal canine illness | Uncommon, can be fatal | Vet same day. Mention the woodland walk |
| Leaf piles | Minor | Check paws afterwards |
When should I ring the vet?
Straight away, without waiting for symptoms, if your dog has eaten a conker, an acorn or any fungus, or has been in standing water you weren't sure about.
Same day if they're vomiting, have diarrhoea, have gone quiet and flat, are drooling more than normal, or are shaking or trembling. That last one matters more in autumn than it does the rest of the year.
And book an appointment if the itching started recently and won't settle, because harvest mites need a prescription rather than a shop-bought treatment.
If you can't reach your vet and you think your dog has eaten something poisonous, Animal PoisonLine is a 24-hour service run for pet owners. There's a charge, and it will tell you whether you need to go in.
What should I actually do this autumn?
Not much, honestly, and that's the point. Most dogs get through autumn with nothing worse than muddy legs.
Two things are worth doing. Put your dog on the lead where the ground is covered in conkers or acorns, for the six or so weeks it lasts. And carry water so they aren't tempted by a pond, which is the single change that removes the only hazard here that can kill quickly.
A travel bottle or a folding bowl costs a few pounds and lives in your coat pocket all autumn.
That's it. No supplement, no seasonal wash, no protective boots. If your dog is well, walk them and enjoy it.