Dogs and conkers – a recent article in the Canine Times – explains how conkers can harm dogs.  It warns dog walkers about the dangers of conkers – for two reasons, says vet Joanna Woodnutt:

Conkers Can Harm Dogs As They Are Poisonous –

Firstly, conkers are particularly hard and non-digestible, she says. Swallowed conkers can cause a gut obstruction, requiring emergency surgery to treat. Secondly, if your dog chews the conker, they still aren’t safe – conkers are poisonous and can induce abdominal pain, drooling and vomiting. So yes, very definitely, conkers can harm dogs.

So keep an eye on your dog when on your walks at this time of year. Teaching your dog to play “leave it” or “drop it” games can prevent conkers being a hazard even if your dog does pick one up.