Are conkers poisonous to dogs?

Horse chestnut trees (Aesculus hippocastanum) are common in parks, playgrounds and streets across the UK and Europe. The shiny brown conkers, along with the leaves, bark and flowers, contain aesculin and saponins. These irritate the gut and, in larger amounts, can affect the nervous system.

Signs often begin within 1 to 6 hours but can be delayed.

Vomiting, diarrhea, drooling, loss of appetite, restlessness and belly pain are the most common. Severe cases may involve dehydration, wobbliness or tremors. Even without poisoning, a conker can block the intestine, causing repeated vomiting and straining.

Conker cases and horse chestnut leaves fallen in autumn carry the same compounds, so puppies chewing leaf litter under the trees can be affected too.

Conkers are round, smooth and ball-sized for many dogs, so they are tempting to carry and chew. Children collecting conkers may throw them for dogs. Explain to children that conkers are not dog toys, and bring a proper ball on autumn walks.

Sweet chestnuts, the edible kind, grow in very spiky cases with several flattened nuts. Conkers grow in cases with fewer, stubbier spikes and are single and round. Horse chestnut leaves are made of five to seven large leaflets spreading from one point, like fingers on a hand.

Conkers brought home for games or crafts, or used as a spider deterrent on windowsills, are easy for dogs to reach. Keep them in a closed container well above nose height.