Acorns and Conkers: Autumn Dangers for Dogs

Acorns, the nuts of oak trees, contain tannins, which can irritate the lining of the stomach and intestines. Dogs who eat a few may only have mild stomach upset, but larger amounts can cause vomiting, diarrhea, and abdominal pain. Acorns, particularly whole ones or caps, can also form a blockage in the stomach or intestines, especially in small dogs.

Unripe acorns may contain more tannins than ripe ones, but all acorns should be avoided. A dog who chews and swallows a lot of acorns, or who is small, is at higher risk. If you are unsure, it is safer to treat it as a reason to call your vet.

Conkers are the shiny brown seeds of the horse chestnut tree, not to be confused with edible sweet chestnuts. They contain a toxin called aesculin, which can cause vomiting, diarrhea, and in more serious cases, weakness, a lack of coordination, and tremors. They are also large and hard, making choking and obstruction possible.

Horse chestnut leaves, flowers, and the spiky green husks can also be harmful. Keep dogs from chewing any part of the tree.

Note: Eating conkers can be an emergency. If your dog has eaten them, contact a veterinarian or an animal poison helpline immediately.

Signs can begin within hours, but a blockage may take a day or more to show. Contact your vet if you notice any of these.

• Vomiting, drooling, or retching.
• Diarrhea, or constipation and straining.
• Loss of appetite, or lethargy.
• A painful or swollen belly, or a hunched posture.
• Tremors, weakness, or lack of coordination (more typical of conkers).
• Blood in the vomit or stool.

Act promptly, and gather information. The details help your vet judge the risk.

1. Stop your dog from eating more, and remove any remaining nuts from their mouth, if safe.
2. Note how many were eaten, the type, and when.
3. Call your veterinarian or a poison helpline. In the US, the ASPCA Animal Poison Control Center is 888-426-4435 and the Pet Poison Helpline is 855-764-7661; a fee may apply.
4. Follow their advice, which may include monitoring at home or bringing your dog in.
5. Do not make your dog vomit unless a vet instructs you to.

Most dogs who pick up acorns do so because they are interesting to carry and chew. A few habits reduce the risk. Keep your dog on a leash under heavily laden trees, and scan the ground ahead. Choose paths with fewer trees during peak fall season. Clear acorns and conkers from your yard, and ask neighbors to do the same if they overhang your property.

Teach a reliable leave-it, practicing with real objects. Reward your dog for turning away, and give a better treat. Use a drop it cue, with trades, for dogs who have already picked something up.

Autumn is a good time to practice. Start with a treat under a cup, then place an acorn near your foot, and reward your dog for ignoring it. Move to items on the ground during walks. Always reward from your hand, not from the floor, and use high-value treats. If your dog is determined, use a muzzle, such as a basket muzzle, for walks in high-risk areas, after proper training.

Acorns and conkers are not the only seasonal risks. Autumn brings other items that tempt dogs.

• Wild mushrooms in damp grass and woods.
• Rotting fruit and fermenting windfalls, which may contain alcohol.
• Piles of wet leaves that hide sharp objects.
• Moldy compost and bins.
• Rat poison and slug pellets near buildings and gardens.
• Spiny horse chestnut husks, and sweet chestnut shells.

Practice with acorns or other objects in a safe place before you try it on a walk.

1. Show your dog an acorn in your hand, and reward when they sniff and look away.
2. Place an acorn on the floor under your shoe, and reward for ignoring it.
3. Uncover it, ready to cover it again, and reward each success.
4. Practice on a leash in the yard with several acorns.
5. Take it to a park, starting where there are few acorns.
6. Always reward from your hand, with a treat better than the acorn.

If you have an oak or horse chestnut tree, pick up fallen nuts daily with a rake or a wide broom, and put them in a sealed bin. Use a leaf blower or rake on piles, and check for hidden nuts. Fence off areas under trees, and supervise your dog. In late autumn, keep an eye out for mushrooms and rotting fruit as well. A little daily care can prevent a costly trip to the vet.