My Dog Ate An Acorn - What Should I Do?

Posted by Volhard Dog Nutrition on Sep 22nd 2025

Acorns are one of autumn's most beautiful signs of the season change; however, what happens if your dog likes to eat them?

Acorns attract dogs who curiously sniff around in wooded areas. Although they may seem harmless to you, acorns, along with oak leaves, pose a potential threat to your dog's health.

If your dog consumes either, prompt intervention is essential to prevent more severe cases of poisoning and facilitate recovery.

Since acorns ripen and begin to fall from oak trees in September (or even sooner, due to climate change), it is time for you to learn all about acorn poisoning in dogs and the ways to prevent such accidents from happening.

Acorn Poisoning and Tannins

Acorn (or Quercus) poisoning occurs when dogs ingest substantial quantities of oak leaves and acorns.

The primary reason for acorn poisoning lies in its components, specifically tannins, a chemical substance derived from phenolic acids (i.e., micronutrients found in plants) that deter herbivores from consuming them.

Tannins are present in high concentrations in oak leaves and in unripe acorns, which are green in color. This high tannin content helps deter animals from eating them. As acorns ripen and turn brown, tannin levels decrease significantly, reducing the risk of acorn poisoning.

Nevertheless, keeping your dog away from ingesting any acorns is imperative. Tannins act by binding with proteins, cellulose, starches, and minerals. Once the binding process is complete, the resulting substances become insoluble and resistant to decomposition.

Therefore, you must be cautious and keep your dog away from water sources that are exposed to oak leaves and acorns. The binding process renders tannins resilient enough against the drying and freezing processes, making oak leaves and acorns dangerous even after the fall season - another reason to keep your yard oak leaf and acorn-free!

Risks of Acorn Ingestion

The risk is especially high when acorns are green or freshly fallen, as tannin levels are at their peak. In addition to chemical toxicity, acorns pose a physical danger; their hard shells can cause choking, get lodged in the esophagus, or create dangerous intestinal blockages.

Symptoms of acorn ingestion may include:

Vomiting and diarrhea (sometimes with blood).
Loss of appetite and lethargy.
Abdominal pain or bloating.
Excessive thirst and frequent urination.
Constipation followed by loose, hemorrhagic stool.

Small breeds are at the greatest risk of severe poisoning or obstruction, but all dogs can suffer complications from eating acorns.

Symptoms of Acorn Poisoning

Acorn poisoning will not be dangerous to your dog’s long-term health as long as you intervene quickly. Approximately 75% of dogs show poisoning symptoms after ingestion of acorns, primarily localized in the stomach, kidneys, and liver. Once your dog shows signs of acorn poisoning, a visit to the veterinarian is critical.

Different types of tannins can cause varying health issues in your dog. Tannins are divided into two categories: hydrolyzable (i.e., dissolvable) tannins, or HTs, and condensed tannins, or CTs.

HTs lead to protein denaturation and cell death in the kidneys and liver, while CTs damage the gastrointestinal mucosa and disrupt nutrient absorption.

Your dog's size can also determine the severity of acorn poisoning. Larger breeds may escape with only a mild digestive upset, while smaller breeds, such as Maltese, Chihuahuas, Schnauzers, Poodles, and Yorkshire terriers, suffer more from acorn poisoning due to their reduced size.

They frequently develop hemorrhagic gastroenteritis, so smaller breeds require extra careful attention during the fall.

The primary acorn poisoning symptoms include:

Anorexia.
Dehydration.
Abdominal pain.
Polydipsia (i.e., excessive thirst).
Polyuria (i.e., excessive need to urinate).
Constipation followed by hemorrhagic diarrhea.
Vomiting.

Acorn poisoning can lead to gastrointestinal (GI), hepatic, and renal dysfunction in more severe cases. Only in extreme cases can acorn poisoning be fatal.

First Aid and When to Seek Veterinary Care

If you suspect your dog has eaten acorns, don't wait for symptoms to worsen. Acorn toxicity can progress quickly. Here's what to do:

Stay calm and remove access to any remaining acorns.
Offer fresh water to help dilute tannins.
Do not induce vomiting unless instructed by your veterinarian; acorns can splinter and cause injury on the way back up.
Monitor your dog closely for signs of vomiting, diarrhea, bloating, or abdominal pain.

Seek immediate veterinary care if you notice:

Repeated vomiting or diarrhea (especially if bloody).
Severe abdominal swelling or pain.
Sudden weakness, collapse, or tremors.
Refusal to eat or drink for more than 24 hours.

Early treatment greatly increases the chance of a full recovery.

Choosing a Proactive Approach to Prevent Acorn Poisoning

Acorn poisoning calls for a preventive rather than a reactive approach. After all, dogs do put things in their mouths; it’s in their instinct.

Therefore, the danger of ingesting an acorn or an oak leaf is always present; although you might be careful and remove the acorn from your dog's mouth on time, the risk doesn't vanish. Instead of being on your toes at all times, you can offer an alternative safe chew, or teach your dog an easy yet invaluable command to prevent acorn or oak leaf ingestion - the "Leave It" command.

Teaching the "Leave It" command to your dog calls for patience and dedication, but after a few short training sessions, your dog should begin to pick up on the command.

Here's a simple guide compiled by our founder, Wendy Volhard, to help you teach the “Leave It” command to your dog in no time!

Teaching the "Leave It" Command

Step #1: Hold a treat between your left hand’s index and middle fingers while covering it with your thumb. Keep your hand pressed against your leg.

Step #2: Show the treat to your dog. As they attempt to retrieve the treat, say “Leave It!” Right afterward, close your hand into a fist and turn it towards the ground.

Your reaction will intrigue your dog and cause it to further investigate your hand. Nuzzling and nibbling your hand or barking may accompany the process.

Step #3: Wait for your dog to break its focus from your hand while remaining silent. At this time, your dog will probably turn its head to the right or the left, showing disinterest in continuing its inspection.

Step #4: Reward your dog with praise and a treat once it no longer focuses on the hand.

Repeat these steps until your dog breaks its attention from your hand each time you give the command. However, remember that you are teaching your dog to forget about an object, not to turn its head. In this case, your dog might be trying to receive its treats as soon as possible by turning its head from your hand only momentarily, before returning its interest to your hand once again. This reaction, however, does not equate to a complete apprehension of the command. More learning steps will need to be taken.

Step #5: Repeat step #1 without turning your hand. If your dog breaks its attention from your hand, reward it with praise and treats.

Once your dog learns to ignore the treat in your hand, you can diversify the technique by placing it on the ground and touching it with your index finger or leaving it unattended.

Gradually, your dog will master the "Leave It" command and refrain from bringing you unwanted objects. If you hit any bumps in the road, check out Wendy Volhard's book for an extensive explanation of the learning steps.

Types of Edible Nuts for Dogs

Acorns aside, can nuts, in general, be added to your dog’s diet? Nuts are not a familiar presence in the canine food bowl, nor do dogs receive the same nutritional benefits from nuts as humans or other animals. If you are thinking about enhancing your dog’s diet by adding some nuts as snacks or training treats, be sure to focus on the following varieties:

#1: Almonds

Although not toxic, almonds are not easily digested in the dog’s stomach. They also represent a choking hazard, regardless of the dog’s size, so be sure that you feed small, unsalted (salt tends to upset the dog’s digestive system) almonds to your dog.

#2: Chestnuts

This rich omega-3 fatty acids and fiber source is ideal for humans, and your dog will definitely enjoy chestnuts too! Add chestnuts to your dog’s food bowl in moderation (not without removing the shell, of course). Their salty and starchy composition can cause gastrointestinal distress and impede the digestive system's function.

#3: Cashews

Their high fat and protein composition can lead to severe medical issues, such as pancreatitis, so be sure that you feed no more than two at a time to your dog. Feed everything in moderation.

Remember that nuts are not always a welcome addition to your dog’s food bowl. Aside from the choking hazard and possible digestive issues if fed in excess, specific nuts, such as peanuts, serve as perfect environments for aflatoxins (i.e., toxins produced by the mold Aspergillus flavus) to sneak their way into your dog, which can cause liver damage and death in extreme cases.

Unfortunately, nuts can contain aflatoxins even if no mold traces are visible; therefore, avoiding nuts altogether might prove to be the safest choice for your dog if you are unable to source wholesome, locally produced nuts.

Ensure that your dog avoids the following varieties of nuts, as they are entirely unsafe for dogs to eat and could cause serious harm even if ingested in small quantities:

Peanuts.
Pistachios.
Macadamia nuts.
Brazil nuts.
Pecan nuts.
Hazelnuts.

Frequently Asked Questions about Acorns and Dogs

Can one acorn really make my dog sick?

Yes. While one acorn may not always be fatal, it can cause digestive upset or, in small dogs, potentially life-threatening blockages or poisoning.

Are oak leaves dangerous, too?

Yes. Both oak leaves and acorns contain tannins, which can be toxic to dogs if they are chewed or ingested.

What if my dog ate an acorn but seems fine?

Sometimes acorns pass without incident, but symptoms can appear hours later. Always call your veterinarian for guidance, even if your dog looks normal at first.

How do I acorn-proof my yard?

Regular raking, fencing off oak areas, and supervising outdoor play are the most reliable ways to keep your dog safe.

Should I keep my dog leashed or closely monitored in oak-heavy areas?

Yes. Oak-heavy areas are full of acorns and fallen leaves, both of which pose a risk to your dog’s health. Keeping your dog leashed or under close supervision ensures they don’t have the chance to pick up and swallow acorns before you can intervene.

What safe alternatives can I give my dog so they're less tempted to explore harmful objects?

Providing safe chew toys and enrichment activities is one of the best ways to redirect your dog's curiosity. Durable chew toys, puzzle feeders, and healthy treats can keep your dog occupied and satisfied, reducing the likelihood that they'll seek out acorns or other unsafe items outdoors.

Protect Your Dog's Health with Volhard Dog Nutrition

Numerous autumnal dangers, such as acorns and oak leaves, may lurk in your own backyard, but as always, overall health through regularly feeding natural, fresh food and proper training will help you keep your canine companion healthy, happy, and safe.

For more advice on dog nutrition, health, and training, contact us and check out our other blogs, too!

Volhard Dog Nutrition and its expert canine nutrition coaches offer online consultations to help more dog parents discover why and how to feed their dogs the healthiest foods!

Speaking to a Volhard canine nutrition coach will help you understand the inseparable relationship between healthy food, a healthy body, and a healthy mind.

If you want to contact one of our Volhard canine nutrition coaches, you can do so by utilizing our Live Chat feature or scheduling a consultation.

References

Blue Cross UK. Acorn poisoning in dogs. Retrieved from https://www.bluecross.org.uk
Colorado State University. Tannins and their effects. Retrieved from https://csu.edu
Dog Care Life. Can dogs eat chestnuts? Retrieved from https://dogcarelife.com
Food and Drug Administration (FDA). Aflatoxins and pet food safety. Retrieved from https://www.fda.gov
Merck Veterinary Manual (MSD). Oak poisoning in animals. Retrieved from https://www.msdvetmanual.com
PetMD. Are nuts safe for dogs? Retrieved from https://www.petmd.com
U.S. Forest Service. Oak tree tannins and protein binding. Retrieved from https://www.fs.usda.gov
Veterinary Information Network (VIN). Hydrolyzable vs. condensed tannins. Retrieved from https://www.vin.com
VetHelpDirect. Acorn poisoning symptoms in dogs. Retrieved from https://vethelpdirect.com
VetStream. Tannins in acorns and toxicity resistance. Retrieved from https://www.vetstream.com
WebMD. Phenolic acids explained. Retrieved from https://www.webmd.com
American Kennel Club (AKC). Cashews and dogs: Risks and benefits. Retrieved from https://www.akc.org
The Guardian. Plantwatch: Acorn crop dips as climate changes. Retrieved from https://www.theguardian.com/science/2015/oct/21/plantwatch-simons-oaks-acorns-spring-flowering-pollination-climate-change