By Dial A Vet Veterinary Team
If your dog has just swallowed a corn cob, or a chunk of one, call your vet now. Corn kernels are a common ingredient in dog food and are not toxic, but the cob is a different object altogether. It is dense, fibrous, does not break down in the stomach, and is often exactly the right size to lodge in a dog's small intestine. Corn cobs are one of the foreign bodies vets see most often in summer, usually after barbecues or a raid on the kitchen bin. Many of these dogs need surgery, and the earlier a vet is involved, the better the options.
Key takeaways
- Plain, cooked corn kernels off the cob are not toxic and are fine for most dogs in small amounts.
- Corn cobs do not digest and are a classic cause of intestinal obstruction in dogs.
- Dogs can seem normal for a day or more after swallowing a cob, then become very unwell.
- Contact your vet as soon as you know or suspect your dog swallowed cob, even if they seem fine.
- Do not try to make your dog vomit at home. A cob can lodge in the oesophagus on the way back up.
- Related: intestinal blockage in dogs, vomiting and diarrhoea.
Why cobs are so dangerous
Dogs rarely chew a cob into small pieces. They gnaw off the kernels and then swallow large sections of cob in a gulp. The cob's woody core is not broken down by stomach acid or enzymes, so it stays the same size as it travels. The stomach outlet and small intestine are narrow, and a cob section can get stuck. Once lodged, it stops food and fluid passing, the gut above it swells, and the pressure can damage the gut wall. If left too long, the intestine can be injured or perforate, causing a life-threatening infection in the abdomen.
Buttered and salted corn adds fat and salt, which can bring on vomiting and diarrhoea, but it is the cob itself that drives the emergency.
Signs of a blockage
Signs can start within hours or may be delayed by one to three days. Watch for:
- Vomiting, often repeated, and sometimes immediately after eating or drinking
- Refusing food or treats
- Lethargy, depression or hiding
- Abdominal pain: a tense belly, a hunched posture, reluctance to lie down or to be picked up
- Straining to pass faeces, or passing little or none
- Diarrhoea in some cases
- Drooling or gulping, which may mean the cob is stuck higher up
When it is an emergency
Treat any swallowed corn cob as an emergency. Call your vet or nearest emergency hospital straight away if:
- You saw your dog swallow a cob or a large piece of one
- A cob is missing from the bin or the barbecue plate and your dog had access
- Your dog is vomiting, off food, has a sore belly or seems flat after a barbecue
- Your dog is retching without producing anything, or has a swollen belly
Do not wait to see whether the cob passes, and do not give food, oil or laxatives in the hope of moving it along. Never try to make your dog vomit at home.
How vets diagnose and treat it
Your vet will ask when your dog ate the cob, examine the belly and assess hydration. X-rays often show a cob as a rectangular shape with a stippled gas pattern from the kernel sockets, and ultrasound can help confirm a blockage. Blood tests help assess dehydration and overall health before anaesthetic.
If the cob is still in the stomach and the dog is seen early, the vet may be able to remove it with an endoscope under anaesthetic. A cob lodged in the intestine generally needs surgery to remove it, and sometimes a damaged section of intestine also has to be removed. After surgery, dogs typically need hospital care with fluids, pain relief and a gradual return to food. Your vet will discuss the plan, the risks and the expected recovery for your dog.
Is corn itself OK?
Plain cooked corn kernels removed from the cob can be an occasional treat. They are not toxic, although many dogs pass them largely undigested. Skip butter, salt and seasonings. Popcorn should be plain and unsalted, and unpopped kernels can be a choking hazard or damage teeth. Corn chips are salty and fatty.
Prevention
Corn cob obstructions are very preventable:
- Put cobs straight into a lidded bin or a bin a dog cannot open, ideally outside.
- Do not leave cobs on plates at the table or barbecue.
- Ask guests and children never to give cobs to dogs.
- Keep dogs away from compost heaps and garden beds where cobs are dumped.
- Do not give cobs as chew toys, even to large dogs.
- Supervise dogs at picnics and barbecues, and keep them on lead near food scraps in parks.
FAQ
My dog swallowed a small piece of cob. Will it pass?
It might, but you cannot know. Call your vet for advice now rather than waiting for signs.
My large dog ate a cob yesterday and seems fine. Is he out of danger?
Not necessarily. Signs can take several days. Call your vet and watch closely for vomiting and appetite changes.
Can I give my dog something to help the cob pass?
No. Oils, laxatives and extra food can make things worse. Let your vet guide you.
Is corn bad for dogs?
Corn kernels are not toxic. The cob is the danger.
Talk with a vet
If you think your dog may have swallowed a corn cob, call your local vet or emergency hospital first. If you are unsure whether to go in, a Dial A Vet veterinarian can help you decide quickly. Book a Dial A Vet consult.
References
- Merck Veterinary Manual. Gastrointestinal Obstruction in Small Animals.
- RSPCA Australia Knowledgebase. What should I feed my dog?
- American Kennel Club. Can Dogs Eat Corn?
- ASPCA Animal Poison Control Center. People Foods to Avoid Feeding Your Pets.
Disclaimer: Educational only. This page does not replace an examination or advice from your own veterinarian. If you are worried about your pet right now, contact your local vet or nearest emergency animal hospital.