By Dial A Vet Veterinary Team
Cornstarch, sold as cornflour in most Australian supermarkets, is a fine white powder made from corn. It thickens sauces and gravies, goes into baking, and is a staple of homemade play dough. If your cat walked through a spill and licked its paws, that is very unlikely to cause harm. What matters more is what the cornstarch was mixed with.
Key takeaways
- Plain cornstarch is not toxic to cats in small amounts. It is almost pure starch and offers no nutritional benefit.
- Gravies and sauces thickened with cornflour often contain onion, garlic, stock powder or salt.
- The RSPCA lists onion, garlic and salt among foods harmful to cats.
- Homemade salt play dough and salt-dough ornaments can cause salt poisoning in pets, according to Pet Poison Helpline.
- Call the Animal Poisons Helpline on 1300 869 738 if your cat ate play dough, salt dough or seasoned gravy.
- Related reading: onions and cats, garlic and cats.
Plain cornstarch
Cornstarch is a refined carbohydrate. Cats are obligate carnivores, and the RSPCA explains that they cannot use plant foods in the way dogs can. Some commercial cat foods do contain grains or starch as part of a balanced formula, as Cornell notes, but plain cornstarch on its own adds nothing to a cat's diet. A lick of spilled powder is not a worry. A large amount could cause a mild tummy upset, and a cloud of fine powder may make a cat sneeze.
Where the real risks are
Gravy and sauces. Cornflour is often used to thicken gravies, stir-fry sauces and casseroles. These commonly contain onion, garlic, stock cubes or salt. Merck Veterinary Manual explains that cats are the most susceptible species to Allium poisoning, and that garlic is roughly three to five times as toxic as onion. Powdered and dehydrated forms are concentrated. Damage to red blood cells may not show for a few days after a cat eats them.
Homemade play dough and salt dough. Many play dough recipes use cornflour along with a large amount of salt. Pet Poison Helpline lists homemade salt play dough and salt-dough ornaments as common sources of salt poisoning in pets. Salt poisoning can start with vomiting and diarrhoea and progress to neurological signs.
Baking mixes. Cornflour goes into many cakes, biscuits and custards. Recipes that include chocolate, raisins, macadamia nuts or sweeteners carry their own risks.
Signs to watch for
After plain cornstarch, most cats show nothing, or a little soft stool. After seasoned food or salt dough, watch for:
- vomiting or diarrhoea
- excessive thirst or urination
- lethargy, wobbliness or tremors
- pale gums, weakness or fast breathing, which can appear days after onion or garlic
When it is an emergency
Call your vet or the Animal Poisons Helpline on 1300 869 738 straight away if your cat:
- ate homemade play dough, salt dough or a salt-dough ornament
- ate gravy, sauce or casserole containing onion or garlic
- is vomiting repeatedly, trembling, wobbly or having a seizure
- seems weak, has pale gums or is breathing fast
Do not try to make your cat vomit at home, and never use salt to induce vomiting.
How vets help
Your vet will want to know what the cornstarch was mixed into and how much your cat ate. For plain powder, monitoring at home is usually enough. For salt dough, your vet may check electrolyte levels and give carefully managed fluids. For onion or garlic, your vet may recommend blood tests and monitoring over several days.
Prevention
- Keep cornflour and baking supplies sealed in the pantry.
- Store play dough in sealed tubs and supervise craft time if you have a cat.
- Hang salt-dough ornaments out of reach, or skip them if your cat is a climber.
- Cool and cover pots of gravy and sauces, and do not leave plates on benches.
- Wipe up spills before your cat walks through them.
FAQ
Is cornstarch in cat food bad?
Not necessarily. Complete and balanced cat foods are formulated as a whole, and some contain starch. Talk with your vet if you have concerns about your cat's diet.
Can I use cornstarch on my cat's skin or coat?
Please ask your vet before putting any powder on your cat. Cats groom and swallow what is on their coat.
My cat ate play dough. What do I do?
Call your vet or the Animal Poisons Helpline on 1300 869 738 now, even if your cat seems fine.
Is cornflour slime safe for cats?
Plain cornflour and water is low risk, but added colours, glitter or other ingredients may not be. Keep craft projects away from your cat.
Talk with a vet
If your cat got into the pantry or the craft box, a Dial A Vet veterinarian can help you decide what to do next. Book a Dial A Vet consult.
References
- Pet Poison Helpline. Salt Is Toxic To Pets.
- Merck Veterinary Manual. Garlic and Onion (Allium spp) Toxicosis in Animals.
- RSPCA Knowledgebase. What should I feed my cat?.
- RSPCA Knowledgebase. Do cats have special nutritional requirements?.
- Cornell Feline Health Center. Feeding Your Cat.
- Animal Poisons Helpline (Australia, 1300 869 738). Animal Poisons Helpline | 24/7 Pet Poisoning Advice.
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.