Official U.S. shopSafety
Mighty K9 Side Effects: Signs to Watch and When to Call a Vet
Most Mighty K9 side effects come from the olive oil, not the C60.
Each 2 mL serving is about 1.8 g of fat and 16.2 kcal, which can cause loose or greasy stool, vomiting or slow weight gain. Fat can also trigger pancreatitis in some dogs, so stop it and call your vet if anything looks wrong.
Not sure it fits your dog? Read who Mighty K9 is for.
Written by the Mighty K9 editorial teamUpdated
The usual suspects
What are the side effects of Mighty K9 in dogs?
The side effects owners are most likely to see come from the olive oil, since the bottle is almost pure fat.
The Guaranteed Analysis lists crude fat at 100% and calories at 8,100 kcal ME/kg; 16.2 kcal ME per 2 mL serving (AAFCO, Reading labels). Some dogs react to any new fat, the way they react to bacon grease off the counter. The ASPCA says fats and oils can cause vomiting and diarrhea in pets (ASPCA, People foods).
Signs to watch for in the first two weeks:
- Loose or soft stool. The most common reaction to added oil. It often settles in a few days.
- Greasy, shiny or pale stool. A sign the fat is passing straight through.
- Vomiting. Repeated vomiting is a reason to stop.
- Slow weight gain. 16.2 kcal a day adds up over months, mostly in small dogs.
- Skipping meals. Some dogs dislike the oily texture.
Note when each sign starts and what your dog ate that day.
The serious one
Can Mighty K9 cause pancreatitis in dogs?
It can in some dogs, because extra fat is a known trigger. The ASPCA lists pancreatitis as a possible result of fats and oils (ASPCA, People foods), and Merck names eating something unusual or fatty as a common risk factor in dogs (Merck Vet Manual, Pancreatitis).
Pancreatitis is swelling of the pancreas, and it can be mild or life-threatening. Dogs who have had pancreatitis usually need a low-fat diet, under 20 g of fat per 1,000 kcal (Merck Vet Manual, Pancreatitis).
Repeated vomiting, a painful or tight belly, the hunched "prayer" position (front legs down, rear end up), refusing food, weakness, or diarrhea with lethargy. Stop the oil and call your vet or an emergency clinic. Do not wait to see if it passes.
Calories
Will Mighty K9 make my dog gain weight?
It can, slowly, if nothing else changes in the bowl. The bars show one serving as a share of a typical day.
For a 12 lb Shih Tzu, one serving is about 4% of the day; for a 70 lb Lab, about 1%. Lean body weight is the single most useful thing an owner can do for joints (ACVS, Osteoarthritis), so trim a few kibbles to make room. See how much to give for the full calorie table.
The unknowns
Is C60 safe for dogs long term?
Nobody knows yet. The C60 safety data is short-term, mostly in rodents, and partly seller-funded.
| Study | Animals and length | What it tells us |
|---|---|---|
| Burres 2024 (Burres et al., 2024) | 20 rats, 14 days | No harm seen, but no safe level could be set. Funded by a C60 seller. |
| Grohn 2021 (Grohn et al., 2021) | Mice, lifetime | No life gain. C60 oil left in strong light for 4-8 days killed 25-50% of mice. |
| Hui 2023 (Hui et al., 2023) | 6 beagles, 9 days | One blood marker only. No control group, no joints, grape seed oil. |
| Ozdemir 2024 review (Ozdemir et al., 2024) | Summary of studies | Long-term safety needs study. C60 can act as an antioxidant or a pro-oxidant. |
| Dogs, months or years | Not published | No study we could find (PubMed search, C60 and dogs). |
Months of daily use in a dog have not been studied. Because light-exposed C60 oil harmed mice, keep the amber bottle capped in a dark cupboard, as the label says, and skip oil that smells sharp or looks off. More on the ESS60 ingredient page; to inspect a bottle, see the batch check steps.
Accidents
What if my dog drinks the whole bottle of Mighty K9?
Call your vet or a pet poison line right away. The product page warning says: "For canine use only. Keep out of reach of children and animals. In case of accidental overdose, contact a health professional immediately."
A whole 60 mL bottle is 30 servings of oil at once, about 486 kcal and 54 g of fat. For a 22 lb dog that is most of a day's calories in pure fat, a real pancreatitis risk. The ASPCA Animal Poison Control Center is at (888) 426-4435; a fee may apply (ASPCA, People foods). If a child swallows some, call Poison Control at 1-800-222-1222.
Medicines
Can I give Mighty K9 with Rimadyl or other dog medicines?
Ask your vet first. There is no published data on how C60 or this product interacts with any dog medicine.
That matters most for dogs on carprofen (Rimadyl) or other NSAIDs. NSAIDs are the most predictably effective arthritis treatment (Merck Vet Manual, Osteoarthritis), and they can upset the stomach on their own. Added fat makes it harder to tell what caused a bout of vomiting.
Talk to your vet if your dog
takes NSAIDs, steroids, thyroid or seizure medicine, is on a prescription diet, is pregnant or nursing, or is under 6 months old.
What to bring
The bottle, the start date and a short log of stool and energy.
Mighty K9 is a supplement for dogs, not a veterinary drug. Ask your vet first if your dog is under 6 months, has had pancreatitis or needs a low-fat diet, is pregnant or nursing, takes any medicine, or is being treated for a condition. Limping or pain needs a vet exam, not just a supplement. See side effects and cautions.
Next steps
When should I stop Mighty K9?
Stop and call your vet if stool stays loose past two or three days, vomiting repeats, or your dog seems sore or quiet. Stop at once for any emergency sign listed above.
Stop the serving
Give plain food only.
Keep the bottle
Save it, the box and the order email.
Call your vet
Say what you saw and when it started.
Remember that limping, crying out, trouble rising, or stiffness that does not ease need a vet exam, not just a supplement.
Reporting
How do I report a problem with Mighty K9 to the FDA?
Use the FDA Safety Reporting Portal, or call your state's FDA consumer complaint coordinator. The FDA asks for the lot number, best-by date, where you bought it, your dog's signs and your vet records, and to keep the packaging (FDA, Report a pet product).
Pet supplements need no FDA approval before sale (FDA, Pet food rules), so owner reports matter. Also call the order desk at +1 (302) 200-3480 and ask about the 30-day guarantee.
FAQ
Mighty K9 side effects FAQ
What are the most common side effects of Mighty K9?
Loose stool, greasy stool and an upset stomach are the most likely, because each 2 mL serving is nearly all olive oil. Some dogs slowly gain weight. Most mild stomach upsets settle in a few days; if they do not, stop and call your vet.
Can Mighty K9 give my dog diarrhea?
Yes, it can, especially in the first week or in dogs with sensitive stomachs. Added fat is a common cause of soft stool. If diarrhea lasts more than two or three days, has blood in it, or comes with vomiting or tiredness, stop the oil and see your vet.
Is C60 olive oil safe for dogs with pancreatitis?
Not without your vet's approval. Dogs that have had pancreatitis usually need a low-fat diet, and each serving adds about 1.8 g of pure fat. Your vet can decide whether any added oil fits your dog's fat budget, or whether it is better skipped.
Can Mighty K9 hurt my dog's liver or kidneys?
There is no study showing that it does, but there is also no long-term study in dogs that checked. The only oral C60 study in dogs lasted 9 days in 6 beagles. Dogs with liver or kidney disease should only start it after a talk with their vet.
Is it safe to give Mighty K9 with carprofen?
No interaction data exists, so ask your vet before mixing them. Carprofen and other NSAIDs can upset the stomach on their own, and added oil can too. Your vet knows your dog's bloodwork and can tell you whether the extra fat is a good idea.
What should I do if my dog ate too much Mighty K9?
Call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435 right away. A whole bottle is about 54 g of fat, which can cause vomiting, diarrhea or pancreatitis. Keep the bottle so you can read the label and lot number to the person on the phone.
Who wrote this
Written and reviewed by
Plain-language pages built from the label panel, the sales page and linked veterinary and public sources.
Last updated . Both our editorial standards and how we check reviews are open to read. This website is run by Themightyk9, the Mighty K9 U.S. shop and a stocking partner, not by the manufacturer. Buying through our order links earns us money.
Keep reading
More about Mighty K9
Serving size
The 2 mL label serving, what it adds in calories and ESS60 by dog size, and when to ask your vet.
Read more
ESS60 (C60)
What C60 is, every study we found from rats to six beagles, and what is still unknown.
Read more
Guaranteed Analysis
Every line of the label panel decoded: fat, the ESS60 asterisk, the calorie math and what is missing.
Read moreMighty K9 U.S. shop, a stocking partner
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