Last updated: March 2025
The short answer: Vegetable oil in dog food is not automatically bad, but the type of oil and the ratio of omega-6 to omega-3 fatty acids determine whether it helps or harms your dog. Some oils can promote inflammation, and a 2025 study suggests a possible link between vegetable oil supplements and adverse food reactions in dogs with skin problems.
Key takeaways:
- Vegetable oil is a broad term covering oils from seeds, fruits, and nuts.
- The ideal omega-6 to omega-3 ratio in a canine diet is around 4:1 to 5:1, matching what wild canines get from whole prey.
- A 2025 study published in the Journal of Veterinary Dermatology found that 14.16% of dogs with skin issues received vegetable oil supplements, and those with adverse food reactions were significantly more likely to be supplemented (29.31% vs 10.10%).
- Oils like safflower, soybean, canola, and flaxseed each have very different fatty acid profiles. For more help reading labels and evaluating ingredients, check out The Ultimate Dog Food Buying Guide.
I started looking into this because I kept seeing vegetable oil on dog food ingredient lists and wondered if it's just cheap filler or actually useful. So my team and I dug into the research. Here is what we found.
First off, what is vegetable oil in dog food? It's an umbrella term for oils extracted from plants. That can mean soybean, canola, sunflower, corn, even olive or coconut oil. Manufacturers use them to provide fat for energy and supply essential fatty acids. According to Pet Food Processing, seed and vegetable oils are a common source of omega-3 and omega-6 fatty acids that can help alleviate skin conditions like dryness and redness. That sounds fine, but the devil is in the details.
The omega-6 to omega-3 ratio is the big deal here. A dog's body needs both types, but too much omega-6 without enough omega-3 drives inflammation. The National Research Council (NRC) suggests a range of 2.6:1 to 26:1, while AAFCO allows up to 30:1. However, many experts believe the ideal is closer to 4:1 to 5:1, which matches the natural diet of wild canines. When we evaluated the fatty acid profiles of common oils using USDA data, we found stark differences. Safflower oil has an omega-6 to omega-3 ratio over 77:1, a lot of inflammatory potential. Soybean oil sits at about 7:1, canola oil at about 2:1 (one of the better choices), and flaxseed oil flips the script with a ratio around 0.3:1 because it is rich in omega-3s. In our testing of commercial dog food labels, we noticed that many brands use generic “vegetable oil” without specifying the source, making it impossible for owners to know the ratio.
Now, what about safety? I came across a 2025 study in the Journal of Veterinary Dermatology that looked at dogs with skin problems. They found that 14.16% of those dogs were receiving vegetable oil supplements. More importantly, dogs diagnosed with adverse food reactions (AFR) were supplemented with oils at a significantly higher rate than dogs with other skin conditions: 29.31% of AFR dogs received oil supplements compared with 10.10% of dogs with other diagnoses. The most common oil was extra-virgin olive oil, making up 70.77% of supplements. The study authors note this is the first evaluation of that link and that causation is not proven, but it raises a flag. If your dog has food allergies or itchy skin, adding extra oil might not help and could worsen things. Our methodology for evaluating this study included cross-referencing the 2025 preliminary data with AAFCO nutrient profiles and consulting with a board-certified veterinary dermatologist.
That said, some vegetable oils do offer benefits. Olive oil, for instance, is generally safe for most dogs in small amounts. The Dog Food Advisor states it is safe to add a small amount of extra-virgin olive oil to your dog’s food, with dosage depending on size. Olive oil contains monounsaturated fats that can reduce inflammation and support skin and coat health. The general guideline is 1 teaspoon per 20 pounds of body weight per day, but start with less. Be careful not to overdo it, because olive oil is calorie-dense and can cause pancreatitis in predisposed dogs.
Another concern is rancidity. Northwest Naturals warns that plant oils are fragile and become rancid easily and quickly, especially given the two-year shelf life of dry kibble. Rancid oils cause inflammation. In our experience, this is worth thinking about when you buy a large bag of kibble, if the oil has gone bad, it could negate any benefits. Learn how to store dog food properly to keep it fresh and safe.
So what should you do? If your dog is healthy and eating a balanced commercial diet, the small amount of vegetable oil already in the food is probably fine. But we recommend avoiding extra oils without a specific reason. If you want to supplement, choose oils with a better omega ratio (canola or flaxseed) and talk to your veterinarian first. If your dog has a history of food allergies or skin problems, it may be safest to skip extra oil entirely until more research clarifies the link, and you can also refer to our guide to choosing a food for dogs with allergies and sensitive stomachs.
One more thing: the term “vegetable oil” on a label is vague. Some brands use it to mean a blend of cheap oils like soybean and corn. If you see just “vegetable oil” without specifics, that is a red flag. Look for named oils so you know what you are getting.
FAQ
#### What is vegetable oil in dog food?
Vegetable oil is a broad term for oils extracted from plants, including seeds, fruits, and nuts. In dog food, common examples are soybean, canola, sunflower, and corn oil. Our team found that many commercial kibbles use soybean oil as the primary fat source.
#### Is vegetable oil safe for dogs?
It depends on the type and amount. Some vegetable oils are safe in moderation, but those high in omega-6 fatty acids can promote inflammation if not balanced with omega-3s. A 2025 study published in the Journal of Veterinary Dermatology found a possible link between vegetable oil supplementation and adverse food reactions in dogs with skin issues.
#### What is the best oil to add to dog food?
Oils with a better omega-6 to omega-3 ratio, such as canola oil (about 2:1) or flaxseed oil (about 0.3:1), are generally better choices than high-omega-6 oils like safflower or sunflower. Always consult your veterinarian before adding oils, and never exceed 10% of your dog’s daily calories from added fat.
#### Can dogs have olive oil?
Yes, olive oil is safe for most dogs in small amounts. It contains healthy monounsaturated fats and antioxidants. The Dog Food Advisor recommends 1 teaspoon per 20 pounds of body weight per day as a starting point, but go lower initially.
#### Does vegetable oil cause allergies in dogs?
There is no proof that vegetable oil causes allergies, but a 2025 preliminary study found that dogs with adverse food reactions were significantly more likely to be receiving vegetable oil supplements (29.31% vs 10.10%). More research is needed to understand whether this is correlation or causation.
#### How much vegetable oil can I give my dog?
If supplementing, the amount depends on your dog’s size. For olive oil, 1 teaspoon per 20 pounds is a common starting point. However, added oils should not exceed 10% of daily calories. It is safer to rely on a balanced commercial diet that already includes appropriate fats.
Disclosure: We may earn a small commission if you purchase through links on this page, at no extra cost to you. This helps support our independent research.
Disclaimer: This article is for informational purposes only and does not constitute veterinary medical advice. Always consult with a licensed veterinarian before making dietary changes for your pet.
