If you've bought brightly colored dog treats—especially vibrant reds and oranges—chances are they contain Red Dye 40, a synthetic petroleum-based colorant. It's the most commonly used artificial color in pet food and treats.
The irony? Dogs can't even see these bright colors the way humans do. Red Dye 40 exists purely for human appeal, not canine health or enjoyment.
This guide explains what Red Dye 40 is, why manufacturers use it, safety concerns, where it's found, and how to avoid it.
Chemical name: Allura Red AC (also called FD&C Red No. 40 or E129 in Europe)
Source: Synthetic azo dye derived from petroleum
Color produced: Bright red to orange, depending on concentration and pH
How it's made: Created through chemical synthesis from petroleum byproducts, not from natural sources like vegetables or fruits.
Red Dye 40 serves one purpose: visual appeal to humans. Here's why manufacturers add it:
The truth: Dogs are dichromatic (similar to red-green colorblind humans). They perceive reds and oranges as brownish-yellow. They can't appreciate or care about bright red treats.
If your dog loves a bright red treat, it's the smell and taste (often from artificial flavoring), not the color.
The FDA considers Red Dye 40 safe for use in pet food, but "safe" means it won't cause acute toxicity at approved levels—not that it's optimal for health.
In humans: Multiple studies link Red Dye 40 to hyperactivity and attention problems in children. The evidence is strong enough that the European Union requires warning labels on foods containing it.
In dogs: While controlled studies are limited, veterinarians and dog owners report similar patterns:
Mechanism: Azo dyes may disrupt neurotransmitter function or trigger histamine release, affecting behavior.
Some dogs are sensitive to artificial dyes, showing:
Food allergy elimination diets often improve when synthetic dyes are removed—sometimes more than removing specific proteins.
The benzidine problem: Red Dye 40 can be contaminated with benzidine and other carcinogenic compounds during manufacturing. The FDA sets maximum contamination limits, but any exposure to known carcinogens raises long-term cancer risk.
Animal studies: Some research shows increased tumor rates in rats exposed to high doses of Red Dye 40, though results are mixed and debated.
Red Dye 40 is banned or restricted in several European countries for human food due to health concerns. The fact that regulations differ so dramatically suggests the safety data isn't as conclusive as the FDA claims.
Red Dye 40 probably won't harm your dog from occasional exposure in small amounts. But:
Given the lack of benefit and potential risks, avoiding Red Dye 40 is a prudent choice.
| Product Type | Likelihood | Why |
|---|---|---|
| Soft chews/chewy treats | Very High | Bright red, orange, or multi-colored chews almost always contain Red 40 and other synthetic dyes |
| Bacon-flavored treats | High | Red dye creates "bacon" appearance in products with no actual bacon |
| Beef-flavored treats | Moderate-High | Red color suggests "real beef" in highly processed products |
| Kibble with colored pieces | High | "Variety" kibbles with red/orange bits for visual interest |
| Colorful bone-shaped chews | Very High | Bright colors appeal to humans shopping for dogs |
| Pill pockets and medication treats | Moderate | Some brands use dyes; check labels carefully |
| Gravy/topper packets | Moderate | Brown gravy may contain caramel coloring; red variants may have Red 40 |
Red Dye 40 isn't the only synthetic color in pet products. Others to watch for:
| Dye Name | Color | Concerns |
|---|---|---|
| Yellow 5 (Tartrazine) | Bright yellow | Linked to hyperactivity, allergic reactions; banned in some countries |
| Yellow 6 (Sunset Yellow) | Orange | Carcinogenic contaminants; allergic reactions; banned in Norway |
| Blue 1 (Brilliant Blue) | Bright blue | Possible link to tumors in animal studies; crosses blood-brain barrier |
| Blue 2 (Indigo Carmine) | Blue | Brain tumor link in animal studies; banned in some countries |
| Red 3 (Erythrosine) | Cherry red | Thyroid tumor link in rats; restricted for cosmetic use |
| Green 3 (Fast Green) | Blue-green | Bladder tumor link in animal studies |
| Caramel coloring | Brown | May contain 4-MEI, a potential carcinogen |
Simple rule: If the ingredient list includes any "FD&C" colors, "Lake" dyes, or numbered colors (Red 40, Yellow 5, etc.), avoid the product.
Quality pet food manufacturers use whole-food ingredients that provide natural coloring:
| Natural Ingredient | Color Provided | Nutritional Benefits |
|---|---|---|
| Beet powder | Red to pink | Fiber, folate, nitrates for circulation |
| Paprika | Red to orange | Vitamin A, antioxidants, anti-inflammatory compounds |
| Tomato powder | Red | Lycopene (antioxidant), vitamins C and K |
| Cranberry powder | Red | Urinary health, antioxidants, vitamin C |
| Turmeric | Orange-yellow | Curcumin (anti-inflammatory), antioxidants |
| Spirulina | Blue-green | Complete protein, B vitamins, iron |
| Carrot powder | Orange | Beta-carotene (vitamin A), fiber |
| Spinach/parsley powder | Green | Vitamins A/K, iron, antioxidants |
Even better approach: Let whole-food ingredients determine color naturally:
Quality ingredients don't need artificial enhancement.
Look for these terms (all mean synthetic dyes):
Safe phrasings:
Red flags (literally):
Natural appearance:
Best options (least likely to contain dyes):
Higher-risk formats:
Some brands explicitly avoid all artificial colors, flavors, and preservatives. Look for:
Don't panic. Most dogs tolerate synthetic dyes without obvious short-term harm. But transitioning to dye-free products is beneficial:
Some dogs show noticeable changes 1-3 weeks after eliminating synthetic dyes:
If you notice improvement, it confirms your dog was sensitive to artificial additives.
Many dog owners don't realize artificial colors serve no purpose for their pets. Share what you've learned—it helps create market demand for better products.
Red Dye 40 is rarely the only problem in heavily dyed products. It's usually accompanied by:
Pattern recognition: If a manufacturer uses artificial colors to make a product look appealing, they're likely cutting corners elsewhere too.
Quality brands don't need synthetic dyes because their ingredients speak for themselves.
Learn more: Common Fillers and Binders in Dog Supplements (And Why They're Used)
Red Dye 40 exists in dog food and treats for one reason: to make products visually appealing to humans. It provides zero nutritional value, and dogs can't even perceive the bright colors it creates.
Why avoid it:
How to avoid it:
Your dog doesn't care if their treats are bright red. They care about smell, taste, and how the food makes them feel. Choose products that prioritize health over human marketing appeal.
Red Dye 40 is FDA-approved for pet food but considered controversial. While acute toxicity is low, concerns include potential links to hyperactivity (documented in children, suspected in dogs), allergic reactions in sensitive dogs, and carcinogenic contaminants (benzidine) found in some batches.
The dye is banned in several European countries for human food. Since it provides no nutritional value and exists purely for human visual appeal (dogs see colors differently), many veterinarians and pet nutritionists recommend avoiding it.
Whole-food ingredients derive natural color from real meat, vegetables, and fruits—no synthetic dyes needed.
Red Dye 40 (Allura Red AC) adds bright red/orange color to dog treats and food but provides no nutritional benefit. Potential effects include:
Most dogs tolerate small amounts without obvious symptoms, but chronic low-level exposure effects are unknown. Since dogs perceive color differently than humans and can't appreciate bright red treats, the dye serves only marketing purposes.
No artificial food dyes are acutely toxic to dogs in typical food concentrations, but several raise safety concerns:
Natural colorings (beet powder, turmeric, spirulina) are safe and provide actual nutrients. Best approach: avoid all synthetic dyes—choose products colored only by whole-food ingredients.
Dog treats contain Red Dye 40 for human appeal, not canine benefit. Dogs see color differently than humans—they're dichromatic (similar to red-green colorblind humans) and can't appreciate bright reds and oranges.
Manufacturers add dyes because:
It's pure marketing. High-quality treats made from whole foods (real meat, organs, vegetables) have natural colors—beef liver is brown, salmon is pink, chicken is tan. Bright artificial colors signal low-quality ingredients and unnecessary additives.
Evidence in dogs is limited but suggestive. In children, multiple studies link Red Dye 40 to hyperactivity and attention problems—strong enough that the EU requires warning labels.
Dog owners and veterinarians report similar patterns: increased restlessness, excitability, difficulty settling, attention problems. However, controlled studies in dogs are lacking.
Mechanism likely involves neurotransmitter disruption or histamine response. Anecdotal evidence is strong: many owners report dramatic behavioral improvements within 1-2 weeks of eliminating artificial dyes.
Given no nutritional benefit and documented hyperactivity link in children, avoiding Red Dye 40 is prudent, especially for already-hyperactive or sensitive dogs.
Natural alternatives provide color from whole-food ingredients:
These natural colorants provide actual nutrition, not just visual appeal. Better approach: let whole-food ingredients determine color naturally—real meat is brown, organs are dark red, salmon is pink, vegetables are green. No colorants needed when using quality ingredients.
To avoid Red Dye 40 and other artificial dyes:
While not all artificial colors are acutely toxic, none provide nutritional value and all carry some risk:
Safety concerns: Potential carcinogenic contaminants (benzidine, 4-aminobiphenyl), links to hyperactivity and behavioral issues, allergic reactions in sensitive dogs, accumulation effects from chronic exposure.
FDA approval ≠ optimal health: These dyes meet safety minimums for preventing immediate toxicity but aren't tested for long-term low-level exposure effects.
Better question: Why use them? Since dogs can't appreciate bright artificial colors and whole-food ingredients provide natural coloring, there's no legitimate reason for synthetic dyes in pet food beyond marketing.
Recommendation: Avoid all synthetic colors (Red 40, Yellow 5/6, Blue 1/2, Green 3, etc.) and choose products colored naturally by real ingredients.
No. USDA organic certification prohibits all synthetic food dyes including Red Dye 40. Organic pet foods can only use colors from natural sources like beet powder, turmeric, or inherent ingredient colors.
However:
If budget is limited, prioritize: no synthetic dyes/flavors, whole-food ingredients, minimal processing, quality protein sources—organic is ideal but not mandatory for avoiding Red Dye 40.
Direct evidence in dogs is lacking, but concerns exist:
The FDA considers Red Dye 40 safe at approved levels, but "safe" means low short-term toxicity, not necessarily optimal for long-term health. Given zero nutritional benefit and potential risks, avoiding synthetic dyes is prudent from cancer prevention perspective.