Dog Elimination Diet — The Complete UK Guide

Last updated: March 2026 · 14 min read

If your dog suffers from persistent itching, recurring ear infections, digestive problems, or chronic skin issues, there's a good chance a food allergy or intolerance is involved. Up to 10% of all allergy cases in dogs are food-related, and the only way to definitively identify the trigger is an elimination diet.

This guide walks you through the entire process — from choosing the right food to interpreting the results. No jargon, no product pushing, just practical steps you can follow at home.

Before You Start: Is an Elimination Diet Right for Your Dog?

An elimination diet is worth trying if your dog has any of these persistent symptoms:

• Skin: Constant scratching, paw licking/chewing, red or inflamed skin, hot spots, hair loss
• Ears: Recurring ear infections (especially yeast infections), head shaking, dark discharge
• Digestive: Chronic loose stools, excessive wind, vomiting, eating grass
• Other: Anal gland problems, facial rubbing, watery eyes

Important: See your vet first to rule out other causes. Flea allergy, environmental allergies, mange, bacterial infections, and hormonal conditions can all mimic food allergy symptoms. An elimination diet is only useful if food is the actual trigger.

Step 1: Choose Your Novel Protein (Week 0)

The foundation of an elimination diet is a novel protein — a protein source your dog has never eaten before. Since your dog can't be allergic to something they've never been exposed to, this gives you a clean baseline.

Common novel proteins available in the UK:

Commercial vs Homemade

You have two options:

Commercial novel protein food (recommended for most owners): A single-protein, grain-free commercial food is the easiest approach. It's nutritionally complete, consistent batch-to-batch, and convenient. Good UK options include:

• Symply Fresh Turkey — single-protein turkey, grain-free, £6.33/kg
• Millie's Wolfheart Riverside Mix — duck + trout, no chicken/egg/grain, £5.08/kg

Homemade (for strict control): Cook a single protein (e.g. boiled duck) with a single carbohydrate (sweet potato or white potato). This gives you maximum ingredient control but isn't nutritionally complete long-term. Limit homemade to the 8-12 week trial period, and discuss vitamin/mineral supplementation with your vet.

Step 2: The Transition (Days 1-7)

Never switch food abruptly — even in an elimination diet. Transition over 5-7 days:

• Days 1-2: 75% old food, 25% new food
• Days 3-4: 50% old food, 50% new food
• Days 5-6: 25% old food, 75% new food
• Day 7: 100% new food

Some digestive upset during transition is normal. Loose stools for a day or two is expected and doesn't mean the new food is wrong.

Step 3: The Elimination Phase (Weeks 1-12)

This is the hard part — and the most important. For the next 8-12 weeks, your dog eats nothing but the novel protein food.

The Rules (Non-Negotiable)

• ❌ No treats — unless they're the same novel protein (boiled duck pieces, freeze-dried turkey)
• ❌ No table scraps — not even a chip, not even a bit of toast
• ❌ No dental chews — most contain chicken or beef derivatives
• ❌ No flavoured medications — check with your vet for unflavoured alternatives
• ❌ No rawhide, pig ears, or bully sticks
• ❌ No other animals' food — if you have multiple pets, feed separately
• ❌ No grass eating — supervise outdoor time if your dog grazes
• ✅ Water only — plain, unflavoured water

What to Track

Keep a simple daily diary. Note:

• Scratching/licking: Frequency and location (paws, ears, belly, face)
• Skin condition: Redness, hot spots, dry patches, overall coat quality
• Ears: Smell, discharge, head shaking
• Stools: Consistency (1-7 Bristol scale) and frequency
• Energy: Any changes in energy levels or behaviour

Week-by-week photos of any skin lesions are invaluable for tracking progress — they reveal gradual improvements that are hard to spot day-to-day.

When to Expect Changes

This is why patience is essential. If you stop at week 4 because "nothing's changed," you may have missed the improvement that was 2 weeks away.

Step 4: Evaluate the Results (Week 8-12)

After 8-12 weeks, you'll be in one of three positions:

Scenario A: Symptoms significantly improved ✅

This confirms a food allergy or intolerance. Your dog's previous diet contained something they react to. You now have a safe baseline food. Move to Step 5 (reintroduction) to identify the specific trigger.

Scenario B: Some improvement, but symptoms remain

Your dog may have a food sensitivity AND environmental allergies. The food component has improved, but environmental triggers remain. Still move to reintroduction to identify food triggers, and discuss environmental allergy management with your vet.

Scenario C: No improvement ❌

Food allergy is unlikely to be the primary cause. Revisit your vet for environmental allergy testing, skin scrapes, or other diagnostics. The elimination diet hasn't been wasted — you've ruled out a major category of allergens, which helps your vet narrow down the real cause.

Step 5: The Reintroduction Phase

This is where you identify exactly which ingredients trigger your dog's symptoms. Stay on the elimination diet as your base, and add one new ingredient at a time.

Reintroduction Order (UK vets typically recommend):

1. Chicken — most common protein allergen in dogs
2. Beef — second most common
3. Wheat — most common grain allergen
4. Dairy (small amount of plain yoghurt)
5. Egg
6. Corn/maize
7. Soy
8. Rice (usually well-tolerated)
9. Oats (usually well-tolerated)

How to Reintroduce

• Add a small amount of the test ingredient to each meal for 7-14 days
• Monitor for any return of symptoms — even subtle ones
• If symptoms return: that ingredient is a trigger. Remove it immediately and wait for symptoms to clear completely before testing the next one
• If no symptoms after 14 days: that ingredient is safe. Move to the next one

This process is slow — 7-14 days per ingredient means testing all common allergens takes 2-4 months. But the result is a definitive list of safe and unsafe ingredients for your specific dog. No guessing, no expensive blood tests, no trial-and-error with random foods.

Common Mistakes to Avoid

• Quitting too early. Skin allergies take 8-12 weeks to resolve. Week 4 is too soon to judge.
• Forgetting hidden ingredients. Worming tablets, joint supplements, flavoured toothpaste, and even some ear drops contain food proteins.
• Not involving the whole household. One family member sneaking a biscuit invalidates weeks of work.
• Reintroducing multiple ingredients at once. If symptoms return, you won't know which ingredient caused it.
• Confusing novel with hypoallergenic. "Hypoallergenic" isn't a regulated term — check the actual ingredients, not the marketing.
• Ignoring environmental factors. If your dog's symptoms are worse in spring/summer, environmental allergies may be the primary cause — pollen, grass, and dust mites aren't solved by diet changes.

Recommended Foods for Elimination Diets

These UK-available grain-free foods work well as elimination diet bases due to their limited, transparent ingredient lists:

• Symply Fresh Turkey — Single protein (turkey), grain-free, £6.33/kg. Our top pick for elimination diets.
• Millie's Wolfheart Riverside Mix — Duck + trout (novel proteins), no chicken/egg/grain, £5.08/kg. Best for dogs who've already had turkey.
• Pooch & Mutt Skin & Coat — Herring-based, omega-3 rich, £5.83/kg. Ideal when allergies primarily cause skin problems.

See our complete grain-free dog food comparison for full reviews of all 11 products.

Breed-Specific Allergy Guides

Some breeds are genuinely predisposed to food-responsive skin and ear problems — if you own one of these, our breed-specific guides pair the elimination-diet method with the evidence for that breed:

• West Highland White Terriers with allergies — one of the most atopy-prone UK breeds; where an elimination trial fits.
• German Shepherds with allergies — food-responsive skin and gut signs, and how to run the trial safely.
• Pugs with allergies — skin-fold and food-trigger overlap, and what an elimination diet can (and can't) fix.

Related Guides

• Best Dog Food for Allergies UK — Our full product recommendations
• Best Dog Food for Itchy Skin UK — When allergies manifest as skin problems
• Best Dog Food for Sensitive Stomach UK — When allergies cause digestive upset
• Is Grain-Free Dog Food Actually Good? — The evidence behind grain-free diets

Frequently Asked Questions