The Best Hydrolysed Dog Food in the UK: Vet-Informed Brand Comparison

Dog Nutrition & Health

Written by Glenn Bell, BCCSDip.HthNut (in progress)  ·  Updated June 2025  ·  12 min read

Quick answer: For UK dogs with food sensitivities, the best non-prescription hydrolysed dog food is Ultimate Pet Foods Ultimate+ Hydrolysed — 100% hydrolysed protein, grain-free, no vet referral needed. For dogs with severe confirmed allergies requiring a formal elimination diet, Royal Canin HP or Hill's z/d remain the prescription gold standard. Full comparison and pricing below.

In this article

  1. What is hydrolysed dog food?
  2. Quick comparison table — all 6 brands
  3. UK pricing breakdown
  4. Brand-by-brand reviews
  5. Prescription vs non-prescription: which does your dog need?
  6. What to look for on the label
  7. How to switch your dog
  8. Frequently asked questions

Hydrolysed dog food has moved from a niche veterinary product to a mainstream option for UK pet owners managing everything from itchy skin to chronic digestive problems. But with more brands entering the market — and significant differences in quality, prescription requirements, and protein sources — choosing the right one has become genuinely confusing.

In this guide, I compare the six most commonly purchased hydrolysed dog food brands available in the UK: Ultimate Pet Foods Ultimate+, Royal Canin Hydrolysed, Hill's z/d, Purina Pro Plan HA, Blue Buffalo HF, and Royal Canin Ultamino. Each is evaluated against the same five criteria: protein quality, hydrolysis completeness, grain status, palatability, and accessibility (prescription vs over-the-counter).

What is hydrolysed dog food?

Hydrolysed dog food contains protein that has been broken down into very small fragments — called peptides — through a process called hydrolysis. These fragments are too small for your dog's immune system to recognise as foreign proteins, which means they are far less likely to trigger an allergic response.

Standard dog food
Intact protein
  • › Large, intact protein chains enter the digestive system
  • › Immune system recognises them as foreign
  • › Triggers an immune response in sensitive dogs
⚠ Potential allergic reaction
Hydrolysed dog food
Hydrolysed protein
  • › Protein broken into tiny peptides before feeding
  • › Fragments too small for the immune system to detect
  • › No immune response triggered
✓ Dramatically reduced allergy risk

It is the same principle behind hypoallergenic formulas for human food allergies. The proteins are the same — chicken, salmon, duck — but they have been pre-digested to a size that bypasses the immune trigger.

Important: Not all hydrolysed foods are equal. Partial hydrolysis reduces allergens; complete hydrolysis eliminates virtually all immune reactivity. The brands reviewed below differ significantly on this point.

Quick comparison: 6 best hydrolysed dog food brands in the UK (2025)

This table covers the key decision factors at a glance. Full reviews for each brand follow below.

Brand Protein source Hydrolysis level Grain-free Prescription Approx. UK price Best for
⭐ Ultimate Pet Foods Ultimate+ (Editor's pick) Freshly prepared duck or salmon 100% hydrolysed Yes Not required £14.99 / 1.5 kg trial
£76.00 / 10 kg		 Everyday feeding, mild–moderate sensitivities
Royal Canin Hydrolysed Protein Hydrolysed soy protein Partial No Rx required ~£60 / 7 kg Vet-directed allergy management
Hill's Prescription Diet z/d Hydrolysed chicken liver Partial No Rx required ~£55 / 6.8 kg Elimination diet trials
Purina Pro Plan HA Hydrolysed soy protein isolate Partial No Rx required ~£65 / 11.4 kg Long-term prescription feeding
Blue Buffalo HF Hydrolysed salmon Partial No Not required ~£45 / 5 kg Chicken / beef protein allergies
Royal Canin Ultamino Hydrolysed poultry feathers (amino acid level) 100% amino acid No Rx required ~£110 / 7.5 kg Severe confirmed allergies — last resort

UK pricing breakdown: how much does hydrolysed dog food cost?

Price varies enormously between prescription and non-prescription hydrolysed dog food — and the cost-per-day difference is even larger once you factor in prescription fees and bag sizes. Here is a full breakdown.

Brand Best price (bag) Per kg Per day* Rx fee Where to buy
⭐ Ultimate Pet Foods Ultimate+ £76.00 / 10 kg
£14.99 trial bag also available 		£7.60 ~£1.67 None ultimatepetfoods.co.uk
Royal Canin Hydrolysed Protein ~£60 / 7 kg ~£8.57 ~£1.71 ~£15–£25 Viovet / Animed Direct
Hill's Prescription Diet z/d ~£55 / 6.8 kg ~£8.09 ~£1.62 ~£15–£25 Pet Drugs Online / Zooplus
Purina Pro Plan HA ~£65 / 11.4 kg ~£5.70 ~£1.14 ~£15–£25 Animed Direct / VetUK
Blue Buffalo HF ~£45 / 5 kg ~£9.00 ~£1.80 None Amazon UK
Royal Canin Ultamino ~£110 / 7.5 kg ~£14.67 ~£2.93 ~£15–£25 Vet practice only

* Estimated daily cost based on 220 g/day for a 10 kg adult dog.

Note on prescription fees: Most UK vets charge £15–£25 for a written prescription for a veterinary diet. Some practices will issue a 3-month or 6-month prescription to reduce this overhead — worth asking. Online dispensaries (Animed Direct, VetUK, Pet Drugs Online) typically offer lower product prices than buying direct from the practice, but you still need the prescription first.
Try before you commit: Ultimate Pet Foods offers a 1.5 kg trial bag for £14.99 — that's enough for around 7 days for a 10 kg dog. Full 10 kg bags are £76.00 (£1.67/day). No prescription required. The Try–Prove–Commit system means you can test palatability and results before buying in bulk.

Brand-by-brand reviews

Each brand reviewed against the same five criteria: protein quality, hydrolysis completeness, grain status, palatability, and value for everyday use.

⭐ Editor's pick — best non-prescription
1. Ultimate Pet Foods Ultimate+ Hydrolysed
Non-prescription  ·  Grain-free  ·  UK-manufactured
★★★★★
9.4 / 10

Ultimate Pet Foods is the only brand in this comparison that starts with freshly prepared meat or fish — not soy isolate or feather meal — and then hydrolises the protein completely. The result is a food that combines clinical-grade allergen management with the palatability of a premium everyday diet. It is manufactured at G.A. Pet Food Partners in the UK using the Freshtrusion® HDP process, which allows a high fresh meat inclusion to be hydrolised post-extrusion.

Best for Dogs with mild to moderate food sensitivities, itchy skin, digestive upset, or owners wanting to trial a hydrolysed diet before a prescription commitment. Available in five targeted formulas: Digestive Care, Skin & Coat Care, Weight Control & Joint Care, Dental Care, and Everyday Health.
Pros
  • 100% hydrolysed protein throughout
  • Grain-free — no wheat, barley or maize
  • No prescription required
  • Freshly prepared meat or fish base
  • UK-manufactured, short supply chain
  • Five targeted formulas for different conditions
  • Try–Prove–Commit sampling system
Cons
  • Newer brand — fewer published clinical trials than Hill's or Royal Canin
  • Not designed for formal vet elimination diet protocols
  • Dry food only — no wet food range currently
Verdict: For the vast majority of UK dogs with food sensitivities, this is the strongest first choice. It removes both protein and grain triggers simultaneously, requires no vet referral, and uses better quality base ingredients than any prescription alternative on the market.
2. Royal Canin Hydrolysed Protein
Prescription required  ·  Contains grain
★★★★☆
7.8 / 10

Royal Canin's hydrolysed range is among the most widely prescribed formulas in UK vet practices. It uses hydrolysed soy protein as its primary source, which effectively reduces allergen load for most dogs. The main limitations are the prescription requirement, a grain-containing base (including maize), and palatability that some dogs find less appealing compared to meat-based alternatives.

Best for Dogs with severe, confirmed food allergies already under veterinary management and specifically prescribed this diet.
Pros
  • Extensive clinical validation and vet familiarity
  • Omega-3 enriched for skin support
  • Available in dry and wet formats
Cons
  • Veterinary prescription required
  • Contains maize — grain trigger not removed
  • Soy base — lower palatability for many dogs
  • Significantly more expensive per kg
Verdict: A solid veterinary option for confirmed allergy cases under professional management. Not the right choice if you want to trial a hydrolysed diet without a vet visit or ongoing prescription costs.
3. Hill's Prescription Diet z/d
Prescription required  ·  Contains grain
★★★★☆
7.5 / 10

Hill's z/d uses hydrolysed chicken liver as its protein source and is clinically validated for food allergy elimination trials. It includes a single carbohydrate source (corn starch) to minimise allergen exposure during diagnostic feeding. Like all Hill's prescription diets, it is not available without a vet prescription.

Best for Dogs undergoing a formal elimination diet trial under veterinary supervision to identify specific food triggers.
Pros
  • Clinically validated hydrolysis process
  • Single carbohydrate source aids diagnostic clarity
  • Good palatability relative to other prescription diets
Cons
  • Prescription only — vet visit required
  • Grain-containing formula
  • Expensive for long-term daily feeding
Verdict: The clearest prescription choice for elimination diet diagnostics. Not designed for long-term everyday feeding without ongoing vet involvement.
4. Purina Pro Plan HA Hydrolysed
Prescription required  ·  Contains grain
★★★☆☆
6.9 / 10

Purina's HA formula uses hydrolysed soy protein isolate as its single protein source, designed for long-term prescription feeding and elimination diets. The soy base means palatability is a common owner complaint, and some dogs need an extended transition period. Like the other prescription brands, it contains grain (corn starch) and requires a vet prescription.

Best for Dogs with multiple confirmed protein allergies requiring long-term prescription management.
Pros
  • Suitable for long-term feeding
  • Slightly lower cost per kg vs Royal Canin HP
  • Good omega fatty acid profile
Cons
  • Prescription only
  • Palatability issues commonly reported
  • Contains grain  ·  soy protein base
Verdict: Adequate for vet-managed long-term cases. The palatability issues are a meaningful drawback — some dogs simply will not eat it consistently enough to be useful.
5. Blue Buffalo HF Hydrolysed
No prescription  ·  Contains grain
★★★☆☆
6.5 / 10

Blue Buffalo HF is one of the few non-prescription hydrolysed formulas available in the UK. It uses hydrolysed salmon as its protein source, making it useful for dogs with chicken or beef protein allergies specifically. However, it contains grain (brown rice, oatmeal), which limits its usefulness for dogs with combined protein and grain sensitivities.

Best for Dogs with confirmed chicken or beef protein allergies who can tolerate grain and do not require a grain-free formula.
Pros
  • No prescription required
  • Novel salmon protein for poultry-allergic dogs
  • Available without vet referral
Cons
  • Contains grain — not suitable for dual-sensitive dogs
  • Partial hydrolysis only
  • Limited UK availability  ·  higher price vs value
Verdict: A reasonable option for dogs with specific poultry allergies, but the grain content is a significant drawback for the majority of sensitive dogs who are also grain-reactive.
6. Royal Canin Ultamino
Prescription required  ·  Contains grain  ·  Severe cases only
★★★★☆
7.2 / 10 (for target use case)

Ultamino sits in a separate category from all others here. It uses hydrolysed poultry feathers broken down to free amino acids — the smallest possible fragment size. This is reserved for dogs with the most severe confirmed food hypersensitivities who have failed on standard hydrolysed diets. At around £110 for 7.5 kg, the cost reflects this specialist positioning.

Best for Dogs with severe, confirmed hypersensitivities who have not responded to standard hydrolysed diets. Not appropriate as a first-line option.
Pros
  • Amino acid level breakdown — maximum allergen elimination
  • Clinically validated for the most severe cases
Cons
  • Very expensive  ·  prescription only
  • Contains grain  ·  not a palatability-first formula
  • Overkill for most dogs with food sensitivities
Verdict: Genuinely valuable for its specific, narrow use case. Not appropriate as a first choice for dogs who have not yet tried standard hydrolysed options.
Try Ultimate Pet Foods Ultimate+ Hydrolysed

Start with a 1.5 kg trial bag for £14.99 — no prescription, no commitment. Full 10 kg bags £76. Ships from the UK.

See the full range →

Prescription vs non-prescription hydrolysed dog food: which does your dog need?

Helpful note: Most dogs with food sensitivities do not need a prescription diet as their first step. Prescription formulas are designed for dogs with confirmed, severe allergies — typically diagnosed after a supervised elimination diet trial.

The main difference between prescription and non-prescription hydrolysed dog food is not quality — it is the level of clinical control and the purpose each is designed for.

Start with a non-prescription hydrolysed food if:

  • Your dog has mild to moderate symptoms (itchy skin, soft stools, occasional digestive upset)
  • You haven't yet done a formal elimination trial
  • You want to avoid the cost and logistics of ongoing vet prescriptions
  • Your dog's symptoms haven't yet been definitively linked to a specific allergen

Consider a prescription formula if:

  • Your vet has diagnosed a specific food allergy through a supervised elimination trial
  • Your dog has not improved on non-prescription hydrolysed food after 8–12 weeks
  • Your dog has severe clinical symptoms requiring professional management
  • You are conducting a formal diagnostic elimination diet and need strict single-ingredient control

What to look for on a hydrolysed dog food label

Not all hydrolysed dog foods are created equal. Here is what the label should tell you before you buy.

1. Is the protein hydrolysis complete or partial?

Look for "hydrolysed [protein]" as the first or second ingredient. If the label does not specify completeness, assume partial hydrolysis only. Complete hydrolysis is typically referenced in clinical documentation or brand pages rather than on the bag itself — if in doubt, contact the manufacturer directly.

2. Is the food genuinely grain-free?

Grain is the second most common dietary trigger after protein in sensitive dogs. A hydrolysed food that still contains wheat, maize, or barley addresses only half the problem. Look for "grain-free" stated explicitly on the front of the packaging.

3. What is the base protein before hydrolysis?

There is a meaningful difference between a food that starts with freshly prepared duck or salmon (then hydrolises it) versus one that starts with soy isolate or rendered feather meal. The former produces better palatability and a more complete amino acid profile. Look for "freshly prepared" in the ingredient list.

4. Single or multiple carbohydrate sources?

For elimination diet purposes, a single carbohydrate source makes it easier to isolate food triggers. For everyday feeding, multiple carbohydrate sources are acceptable as long as none are grain-based.

How to switch your dog to hydrolysed food

Transitioning too quickly can cause digestive upset even with the most gentle hydrolysed formula. A gradual transition over 7–10 days is recommended for most dogs.

Days 1–3 75% current food, 25% hydrolysed. Monitor for loose stools or behavioural changes.
Days 4–6 50% current food, 50% hydrolysed. Most dogs adapt well at this stage.
Days 7–9 25% current food, 75% hydrolysed. Continue monitoring stool consistency.
Day 10 onwards 100% hydrolysed food. Allow 6–8 weeks to see full benefits for skin and allergy symptoms.
Important: If you are using a hydrolysed diet as part of a formal elimination trial, do not mix with the previous food during the trial period — this defeats the diagnostic purpose. Follow your vet's specific instructions.

Frequently asked questions

Ultimate Pet Foods Ultimate+ Hydrolysed is the strongest non-prescription option currently available in the UK. It uses 100% hydrolysed protein from freshly prepared meat or fish, is completely grain-free, and is manufactured in the UK without requiring a vet referral. It is available in five targeted formulas depending on your dog's specific health concern.
No — not all hydrolysed dog foods require a prescription. Prescription formulas such as Royal Canin HP, Hill's z/d, and Purina HA are classified as veterinary therapeutic diets and require a vet to authorise each purchase. Non-prescription alternatives including Ultimate Pet Foods Ultimate+ can be purchased directly without a vet visit.
Ultimate Pet Foods Ultimate+ starts at £14.99 for a 1.5 kg trial bag, with full 10 kg bags at £76.00 — working out at £7.60 per kg, or approximately £1.67 per day for a 10 kg dog. Prescription formulas cost significantly more: Royal Canin HP and Hill's z/d run £55–£110 per bag, plus an additional £15–£25 per prescription fee each time you reorder. The real-world monthly cost of a prescription hydrolysed diet for an average dog is typically £80–£140 once prescription fees are included.
For palatability and nutritional completeness, freshly prepared meat or fish that has been hydrolised post-cooking is superior to soy isolate or feather meal-based alternatives. Hydrolised duck and hydrolised salmon are both well-tolerated novel proteins. Soy-based hydrolysis (Royal Canin, Purina) is clinically effective but scores lower on palatability for many dogs.
Allow 6–8 weeks on a hydrolysed diet before assessing whether it's working. Digestive improvements (stool consistency, reduced gas) often appear within 2–3 weeks. Skin and coat improvements typically take the full 6–8 week window to become clearly visible.
Yes. Complete and balanced hydrolysed dog foods — including all options reviewed here — are formulated for long-term daily feeding. There is no nutritional reason to cycle on and off a hydrolysed diet if your dog is thriving on it.
Yes, in cases where skin irritation is triggered by a food allergy. Hydrolysed food removes the immune trigger (the intact protein) so the skin's inflammatory response reduces over time. This typically takes 6–8 weeks to be clearly visible. If skin issues persist beyond this period on a hydrolysed diet, the trigger may be environmental (pollen, dust mites) rather than dietary.
Grain-free dog food removes cereal grains (wheat, maize, barley) as potential dietary triggers. Hydrolysed dog food removes the risk of protein-based allergic reactions by breaking protein into tiny fragments. They address different types of food sensitivity. The most comprehensive option — for dogs with both protein and grain sensitivities — is a food that is both hydrolysed and grain-free, as with Ultimate Pet Foods Ultimate+.
GB
About the author: Glenn Bell
BCCSDip.HthNut (in progress)  ·  Canine First Aid certified  ·  HubSpot Content Marketing certified  ·  Google Analytics & Google Squared qualified

Glenn is the founder of Ultimate Pet Foods and spent two years as a professional dog walker and home boarder before building the brand. He founded UPF after his yellow Labrador, Kirk, developed food sensitivities — an experience that drove him to understand canine nutrition from the ground up rather than taking ingredient lists at face value.

Every product reviewed on this site has been evaluated against the same formulation criteria Glenn developed for the UPF range. His miniature dachshund Ted acts as daily product tester and brand mascot — and has strong opinions about palatability.
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