Dog Food Allergies: Elimination Diet Testing, Novel Protein vs Hydrolyzed Diets

Dog Food Allergies

Dog food allergies affect approximately 10-15% of dogs with skin disease and 15-20% of dogs with chronic ear infections, representing the third most common canine allergy after flea allergy and environmental allergies (atopic dermatitis). Food allergy symptoms include year-round non-seasonal itching particularly affecting face, ears, paws, and groin; chronic recurrent ear infections; skin inflammation and secondary bacterial infections; and gastrointestinal signs including vomiting, diarrhea, or excessive gas in 20% of food-allergic dogs. This comprehensive guide examines dog food allergy diagnosis across USA, UK, Australia, and Asian markets, analyzing the gold-standard 8-12 week elimination diet trial using novel protein sources (proteins dogs never consumed before) or hydrolyzed protein diets, distinguishing food allergies from environmental allergies based on seasonality and symptom patterns, debunking unreliable blood and saliva allergy tests, and comparing commercial prescription hypoallergenic diets versus homemade elimination diets for accurate diagnosis and long-term management of food-allergic dogs throughout 10-15 year lifespans.

Understanding Food Allergies in Dogs

Food allergies develop when dogs’ immune systems identify specific food proteins as threats, mounting inappropriate inflammatory responses producing skin inflammation, itching, and gastrointestinal symptoms. True food allergies differ from food intolerances or sensitivities—allergies involve immune system reactions while intolerances cause digestive upset without immune involvement. The most common food allergens in dogs include beef (34% of food-allergic dogs), dairy products (17%), chicken (15%), wheat (13%), lamb (6%), and egg (5%), though any protein source can potentially trigger allergies in individual dogs. Notably, these common allergens represent the most frequently-fed proteins, suggesting exposure frequency rather than inherent protein properties drives allergy development.

Food allergies can develop at any age unlike puppy food sensitivities that dogs typically outgrow, with most food-allergic dogs developing symptoms between 1-5 years though some cases emerge in senior dogs. Additionally, food allergies develop gradually over months to years of exposure to triggering proteins rather than appearing immediately after first exposure to new foods. This delayed development means dogs can consume certain proteins for years without problems before suddenly developing allergies to those same ingredients, confusing owners who assume long-tolerated foods cannot cause allergies.​

Genetic predisposition affects certain breeds including Labrador Retrievers, West Highland White Terriers, Cocker Spaniels, German Shepherds, and Golden Retrievers showing higher food allergy incidence compared to other breeds. However, any breed or mixed breed dog can develop food allergies, making breed alone insufficient for ruling out food allergies as potential causes of chronic skin problems. These breed predispositions likely reflect genetic factors affecting immune system regulation and barrier function in skin and gastrointestinal tract rather than breed-specific sensitivity to particular proteins.​

The relationship between food allergies and environmental allergies proves complex, with 20-30% of dogs having concurrent food and environmental allergies complicating diagnosis and treatment. Dogs showing persistent year-round itching despite controlling fleas and trying allergy medications may have food allergies alone, environmental allergies alone, or both conditions requiring separate management strategies. The only reliable method distinguishing these overlapping conditions involves proper elimination diet trials, as symptom patterns alone rarely provide definitive diagnosis when individual variation creates confusing clinical pictures.​

Clinical Signs and Symptom Patterns

Skin itching (pruritus) represents the primary food allergy symptom in 80-90% of cases, characteristically affecting face, ears, paws, armpits, groin, and perianal areas rather than evenly distributed across entire body. Dogs show intense scratching, licking, chewing, and rubbing affected areas, often creating secondary skin damage including hair loss, redness, excoriation, and bacterial or yeast infections from constant trauma. The non-seasonal year-round nature of food allergy itching contrasts with seasonal environmental allergies showing symptom exacerbation during spring and fall when pollen counts peak, though this distinction blurs in regions with year-round pollen or in dogs with concurrent food and environmental allergies.

Recurrent ear infections occurring 4+ times annually suggest food allergies especially when infections affect both ears simultaneously, respond temporarily to treatment but rapidly recur after medication cessation, and occur outside typical allergy seasons. Food-allergic dogs’ ear infections often involve both bacterial and yeast organisms, creating chronic inflammation requiring repeated treatments. Some dogs show ear infections as their only food allergy symptom without obvious skin itching elsewhere, making food allergies easy to miss when focusing solely on ear disease without considering underlying allergic causes.​

Gastrointestinal symptoms including chronic diarrhea, soft stools, increased defecation frequency, vomiting, excessive gas, or abdominal discomfort affect 10-20% of food-allergic dogs either alone or combined with skin symptoms. These GI signs overlap extensively with other conditions including inflammatory bowel disease, parasites, and food intolerances, requiring veterinary evaluation ruling out alternative explanations before attributing symptoms to food allergies. Some dogs show exclusively GI symptoms without any skin involvement, while others display combined skin and GI manifestations creating more obvious allergy pictures.​

Secondary complications from chronic scratching include skin infections (pyoderma), yeast overgrowth (Malassezia dermatitis), thickened elephant-like skin (lichenification), hyperpigmentation creating dark discolored skin, and seborrhea producing excessive scaling or greasiness. These secondary changes often become more problematic than underlying allergies, requiring concurrent treatment addressing infections and inflammation while implementing elimination diets diagnosing and managing root allergic causes. Owners sometimes mistake these secondary changes for primary skin diseases, treating symptoms without addressing underlying food allergies perpetuating the cycle of temporary improvement followed by rapid relapse.​

Elimination Diet Trial: The Gold Standard Diagnosis

The 8-12 week elimination diet trial represents the only reliable method diagnosing food allergies, involving feeding single novel protein and carbohydrate source dogs have never consumed previously while strictly avoiding all other foods, treats, flavored medications, and human food. Novel proteins commonly used include venison, duck, rabbit, kangaroo, or salmon (if dogs never ate fish), paired with novel carbohydrates like sweet potato or potato (if dogs never ate these specifically). The diet continues for minimum 8 weeks though 12 weeks proves more reliable as some dogs require extended periods showing improvement, with gradual symptom reduction indicating food allergies as diagnosis.

Strict compliance during trials proves absolutely critical, as even tiny amounts of previous proteins—single treat, flavored medication, stolen food, or rawhide chew—can trigger allergic reactions maintaining symptoms throughout trial invalidating diagnostic conclusions. This strictness requires family education ensuring all household members understand “no exceptions” rules, securing garbage preventing scavenging, preventing food begging, and switching to unflavored medications or reformulating necessary flavored medications. Many elimination diet failures result from compliance lapses rather than incorrect diagnosis, with owners unaware that “just one treat” ruins weeks of dietary restriction.

Commercial novel protein diets available from veterinary prescription lines including Hill’s d/d, Royal Canin Selected Protein, and Purina Pro Plan Veterinary Diets offer convenience over homemade diets while providing nutritionally complete balanced formulations. These diets cost $60-120 for 25-30 pound bags representing significant expense compared to regular food, though prevent nutritional imbalances possible with improperly-formulated homemade diets. However, some veterinary dermatologists prefer homemade elimination diets using single whole-food protein and carbohydrate sources for maximum diagnostic accuracy, as commercial diets sometimes contain trace contamination from shared manufacturing equipment processing multiple protein sources.​

Symptom improvement during elimination trials typically begins at 4-6 weeks with gradual progressive improvement through 8-12 weeks, though some dogs show dramatic improvement within 2-3 weeks while others require full 12 weeks revealing definitive patterns. If symptoms completely resolve during the trial, food allergies are confirmed. If symptoms significantly improve but don’t fully resolve, concurrent food and environmental allergies may exist. If absolutely no improvement occurs despite perfect compliance, food allergies are unlikely and environmental allergies or other skin diseases require investigation. The challenge phase involves reintroducing original diet or specific ingredients watching for symptom return, with relapse within 7-14 days definitively confirming food allergies as diagnosis.

Hydrolyzed Protein Diets as Alternative Approach

Hydrolyzed protein diets contain proteins broken down through enzymatic or chemical hydrolysis into tiny molecular fragments too small for immune systems to recognize as allergens, theoretically preventing allergic reactions regardless of original protein source. These diets including Hill’s z/d, Royal Canin Hydrolyzed Protein, and Purina HA use extensively-hydrolyzed proteins from chicken, soy, or salmon reduced to peptides under 1000-3000 daltons molecular weight below typical 10,000-70,000 dalton intact proteins triggering allergic responses. The advantage involves not requiring identification of specific novel proteins dogs never consumed, working theoretically for any food allergy regardless of triggering proteins.

Research shows 80-90% of food-allergic dogs respond to appropriately-hydrolyzed diets with symptom resolution comparable to novel protein elimination diets, though 10-20% continue showing symptoms suggesting inadequate hydrolysis or reactions to non-protein diet components. Some studies question whether certain hydrolyzed diets achieve sufficient protein breakdown, with variable quality between manufacturers and products affecting clinical effectiveness. Additionally, palatability issues affect some hydrolyzed diets, with dogs refusing to eat certain formulations despite owners’ best efforts making compliance impossible during diagnostic trials.​

Cost considerations affect hydrolyzed diet selection, with prescription formulations costing $70-150 for 20-25 pound bags representing substantial ongoing expense throughout dogs’ lives if food allergies require permanent dietary management. These prices substantially exceed premium regular dog foods costing $40-70 for comparable bag sizes, creating financial burden for some families managing food-allergic dogs. However, hydrolyzed diets eliminate guesswork about novel proteins and provide complete balanced nutrition without formulation expertise required for homemade diets, potentially justifying premium pricing for convenience and nutritional certainty.​

The primary limitation of hydrolyzed diets involves diagnostic uncertainty—successful response confirms food allergies but doesn’t identify specific triggering proteins, preventing knowledge about which ingredients to avoid if owners want to explore alternative diets. Novel protein trials provide specific information about tolerated versus problem ingredients enabling future diet selections, while hydrolyzed diets simply work without revealing underlying allergen identities. Some owners prefer knowing specific allergens through novel protein trials, while others accept permanent hydrolyzed diet feeding without investigating specific triggers when symptom control proves adequate.​

Distinguishing Food from Environmental Allergies

Seasonality represents the most useful clinical distinction, with environmental allergies typically showing seasonal patterns correlating with pollen seasons (spring and fall in most regions) while food allergies produce consistent year-round symptoms. However, this distinction fails in areas with year-round vegetation producing continuous pollen, in dogs allergic to indoor allergens like dust mites or mold showing non-seasonal symptoms, and in dogs with both food and environmental allergies showing complex seasonal worsening overlaying year-round baseline symptoms. Geographic location significantly affects interpretation—dogs in Southern California or Florida experience less clear seasonal patterns compared to dogs in regions with distinct winter dormancy eliminating pollen exposure.

Age of onset provides some guidance, with environmental allergies typically developing in young adults ages 1-3 years while food allergies show more variable onset occurring at any age including middle-aged and senior dogs. However, substantial overlap exists with some environmental allergies developing in older dogs and many food allergies appearing during typical environmental allergy age ranges, limiting diagnostic utility of age alone. Additionally, dogs can develop both conditions simultaneously or sequentially, further complicating age-based predictions about allergy types.​

Response to allergy medications including antihistamines, corticosteroids, or newer allergy drugs like Apoquel and Cytopoint provides limited diagnostic information, as both food and environmental allergies may respond partially to these medications though environmental allergies typically show more dramatic improvement. Food-allergic dogs often show persistent symptoms despite medications that successfully control environmental allergies, though this pattern proves inconsistent with some food-allergic dogs responding well to medications. Using medication response as diagnostic tool proves unreliable compared to proper elimination diet trials definitively distinguishing food from environmental triggers.​

The only definitive method separating food from environmental allergies involves successful elimination diet trials showing complete or near-complete symptom resolution, confirming food allergies as primary or major contributing problem. If elimination diets produce no improvement despite perfect compliance, environmental allergies or other skin diseases become leading diagnoses requiring appropriate diagnostic and treatment approaches. Many dogs have both conditions requiring dual management including allergen-specific immunotherapy or medications for environmental allergies plus dietary restriction managing food allergies simultaneously for optimal symptom control.

Unreliable Allergy Tests and Marketing Claims

Blood tests and saliva tests marketed for food allergy diagnosis including IgE testing and various “sensitivity panels” lack scientific validation with numerous studies showing poor correlation between test results and actual food allergies diagnosed through elimination diet trials. These tests frequently identify multiple “positive” ingredients including foods dogs have eaten without problems for years, while missing actual food allergens confirmed through diet trials. The tests measure antibodies to food proteins, though presence of antibodies doesn’t necessarily indicate clinical allergies, as healthy dogs without food allergies often have positive results on these unreliable tests.

Veterinary dermatologists and leading veterinary organizations universally recommend against using blood or saliva food allergy tests, consistently emphasizing that proper elimination diet trials represent the only reliable diagnostic method despite being time-consuming and challenging. The marketing of these quick-result tests appeals to owners wanting easy answers without 8-12 week dietary restriction challenges, though acting on unreliable test results leads to unnecessary dietary restrictions eliminating healthy ingredients while potentially missing actual allergens. Money spent on these tests ($200-500) would be better allocated toward prescription elimination diet foods or veterinary dermatology consultations guiding proper diagnostic protocols.​

Similarly, “limited ingredient diets” marketed by premium pet food companies as solutions for food allergies often prove inadequate for diagnosis or management, as these over-the-counter foods frequently contain proteins dogs previously consumed, undergo manufacturing in facilities creating cross-contamination with other proteins, or lack sufficient quality control ensuring ingredient purity required for diagnostic elimination trials. While these diets serve useful purposes for dogs with diagnosed specific food intolerances or for general diet simplification, they shouldn’t substitute for proper prescription elimination diets or veterinary-supervised homemade formulations during diagnostic trials.​

Intradermal allergy testing used for diagnosing environmental allergies cannot test for food allergies, as this testing method proves unreliable for food allergen identification. Some confusion exists because veterinary dermatologists perform intradermal testing, leading owners to assume all allergy types can be tested this way. However, dermatologists specifically limit intradermal testing to environmental allergens, relying exclusively on elimination diet trials for food allergy diagnosis. Understanding this limitation prevents wasted expectations and resources pursuing inappropriate testing methods when proper elimination trials provide definitive answers.​

Commercial Prescription Diets vs Homemade Elimination Diets

Prescription veterinary elimination diets offer convenience, guaranteed complete balanced nutrition meeting AAFCO standards, and consistent ingredient quality with quality control measures reducing cross-contamination risks. Major manufacturers including Hill’s, Royal Canin, and Purina conduct feeding trials validating nutritional adequacy and maintain dedicated production lines for selected protein diets minimizing contamination. These diets are available in multiple novel protein options including venison, duck, salmon, kangaroo, and hydrolyzed varieties, providing flexibility for dogs with multiple food allergies or preferences. The primary disadvantage involves high cost ($60-120 for 25-30 pound bags) creating significant ongoing expense and potential availability issues if specific formulations face shortages or discontinuation.​

Homemade elimination diets allow complete control over ingredients using whole foods and ensuring no cross-contamination from manufacturing, though require careful formulation by veterinary nutritionists preventing nutritional imbalances during extended feeding periods. Simple recipes using single protein source (like diced boiled turkey breast or ground venison) with single carbohydrate (sweet potato or white rice) plus essential supplements including calcium carbonate, multivitamin, and fish oil can sustain dogs through 8-12 week trials. However, homemade diets become problematic for long-term feeding without professional nutritionist consultation formulating complete balanced recipes preventing deficiencies in calcium, vitamins, minerals, and essential fatty acids developing during months to years of restricted diets.

Cost comparison shows homemade diets potentially saving money compared to prescription foods, with whole food ingredients costing approximately $3-6 daily for medium-sized dogs versus $4-8 daily for prescription diets depending on specific proteins selected. However, this calculation excludes time investment shopping, preparing, and cooking homemade diets versus convenient bagged commercial foods. Additionally, nutritionist consultation fees ($200-400) for proper long-term homemade formulation offset some cost savings, though one-time investment provides permanent recipe access. The financial calculation depends on individual circumstances including available time, cooking skills, and access to reasonably-priced novel protein sources.​

Compliance challenges differ between approaches, with commercial diets offering convenience improving compliance though high costs potentially causing owners seeking cheaper alternatives prematurely ending trials. Homemade diets require dedication to shopping and cooking creating compliance barriers for busy owners, though some families find homemade preparation ensures they absolutely know ingredients fed without concerns about manufacturing issues. Success with either approach requires owner commitment to strict adherence regardless of methodology selected, making the “best” option highly individual based on family circumstances, resources, and preferences rather than one approach universally superior for all situations.​

Managing Dogs with Confirmed Food Allergies

Permanent dietary management becomes necessary after food allergy diagnosis, requiring either continued novel protein diet dogs successfully tolerated during trials, permanent hydrolyzed diet feeding, or systematic food challenges identifying specific safe ingredients enabling more varied long-term diets. Some owners maintain successful trial diets permanently avoiding the complexity of food challenges, accepting diet monotony ensuring symptom control without risk of reintroducing allergens. Others prefer identifying specific safe proteins through sequential food challenges, gradually expanding dietary variety by testing individual new ingredients one at a time over 2-week periods watching for symptom return.​

Food challenge protocols involve introducing single new ingredient to base diet maintaining all other components constant, feeding exclusively this modified diet for 2 weeks, and monitoring for symptom recurrence. If symptoms remain absent, that ingredient is considered safe and permanently added to the dog’s diet, then next novel ingredient is tested following the same process. If symptoms return, the challenged ingredient is confirmed as allergen and permanently eliminated, returning to previous safe diet allowing symptoms resolving before testing next ingredient. This methodical process continues until owners identify multiple safe ingredients providing dietary variety while definitively knowing which proteins require avoidance.​

Label reading skills become essential for managing food-allergic dogs, as ingredients listed as “poultry meal,” “meat by-products,” or “animal digest” may contain problem proteins disguised by generic terminology. Similarly, foods listing multiple protein sources create risks for dogs allergic to any component protein. Owners must learn identifying hidden ingredients in treats, chews, flavored medications, toothpaste, and supplements potentially containing beef, chicken, or dairy derivatives sabotaging dietary management efforts. This vigilance extends throughout dogs’ lives as permanent management requirement, not temporary restriction during diagnostic periods.​

Accidental exposure management requires recognizing that single dietary indiscretion can trigger symptom flares lasting days to weeks, necessitating returning to strict elimination diet until symptoms resolve before resuming regular management diet. Family education ensures all household members understand the importance of dietary restriction, preventing well-meaning treat-giving by children, visiting relatives, or neighbors who don’t appreciate the medical necessity of dietary management. Dog training addressing begging behaviors and counter-surfing reduces theft risks, while secure garbage management prevents scavenging exposures undermining careful dietary control.​

International Availability and Regional Considerations

USA prescription elimination diet availability proves excellent through veterinary distribution channels, with all major manufacturers (Hill’s, Royal Canin, Purina) offering multiple novel protein and hydrolyzed options through veterinary clinics and online veterinary pharmacies. Insurance coverage for prescription diets remains uncommon even with comprehensive pet insurance policies, leaving owners paying full costs throughout dogs’ lives. Regional variation exists in novel protein availability, with exotic proteins like kangaroo more readily available in Western states compared to Midwest or Southern regions where venison proves more accessible.

UK veterinary elimination diet options mirror USA availability with prescription diets from Royal Canin, Hill’s, and Purina widely available through veterinary practices. British veterinary culture strongly emphasizes proper elimination diet trials over unreliable blood tests, with robust client education about diagnostic gold standards. Costs in GBP convert to slightly higher than USA pricing accounting for currency differences. Novel protein availability varies by region with venison, salmon, and duck most commonly accessible throughout UK regions.

Australian prescription diet market offers similar options though kangaroo represents locally-available novel protein more accessible than in other markets, with several Australian brands incorporating kangaroo into elimination diet formulations. Remote area access proves challenging with extended shipping times and limited refrigeration for frozen homemade diet ingredients affecting practical implementation. Urban areas including Sydney, Melbourne, and Brisbane show excellent prescription diet availability through veterinary clinics and specialty pet stores stocking prescription lines.

Asian markets show variable prescription diet availability with Japan and Singapore offering robust veterinary pharmaceutical distribution including major international brands, while developing markets including India, Philippines, and Thailand show more limited specialized product availability. Novel proteins common in Asian markets may include unusual options from local protein sources, though hydrolyzed diets prove most consistently available across Asian regions. Language barriers sometimes complicate label reading and ingredient verification requiring veterinary assistance ensuring appropriate product selection for food-allergic dogs.

Common Questions About Dog Food Allergies

How long does an elimination diet trial take?
Minimum 8 weeks with 12 weeks preferred, as some dogs require extended periods showing definitive improvement distinguishing food allergies from other conditions. The trial requires strict adherence with absolutely no other foods, treats, or flavored items during entire period. If symptoms dramatically improve during the trial, diagnosis is confirmed, though challenge phase reintroducing original diet observing for symptom return provides final confirmation.

Can blood tests diagnose food allergies in dogs?
No—blood and saliva food allergy tests lack scientific validation showing poor correlation with actual allergies diagnosed through elimination diet trials. These unreliable tests identify false positive “allergies” to foods dogs tolerate while missing actual allergens, leading to unnecessary dietary restrictions and incorrect management. Proper elimination diet trials represent the only reliable diagnostic method despite requiring 8-12 weeks compared to quick test results.

What are the most common food allergens in dogs?
Beef (34%), dairy (17%), chicken (15%), wheat (13%), lamb (6%), and egg (5%) represent most common food allergens, though any protein can potentially trigger allergies. These proteins cause problems because they’re most commonly fed rather than being inherently more allergenic, as novel proteins dogs never consumed before rarely cause allergies until dogs gain exposure developing immune responses over months to years.​

Are grain-free diets better for dogs with food allergies?
No—grain allergies prove rare in dogs with wheat representing only 13% of food allergies while protein sources (beef, chicken, dairy, lamb) cause 72% of food allergies. Grain-free trend reflects marketing rather than medical necessity for most dogs, with protein sources representing primary allergy concerns requiring management through novel or hydrolyzed protein diets regardless of grain content.​

Can dogs suddenly develop food allergies to foods they’ve eaten for years?
Yes—food allergies develop gradually after repeated exposure over months to years rather than appearing immediately after first exposure. Dogs can eat certain proteins for years without problems before immune systems develop allergic responses to those previously-tolerated ingredients. This delayed development confuses owners assuming long-term diet couldn’t cause sudden problems, though this pattern represents typical food allergy development.​

What’s the difference between novel protein and hydrolyzed protein diets?
Novel protein diets use intact proteins from sources dogs never consumed before (like venison, duck, kangaroo), while hydrolyzed diets contain proteins broken into tiny fragments too small for immune recognition regardless of original protein source. Novel protein trials identify specific safe ingredients enabling future diet selection, while hydrolyzed diets work without revealing specific allergens requiring permanent hydrolyzed diet feeding for ongoing management.

How much do prescription hypoallergenic diets cost?
Prescription elimination diets cost $60-120 for 25-30 pound bags ($100-250 monthly for medium-large dogs), substantially more expensive than regular premium dog foods costing $40-70 for comparable sizes. This represents significant ongoing lifetime expense for food-allergic dogs requiring permanent dietary management, though prevents medical costs treating chronic skin infections and ear problems resulting from unmanaged food allergies.

Can I use over-the-counter limited ingredient diets instead of prescription foods?
Over-the-counter limited ingredient diets generally prove inadequate for diagnostic elimination trials due to potential cross-contamination during manufacturing, lack of sufficient quality control, and often containing commonly-fed proteins dogs previously consumed. While these foods serve purposes for dogs with diagnosed specific tolerances, proper diagnosis requires prescription elimination diets or veterinary-supervised homemade formulations ensuring ingredient purity necessary for accurate testing.​

Achieving Successful Food Allergy Management

Successfully diagnosing and managing dog food allergies requires understanding that elimination diet trials represent the only reliable diagnostic method despite 8-12 week time commitment requiring strict adherence avoiding all foods, treats, and flavored items beyond prescribed diet, with blood and saliva tests proving scientifically invalid despite marketing claims offering quick convenient results. Treatment involves permanent dietary management using novel protein diets, hydrolyzed protein formulations, or carefully-identified safe ingredients through systematic food challenges, requiring lifelong vigilance reading labels, educating family members, and managing environmental temptations including garbage, counter-surfing, and well-meaning treat-offering by visitors who don’t understand medical necessity of dietary restriction. While food allergies create frustration and expense through premium prescription diets and lifestyle modifications preventing dietary indiscretions, proper diagnosis and consistent management dramatically improve quality of life for allergic dogs by eliminating chronic itching, recurrent ear infections, and skin inflammation that otherwise persist despite symptomatic medications failing to address root allergic causes. Understanding the distinction between food and environmental allergies based on seasonality, symptom patterns, and elimination diet trial responses enables appropriate diagnosis preventing unnecessary dietary restrictions when environmental allergens rather than food proteins drive symptoms, ensuring that expensive long-term dietary management specifically targets dogs with confirmed food allergies rather than being applied indiscriminately to all itchy dogs regardless of actual allergic triggers.