Vet Tips 2025: Inhalant Allergies and Itchy Skin in Horses—What to Know 🐎🌾

By Dr Duncan Houston BVSc

When your horse just won’t stop scratching—even in winter—it’s time to dig deeper. While fly allergies are the top cause of summer itching, horses who remain itchy in colder months may be dealing with something else: inhalant allergies, also known as atopy. 🌬️🐴

What Is Atopy in Horses? 🧠🌿

Atopy is a form of allergic reaction caused by inhaled environmental allergens. These can include:

• 🌾 Grass, tree, or weed pollens
• 🧬 Molds and spores
• 🏡 Dust mites and stable dust
• 🍃 Environmental pollutants

Unlike food allergies, atopy usually starts seasonally and may eventually become a year-round issue. 😟

Signs of Atopy in Horses 🐴🩺

Atopic horses often exhibit:

• 🤕 Itching of the face, legs, neck, mane, and tail
• 🔁 Rubbing or scratching on fences, posts, or stalls
• 🧱 Skin thickening, hair loss, or abrasions
• 💥 Secondary bacterial or fungal infections

It usually begins before age 7 and becomes more persistent over time. 🕐

Is It Just Insect Allergies? 🦟❄️

Many horses with insect bite sensitivity (like Culicoides allergies) improve dramatically in winter. So, if your horse is only itchy in summer, it’s probably insect-related. 🪰

But if scratching persists in winter, other causes must be considered. 🤔

What Else Causes Itch in Winter? ❄️🧼

• 🧬 Inhalant allergies (atopy)
• 🌾 Food allergies (rare but possible)
• 🕷️ Lice—biting and sucking varieties
• 🧫 Ringworm (fungal)
• 🦠 Bacterial or yeast skin infections
• 🧪 Immune-mediated skin conditions

Diagnosing the cause of pruritus (itchiness) requires a veterinary skin exam and often lab testing. 🔬

Is It a Food Allergy? 🍽️🤷‍♂️

Food allergies are rare in horses, but they do happen. Signs can overlap with atopy, so your vet may suggest an elimination diet trial:

How a Diet Trial Works 📋🐴

• 🥗 Feed only one forage (usually grass hay) for 4+ weeks
• 🚫 Eliminate alfalfa, peanut hay, soy, molasses, and “sweet feeds”
• 🧪 Slowly reintroduce one ingredient at a time to identify triggers

Common feed allergens in horses include:

• 🌱 Soy
• 🍬 Molasses
• 🌾 Alfalfa or peanut hay

This process takes time and patience—but can be very revealing. 🔍

Treatment Options for Atopy and Winter Itch 💊🧴

Your veterinarian may recommend:

• 💉 Antihistamines or corticosteroids
• 🧼 Medicated shampoos and conditioners
• 🦠 Antibiotics or antifungals for secondary infections
• 🍃 Environmental management (better ventilation, dust control)

Each case is unique, so targeted treatment is essential. 🎯

Don’t Forget Parasites 🕷️⚠️

Winter itch can sometimes be caused by:

• 🪰 Lice—look for thinning hair and restlessness
• 🧫 Ringworm—circular lesions, often on the head and neck

Your vet may recommend skin scraping, fungal cultures, or topical parasiticides. 🧪

Need Help Solving the Itch? Ask A Vet 📱🐴

Itching can be frustrating and painful—for both horse and owner. If you're unsure what’s behind the scratching, chat with an equine vet at Ask A Vet.

Download the Ask A Vet app for 24/7 help with diet trials, skin treatment plans, and allergy diagnostics. 🧬🐎

Final Thoughts: Don’t Scratch Your Head—Scratch the Itch! 🧠🐾

Chronic itch in horses is never “just” a skin problem—it could be a deeper allergic issue, infection, or nutritional concern. The key is early diagnosis and a strategic plan. 🗺️

Let us help you decode the scratch. Visit Ask A Vet today for answers that bring comfort. 🐎💙