🐴 Vet Insight 2025: Understanding Urticaria (Hives) in Horses and What Those Bumps Really Mean 🧬🩹

Author: Dr Duncan Houston, BVSc

Urticaria, also known as hives, is one of the most common equine skin conditions veterinarians encounter. While these soft, fluid-filled bumps may look alarming, they are not a disease themselves—but a clinical sign of an underlying issue. In this 2025 veterinary guide, Dr Duncan Houston explains what urticaria means, what causes it, and how to treat it safely and effectively. 🐎🧠

🔍 What Is Urticaria?

Urticaria consists of raised, round to oval skin swellings (called wheals) that range in size from 1 to 5 inches. They are typically:

• 💧 Filled with fluid (edematous)
• 🩺 Compressible—you can press them in with a fingertip
• ⏱️ Sudden in appearance and often transient

Commonly found on the neck and thorax, urticaria can occasionally become severe, with multiple wheals merging into larger areas. Some may even ooze small amounts of serum. 🧬

🧠 What Causes Urticaria?

Urticaria is a hypersensitivity reaction—an exaggerated immune response to allergens or irritants. Common triggers in horses include:

• 🦟 Flying insects like mosquitoes and midges
• 🌿 Environmental allergens such as mold, dust, or pollen
• 🧴 Topical products or chemical exposures
• 🍽️ Feed ingredients or supplements
• 🦠 Rarely, ringworm or other infections in allergic horses

Though less common, autoimmune conditions and internal infections can also cause urticaria. These are typically considered only in chronic, non-responsive cases. 🔬

🩺 Signs to Look For

Urticaria is generally easy to recognize:

• 🟣 Small to large raised skin bumps
• 📍 Often appear suddenly
• 💧 Soft and fluid-filled
• 🔁 May change location or size over hours or days
• 🐴 Occasional itching or rubbing (though many horses are not itchy)

🧪 Diagnosis: When to Call the Vet

While many cases of urticaria resolve on their own, it’s important to consult your vet if:

• ⏱️ Bumps persist for more than 2–3 days
• 🔄 The condition recurs frequently
• 💥 The lesions grow in size or merge
• 🧬 You suspect infection or immune disorders

Veterinary workup may include:

• 🧫 Skin biopsy in chronic or unresponsive cases
• 🔬 Fungal culture to rule out ringworm before prescribing steroids
• 🩺 Allergy testing if a cause is unclear or symptoms are recurrent

💊 Treatment Options in 2025

Mild cases of urticaria may not require any treatment. However, when intervention is needed, here are the most common options:

1️⃣ Cortisone (Steroid) Therapy

• 🧴 Effective at reducing inflammation and swelling
• ⚠️ Should be used cautiously if ringworm or infection is suspected
• 💉 Given orally or as an injectable

2️⃣ Antihistamines

• 💊 May be prescribed to reduce allergic response
• 🔁 Most useful for horses with chronic, seasonal urticaria

3️⃣ Environmental Management

• 🦟 Use fly sheets and repellents to reduce insect exposure
• 🧽 Rinse horses after turnout to remove allergens
• 🏕️ Stable during peak mosquito times (dawn and dusk)

4️⃣ Dietary Review

• 🍽️ Eliminate or test feed additives and supplements
• 🥕 Consider switching hay or grain if a reaction is suspected

🚫 What Not to Do

• ❌ Don’t use long-term steroids without confirming it’s not ringworm
• ❌ Don’t ignore persistent or worsening lesions
• ❌ Avoid “guessing” allergy causes—consider testing

🧠 Vet Tip from Dr Duncan Houston

"Urticaria might look dramatic, but most cases are benign. Still, a few can point to deeper immune issues. If it recurs or doesn’t go away, get a vet involved early." 🐴🧠

🛡️ Prevention Tips for Allergy-Prone Horses

• 🧼 Use hypoallergenic shampoos and avoid harsh sprays
• 🦟 Fly protection during insect seasons
• 🌿 Control exposure to moldy hay or dusty bedding
• 📋 Keep a journal to track flare-ups and potential triggers

🔚 Final Thoughts: Don’t Panic—Investigate

Urticaria is usually more alarming in appearance than in consequence. But knowing the cause and having a vet plan ready will keep your horse comfortable and safe. 🐎🩹

Need help identifying skin lesions or managing equine allergies? Visit AskAVet.com or download the Ask A Vet app for expert help anytime. 🧴📱