Vet Insights: Investigating Weight Loss in Horses 2025 🐴🔍

By Dr Duncan Houston, BVSc

While equine obesity gets a lot of attention, unintentional weight loss in horses remains a serious and sometimes puzzling problem for owners and veterinarians alike. When a horse drops weight unexpectedly or fails to gain, it’s crucial to act fast and investigate thoroughly. 🐎📉

In this 2025 vet-approved guide, Dr Duncan Houston explains how to assess and manage equine weight loss, from body scoring to diagnostic workups and feeding strategies. 💊🩺

1. When Weight Loss Is a Concern ⚠️

Not all thin horses are unhealthy—but a horse losing weight without a clear reason always warrants evaluation. Key red flags include:

• 📉 Ongoing loss of condition despite adequate feeding
• 🧴 Visible ribs, hip bones, or muscle wasting
• 🐴 Behavioral changes or lethargy
• 🩺 Recent illness, colic, or surgery

2. Body Condition Scoring (BCS) 🧠

First step? Assign a Body Condition Score (BCS). This 1–9 scale helps quantify condition:

• 1/9 – Emaciated
• 3–4/9 – Thin
• 5–6/9 – Ideal
• 7–9/9 – Overweight to obese

BCS is determined by evaluating fat deposits over the neck, withers, ribs, tailhead, and shoulders. A score of 4 or below means a closer look is needed. 🕵️‍♂️

3. Feed Intake: Are They Actually Eating? 🍽️

Sometimes it’s not what you feed—it’s what the horse actually eats. Key tips:

• 🔍 Monitor feed closely—use individual buckets
• 🚫 Separate from herd if needed to rule out bullying or food stealing
• 📊 Measure amounts consumed daily

If all horses in the group are thin, suspect poor feed quality. If only one horse is affected, suspect health or social issues. 🧠

4. Dental Problems and Oral Pain 🦷

Poor dentition is a leading cause of weight loss, especially in older horses. Look for:

• 🥕 Dropping feed ("quidding")
• 😬 Slow chewing or head tossing
• 🦷 Sharp points or loose teeth

Solution: Schedule a full oral exam under sedation with a speculum—quick visual checks often miss hidden dental disease. 🩺

5. Internal Abscesses and GI Disease 🦠

When external signs are absent, deeper diagnostics are needed. Consider:

• 🔍 Rectal exam: May detect tumors, abscesses, or impactions
• 🦠 Lawsonia intracellularis: Causes silent enteropathy in young horses
• 🧪 Chronic GI inflammation: Can impair nutrient absorption

Foals and young horses may also experience weight loss without diarrhea—watch for intermittent colic, fatigue, and edema. 📋

6. Bloodwork: Hidden Clues 🧪

Blood testing is essential when clinical signs are vague. Key tests include:

• 🔬 Complete Blood Count (CBC): Detects anemia or infection
• 🧬 Serum Chemistry: Evaluates liver, kidney, electrolytes, and protein
• 📉 Low total protein: May signal malabsorption or chronic disease

These results help guide further testing or treatment. 📊

7. Nutritional Gaps: Are You Meeting Needs? 🧂

Even the best-looking hay may lack key nutrients. Review the entire ration:

• 🌾 Hay quality: Early-cut, leafy, dust-free is best
• 🥣 Concentrates: Add calories if hay alone isn’t enough
• 🧪 Minerals & vitamins: Consider a balancer pellet

Also assess for special needs: senior, lactating, or high-performance horses require more calories and protein. ⚡

8. Environmental & Behavioral Factors 🐴

Stress, bullying, or poor shelter access may affect feed intake. Red flags include:

• 🐴 Herd mate aggression at feeding time
• 🏕️ Limited access to shelter or hay feeders
• 🌀 Chronic anxiety or cribbing behavior

Isolate the horse temporarily to observe feeding and reduce competition. 🧘

9. Summary Table: Diagnostic Plan 📋

10. When to Escalate Diagnostics 🧬

If common causes are ruled out and the horse continues to lose weight, consider:

• 🔬 Gastroscopy (check for ulcers)
• 🧫 Fecal testing for parasites or bacteria
• 📦 Biopsy or imaging for internal disease

Referral to an internal medicine specialist may be warranted. 📈

11. Final Thoughts from Dr Duncan Houston 💬

Unexplained weight loss is never “just old age.” Horses losing weight require a full workup—starting with careful observation and progressing to diagnostics. Whether it's a dental issue, GI disease, or something more serious, early detection is the key to recovery. 🐎🔍

Need help evaluating your horse’s condition or getting a second opinion? Visit AskAVet.com or download the Ask A Vet app 📲 to connect with trusted equine veterinarians who can help you get to the bottom of weight loss concerns.

— Dr Duncan Houston, BVSc