Weight Loss in Horses: Dental, Ulcer, or Worming Issue?

Unexplained weight loss in horses can be worrying for owners, especially when appetite appears normal. While seasonal changes and workload can play a role, persistent or unexplained weight loss often indicates an underlying health issue.

Three of the most common causes are dental problems, gastric ulcers, and parasite (worm) burdens. Understanding the differences can help you know when to seek veterinary advice.

When Should Weight Loss Be a Concern?

You should monitor weight loss closely if:

• Your horse is losing condition despite adequate feed

• Ribs, hips, or spine are becoming more visible

• There is reduced topline or muscle loss

• Behaviour or performance has changed

Sudden or progressive weight loss should always be investigated.

Dental Problems

How Teeth Affect Weight

Dental issues can make chewing uncomfortable or ineffective, meaning horses may not extract enough nutrition from their feed.

Common Signs of Dental Issues

• Dropping partially chewed feed (quidding)

• Eating more slowly or avoiding hard feed

• Bad breath or excessive salivation

• Weight loss despite good appetite

• Head tossing or resistance when ridden

How Your Vet Can Help

Routine dental examinations allow your vet or equine dental technician to identify sharp edges, overgrowths, or abnormal wear. Most horses require a dental check at least once a year, and more frequently for older horses.

Gastric Ulcers

Why Ulcers Cause Weight Loss

Equine Gastric Ulcer Syndrome (EGUS) is common, particularly in performance horses, but can affect any horse. Ulcers can cause discomfort, reduced appetite, and poor nutrient absorption.

Signs That May Suggest Ulcers

• Weight loss or difficulty maintaining condition

• Girthiness or sensitivity around the stomach area

• Behavioural changes or irritability

• Reduced performance

• Intermittent appetite changes

Diagnosis and Treatment

Gastroscopy is the only definitive way to diagnose ulcers. Treatment usually involves medication alongside management and dietary changes.

Worming Issues

Parasites and Weight Loss

Internal parasites can reduce nutrient absorption and cause weight loss, even if a horse is eating well.

Signs of a Worm Burden

• Weight loss or poor condition

• Dull coat

• Lethargy

• Diarrhoea or changes in droppings

• Young or elderly horses may be more affected

Modern Worming Advice

Targeted worming programmes based on faecal egg counts are now recommended, rather than routine blanket worming. Your vet can advise on an appropriate parasite control plan.

Other Possible Causes

While dental, ulcer, and worming issues are common, other causes of weight loss include:

• Chronic pain or lameness

• Liver or kidney disease

• Hormonal conditions

• Stress or changes in routine

A thorough veterinary assessment may be required if initial checks are normal.

When Should You Call the Vet?

Contact your vet if:

• Weight loss continues despite dietary changes

• You notice additional signs such as behaviour changes or discomfort

• Your horse is older, very young, or has underlying health conditions

• You are unsure where to start

Early investigation often leads to quicker and more effective treatment.

In Summary

Weight loss in horses should never be ignored. Dental problems, gastric ulcers, and worming issues are common causes, but a proper assessment is essential to identify the underlying problem.

If you are concerned about your horse’s weight or condition, your vet can help create a tailored plan to keep your horse healthy and comfortable.