Lack, Loss, or Decreased Appetite (Anorexia) in Horses

Key Takeaways

Anorexia in horses is a noticeable decrease in appetite. 

• Appetite in horses fluctuates depending on many factors, and anorexia refers to a significant decrease in feed intake, to the point where caloric needs are not being met

• Causes include underlying illnesses such as kidney or liver disease, digestive problems, infections, and tumors

• Other causes relate to the inability to eat due to dental problems, pain in the mouth or esophagus, inability to chew, or inability to reach food

• Horses with anorexia require prompt veterinary attention

• If anorexia is accompanied by fever, signs of pain, or excessive nasal discharge, emergency veterinary attention is required

• Diagnostic tools include physical examination, bloodwork, and diagnostic imaging

• Treatments include dental care, medication, management changes, and changes to the diet

A Closer Look: What is Anorexia in Horses?

Reduced appetite is common in horses. Horses’ appetite fluctuates depending on the time of year, the calories required to support activity levels, quality of the feed, and many other factors. Lack of appetite relating to these factors do not necessarily require veterinary attention. Examples include:

• Increased activity level

• Temperature changes

• Stress level

• Competition within the social hierarchy of the horse herd

• Loneliness or depression

• Management changes

• Dislike of particular feed

• Resistance to changes in feed

If poor appetite persists for several weeks, or the horse is dull or lethargic, showing signs of discomfort, or losing weight prompt veterinary attention is required. 

If any of the following symptoms are seen with anorexia

• Fever • Colic • Increased respiratory rate 

• Profound nasal discharge • Retching • Gagging

then emergency veterinary attention is needed.

Possible Causes

Causes of anorexia in horses vary widely because many body systems are involved in eating and digestion. Horses that feel unwell because of an underlying illness generally have a poor appetite. 

Underlying illnesses that commonly affect appetite include:

• Digestive issues such as gastric ulcers

• Renal disease

• Liver disease

• Infections, including pneumonia

• Musculoskeletal issues, such as laminitis

• Tumors such as lymphoma

• Side effects from medications

• Vitamin B1 (thiamine) deficiency

• Poisoning, such as alfatoxicosis

Horses may also stop eating if they cannot chew properly, swallow properly, or access their food. Causes include:

• Dental issues including sharp or broken teeth, oral ulcers, or tooth root abscesses

• Neck or back pain 

• Swelling of the lips from bee stings or snake bites

• Injury or tumors affecting the tongue

• Swollen lymph nodes from conditions such as strangles 

• Muscle paralysis from conditions such as tetanus or botulism

• Neurologic disease such as facial paralysis

• Foreign body lodged in the mouth or under the gums 

• Choke

Non-medical reasons horses may not eat include:

• Social hierarchy, including a boss horse, not allowing lower ranked horses to eat

• Unpalatable feed, either due to the horse’s preferences, spoiled feed due to mold, or behavioral resistance to changes in feed

• Issues related to psychological well-being, including separation anxiety, changes in management, or stress because of travel or other factors

Risk Factors

The severity of anorexia in horses varies depending on the length of time it lasts, the underlying cause, and whether the horse is willing to eat anything at all. 

Anorexia with a sudden onset typically indicates a serious underlying condition that requires emergency veterinary care, such as colic or choke. Similarly, anorexia accompanied by fever, excessive nasal discharge, kicking or biting at the abdomen, or rolling or thrashing on the ground requires emergency veterinary care.

Horses that are still eating, but with a reduced appetite, require prompt veterinary attention to identify any underlying conditions.

Testing and Diagnosis

Diagnostic tools include:

• Physical exam

• Bloodwork

• Diagnostic imaging including X-rays and ultrasounds

• Urinalysis

• Oral examination

• Endoscopy to evaluate the stomach

• Rectal palpation

Treatment depends on the underlying cause. Treatments include:

• Dental float: adjusting the bite of the teeth by reshaping them

• Changes to the diet to soften feed, to stimulate the appetite, or eliminate irritants

• Intestinal protectants

• Supplementing missing nutrients

• Changes to feeding location 

• Pain medications

• Antibiotics

• Anti-inflammatory medications

Similar symptoms

Lack or loss of appetite is self evident and not likely to be confused with other symptoms. A physical inability or lack of desire to eat may be confused with decreased food intake due to social or behavioral reasons.

Associated Symptoms

Anorexia is sometimes accompanied by other symptoms including:

• Increased salivation 

• Quidding (chewing up and spitting out food, especially hay)

• Weight loss

• Yellow gums