Weight Loss

A horse presenting with weight loss is seen commonly in equine practice and there are multiple causes. Weight loss can either occur suddenly (acute) or occur more slowly over a long period of time (chronic).

The causes and methods a veterinary surgeon uses to investigate weight loss are as follows.

Causes

Reduced food intake

  • Dental Disease: Dental pain can prevent horses from eating and, therefore, cause weight loss.
  • Illness: Horses with a fever, can be from an infection anywhere in the body, will often go off their food an loose weight. The underlying disease should be diagnosed and treated.
  • Inappropriate feeding: Horses will lose weight if they are not being fed enough for the work they are doing.
  • Competition for food: When horses are out in a paddock together a hierarchy develops and some animals may prevent others from gaining access to any feed.

Reduced digestion of feed

  • Liver disease: The liver produces many enzymes required for digestion and excretes waste products. Without normal liver function horses will lose weight. See section on liver disease.
  • Malabsorption syndrome: With this condition horses are unable to absorb digested nutrients properly.

Increased losses

These conditions cause damage to the intestines allowing proteins to be lost, a protein losing enteropathy.

  • Larval cyathostomosis
  • Infiltrative bowel disease
  • Tumours (lymphosarcoma)
  • Enteritis

Approach to the weight loss case

  • Rule out diet change and poor feeding
  • Check teet
  • Assess worming and recent drug treatment
  • Determine if acute (has occurred suddenly) or chronic (occurred slowly over a longer period of time).
  • Blood test: Can assess liver and kidney enzymes, protein levels and degree of inflammation or infection.
  • Rectal exam
  • Oral glucose tolerance test: This test can assess the way the intestines are working by how glucose is absorbed into the bloodstream after feeding a sugar-rich meal.
  • Ultrasound scan: A vet can see certain areas of the abdomen using a scanner.
  • Rectal biopsy: A section of the wall lining of the rectum can be removed and then analysed in a specialist laboratory.
  • Surgery: In some cases the only way to diagnose the cause of weight loss is to look into the abdomen surgically.