What you see. The starting point for addressing any equine health related issue is your observation.


Weight Loss, Thin, Losing Weight


Weight loss in horses can result from a few main causes and lots of less common causes. A primary consideration is whether a horse's energy expenditure exceeds their nutritional intake- simply not enough nutrition for the calories expended. Perhaps work load has increased and there has been no corresponding increase in caloric intake,

Weight loss is commonly seen in an individual horse that is fed in a group. In this case, a dominant horse prevents the thin horse from eating its full ration. The horse is just getting less nutrition than you think.

Dental issues can reduce a horse's ability to properly process feed but this is less common than many people think. Poor chewing/grinding is far more common in older horses. Older horses tend to become progressively harder keepers due to a combination of dental issues and a reduced ability to absorb and utilize nutrients, along with an increasing incidence of PPID and chronic diseases of all kinds.

Internal parasitism, the presence of intestinal worms can reduce efficiency of digestion and utilization of nutrients.

Other somewhat less common causes of weight loss include chronic diseases of many types: endocrine disease like PPID, cancer, chronic respiratory issues and especially chronic pain.

  • Code Orange

    Call Your Vet at Their First Available Office Hours
    • If this problem seems severe and has come on suddenly.
  • Code Yellow

    Contact Your Vet at Your Convenience for an Appointment
    • If you consider this a chronic and relatively mild problem that is not changing rapidly.
    • If the results of the Whole Horse Exam (WHE) suggest the horse is otherwise normal.

your role


What To Do

Know the common causes of weight loss and try to determine whether any of them may be affecting your horse. Especially consider your feeding program and whether the horse may not be getting access to enough feed. Assess your horse's general health using the Whole Horse Exam (WHE), and share your findings and concerns with your vet.

What Not To Do

Do not make assumptions about the cause because if there is underlying disease, it may progress to become a more severe problem.

your vet's role

A veterinary history and physical exam (including a dental exam) can go a long way toward identifying a cause. To rule out underlying disease, your vet may offer to perform diagnostic tests to examine blood cells, look for parasites and assess organ function.
Questions Your Vet Might Ask:
  • What is the horse currently eating?
  • Are you feeding the horse alone or in a group?
  • Does your horse seem normal otherwise?
  • When did you first notice this?
  • Do you think your horse is getting enough feed?
  • What is the horse's age, sex, breed and history?
  • Does the horse seem to be having difficulty eating or dropping feed?
  • Is the horse simply not interested in the feed?
  • Does the horse have diarrhea?
  • What is your parasite control program?
  • What are the results of the Whole Horse Exam (WHE)?
  • When did your horse last have a dental exam or dental work?
  • What were the findings?

Diagnostics Your Vet May Perform

Figuring out the cause of the problem. These are tests or procedures used by your vet to determine what’s wrong.

Very Common
Less Common
more diagnostics

Diagnoses Your Vet May Consider

The cause of the problem. These are conditions or ailments that are the cause of the observations you make.

Very Common
Less Common
more diagnoses

further reading & resources

Author: Doug Thal DVM Dipl. ABVP