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


Edema or Firm Swelling Under Belly of Very Pregnant Mare


A variety of problems can cause swelling at the lowest part of the belly. The most common cause in late pregnancy results from the weight of the pregnancy interfering with the mare's circulation, causing fluid to seep out into the tissue planes (edema). It is a more common finding in the last weeks of pregnancy in large mares with very pendulous bellies.

Ventral edema in late pregnancy is usually not painful, and will indent and retain its form momentarily if you push your thumb into it. It has the texture of closed-cell foam. Ventral edema usually resolves quickly after a mare foals. Rarely, however, rupture of the abdominal wall can cause excessive swelling here too.

  • Code Orange

    Call Your Vet at Their First Available Office Hours
    • If this problem seems severe and has come on suddenly.
    • If the swelling is large, painful or growing rapidly.
    • If the results of the Whole Horse Exam (WHE) in the resting horse indicate fever (Temp >101F/38.3C) or heart rate greater than 48 BPM.
  • Code Green

    Contact Your Vet to Obtain Useful Advice & Resources
    • You have any concerns about the late-term pregnant mare.

your role


What To Do

Assess the horse's general health using the Whole Horse Exam on Late-Term Mare (WHE), paying particular attention to the mare's attitude and appetite.

If the mare appears healthy, then this sign may not be a cause for concern. However, if the mare shows any other signs of illness or abnormalities, contact your vet with your findings and concerns.

What Not To Do

Do not try to cut open (lance) and drain this fluid.

your vet's role

Your vet differentiates "normal" edema from more serious edema or other conditions upon physical examination. If they are concerned, they may recommend additional diagnostics such as ultrasound, to assess the pregnancy and the integrity of the abdominal wall.
Questions Your Vet Might Ask:
  • What are the mare's breeding dates?
  • Does the mare's attitude and appetite seem normal?
  • What is the horse's age, sex, breed and history?
  • What are the results of the Whole Horse Exam (WHE)?
  • How close does the mare appear to foaling based on udder and pelvic ligaments?

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