Horse Side Vet Guide ®

Equine Health Resource

Milk or Clear Fluid Out of Udder or Teats of Non-Pregnant, Non-Lactating Mare

Code Yellow - Contact Your Vet at Your Convenience for an Appointment

Code Yellow - Contact Your Vet at Your Convenience for an Appointment

    Some mares lactate despite not being pregnant and not nursing a foal. There may be hormonal reasons for this, but the scientific explanation remains unclear.

    There is some speculation about whether mares that have Cushing’s disease (PPID) might produce hormones that cause milk production. The appearance of the milk in these mares can range from clear to white to honey-colored.

    Taken alone, with no other abnormalities or signs of illness, this type of lactation (“witches milk”) is not of great concern.

    However, rarely fluid can be milked from the teats of mares that have swelling near the udder, as the result of an abscess in the area caused by Pigeon Fever. In addition, these mares may also be more susceptible to mastitis.

    Mastitis usually causes half the udder to swell suddenly and that side will also be warm and possibly painful. When milk is stripped out, it is often a yellow colored thick fluid that contains clots.


    Assess your horse’s general health using the Whole Horse Exam (WHE), paying particular attention to rectal temperature, attitude and appetite. Look for swelling of the udder and differences in the appearance of left and right sides. Strip a few drops of milk into your palm and study the appearance of the fluid.

    As long as the udder is non-painful and not swollen, and the fluid appears clear or white, there is probably not much to worry about. However, if this observation is accompanied by any other sign of illness or the mare’s udder seems hot, painful or swollen, contact your vet with your findings and concerns.

    In mares that have consistent fluid in their udder, it is important to watch this area for a change in appearance or swelling, and share your findings and concerns with your vet early if you do notice a problem.


    Your vet may recommend hormonal testing if, taken with other abnormalities, there is any cause for concern.

    Author: Doug Thal DVM Dipl. ABVP


    We're not around right now. But you can send us an email and we'll get back to you, asap.