Download Causes and Treatment of Agalactia/Hypogalactia in Mares

Causes and Treatment of
Agalactia/Hypogalactia in Mares
Etta Agan Bradecamp DVM, DACT, DABVP
Rood & Riddle Equine Hospital
Physiology of lactation
The hypothalamic-pituitary axis, ovaries and placenta all play a role in udder
development and initiation of lactation. Factors involved in lactogenesis include: estrogen,
progesterone, prolactin, oxytocin, growth hormone, insulin and thyroid hormone.
 Estrogen – induces development of mammary ducts
 Progesterone – stimulates lobuloaveolar growth and inhibits lactogenesis
 Prolactin – rise in prolactin production by lactotrophs in the anterior pituitary stimulates
lactogenesis, controlled by dopamine secretion from the hypothalamus
 Oxytocin – synthesized in the hypothalamus, causes contraction of myoepithelial cells
around the alveoli and expulsion of milk
Causes of agalactia
1. Idiopathic: most commonly in primiparous mares, however there is the rare mare that
repeatedly fails to develop an udder for unknown reason
2. Ingestion of ergot alkaloid (fescue toxicosis)
3. Administration of a dopamine agonist such as pergolide or bromocryptine
4. Inadequate nutrition
5. Selenium deficiency
6. Stress
7. Systemic illness, surgery
Treatment
The primary focus of treatment in mares with agalactia is to increase prolactin production by
blocking the inhibitory affect of dopamine. Ergot alkaloids suppress prolactin production
through their action as dopamine receptor agonists and serotonin antagonists. Compounds that
block the inhibitory action of dopamine are:
 Thyrotropin-releasing hormone (2.0 mg SC q 12 hrs)
 Reserpine (0.5-2.0 mg IM q 48 hrs) (0.01 mg/kg PO q 24 hrs): May cause sedation and
diarrhea.
 Phenothiazine tranquilizers
 Butyrophenones
 Metaclopramide (25 mg IM q 12 hrs)
 Domperidone (1.1 mg/kg PO q 24 hrs)
 Sulpiride (50 mg/100kg IM q 12 hrs)
Compounds that are serotonin receptor agonists include:
 Buspirone
 Dichlorophenyl piperazine
Mares should be removed from endophyte infected fescue pasture a minimum of 30 and ideally
60-90 days prior to expected due date. If this is not possible, domperidone administration should
be started approximately 30 days prior to the expected due date. In mares that are removed from
infected pasture domperidone treatment should be initiated if no udder development has occurred
by 2 weeks prior to the expected due date.
In mares that exhibit idiopathic hypogalactia post foaling domperidone alone or in combination
with reserpine can be effective in stimulating milk production. Mares with sick foals that are not
nursing should be milked frequently (every two hours) to keep milk production stimulated. It is
also imperative to maintain a positive energy balance in post-foaling mares. Mares that foal
early in the year are more likely to lose weight in the first two months of lactation due to being in
a negative energy balance. This results in reduced milk production and decreased weight gain in
their foals when compared to foals from mares that remained in a positive energy balance.
Special attention should also be paid to the nutrition of lactating mares that suffer from illness or
undergo major surgery.
Due to pergolide being a dopamine agonist, mares being treated for PPID (Cushings) should
discontinue treatment for approximately 30 days prior to their expected due date to allow for
normal udder development to occur. Treatment can resume after foaling and does not appear to
have a negative affect on lactation at that time.