ISSN 2398-2977      

Female: agalactia / hypogalactia

pequis

Introduction

  • Complete (agalactia) or partial (hypogalactia) failure of the mammary gland to secrete milk or colostrum following parturition.
  • Cause: include ergot alkaloid ingestion, systemic illness, medication for cushing's, injury, infection or neoplasia of the mammary gland, and inadequate nutrition.
  • Signs: little or no udder development, stimulation of pituitary prolactin synthesis.
  • Diagnosis: clinical signs.
  • Treatment: removal of causative agents, stimulation of pituitary prolactin synthesis.
  • Prognosis: generally good, but depend on cause.

Pathogenesis

Etiology

  • Spontaneous agalactia, usually primiparous mares.
  • Ergot alkaloid induced toxicity - toxin produced by endophytes growing on tall fescue grasses (USA) black oats (Brazil) and rye grass (Argentina).
  • Administration of dopamine agonists, eg pergolide   Pergolide  or bromocriptine   Bromocriptine   for treatment of Cushing's during late pregnancy.
  • Maternal systemic disease or inadequate nutrition causing hypogalactia.
  • Selenium deficiency (hypogalactia).
  • Mastitis   Mammary gland: mastitis  .
  • Mammary hypoplasia or aplasia.
  • Mammary neoplasia   Adenocarcinoma: mammary  .
  • Trauma to the mammary gland.

Predisposing factors

General
  • Primiparous mare.
  • Mare in poor body condition or with systemic illness.
  • Exposure to ergot-alkaloids in feed or pasture.
  • Treatment with dopamine agonists.
  • Premature foaling.

Pathophysiology

  • During pregnancy, mammary development and galactopoiesis are influenced by ovarian and adrenal steroids, oxytocin, prolactin, thyroid hormones, growth hormone, insulin and other factors.
  • During the final week of gestation, a fall in progesterone is thought to stimulate a surge of prolactin release from the anterior pituitary gland, regulated by the hypothalamic secretion of dopamine.
  • The rise in prolactin is at least partly responsible for the final development of the mammary gland and initiation of milk secretion by specialized epithelia cells into the lumen of alveoli and small ducts.
  • Following parturition, large pulses of prolactin continue to be released from the pituitary in response to the sucking timulus from the foal; this appears to be important for maintaining galactopoiesis in the neonatal period.
  • Oxytocin   Oxytocin  is released from the neurohypophysis in response to the foal sucking and this helps to stimulate milk "let down".
  • Ergot alkaloids supress prolactin secretion due to their action as dopamine receptor agonists and serotonin antagonists; pergolide   Pergolide  and bromocriptine   Bromocriptine  also block prolactin release by their action on dopamine receptors.
  • Agalactic and often hypogalactic mares have low serum prolactin levels.

Timecourse

  • Agalactia is apparent at parturition.
  • Hypogalactia may not be obvious for 24 h or more, when the foal starts to show signs of dehydration or lethargy.
  • A mare with normal mammary development and colostrum production at parturition may become hypogalactic following systemic illness, eg endotoxemia   Endotoxemia: overview   and laminitis   Foot: laminitis  secondary to retention of fetal membranes.
  • Hypogalactia can also develop if the newborn foal is sick and is unable to nurse for several days; regular milking helps to prevent this.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Singh M P & Chanel K S (1997) Treatment of agalactia in two mares. Equine Vet Educ 9, 60-61 VetMedResource.
  • Cross D L, Redmond L M & Strickland J R (1995) Equine fescue toxicosis: signs and solutions. J Anim Sci 73 (3), 899-908 PubMed.
  • Ireland F W, Loch W E, Worthy K & Anthony R V (1991) Effects of bromocriptine and perphenazine on prolactin and progesterone concentrations in pregnant pony mares during late gestation. J Reprod Fertil 92 (1), 179-186 PubMed.
  • Worthy K, Escreet R, Renton J P et al (1986) Plasma prolactin concentrations and cyclic activity in pony mares during parturition and early lactation. J Reprod Fert 77 (2), 569-574 PubMed.

Other sources of information

  • McCue P & Sitters S (2011) Lactation. In: Equine Reproduction. Eds: McKinnon A O, Squires E L, Vaala W E & Varner D D. pp 1119-1129.
  • Albrecht B A (2007) Mastitis. In: Current Therapy in Equine Reproduction. Eds: Samper J C, Pycock J F & McKinnon A O. pp 441-445.

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