Lactating male goats

Keywords: lactation, male, caprine, goat

An adult male Saanen goat showed transient lactation; increasing and decreasing over a period of several years, producing as much as 250 to 300 ml per day. When milking was stopped for several weeks then lactation diminished significantly. This suggested (as expected) that the physical stimulus of milking stimulated lactation in this male.

This buck had normal libido and a breeding soundness examination showed his semen to be normal. He was highly fertile; 14 of 17 does conceiving to first service by this buck.

Lactation in male goats is unusual but not rare. Lactation in male goats is poorly understood. The karyotypes of these bucks are usually normal i.e. 60XY. Critical scrutiny of this syndrome is lacking.

Image size: 2500 x 2659px

It is interesting to contemplate the potential roles that estradiol and prolactin play in lactation. These samples (the number is shown within each bar) were taken at 2 day intervals from the lactating buck shown above, a lactating castrated male goat with an adrenal adenoma, and lastly, a normal, non-lactating castrated buck.

Image size: 1200 x 784px

The role of estradiol in the genesis of lactation is discussed elsewhere in LORI, in the context of the lactating male goat with the adrenal adenoma. It would appear that estradiol plays a role in lactation in non-castrated males as well. The source of estradiol in affected goats could be either adrenal or testicular in origin; this has not been established in goats without neoplasia.

Interestingly, lactation is not uncommon in virgin female goats as well, some producing substantial amounts of milk over many years. This suggests that the caprine mammary gland may be highly sensitive slight galactogenic stimuli. 

Adrenal adenoma causing lactation in a male

Keywords: lactation, male, adrenal, adenoma.

A six year old Toggenburg wether (castrated male) was presented with clinical signs of lactation. During 8 days of observation, 250 ml of milk was produced on the first day but daily production thereafter varied between 2 and 20 ml. The secretion had the appearance of normal milk with a somatic cell count of 1,380,000/ml (normal range for goats: 282,500 to 1,660,000 cells/ml). The milk protein content was 2.7%, fat 1.7% and lactose 2.3% (approximately 65%, 40%, and 55% of the respective normal values for female goats).

Image size: 1500 x 2434px

Milk production continued for approximately three years and at the end of this period, the goat and his normal, non-lactating male (fraternal) twin brother were donated for further study and euthanasia.

Serial serum sampling was conducted to form endocrine profiles of the affected goat and his twin. There was an increased serum concentrations of estradiol 17 beta, abnormal dexamethasone suppression of cortisol and an exaggerated response to ACTH in comparison with the non-lactating male. Based on these findings, a presumptive diagnosis of adrenal cortical neoplasia was made in the lactating goat.

Interestingly, ACTH did not cause increased estradiol concentrations in either the lactating male or the normal non-lactating male.

When the goat was euthanized at the end of this period, postmortem findings included nodules of adrenal hyperplasia in both adrenals, and the single large adrenal cortical adenoma in the left adrenal as shown below.

Image size: 2257 x 1161px

Ether extracts of the adenoma contained more cortisol (217 versus 153 nmol/L of extract) and estradiol 17p (618 versus 189 pg/ mL of extract) than the surrounding adrenal tissue. On gross examination, the adenohypophysis was normal, and although there was  hyperplasia of acidophilic cells, the only evidence of neoplasia was in the adrenal glands.

High serum concentrations of estradiol 17 beta in the lactating male goat were probably of cardinal importance in lactogenesis. In that regard, estrogen treatment has been used to induced lactation in goats and other ruminants. Also, increased serum of estrogens are known to stimulate the release of prolactin, growth hormone (GH), IGF-1 and thyroxine; all of which were significantly elevated in this goat compared to his non-lactating brother. Finally, current literature suggests that prolactin, GH, IGF-1 and thyroxine are lactogenic and lactopoetic hormones in goats.

Lactation in male goats is not rare but it is seldom associated with neoplasia.

References  and details of the endocrinology of this case is discussed in:  Löfstedt, R.M. et al. 1994 Adrenal neoplasia causing lactation in a male goat. J Vet Internal Med. 8: 382-384