Teasing and buck rags

Keywords: caprine, goat, teasing, breeding, estrus

As shown here, a 'buck rag" can be used to assist in estrous detection. These rags are made by rubbing a rag over the cornual glands caudo-medial to the horns of a male goat. These rags are highly odoriferous and should be stored in sealed jars ('buck jars").

Figure 1. The use of a "Buck-rag" for estrous detection in a doe. Note that the doe shows interest and wags her tail rapidly (black arrow) when the buck-rag is presented to her. After this first sign of interest, rump pressure can be applied (see insert). If the doe remains stationary during rump pressure, it is likely that she will be receptive to a male i.e. in estrus. Image size: 1218 x 1036 px.

Some care must be exercised  when interpreting behavior with a buck rag test because of  the naturally inquisitive nature of goats.

Does can be inseminated once, 12 to 24 hours after the onset of standing estrus. However, two inseminations at 12 and 24 hours will give better results. Pregnancy rates should exceed 60%.

Caprine neonatal genitals

Keywords: caprine, goat, uterus, testes, neonate, testis, ovary

Caprine neonates taken from a doe euthanized  at term. The first thought that may enter one's mind should these be bovine triplets, is that of freemartinism. However freemartinism is rare in goats. With perhaps 2 to 11 percent  triplets in various  breeds of goats, freemartins would be disastrous for the species.  The main trust of this entry then, is the absence of freemartinism in the two female kids co-triplet with this male and in that absence, normal genital anatomy in all three triplets.

Figure 1. Image size:1072 x 841px

As for all domestic ruminants, the testes have descended into the scrotum before birth in goats. Cryptorchidism is rare in goats. Therefore the situation shown here is normal.

Figure 2. Internal genitalia of a male caprine neonate. Note the testis within the scrotum and the diminished gubernaculum. Image size:1432 x 868px

Figure 3.  Internal genitalia of a female caprine neonate.  Note that the uterus is normally developed. If this animal had been a freemartin, development of the uterus (mullerian in origin) would have been suppressed by mullerian inhibiting hormone from sertoli cells in the male co-triplet. Also note the presence of the umbilical arteries on either side of the bladder (which continues as the urachus). These vessels  become the round ligaments of the bladder in the postnatal animal. Image size: 1362 x 880px

Selected references:

Amann, R.P. and Veeramachaneni D.N.R. 2007 Cryptorchidism in common eutherian mammals
Reproduction 133:541–561

Padula A.M. 2005 The freemartin syndrome: an update. Anim. Reprod. Sci.87:93–109

Polled intersex syndrome

Keywords: goat, caprine, PIS, AMH

Polled intersex syndrome (PIS) is a classic condition, known to all veterinary students. This is because it is controlled quite simply, by advising clients to use a horned buck for breeding. That is because PIS is associated with the polled gene and when a goat is homozygous for the polled gene, PIS is likely to manifest itself. The polled gene is also dominant, therefore a buck will be polled even if it is heterozygous for the polled gene. The corollary is that the polled gene cannot be inherited by a kid if the herd sire has horns. It also means that even if the doe bred to the horned buck is either hetero- or homozygous for the polled gene, the fetus cannot be homozygous for the polled gene and will not manifest PIS.

The following images (more that 40 years old but still valuable) show the reproductive tract of a PIS goat. It should be mentioned that there is no "typical" manifestation of PIS therefore these image cannot be regarded as typical.  Some goats are highly feminized, others very masculine. This is an extreme manifestation of PIS.

Figure 1. The ambiguous external genitalia of a polled intersex male. The testes are visible in the flattened scrotum. Image size: 500 x 726px

Figure 2. The internal genitalia of the animal shown in figure 1. Note the almost complete suppression of the paramesonephric (mullerian) system (uterus and cervix) . The mesonephric (wolffian) system is visible on either side of the paramesonephric system. Also note the urogenital sinus, a part of the tubular system that would have developed into the vagina in a female. There is no cervix; a part of the paramesonephric system completely suppressed by AMH. Image size: 1091 x 894px

Testes are invariably present in the PIS syndrome. External genitalia can be female in appearance, male-like or as was the case here, ambiguous. In many cases they are not "sex-reversed" or male pseudohermaphrodites because the testes and the rest of the genital tract are congruent.

This male had a müllerian system that was severely suppressed. This is not surprising because anti müllerian hormone (AMH)* is produced by the testes in PIS goats. The testes in PIS goats usually have no spermatogonia but do have both sertoli and leydig cells; the former being a source of AMH, the latter, a source of testosterone. With regard to testosterone, it is not surprising then, that PIS goats are often strongly masculinized and used as teaser males. The testes may descend in some PIS goats but more often, they are cryptorchid (as was the case here). As is occasionally the case with cryptorchid testes, they can become neoplastic.

Figure 3. Scrotum of a suspect intersex male goat. This male was infertile, producing no sperm when electro-ejaculated. He had a small scrotum, small testicles and was polled. Therefore it was presumed that he was homozygous polled and an intersex goat. Image size: 768 x 564px

Notes The genetic cause of PIS is extremely complex. The dominant gene for polledness and the recessive gene for PIS appear to lie close to one another on chromosome #1. There is thought that they might even be the same gene with pleiotropic functions. This abnormality is associated with the absence the FOXL2 and PISRT1 genes in PIS goats. These genes (and others) are present in normal females, coding for the development of ovaries. In their absence, testes develop. Therefore it is not the mere presence of the SRY, SOX9 and downstream genes that code for testes development; the absence of FOXL2 and PISRT1 is also important. In fact, even though SOX9 is present in female goats, its expression is usually inhibited by PISRT1. However, if PISRT1 is absent, SOX9 will be expressed and testes will develop, even though SRY is not present. These facts are important to bear in mind when one contemplates how it is possible for an animal with a normal 60 XX karyotype to have testes, especially if it is SRY negative. Indeed, that is the case in all goats with PIS.

* Also known as müllerian (mullerian) inhibiting hormone (MIH) or müllerian inhibiting substance
 (MIS).

Selected references:

E. Pailhoux, E. et al 1994. Molecular analysis of 60,XX pseudohermaphrodite polled goats for the presence of SRY and ZFY genes. J Reprod. fert. 100491-496

E. Pailhoux, E. et al 2005. Positional cloning of the PIS mutation in goats and its impact on understanding mammalian sex-differentiation. Genet. Sel. Evol. 37 (Suppl. 1):S55–S64

E. Pailhoux, E. et al 2002. Ontogenesis of female-to-male sex-reversal in XX polled goats. Developmental dynamics. 224:39-50

Boulanger, L. et al. 2014. FOXL2 Is a Female Sex-Determining Gene in the Goat. Current biology. 24:404-408

King, W.W. et al. 2002. Multiple congenital genitourinary anomalies in a polled goat. Contemporary topics: American society of animal science. 41:39-42

Li, X. et al. 2011. Special variations within 11.7 kb fragment in goat polled intersex syndrome. African journal of biotechnology. 10:6695-6699.

Schibler, L. et al. 2000. Fine Mapping Suggests that the Goat Polled Intersex Syndrome and the Human Blepharophimosis Ptosis Epicanthus Syndrome Map to a 100-kb Homologous Region Genome research. 10:311-318

Yokata, S. et al. 2011. Polled Intersex Syndrome with Urethral Atresia in a Goat J. Vet. Med. Sci. 73: 1355–1357

Hydrometra and pseudopregnancy

Keywords: caprine, goat, pseudopregnancy, hydrometra

This condition is occasionally reported in other animals but it is only in goats that it is common and fairly well characterized.

For unknown reasons, there is sudden cessation of luteolysis in the absence of pregnancy. It is usually noticed during the fall and winter when goats are normally having estrous cycles.

Clear, sterile fluid accumulates in the uterus; so clear that it resembles water (see below). This gives rise to the term "hydrometra". Also, because affected does are not cycling and the condition is frequently diagnosed when most does are pregnant, the condition is also known as ‘pseudopregnancy’.

Image size: 943 x 872 px

Fluid remains in the uterus for a variable period of time sustained by the presence of one or more corpora lutea; in this case, two.  The progestogenic environment maintains uterine quiescence and closure of the the cervix. Up to ten liters of fluid accumulation has been reported in some cases yet uterine rupture has not been documented. After a variable period of time, spontaneous luteolysis occurs and the fluid is discharged. The lay term for this discharge is "cloud burst".

Usually, individual does are not presented for treatment for hydrometra. The author has encountered this condition in goats while performing ultrasound for pregnancy diagnosis. In such cases, it is easily diagnosed because does are usually tested for pregnancy when placentomes are well developed (> 90 days). In these cases, there are large amounts of fluid in the uterus but no placentomes and obviously, no fetuses.

Hydrometra is most prevalent in older does. The graph below shows the numbers of does in age categories (there are more young does than older does) but also shows that there is a relative increase in hydrometra cases as does age.

Image size: 1408x1080px

In some herds, up to 20% of the does experience hydrometra; in others, the incidence is usually far lower. This has given rise to speculation that hydrometra may have a genetic basis but at this time, selective culling of affected does is not generally recommended.

Luteolytic doses of prostaglandin are curative but several treatments at 10 to 12 day intervals may be required in some cases. Apparently does should not be bred at the first induced estrus after treatment for hydrometra because fertility can be very low at that time.

Note: Images of hydrometra are not common because the condition does not affect long term fertility and does are seldom culled as a consequence. This case was a chance finding in a doe that was euthanized for an unrelated condition.

References: 

Fatet, A. et al. 2011. Reproductive cycle of goats Animal Reprod. Sci. 124:211–219

Hesselink, J.W. 1993 Incidence of hydrometra in dairy goats. Vet. Record. 132: 110-112

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