Key Points

• Intact female guinea pigs are “sows” and intact males are “boars”.
• Mature boars have distinct scrotal pouches and testes that are large.
• Male guinea pigs have actually a few accessory intercourse glands, including big, paired seminal vesicles or vesicular glands, that can be recognised incorrectly as uterine horns.
• Puberty does occur at more or less 2 months in females and between 2-3 months in men.
• The symphysis that is pubic within the last times of maternity.
• Separation for the symphysis that is pubic be insufficient in sows bred after 7-8 months of age and dystocia can lead to these people. Other potential reasons for dystocia include obesity and fetal size that is large.
• Sows frequently give delivery to 2-4 large, precocial pups. Other rodent types generally speaking have big litters.
• Pregnancy toxemia is definitely a essential reason behind perinatal mortality in guinea pigs. This disorder is oftentimes seen in primiparous, overweight sows in belated gestation. The prognosis is normally guarded. Minmise the danger of pregnancy toxemia by motivating workout, preventing obesity, and minimizing stress when you look at the expecting sow.
• Unilateral or bilateral ovarian cysts are quite typical, especially in older sows.
• Ovariohysterectomy or ovariectomy is preferred to stop the growth of ovarian cysts as well as other problems that are reproductive non-breeding friend sows.

Introduction

Guinea pigs are helpful in reproductive studies simply because they share numerous reproductive faculties with humans (Fig 1). 26 Like people, guinea pigs have a very hemochorial placenta, for which maternal blood will come in direct experience of the fetal chorion, along with comparable trophoblast intrusion habits and uterine vasculature that is comparable. 20 , 23 adult friend finde , 26 The guinea pig’s gestation duration could be split into trimesters, analogous towards the condition that is human. 26 needless to say, some popular features of guinea pig reproductive anatomy and physiology are distributed to other users of purchase Rodentia, as well as other features are unique for this unique species. This short article product reviews physiology and physiology regarding the guinea pig reproductive tract and summarizes some clinically significant medical dilemmas.

Figure 1.Guinea pigs (Cavia porcellus) are of help in lots of reproductive studies.

Intact male guinea pigs, or “boars”, enter puberty between 70-90 times, nonetheless men commence to show intimate behavior, such as for example mounting, at 1 month of age. 9 , 17 , 23 At 2 months, boars start to ejaculate while mounting. 23 Expression of sexual behavior and development that is physical notably suppressed in the event that boar is housed having its mom and/or siblings. 11

Boars are usually bigger than females, with both sexes having a pair that is single of mammae. 5 Mature boars have big, paired testes, that are found on either region of the perineum in distinct, superficial scrotal sacs (Fig 2). 5 , 9 , 23 The testicles are frequently completely descended in to the scrotum by 81 times. 2 In the event that testes never have descended by 4 months of age, the guinea pig is highly recommended cryptorchid. 9 The canals that are inguinal available for life. 9 , 19 to avoid herniation post-castration, numerous clinicians start using a shut method or even a modified open method, where in actuality the tunica is roofed into the suture which is used to connect from the spermatic cable and vessels. 32

Figure image that is 2.Gross of testicle (arrow) in an adult boar (Cavia porcellus). The epididymis lies over the dorsolateral area for the testis. The end for the epididymis offers increase into the ductus deferens. Credit: Drury Reavill, DVM, DABVP (Avian Training), DACVP. Click image to expand.

Clinical Suggestion: Although big, paired testes are obvious in mature boars, sex identification could be challenging in young pups. In the event that testicles aren’t apparent, sexing are facilitated by putting mild force at the beds base associated with prepuce to partially extrude your penis. 23

The penis that is s-shaped of the human anatomy and glans. Guinea pigs have an os penis, which will be discovered inside the dorsal area associated with the whole amount of the glans. 9 , 19 Like other hystricomorph rodents, your penis even offers moment, saw-toothed spurs that are white dorsolaterally in 2 synchronous lines through the urethral orifice to your glans. Additionally there is an intromittent sac on the ventral area associated with the glans penis. 9 During erection, the sac everts and two styles that are horny. 5 , 9 , 23 the event among these 3-5 mm projections that are long unknown. 9

Male reproductive glands include the seminal vesicles (vesicular glands), coagulating glands, bulbourethral glands, plus the prostate (Fig 3). 5 , 27 A rudimentary preputial gland may be contained in the boar. 9

Figure 3. Reproductive structure regarding the guinea pig (Cavia porcellus) boar. (A) seminal vesicle (B) testis C) vas deferens (D) anterior prostate gland or coagulating gland (E) urinary bladder (F) Cowper’s or bulbourethral gland (G) urethra (H) penis (we) epididymis. Picture credit: Drs. Craig Franklin and Cindy Besch-Williford. Click image to expand.

• The big, clear, smooth vesicles that are seminal the biggest reproductive glands of this boar, calculating as much as 100 mm in total and 6-9 mm in diameter. These long, coiled, paired blind sacs lie ventral to the ureters and go into the urethra by a set of ducts immediately caudodorsal towards the ductus deferens. 9 , 19 , 23 , 27

Clinical Tip: The big, paired seminal vesicles can be seen erroneously as uterine horns.

Each hair follicle associated with the guinea pig is related to an androgen-dependent sebaceous gland. These glands are numerous across the straight back and may also be discovered all over anal area, where these are generally called the caudal gland or “grease gland”. 9 , 23 The caudal gland is more developed into the boar and it is employed for scent marking (Fig 4). Boars often rub or hit their rump against an area, therefore the secretions deposited act as a sexual attractant and to mark territory. 9 , 23

Figure 4.Caudal gland (big arrow) and perineum (little arrow) in a male guinea pig (Cavia porcellus). Supply: Uwe Gille via Wikimedia Commons. Click image to enlarge.

Puberty does occur around 2 months of age within the guinea that is female or “sow”. 23 Peak reproduction is seen between 3-4 to 20 months and reproduction might continue until 4-5 years. 19 , 23 Guinea pigs are seasonally breed and polyestrous year-round in captivity. 9 , 23 Sows are spontaneous ovulators, having a cycle that is estrous 15-17 times (range 13-21 times). 19 Sows display distinct indications of proestrus and estrus. During proestrus, sows are more active, chasing cage mates around, swaying their hindquarters, and creating a definite sound that is guttural. Estrus lasts 6-11 hours, and with this time the sow shows lordosis, curvature associated with back with elevated sides, along with vulvar dilation. 23

The sow possesses a pair that is single of mammary glands with an individual couple of inguinal mammary nipples (Fig 5), but supernumerary nipples are normal. 9 , 19 , 22 compared to the boar, the sow’s nipples are much longer and much more prominent. 9

Figure 5.Both male and guinea that is female (Cavia porcellus) have an individual couple of inguinal mammary glands. Source: Drury Reavill, DVM, DABVP (Avian Training), DACVP. Click image to expand.

Sows have paired ovaries and a bicornuate womb, composed of paired uterine horns, an uterine that is short, and just one os cervix (Fig 6, Fig 7). 5 , 9 , 23

Figure 6.View of just one uterine horn (arrow) in mature guinea pig (Cavia porcellus). Source: Drury Reavill, DVM, DABVP (Avian training), DACVP Click image to enlarge.

Figure 7.Gross view regarding the uterine horns (little arrows) and the body (big arrow) in a guinea pig (Cavia porcellus). Supply: Drury Reavill, DVM, DABVP (Avian Training), DACVP. Click image to expand.

During anestrus and pregnancy, the genital opening in hystricomorph rodents is sealed having an epithelial membrane called the genital closing membrane layer. The membrane layer starts at estrus, Day 26 or 27 of gestation, as well as parturition in several pets. 19 , 22 , 23 , 29 The sow includes a depression that is y-shaped perineal cells. The vulvar opening lies at the intersection associated with branches additionally the anal area is situated at the foot of the Y (Fig 8). 23

Figure 8.Y-shaped despair into the perineum of the guinea pig sow (Cavia porcellus), illustrating the vulva (white arrow) while the anal area (yellow arrow). Supply: Dorcas O’Rourke, DVM, MS, DACLAM. Click image to expand.

Copulation

Each time a female that is receptive introduced, the boar starts to purr and sway their posterior back and forth, while circling, and often cleaning resistant to the sow as well as spraying urine during the sow. In the event that feminine is unreceptive, aggressive male behavior might be seen such as for instance barbering hair in the female’s neck. 19 A receptive feminine will let the male to sniff and lick her anogenital area. 6 , 11 , 19 She assumes the lordosis place and enables a man to mount her. Whether ejaculation does occur or otherwise not, the male will perform vaginal grooming by dragging their perineum across the cage flooring. Meanwhile the feminine doubles over and makes use of her lips to groom her genitals. 19 Mating frequently does occur at night. 8

Copulation is verified because of the existence of a company, rubbery deposit inside the vagina called the copulatory or genital plug, consists of an excellent mass of ejaculatory fluid. 23 There are lots of theories regarding the purpose of the copulatory plug in rodents, including semen storage space, prevention of sperm leakage, advertising of semen transport, and/or to stop later on fertilization by other men. 23 The copulatory plug falls out a long time after mating. 23

The guinea that is average maternity persists 68 times, with a reported array of 59-72 times. 9 , 19 , 23 These times vary with stress, parity, and litter size. 23 average size that is litter 2-4 pups with a variety of 1-13 pups. 23 clear stomach distension just isn’t seen until belated gestation. 8