The guinea pig (Cavia porcellus) is a favorite friend animal and a typical research model.

Key Points

• Intact female guinea pigs are “sows” and intact males are “boars”.
• Mature boars have actually distinct scrotal pouches and testes that are large.
• Male guinea pigs have actually a few sex that is accessory, including big, paired seminal vesicles or vesicular glands, which is often recognised incorrectly as uterine horns.
• Puberty does occur at about 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 him or her. Other prospective factors behind dystocia consist of obesity and big fetal size.
• Sows usually give delivery to 2-4 big, precocial pups. Other rodent types generally speaking have actually big litters.
• Pregnancy toxemia is definitely a essential reason behind perinatal mortality in guinea pigs. This problem is frequently noticed in primiparous, overweight sows in belated gestation. The prognosis is normally guarded. Minmise the chance of maternity toxemia by motivating workout, preventing obesity, and minimizing stress in the expecting sow.
• Unilateral or bilateral ovarian cysts are common, 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 since they share numerous traits that are reproductive people (Fig 1). 26 Like people, guinea pigs have a very hemochorial placenta, for which maternal bloodstream is available in direct experience of the fetal chorion, in addition to comparable trophoblast intrusion habits and uterine vasculature that is comparable. 20 , 23 , 26 The guinea pig’s gestation duration can certainly be divided in to trimesters, analogous to your condition that is human. 26 needless to say, some popular features of guinea pig reproductive anatomy and physiology are distributed to other people of Order Rodentia, as well as other features are unique for this species that is special. This short article product reviews structure and physiology of this guinea pig reproductive tract and summarizes some clinically significant medical issues.

Figure 1.Guinea pigs (Cavia porcellus) are helpful in several reproductive studies.

Intact guinea that is male, or “boars”, enter puberty between 70-90 times, nevertheless men start to show intimate behavior, such as for example mounting, at 30 days of age. 9 , 17 , 23 At 2 months, boars start to ejaculate while mounting. 23 Expression of intimate behavior and development that is physical considerably suppressed in the event that boar is housed using its mother and/or siblings click for source. 11

Boars are generally bigger than females, with both sexes having a solitary couple of inguinal mammae. 5 Mature boars have big, paired testes, that are found on either part regarding the perineum in distinct, superficial scrotal sacs (Fig 2). 5 , 9 , 23 The testicles are frequently completely descended to the scrotum by 81 times. 2 In the event that testes have not descended by 4 months of age, the guinea pig should be thought about cryptorchid. 9 The canals that are inguinal available for a lifetime. 9 , 19 to avoid herniation post-castration, numerous clinicians start using a shut strategy or even a modified available method, in which the tunica is roofed within the suture which is used to connect from the spermatic cable and vessels. 32

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

Clinical Tip: Although big, paired testes are clear in mature boars, gender identification could be challenging in young pups. In the event that testicles aren’t apparent, sexing are facilitated by putting mild stress at the beds base for the prepuce to partially extrude your penis. 23

The penis that is s-shaped of the human anatomy and glans. Guinea pigs possess a penis that is os which will be discovered inside the dorsal area associated with the entire amount of the glans. 9 , 19 Like many hystricomorph rodents, your penis even offers moment, saw-toothed spurs that are white dorsolaterally in 2 parallel lines through the urethral orifice into the glans. Addititionally there is a sac that is intromittent the ventral area regarding the glans penis. 9 During erection, the sac everts and two styles that are horny. 5 , 9 , 23 the event of those 3-5 mm projections that are long unknown. 9

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

Figure 3. Reproductive anatomy 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. Photo credit: Drs. Craig Franklin and Cindy Besch-Williford. Click image to expand.

• The large, 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 instantly caudodorsal into the ductus deferens. 9 , 19 , 23 , 27

Clinical Suggestion: The big, paired vesicles that are seminal be seen erroneously as uterine horns.

Each locks follicle regarding the guinea pig is related to an androgen-dependent gland that is sebaceous. These glands are numerous over the as well as may also be discovered round the rectum, 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 utilized for fragrance marking (Fig 4). Boars usually rub or push their rump against an area, and also the secretions deposited act as a sexual attractant and to mark territory. 9 , 23

Figure gland that is 4.Caudalbig arrow) and perineum (little arrow) in a male guinea pig (Cavia porcellus). Supply: Uwe Gille via Wikimedia Commons. Click image to expand.

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 carry on until 4-5 years old. 19 , 23 Guinea pigs are seasonally polyestrous and breed 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 signs and symptoms of estrus and proestrus. 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 in this time the sow shows lordosis, curvature regarding the back with elevated sides, in addition to vulvar dilation. 23

The sow possesses a solitary set of inguinal mammary glands with just one set of inguinal mammary nipples (Fig 5), but supernumerary nipples are normal. 9 , 19 , 22 in comparison to the boar, the sow’s nipples are much longer and much more prominent. 9

Figure 5.Both male and female guinea pigs (Cavia porcellus) have just one set of inguinal mammary glands. Supply: Drury Reavill, DVM, DABVP (Avian Training), DACVP. Click image to enlarge.

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 one uterine horn (arrow) in mature guinea pig (Cavia porcellus). Supply: Drury Reavill, DVM, DABVP (Avian training), DACVP Click image to expand.

Figure 7.Gross view associated with uterine horns (little arrows) and human body (big arrow) in a guinea pig (Cavia porcellus). Source: Drury Reavill, DVM, DABVP (Avian Training), DACVP. Click image to enlarge.

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, 26 or 27 of gestation, and at parturition in many animals day. 19 , 22 , 23 , 29 The sow includes a depression that is y-shaped perineal cells. The opening that is vulvar at the intersection associated with branches additionally the rectum is found during the foot of the Y (Fig 8). 23

Figure 8.Y-shaped depression within the perineum of the guinea pig sow (Cavia porcellus), illustrating the vulva (white arrow) additionally the rectum (yellow arrow). Supply: Dorcas O’Rourke, DVM, MS, DACLAM. Click image to expand.

Copulation

whenever a receptive feminine is introduced, the boar starts to purr and sway their posterior back and forth, while circling, and often cleaning from the sow and even spraying urine in the sow. In the event that feminine is unreceptive, aggressive male behavior could be seen such as for example barbering hair from the neck that is female’s. 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 perhaps not, a man 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 confirmed by the existence of a company, rubbery deposit in the vagina called the copulatory or plug that is vaginal made up of an excellent mass of ejaculatory fluid. 23 there are many theories in the purpose of the copulatory plug in rodents, including semen storage space, avoidance of semen leakage, advertising of semen transportation, 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 differ 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