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

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 accessory intercourse glands, including big, paired seminal vesicles or vesicular glands, that could be seen erroneously as uterine horns.
  • Puberty does occur at about 2 months in females and between 2-3 months in men.
  • The pubic symphysis separates within the last times of maternity.
  • Separation associated with the pubic symphysis may be insufficient in sows bred after 7-8 months of age and dystocia may result in him or her. Other possible reasons for 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 a important reason behind perinatal mortality in guinea pigs. This problem is frequently noticed in primiparous, overweight sows in belated gestation. The prognosis is actually guarded. Minmise the danger of maternity toxemia by motivating workout, preventing obesity, and minimizing stress in the pregnant 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 reproductive issues in non-breeding friend sows.

Introduction

Guinea pigs are of help in reproductive studies since they share numerous reproductive faculties with people (Fig 1). 26 Like people, guinea pigs have a very hemochorial placenta, for which maternal bloodstream will come in direct experience of the fetal chorion, also comparable trophoblast invasion habits and uterine vasculature that is comparable. 20 , 23 , 26 The guinea pig’s gestation duration could be split into 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 in purchase Rodentia, along with other features are unique for this species that is special. 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 several studies that are reproductive.

Intact guinea that is male, or “boars”, enter puberty between 70-90 times, but men start to show intimate behavior, such as for example mounting, at four weeks of age. 9 , 17 , 23 At 2 months, boars start to ejaculate while mounting. 23 Expression of intimate behavior and physical development is 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 solitary couple of inguinal mammae. 5 Mature boars have big, paired testes, that are situated on either region of the perineum in distinct, shallow 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 never have descended by 4 months of age, the guinea pig should be thought about cryptorchid. 9 The inguinal canals remain available for a lifetime. 9 , 19 to avoid herniation post-castration, many clinicians start using a shut strategy or a modified available method, in which the tunica is roofed into the suture that is used to connect from the spermatic cable and vessels. 32

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

Clinical Suggestion: Although big, paired testes are unmistakeable in mature boars, sex identification may be challenging in young pups. In the event that testicles aren’t apparent, sexing are facilitated by putting mild stress at the bottom of this prepuce to partially extrude your penis. 23

The S-shaped penis comprises of a human anatomy and glans. Guinea pigs have an os penis, that will be discovered inside the dorsal area of this whole amount of the glans. 9 , 19 Like many hystricomorph rodents, your penis comes with moment, saw-toothed white spurs arranged dorsolaterally in 2 synchronous lines through the urethral orifice into the glans. There’s also 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 big event of the 3-5 mm projections that are long unknown. 9

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

Figure 3. Reproductive structure for 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 enlarge.

  • 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 sacs that are blind 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 seminal vesicles can be seen erroneously as uterine horns.

Each locks follicle associated with guinea pig is connected with an androgen-dependent sebaceous gland. These glands are numerous across the relative straight back and may also be discovered all over anus, where they truly are called the caudal gland or “grease gland”. 9 , 23 The caudal gland is more developed into the boar and it is useful for fragrance marking (Fig 4). Boars usually rub or click their rump against an area, plus the secretions deposited act as a sexual attractant and to mark territory. 9 , 23

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

Puberty happens around 2 months of age when you look at the feminine guinea pig or “sow”. 23 Peak reproduction is seen between 3-4 to 20 months and reproduction may 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 indications of estrus and proestrus. During proestrus, sows are more active, chasing cage mates around, swaying their hindquarters, and producing a definite sound that is guttural. Estrus lasts 6-11 hours, and in this right time the sow shows lordosis, curvature associated with the spine with elevated hips, along with vulvar dilation. 23

The sow possesses a pair that is single of mammary glands with an individual set of inguinal mammary nipples (Fig 5), nevertheless supernumerary nipples are typical. 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 just one set of inguinal mammary glands. Supply: Drury Reavill, DVM, DABVP (Avian Training), DACVP. Click image to expand.

Sows have paired ovaries and a bicornuate womb, composed of paired uterine horns, a brief uterine human anatomy, 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). Supply: Drury Reavill, DVM, DABVP (Avian training), DACVP Click image to expand.

Figure 7.Gross view regarding the uterine horns (little arrows) and human 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 closure membrane. 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 Y-shaped despair in perineal cells. The vulvar opening lies at the intersection of this branches therefore the rectum is found in the foot of the Y (Fig 8). 23

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

Copulation

Whenever a female that is receptive introduced, the boar starts to purr and sway his posterior back and forth, while circling, and often cleaning up against the sow if not spraying urine during the sow. In the event that feminine is unreceptive, aggressive male behavior are seen such as for example barbering hair from the female’s throat. 19 A receptive feminine will enable the male to sniff and lick her anogenital area. adult free friend finder 6 , 11 , 19 She assumes the lordosis place and enables a man to mount her. Whether ejaculation does occur or otherwise not, the male shall perform vaginal grooming by dragging their perineum across the cage flooring. Meanwhile the doubles that are female and utilizes 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 in the vagina called the copulatory or genital plug, made up of a good mass of ejaculatory fluid. 23 there are numerous 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 normal guinea pig 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 is certainly not seen until belated gestation. 8