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

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

Key Points

  • Intact guinea that is female 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, which is often recognised incorrectly as uterine horns.
  • Puberty does occur at around 2 months in females and between 2-3 months in men.
  • The symphysis that is pubic within the last few days of pregnancy.
  • Separation associated with the pubic symphysis may 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 frequently give delivery to 2-4 big, precocial pups. Other rodent species generally speaking have actually big litters.
  • Pregnancy toxemia is definitely a cause that is important of mortality in guinea pigs. This disorder is frequently noticed in primiparous, obese sows in belated gestation. The prognosis is usually guarded. Minmise the chance of being pregnant toxemia by motivating workout, preventing obesity, and minimizing stress in the sow that is pregnant.
  • Unilateral or bilateral ovarian cysts are quite typical, especially in older sows.
  • Ovariohysterectomy or ovariectomy is advised to avoid the introduction of ovarian cysts along with other problems that are reproductive non-breeding friend sows.

Introduction

Guinea pigs are of help in reproductive studies simply because they share numerous traits that are reproductive people (Fig 1). 26 Like people, guinea pigs have a very hemochorial placenta, by which maternal bloodstream is available in direct connection with 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 split into trimesters, analogous towards the condition that is human. 26 needless to say, some top features of guinea pig reproductive anatomy and physiology are distributed to other people in purchase Rodentia, as well as other features are unique for this unique species. This short article product reviews physiology and physiology associated with the guinea pig tract that is reproductive summarizes some clinically significant medical issues.

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

Intact male guinea pigs, or “boars”, enter puberty between 70-90 times, but males 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 real development is notably suppressed if the boar is housed having its mom and/or siblings. 11

Boars are 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 usually completely descended to the scrotum by 81 times. 2 In the event that testes have never 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 technique or perhaps a modified available strategy, where in actuality the tunica is roofed when you look at 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 surface that is dorsolateral of testis. The end associated with the epididymis offers increase to your ductus deferens. Credit: Drury Reavill, DVM, DABVP (Avian Training), DACVP. Click image to expand.

Clinical Suggestion: Although big, paired testes are clear 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 of this prepuce to partially extrude your penis. 23

The penis that is s-shaped of the human body and glans. Guinea pigs have a penis that is os which will be discovered in the dorsal area associated with whole period of the glans. 9 , 19 Like other hystricomorph rodents, your penis comes with moment, saw-toothed white spurs arranged dorsolaterally in 2 synchronous lines through the urethral orifice to your glans. Additionally there is an intromittent sac on the ventral area regarding the glans penis. 9 During erection, the sac everts and two horny styles protrude. 5 , 9 , 23 the big event of the 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 gland that is preputial additionally be present 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.

adult dating

  • The big, clear, smooth seminal vesicles are the largest 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 Suggestion: The big, paired seminal vesicles can be recognised incorrectly as uterine horns.

Each locks follicle of this guinea pig is connected with an androgen-dependent gland that is sebaceous. These glands are numerous over the relative straight back and will also be discovered all over rectum, where they’ve been called the caudal gland or “grease gland”. 9 , 23 The caudal gland is more developed within the boar and it is useful for fragrance marking (Fig 4). Boars often rub or click their rump against a area, additionally 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 happens around 2 months of age within the feminine guinea pig or “sow”. 23 Peak reproduction is observed between 3-4 to 20 months and reproduction may carry on until 4-5 years old. 19 , 23 Guinea pigs are seasonally breed and polyestrous year-round in captivity. 9 , 23 Sows are spontaneous ovulators, by 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 guttural noise. Estrus lasts 6-11 hours, and in this time the sow shows lordosis, curvature for the back with elevated sides, in addition to vulvar dilation. 23

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

Figure 5.Both male and guinea that is female (Cavia porcellus) have just one couple 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 just one uterine horn (arrow) in mature guinea pig (Cavia porcellus). Source: Drury Reavill, DVM, DABVP (Avian training), DACVP Click image to expand.

Figure 7.Gross view associated with 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.

The vaginal opening in hystricomorph rodents is sealed with an epithelial membrane called the vaginal closure membrane during anestrus and pregnancy. The membrane layer starts at estrus, 26 or 27 of gestation, and at parturition in many animals day. 19 , 22 , 23 , 29 The sow possesses depression that is y-shaped perineal cells. The opening that is vulvar at the intersection associated with branches as well as the anal area is found 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) as well as the rectum (yellow arrow). Supply: Dorcas O’Rourke, DVM, MS, DACLAM. Click image to enlarge.

Copulation

whenever a receptive female is introduced, the boar starts to purr and sway their posterior from side to side, while circling, and quite often cleaning resistant to the sow as well as spraying urine during the sow. In the event that female is unreceptive, aggressive male behavior can be seen such as for instance barbering hair in the female’s throat. 19 A receptive feminine will permit the male to sniff and lick her anogenital area. 6 , 11 , 19 She assumes the lordosis place and permits 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 happens at nighttime. 8

Copulation is verified because of the existence of a strong, rubbery deposit in the vagina called the copulatory or genital plug, consists of a great mass of ejaculatory fluid. 23 there are many theories from the purpose of the copulatory plug in rodents, including semen storage space, avoidance of semen leakage, promotion of semen transportation, and/or to stop later 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 vary with stress, parity, and size that is litter. 23 average size that is litter 2-4 pups with a variety of 1-13 pups. 23 clear stomach distension isn’t seen until belated gestation. 8

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