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 guinea that is female are “sows” and intact males are “boars”.
  • Mature boars have actually distinct scrotal pouches and big testes.
  • Male guinea pigs have actually a few accessory sex glands, including large, paired seminal vesicles or vesicular glands, that can easily be seen erroneously as uterine horns.
  • Puberty occurs at around 2 months in females and between 2-3 months in men.
  • The pubic symphysis separates within the last few 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 reasons for dystocia include obesity and big fetal size.
  • Sows frequently give delivery to 2-4 big, precocial pups. Other rodent types generally speaking have actually big litters.
  • Pregnancy toxemia is definitely a cause that is important of mortality in guinea pigs. This disorder is oftentimes seen in primiparous, overweight sows in belated gestation. The prognosis is frequently 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 cysts that are ovarian quite typical, especially in older sows.
  • Ovariohysterectomy or ovariectomy is preferred to stop the introduction of ovarian cysts as well as other reproductive issues in 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, along with comparable trophoblast intrusion habits and uterine vasculature that is comparable. 20 , 23 , 26 The guinea pig’s gestation duration may also be divided in to trimesters, analogous towards the individual condition. 26 needless to say, some top features of guinea pig reproductive anatomy and physiology are distributed to other people of purchase Rodentia, as well as other features are unique for this unique species. This short article ratings 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 of help in lots of reproductive studies.

Intact guinea that is male, adult fried finder or “boars”, enter puberty between 70-90 times, nonetheless 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 real development is considerably suppressed in the event that boar is housed having its mom and/or siblings. 11

Boars are generally bigger than females, with both sexes having a solitary set of inguinal 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 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 canals that are inguinal available for a lifetime. 9 , 19 To prevent herniation post-castration, numerous clinicians start using a shut technique or perhaps a modified available method, where in actuality the tunica is roofed into the suture which is used to connect off the spermatic cable and vessels. 32

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

Clinical Suggestion: Although large, paired testes are clear in mature boars, sex identification may be challenging in young pups. If the testicles are not 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 a human anatomy and glans. Guinea pigs have an os penis, which will be discovered inside the dorsal area regarding the whole duration of the glans. 9 , 19 Like other hystricomorph rodents, the penis even offers 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 associated with glans penis. 9 During erection, the sac everts and two horny styles protrude. 5 , 9 , 23 the big event among these 3-5 mm long projections is 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 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 big, clear, smooth seminal vesicles are 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 enter the urethra by a couple 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 hair follicle associated with guinea pig is connected with an androgen-dependent gland that is sebaceous. These glands are numerous across the relative straight back and will also be discovered round the anal area, where they have 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 usually rub or push on their rump against a area, therefore 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). Supply: Uwe Gille via Wikimedia Commons. Click image to expand.

Puberty happens around 2 months of age into the feminine guinea pig or “sow”. 23 Peak reproduction is observed between 3-4 to 20 months and reproduction may continue until 4-5 years. 19 , 23 Guinea pigs are seasonally polyestrous and breed year-round in captivity. 9 , 23 Sows are spontaneous ovulators, with a cycle that is estrous 15-17 times (range 13-21 times). 19 Sows display distinct signs of proestrus and estrus. 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 right time the sow shows lordosis, curvature for the back with elevated sides, in addition to vulvar dilation. 23

The sow possesses a pair that is single of mammary glands with an individual set of inguinal mammary nipples (Fig 5), but supernumerary nipples are typical. 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) possess a solitary 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). Supply: 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 (large 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 lots of pets. 19 , 22 , 23 , 29 The sow features a depression that is y-shaped perineal cells. The vulvar opening lies at the intersection associated with the branches and also the rectum is based during the base of the Y (Fig 8). 23

Figure 8.Y-shaped despair when you look at the perineum of a guinea pig sow (Cavia porcellus), illustrating the vulva (white arrow) additionally the rectum (yellow arrow). Source: Dorcas O’Rourke, DVM, MS, DACLAM. Click image to expand.

Copulation

When a receptive feminine is introduced, the boar begins to purr and sway their posterior back and forth, while circling, and quite often cleaning resistant to the sow if not spraying urine during the sow. In the event that feminine is unreceptive, aggressive male behavior might be seen such as for example 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 enables the male to mount her. Whether ejaculation happens or perhaps not, a man shall perform vaginal grooming by dragging their perineum across the cage flooring. Meanwhile the feminine doubles over and utilizes her lips to groom her genitals. 19 Mating often does occur at nighttime. 8

Copulation is verified because of the existence of a company, rubbery deposit in the vagina called the copulatory or genital plug, consists of a solid mass of ejaculatory fluid. 23 there are numerous theories from 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 size that is litter. 23 typical litter size is 2-4 pups with a selection of 1-13 pups. 23 Obvious stomach distension just isn’t seen until belated gestation. 8

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