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

The guinea pig (Cavia porcellus) is a favorite companion 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 may be 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 of this pubic symphysis may be insufficient in sows bred after 7-8 months of age and dystocia may result in him or her. Other prospective reasons for dystocia consist of obesity and big fetal size.
  • Sows usually give delivery to 2-4 big, precocial pups. Other rodent types generally have actually large litters.
  • Pregnancy toxemia is definitely a cause that is important of mortality in guinea pigs. This problem is usually seen in primiparous, overweight sows in belated gestation. The prognosis is oftentimes guarded. Reduce 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 common, especially in older sows.
  • Ovariohysterectomy or ovariectomy is advised to stop the growth of ovarian cysts as well as other problems that are reproductive non-breeding friend sows.

Introduction

Guinea pigs are of help in reproductive studies since they share numerous traits that are reproductive humans (Fig 1). 26 Like people, guinea pigs have a very hemochorial placenta, for which maternal bloodstream is available in direct connection with the fetal chorion, in addition to comparable trophoblast invasion habits and uterine vasculature that is comparable. 20 , 23 , 26 The guinea pig’s gestation duration can be divided in to trimesters, analogous towards the peoples condition. 26 needless to say, some popular 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 article ratings structure and physiology associated with the guinea pig tract that is reproductive summarizes some clinically significant medical dilemmas.

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

Intact male guinea pigs, or “boars”, enter puberty between 70-90 times, nonetheless 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 development that is physical notably suppressed in the event that boar is housed using its mom and/or siblings. 11

Boars are generally bigger than females, with both sexes having a solitary couple of inguinal mammae. 5 Mature boars have big, paired testes, which 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 days. 2 In the event that testes never have descended by 4 months of age, the guinea pig should be thought about cryptorchid. largest adult dating site adult friend finder 9 The canals that are inguinal available for a lifetime. 9 , 19 to avoid herniation post-castration, numerous clinicians use a shut method or a modified available method, in which the tunica is roofed when you look at 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 dorsolateral area of this testis. The end associated with the epididymis provides increase towards the ductus deferens. Credit: Drury Reavill, DVM, DABVP (Avian Practice), DACVP. Click image to expand.

Clinical Suggestion: Although big, paired testes are clear in mature boars, gender identification may be challenging in young pups. In the event that testicles aren’t apparent, sexing can be facilitated by putting pressure that is gentle the beds base of this 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, that will be discovered in the dorsal area associated with the whole amount 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 into the glans. Addititionally 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 of those 3-5 mm projections that are long unknown. 9

Male reproductive glands include the seminal vesicles (vesicular glands), coagulating glands, bulbourethral glands, additionally the prostate (Fig 3). 5 , 27 A rudimentary preputial gland may additionally 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 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 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 hair follicle associated with the guinea pig is connected with an androgen-dependent gland that is sebaceous. These glands are numerous over the as well as may also be discovered across the anal area, where they truly are 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 click 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 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 signs and symptoms of proestrus and estrus. During proestrus, sows are more active, chasing cage mates around, swaying their hindquarters, and creating a definite guttural sound. Estrus lasts 6-11 hours, and with this time the sow shows lordosis, curvature for the back with elevated hips, 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), nevertheless supernumerary nipples are normal. 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 female guinea pigs (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 quick 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 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 features a depression that is y-shaped perineal cells. The vulvar opening lies at the intersection associated with branches plus the rectum is situated during the root of the Y (Fig 8). 23

Figure 8.Y-shaped despair within the perineum of a 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 their posterior back and forth, while circling, and quite often cleaning from the sow and on occasion even spraying urine during the sow. In the event that feminine is unreceptive, aggressive male behavior can be seen such as for example barbering hair regarding the female’s throat. 19 a female that is receptive 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 happens or otherwise not, a man shall perform vaginal grooming by dragging their perineum over the cage flooring. Meanwhile the feminine doubles over and utilizes her lips to groom her genitals. 19 Mating frequently occurs at night. 8

Copulation is verified by the presence of a company, rubbery deposit inside the vagina called the copulatory or genital plug, consists of a great mass of ejaculatory fluid. 23 there are numerous theories regarding 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 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 dates differ with strain, parity, and size that is litter. 23 Normal litter size is 2-4 pups with a selection of 1-13 pups. 23 clear abdominal distension just isn’t seen until belated gestation. 8

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