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

The guinea pig (Cavia porcellus) is a well known 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 big testes.
  • Male guinea pigs have actually a few accessory intercourse glands, including big, paired seminal vesicles or vesicular glands, that can easily be recognised incorrectly as uterine horns.
  • Puberty does occur 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 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 frequently give delivery to 2-4 big, precocial pups. Other rodent types generally speaking have actually big litters.
  • Pregnancy toxemia is definitely a essential cause of perinatal mortality in guinea pigs. This problem is frequently seen in primiparous, overweight sows in late gestation. The prognosis is generally guarded. Minmise the chance of being pregnant toxemia by motivating workout, preventing obesity, and minimizing stress in the expecting sow.
  • 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 dilemmas in non-breeding friend sows.

Introduction

Guinea pigs are of help in reproductive studies since they share numerous reproductive characteristics with human beings (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, in addition to comparable trophoblast invasion habits and uterine vasculature that is comparable. 20 , 23 , 26 The guinea pig’s gestation duration can be split into trimesters, analogous into the condition that is human. 26 needless to say, some attributes of guinea pig reproductive anatomy and physiology are distributed to other users of purchase Rodentia, along with other features are unique for this species that is special. This article ratings physiology and physiology associated with guinea pig tract that is reproductive summarizes some clinically significant medical problems.

Figure 1.Guinea pigs (Cavia porcellus) are helpful in lots of 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 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 considerably 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, that are situated on either part associated with 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 inguinal canals remain available for life. 9 , 19 to avoid herniation post-castration, numerous clinicians start using a shut strategy or a modified available strategy, where in fact 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 tail regarding the epididymis provides rise towards the ductus deferens. Credit: Drury Reavill, DVM, DABVP (Avian Training), DACVP. Click image to expand.

Clinical Tip: 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 force at the beds base associated with 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 is discovered inside the dorsal area associated with whole period of the glans. 9 , 19 Like many hystricomorph rodents, your penis comes with minute, saw-toothed white spurs arranged dorsolaterally in 2 synchronous lines through the urethral orifice to your glans. There’s also an intromittent sac on the ventral area for the glans penis. 9 During erection, the sac everts and two horny styles protrude. 5 , 9 , 23 the big 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, plus the prostate (Fig 3). 5 , 27 A rudimentary gland that is preputial additionally be contained in the boar. 9

Figure 3. Reproductive structure of this 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 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 couple of ducts instantly caudodorsal towards the ductus deferens. 9 , 19 , 23 , 27

Clinical Suggestion: The large, paired seminal vesicles can be recognised incorrectly as uterine horns.

Each locks follicle for the guinea pig is related to an androgen-dependent sebaceous gland. These glands are numerous over the straight back and may also be discovered round the rectum, where they’ve been called the caudal gland or “grease gland”. 9 , 23 The caudal gland is much more developed when you look at the boar and it is utilized for fragrance marking (Fig 4). Boars often rub or click their rump against a surface, 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 does occur around 2 months of age into the feminine guinea pig or “sow”. 23 Peak reproduction is seen between 3-4 to 20 months and reproduction might carry on until 4-5 years. 19 , 23 Guinea pigs are seasonally polyestrous and breed year-round in captivity. 9 , 23 Sows are spontaneous ovulators, having an estrous period between 15-17 times (range 13-21 times). 19 Sows exhibit distinct signs and symptoms of proestrus and estrus. During proestrus, sows are more active, chasing cage mates around, swaying their hindquarters, and creating a distinct guttural noise. Estrus lasts 6-11 hours, and with this time the sow shows lordosis, curvature regarding the back with elevated sides, in addition to vulvar dilation. 23

The sow possesses a solitary couple of inguinal mammary glands with just one set of inguinal mammary nipples (Fig 5), but supernumerary nipples are typical. 9 , 19 , 22 in comparison with the boar, the sow’s nipples are 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, 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 for the uterine horns (little arrows) and the 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 opens 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 regarding the branches together with anal area is based at 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) plus the anal area (yellow arrow). Supply: Dorcas O’Rourke, DVM, MS, DACLAM. Click image to enlarge.

Copulation

Each time a receptive feminine is introduced, the boar starts to purr and sway their posterior back and forth, while circling, and often brushing resistant to the sow and sometimes even spraying urine in the sow. In the event that feminine is unreceptive, aggressive male behavior might be seen such as for example barbering hair regarding the female’s throat. 19 a female that is receptive enable the male to sniff and lick her anogenital area. 6 , 11 next page, 19 She assumes the lordosis position and permits the male to mount her. Whether ejaculation does occur or perhaps not, a man will perform vaginal grooming by dragging their perineum over the cage flooring. Meanwhile the doubles that are female and makes use of her mouth to groom her genitals. 19 Mating frequently happens at night. 8

Copulation is verified because of the existence of a strong, rubbery deposit in the vagina called the copulatory or genital plug, made up 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, advertising of sperm transport, and/or to stop later on fertilization by other males. 23 The copulatory plug falls out several hours 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 size that is litter. 23 typical litter size is 2-4 pups with a variety of 1-13 pups. 23 clear stomach distension is certainly not seen until belated gestation. 8