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

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

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, 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 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 can lead to these people. Other possible reasons for dystocia include 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 crucial cause of perinatal mortality in guinea pigs. This problem is usually noticed in primiparous, overweight sows in belated gestation. The prognosis is normally guarded. Minmise the chance of being pregnant toxemia by motivating workout, preventing obesity, and minimizing stress in the pregnant sow.
  • Unilateral or bilateral ovarian cysts are quite typical, especially in older sows.
  • Ovariohysterectomy or ovariectomy is preferred to avoid the growth of ovarian cysts as well as other problems that are reproductive non-breeding friend sows.

Introduction

Guinea pigs are helpful in reproductive studies simply because they share numerous reproductive faculties with humans (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 comparable uterine vasculature. 20 , 23 , 26 The guinea pig’s gestation duration can be split into trimesters, analogous into the human being condition. 26 needless to say, some top features of guinea pig reproductive anatomy and physiology are distributed to other users of purchase Rodentia, along with other features are unique for this unique species. This short article product reviews physiology and physiology regarding the guinea pig tract that is reproductive summarizes some clinically significant medical issues.

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

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

Boars tend to be bigger than females, with both sexes having a pair that is single of mammae. 5 Mature boars possess large, 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 in 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 inguinal canals remain available for a lifetime. 9 , 19 to avoid herniation post-castration, numerous clinicians use a shut strategy or even a modified available strategy, in which the tunica is roofed within 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 for the epididymis offers rise to your 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 could 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 for the 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 surface associated with the whole duration of the glans. 9 , 19 Like other hystricomorph rodents, your penis even offers moment, saw-toothed spurs that are white dorsolaterally in 2 synchronous lines through the urethral orifice to your glans. There is an intromittent sac on the ventral area for the glans penis. 9 During erection, the sac everts and two styles that are horny. 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, and also 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 (I) epididymis. Picture credit: Drs. adult friend search Craig Franklin and Cindy Besch-Williford. Click image to expand.

  • The big, transparent, 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 set of ducts instantly caudodorsal towards the ductus deferens. 9 , 19 , 23 , 27

Clinical Suggestion: The large, paired vesicles that are seminal be seen erroneously as uterine horns.

Each locks follicle for the guinea pig is connected with an androgen-dependent gland that is sebaceous. These glands are numerous across the straight back and may also be discovered across the anus, where these are generally 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 often rub or push on their rump against an area, together with 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 when you look at the feminine guinea pig or “sow”. 23 Peak reproduction is seen between 3-4 to 20 months and reproduction might continue 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 an estrous period between 15-17 times (range 13-21 times). 19 Sows display distinct signs and symptoms of proestrus and estrus. During proestrus, sows become more active, chasing cage mates around, swaying their hindquarters, and producing a definite sound that is guttural. Estrus lasts 6-11 hours, and with 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 longer and much more prominent. 9

Figure 5.Both male and female guinea pigs (Cavia porcellus) have just one couple 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, 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 the 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, Day 26 or 27 of gestation, and also at parturition in several pets. 19 , 22 , 23 , 29 The sow includes a Y-shaped despair in perineal cells. The vulvar opening lies at the intersection for the branches therefore the anus is found in the root of the Y (Fig 8). 23

Figure 8.Y-shaped despair when you look at the perineum of the guinea pig sow (Cavia porcellus), illustrating the vulva (white arrow) additionally the rectum (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 even spraying urine during the sow. In the event that female is unreceptive, aggressive male behavior could be observed 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 enables the male to mount her. Whether ejaculation occurs or perhaps not, the male will perform vaginal grooming by dragging his perineum across the cage flooring. Meanwhile the feminine doubles over and makes use of her lips to groom her genitals. 19 Mating frequently does occur at nighttime. 8

Copulation is confirmed because of the existence of a strong, rubbery deposit inside the vagina called the copulatory or genital plug, consists of a great mass of ejaculatory fluid. 23 There are lots of theories regarding the purpose of the copulatory plug in rodents, including semen storage, avoidance of semen leakage, advertising of semen transport, 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 days. 9 , 19 , 23 These times differ with stress, parity, and litter size. 23 Average litter size is 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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