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 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 large, paired seminal vesicles or vesicular glands, that can easily be seen erroneously as uterine horns.
  • Puberty does occur at more or less 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 inadequate in sows bred after 7-8 months of age and dystocia can lead to these individuals. Other possible reasons for dystocia include obesity and big fetal size.
  • Sows usually give delivery to 2-4 large, precocial pups. Other rodent types generally speaking have actually big litters.
  • Pregnancy toxemia is definitely a essential reason behind perinatal mortality in guinea pigs. This disorder is frequently seen in primiparous, overweight sows in belated gestation. The prognosis is usually guarded. Reduce the danger of maternity toxemia by motivating workout, preventing obesity, and minimizing stress in the expecting sow.
  • Unilateral or bilateral ovarian cysts are common, especially in older sows.
  • Ovariohysterectomy or ovariectomy is preferred to avoid the growth of ovarian cysts along with other reproductive dilemmas in non-breeding friend sows.

Introduction

Guinea pigs are of help in reproductive studies simply because they share numerous traits that are reproductive humans (Fig 1). 26 Like people, guinea pigs possess a hemochorial placenta, by which maternal bloodstream will come in direct connection with the fetal chorion, in addition to comparable trophoblast intrusion patterns 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 options that come with 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 ratings physiology and physiology for the guinea pig reproductive tract and summarizes some clinically significant medical dilemmas.

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

Intact male guinea pigs, 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 commence to ejaculate while mounting. 23 Expression of intimate behavior and real development is somewhat suppressed in the event that boar is housed featuring its mom and/or siblings. 11

Boars are usually bigger than females, with both sexes having a pair that is single of 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 in to the scrotum by 81 days. 2 In the event that testes never have descended by 4 months of age, the guinea pig is highly recommended cryptorchid. 9 The canals that are inguinal available for a lifetime. 9 , 19 to avoid herniation post-castration, many clinicians use a shut strategy or a modified available strategy, where in fact the tunica is included into 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 provides increase 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 are facilitated by putting mild stress at the bottom of this prepuce to partially extrude your penis. 23

The penis that is s-shaped of a human body and glans. Guinea pigs have a penis that is os that is discovered inside the dorsal area of this whole duration of the glans. 9 , 19 Like many hystricomorph rodents, your penis comes with moment, saw-toothed white spurs arranged dorsolaterally in 2 synchronous lines through the urethral orifice to your glans. Addititionally there is a sac that is intromittent 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 the 3-5 mm long projections is unknown. 9

Male reproductive glands include the seminal vesicles (vesicular glands), coagulating glands, bulbourethral glands, therefore the prostate (Fig 3). 5 , 27 A rudimentary gland that is preputial 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 enter the urethra by a couple of ducts instantly caudodorsal into the ductus deferens. 9 , 19 , 23 , 27

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

Each locks follicle associated with the guinea pig is connected with an androgen-dependent sebaceous gland. These glands are numerous over the as well as may also be found round the rectum, where these are typically 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 scent marking (Fig 4). Boars often rub or push on their rump against an area, therefore the secretions deposited act as a sexual attractant and to mark territory. 9 , 23

Figure 4.Caudal gland (big 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 guinea that is female 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 breed and polyestrous year-round in captivity. 9 , 23 Sows are spontaneous ovulators, with an estrous period between 15-17 times (range 13-21 times). 19 Sows exhibit distinct signs and symptoms of estrus and proestrus. During proestrus, sows become more active, chasing cage mates around, swaying their hindquarters, and creating a definite sound that is guttural. Estrus lasts 6-11 hours, and with this time the sow shows lordosis, curvature associated with spine with elevated hips, in addition to vulvar dilation. 23

The sow possesses a solitary couple of inguinal mammary glands with an individual couple of inguinal mammary nipples (Fig 5), nevertheless supernumerary nipples are normal. 9 , 19 , 22 in comparison with the boar, the sow’s nipples are much much 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 expand.

Sows possess 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 anatomy (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 features a depression that is y-shaped perineal cells. The opening that is vulvar at the intersection of this branches as well as the anal area is situated during the root 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) additionally the anal area (yellow arrow). Supply: Dorcas O’Rourke, DVM, MS, DACLAM. Click image to expand.

Copulation

whenever a female that is receptive russian mail order wives introduced, the boar starts to purr and sway their posterior back and forth, while circling, and quite often cleaning resistant to the sow and even spraying urine during the sow. In the event that female is unreceptive, aggressive male behavior could be seen such as for instance barbering hair regarding the neck that is female’s. 19 A receptive feminine will enable the male to sniff and lick her anogenital area. 6 , 11 , 19 She assumes the lordosis place and permits the male to mount her. Whether ejaculation happens or otherwise not, the male will perform vaginal grooming by dragging his perineum across the cage flooring. Meanwhile the doubles that are female and makes use of her lips to groom her genitals. 19 Mating frequently does occur at nighttime. 8

Copulation is verified by the presence of a company, rubbery deposit inside the vagina called the copulatory or plug that is vaginal consists of a solid mass of ejaculatory fluid. 23 there are many theories from the purpose of the copulatory plug in rodents, including sperm 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 average size that is litter 2-4 pups with a selection of 1-13 pups. 23 clear abdominal distension is certainly not observed until belated gestation. 8

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