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 about 2 months in females and between 2-3 months in men.
- The pubic symphysis separates within the last few times of maternity.
- Separation associated with symphysis that is pubic be insufficient in sows bred after 7-8 months of age and dystocia may result in these people. Other possible factors behind dystocia include obesity and fetal size that is large.
- Sows frequently give delivery to 2-4 large, precocial pups. Other rodent types generally speaking have actually large litters.
- Pregnancy toxemia is definitely a cause that is important of mortality in guinea pigs. This problem is frequently noticed in primiparous, overweight sows in belated gestation. The prognosis is usually guarded. Minmise the danger of maternity toxemia by motivating exercise, preventing obesity, and minimizing stress when you look at the expecting sow.
- Unilateral or bilateral cysts that are ovarian common, especially in older sows.
- Ovariohysterectomy or ovariectomy is preferred to prevent the growth of ovarian cysts along with other problems that are reproductive non-breeding friend sows.
Introduction
Guinea pigs are of help in reproductive studies simply because they share numerous reproductive characteristics with people (Fig 1). 26 Like humans, guinea pigs possess a hemochorial placenta, in which maternal bloodstream will come in direct experience of the fetal chorion, along with comparable trophoblast intrusion patterns and uterine vasculature that is comparable. 20 , 23 , 26 The guinea pig’s gestation period can be divided in to trimesters, analogous towards the individual condition. 26 Of course, some options that come with 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 short article ratings anatomy and physiology of this guinea pig tract that is reproductive summarizes some clinically significant medical issues.
Figure 1.Guinea pigs (Cavia porcellus) are helpful in a lot of reproductive studies.
Intact guinea that is male, or “boars”, enter puberty between 70-90 times, but men commence to show sexual behavior, such as for example mounting, at 30 days of age. 9 , 17 , 23 At 2 months, boars commence to ejaculate while mounting. 23 Expression of sexual behavior and real development is somewhat 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 usually completely descended into 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 a lifetime. 9 , 19 to avoid herniation post-castration, numerous clinicians use a shut technique or a modified available strategy, in which the tunica is roofed 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 across the dorsolateral area associated with the testis. The end of this 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 clear 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 bottom associated with the prepuce to partially extrude your penis. 23
The S-shaped penis comprises of a human body and glans. Guinea pigs possess a penis that is os which will be discovered in the dorsal area of this whole duration of the glans. 9 , 19 Like other hystricomorph rodents, your penis even offers moment, saw-toothed spurs that are white dorsolaterally in two parallel lines through the urethral orifice to your glans. There’s also an intromittent sac on the ventral area regarding the glans penis. 9 During erection, the sac everts and two horny styles protrude. 5 , 9 , 23 the big event among these 3-5 mm projections that are long unknown. 9
Male reproductive glands include the seminal vesicles (vesicular glands), coagulating glands, bulbourethral glands, plus 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 large, 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 towards the ductus deferens. 9 , 19 , 23 , 27
Clinical Suggestion: The big, 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 as well as will also be discovered across the anal area, where they truly are called the caudal gland or “grease gland”. ۹ , ۲۳ The caudal gland is more developed into the boar and it is employed for fragrance marking (Fig 4). Boars usually rub or push on 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.Caudallarge 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 within the guinea that is female or “sow”. ۲۳ Peak reproduction is seen between 3-4 to 20 months and reproduction might carry adult finder 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 display distinct indications of proestrus and estrus. During proestrus, sows are more active, chasing cage mates around, swaying their hindquarters, and creating a distinct sound that is guttural. Estrus lasts 6-11 hours, and in this right time the sow shows lordosis, curvature associated with back with elevated sides, 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 typical. 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 Practice), 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 regarding 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, 26 or 27 of gestation, and at parturition in many animals day. 19 , 22 , 23 , 29 The sow features a Y-shaped despair in perineal cells. The opening that is vulvar at the intersection regarding the branches and also the anal area is found 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) while the anal area (yellow arrow). Supply: Dorcas O’Rourke, DVM, MS, DACLAM. Click image to expand.
Copulation
Whenever a receptive feminine is introduced, the boar starts to purr and sway his posterior back and forth, while circling, and quite often cleaning resistant to the sow and sometimes even spraying urine during the sow. In the event that feminine is unreceptive, aggressive male behavior might be observed such as for instance barbering hair in the female’s throat. 19 a female that is receptive let 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 does occur or otherwise not, the male will perform vaginal grooming by dragging their perineum along the cage flooring. Meanwhile the feminine doubles over and utilizes her lips to groom her genitals. 19 Mating frequently happens at nighttime. 8
Copulation is verified by the existence of a company, rubbery deposit inside the vagina called the copulatory or genital plug, made up of an excellent mass of ejaculatory fluid. 23 there are many theories in the function of the copulatory plug in rodents, including semen storage, prevention of semen leakage, advertising of sperm 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 days, with a reported array of 59-72 times. 9 , 19 , 23 These dates differ with stress, parity, and litter size. 23 average size that is litter 2-4 pups with a selection of 1-13 pups. 23 Obvious stomach distension just isn’t seen until belated gestation. 8
