Rat, Mouse and Guinea Pig Reproduction: Sexual Maturity, Pregnancy and Breeding Risks

By Dr Duncan Houston

Rats, mice and guinea pigs are all rodents, but their reproductive biology is not interchangeable.

Rats and mice have short reproductive cycles, pregnancies lasting approximately three weeks and relatively large litters of tiny, undeveloped pups. Guinea pigs have a much longer pregnancy and produce fewer, unusually large pups that are born fully furred, mobile and able to eat solid food.

The practical concern is accidental breeding. Each species can reproduce rapidly, females may return to fertile heat soon after giving birth and sexual maturity can occur before an owner realises that young animals need to be separated.

Quick Answer

Rats commonly reach sexual maturity between approximately 6 and 12 weeks, while mice usually mature at around 6 to 8 weeks. Guinea pig puberty is more variable: females may enter their first estrus from around 5 to 6 weeks, while males commonly become fertile at approximately 8 to 10 weeks, although earlier maturation has been reported. (merckvetmanual.com)

Rat pregnancy lasts approximately 21 to 23 days, mouse pregnancy 19 to 21 days and guinea pig pregnancy 59 to 72 days. All three species can return to fertility rapidly after giving birth, so the male must be removed before delivery if another immediate pregnancy is not intended. (merckvetmanual.com)

Reproduction at a Glance

The figures below are biological ranges. They are not recommendations to begin breeding at the earliest possible age.

Reproductive feature	Rat	Mouse	Guinea pig
Typical sexual maturity	Males 6–10 weeks; females 8–12 weeks	Both sexes 6–8 weeks	Females may cycle from about 5–6 weeks; males commonly fertile around 8–10 weeks
Estrous cycle	4–5 days	4–5 days	13–25 days, commonly about 15–17 days
Receptive estrus	Approximately 10–20 hours	Approximately 10–20 hours	Approximately 6–11 hours
Gestation	21–23 days	19–21 days	59–72 days
Typical litter size	8–18 pups	5–12 pups	1–7 pups, commonly about 3
Newborn development	Hairless, blind and deaf	Hairless, blind and deaf	Fully furred, eyes open and mobile
Usual weaning	Around 21 days	Around 21 days	Around 3 weeks
Postpartum fertility	Returns rapidly	Pregnancy possible within 24 hours	Fertile estrus commonly occurs 2–10 hours after birth

Current Merck reproductive data support the rat and mouse ranges, while recent guinea pig references confirm the longer reproductive cycle, prolonged gestation and much earlier possible onset of puberty than a simple laboratory breeding table may suggest. (merckvetmanual.com)

Are Guinea Pigs Really Comparable With Rats and Mice?

Guinea pigs belong to the caviomorph or hystricomorph branch of rodents, while rats and mice are myomorph rodents. This evolutionary distinction is reflected in their body structure, digestive anatomy and reproductive strategy. (merckvetmanual.com)

Rats and mice prioritise frequent reproduction. Their pregnancies are short, their litters are large and their newborns are altricial, meaning they are born highly dependent on the mother.

Guinea pigs invest far more development into each pregnancy. Their pups are precocial and are born with:

• Fur

• Open eyes

• Erupted teeth

• Functional limbs

• The ability to walk within hours

• The ability to begin tasting solid food almost immediately

They still need maternal milk, but their advanced development at birth explains why guinea pig gestation lasts roughly three times as long as mouse gestation. (merckvetmanual.com)

When Do Rats Become Sexually Mature?

Male rats commonly become sexually mature at approximately 6 to 10 weeks, while females usually mature at approximately 8 to 12 weeks. Optimal sperm production in males may develop later than the earliest signs of puberty, but pregnancy is possible before a rat appears fully grown. (merckvetmanual.com)

Female rats have an estrous cycle lasting approximately four to five days. Receptive estrus generally lasts 10 to 20 hours, during which ovulation and mating can occur. (merckvetmanual.com)

Rat pregnancy is short:

• Gestation lasts approximately 21 to 23 days.

• Litters commonly contain 8 to 18 pups.

• Pups are born blind, deaf and largely hairless.

• Weaning usually occurs at approximately 21 days. (merckvetmanual.com)

A female can become fertile again shortly after giving birth. Keeping the male with the mother may therefore result in the mother nursing one litter while already pregnant with the next, which places substantial nutritional and physiological demand on her. (merckvetmanual.com)

When Do Mice Become Sexually Mature?

Both male and female mice usually become sexually mature at approximately 6 to 8 weeks.

Female mice also cycle every four to five days, with estrus generally lasting 10 to 20 hours. Pregnancy lasts only 19 to 21 days, and a female may become pregnant again within 24 hours of delivering a litter. (merckvetmanual.com)

Mouse litters commonly contain 5 to 12 pups, although larger litters occur. The pups are born blind, deaf and hairless and are usually weaned at approximately three weeks. (merckvetmanual.com)

Mice can theoretically produce many litters within one year, but biological capacity should not be confused with humane breeding practice. Repeated pregnancy, lactation, inadequate nutrition, crowding and disturbance increase the risk of poor maternal condition, abandonment and loss of pups. (merckvetmanual.com)

When Do Guinea Pigs Become Sexually Mature?

Guinea pig maturity is the area where owners are most likely to be misled by one simplified chart.

Laboratory tables may list sexual maturity at approximately 10 to 12 weeks. However, clinical and research data show substantial individual variation, with female puberty sometimes occurring much earlier. One 2022 study noted that puberty is commonly reported between approximately 55 and 70 days, while first estrus may vary widely and can occur earlier in some individuals. (merckvetmanual.com)

Male guinea pigs commonly become fertile at approximately 8 to 10 weeks, but reproductive development may begin earlier. A 2025 review placed functional sexual maturity under favourable conditions at approximately 45 to 55 days. (FAO AGRIS)

The safest practical rule is not to wait until a young guinea pig visibly mounts another animal. Have the sexes professionally confirmed around weaning and separate opposite-sex pups before the earliest plausible fertility window.

Sexing guinea pigs is not always as straightforward as pet shops make it look. The clitoris can be mistaken for a penis, young males may have incompletely descended testes and incorrect sex identification is a frequent cause of surprise pregnancies.

How Does the Female Reproductive Cycle Differ?

Rats and Mice

Female rats and mice have short estrous cycles of approximately four to five days. Their reproductive systems move quickly from one fertile period to the next, allowing frequent litters when males and females remain together. (merckvetmanual.com)

Sterile mating may induce a pseudopregnancy lasting approximately 12 days in either species. During that time, the female’s hormonal state temporarily resembles pregnancy even though no embryos are present. (merckvetmanual.com)

Guinea Pigs

Guinea pigs are nonseasonal, spontaneously ovulating animals under typical domestic conditions. Their reproductive cycle commonly lasts around 15 to 17 days, although the wider reported range is approximately 13 to 25 days. The female is receptive to mating for a relatively short period near the end of the cycle. (merckvetmanual.com)

The vaginal opening is normally covered by a closure membrane that opens around estrus and parturition. Monitoring this membrane can help time mating in research settings, but it is not a reliable or necessary home breeding test. (PubMed Central (PMC))

Routine pseudopregnancy after sterile mating is not considered a typical guinea pig pattern in the same way it is in rats and mice. However, abdominal enlargement in a female guinea pig should never be casually labelled a false pregnancy because ovarian cysts, uterine disease, obesity and internal masses can look similar. (BioRxiv)

Why Does Postpartum Estrus Matter?

Postpartum estrus means a female becomes fertile again shortly after giving birth.

This happens in all three species:

• Female mice may become pregnant again within 24 hours.

• Female rats can return to fertility rapidly after delivery.

• Guinea pigs commonly enter a fertile postpartum estrus approximately 2 to 10 hours after parturition. (merckvetmanual.com)

A male left with a guinea pig sow can therefore impregnate her again before the end of the day in which she gave birth.

This is not a harmless breeding shortcut. Back-to-back pregnancy means the female is supporting:

• Recovery from delivery

• Milk production

• A new pregnancy

• Her own maintenance requirements

The mistake I see most often is removing the male after the babies have been born. By then, the next pregnancy may already have occurred.

How Are the Newborns Different?

Rat and Mouse Pups

Rat and mouse pups are altricial.

They are born:

• Hairless or sparsely furred

• Blind

• Deaf

• Unable to regulate body temperature effectively

• Entirely dependent on the mother for warmth, milk and stimulation

The nest must remain warm, dry and quiet. Excessive disruption, inadequate food or water, overcrowding and illness can contribute to maternal abandonment or cannibalism. (merckvetmanual.com)

Guinea Pig Pups

Guinea pig pups are precocial.

They are born fully furred with open eyes, erupted teeth and functional limbs. They begin eating hay and other solid foods early but continue nursing until weaning. (merckvetmanual.com)

A newborn guinea pig eating solid food does not mean it no longer needs its mother. Nursing provides essential nutrition during early development even though the pup looks like a miniature adult.

Does “Breeding Life” Mean It Is Safe To Keep Breeding?

No.

The original table used reproductive-life ranges of approximately:

• 9 to 12 months for rats

• 9 months for mice

• 24 months for guinea pigs

These are laboratory colony productivity references. They describe the period during which breeding performance is typically efficient, not a welfare recommendation to produce repeated litters throughout that entire time. (merckvetmanual.com)

Fertility may continue outside those ranges, but reproductive efficiency and pregnancy outcomes can worsen with:

• Increasing parental age

• Obesity

• Poor body condition

• Malnutrition

• Disease

• Previous difficult pregnancies

• Excessive litter frequency

• Inadequate recovery between litters

A 2023 guinea pig breeding study found that parental age, parity and pairing strategy influenced pregnancy and neonatal outcomes, with substantial stillbirth and early neonatal loss within the study population. (PubMed Central (PMC))

The biological ability to reproduce is a very low bar. A responsible breeding decision requires the animal to be healthy enough to do so with an acceptable welfare risk.

Why Is Guinea Pig Pregnancy More Dangerous?

Guinea pig pregnancy presents several risks that are less common in ordinary rat and mouse breeding.

The Pups Are Large

Guinea pig pups are large and advanced relative to the mother’s body size. A small litter may contain one or two particularly large fetuses, increasing the risk that a pup cannot pass through the birth canal.

Pregnancy Is Long

Gestation lasts approximately 59 to 72 days. During late pregnancy, the sow carries a substantial fetal mass and may have considerably reduced abdominal space for the gastrointestinal tract and other organs. (merckvetmanual.com)

Dystocia Is a Major Concern

Dystocia means difficult or obstructed labour.

Possible causes include:

• An oversized fetus

• Abnormal fetal position

• Uterine inertia

• Maternal exhaustion

• Obesity

• Pelvic abnormalities

• Uterine torsion

• Fetal death

• Maternal metabolic disease

Traditional teaching places considerable emphasis on progressive stiffening or mineralisation of the pubic symphysis in females having their first pregnancy later in life. However, a 2024 imaging study found that guinea pig dystocia cannot be explained solely by symphyseal ossification, meaning maternal age remains relevant but is not the only factor determining whether delivery will be possible. (PubMed Central (PMC))

This distinction matters. Breeding a young guinea pig does not make pregnancy safe, and an older first-time sow does not develop dystocia for one simple anatomical reason in every case.

Pregnancy Toxaemia

Pregnancy toxaemia or ketosis most often occurs during late pregnancy or shortly after birth.

Affected guinea pigs may develop:

• Reduced appetite

• Complete food refusal

• Reduced activity

• Weakness

• Rapid weight loss

• Dehydration

• Laboured breathing

• Neurological signs

• Collapse

Two overlapping forms have been described: a metabolic or fasting-associated form and a circulatory form resembling preeclampsia. Obesity, stress, reduced food intake and large fetal demands may contribute. (PubMed Central (PMC))

A pregnant guinea pig that stops eating is not merely being uncomfortable because she is heavily pregnant. It should be treated as a same-day emergency.

Are Reproductive Complications Common in Rats and Mice?

Dystocia is less prominent in rats and mice than in guinea pigs, but it still occurs.

Possible warning signs include:

• A pup visibly lodged in the birth canal

• Repeated contractions without delivery

• Labour stopping while pups remain

• Abnormal discharge

• Maternal weakness

• Severe lethargy

• Breathing changes

• Failure to care for delivered pups

A 2025 prospective assessment of murine dystocia described visible obstruction, protracted labour, contractions without delivery and cessation of contractions as important warning signs. (PubMed Central (PMC))

Older maternal age, obesity, abnormal fetuses, uterine abnormalities, poor nutrition and environmental stress may all interfere with reproductive performance.

Do Mounting Times and Ejaculation Counts Matter to Pet Owners?

Usually not.

Laboratory researchers may record:

• Number of mounts

• Number of intromissions

• Time to ejaculation

• Refractory periods

• Number of ejaculations

These measurements can be useful when studying neuroendocrinology, fertility or sexual behaviour. They do not reliably tell a pet owner whether conception occurred.

Mating may happen:

• Very quickly

• At night

• When nobody is watching

• Without obvious noise or fighting

• Before an owner realises the animals are sexually mature

Conversely, mounting does not always mean successful fertilisation. It may also reflect social dominance, excitement or unsuccessful courtship.

The only safe assumption after unprotected opposite-sex contact is that pregnancy is possible.

How Worried Should You Be?

Lower Risk

The animals:

• Have been professionally sexed

• Live in correctly separated same-sex groups

• Have had no contact with an intact opposite-sex animal

• Are eating, active and behaving normally

Action: Continue routine monitoring and recheck the sex of growing animals if there is any uncertainty.

Moderate Concern

There has been:

• Brief unsupervised contact between opposite sexes

• A pet-shop sexing error

• Mounting between supposedly same-sex animals

• A male gaining access to a female’s enclosure

• Unexplained gradual weight gain

Action: Separate the animals immediately and contact an exotics veterinarian within 24 to 48 hours. Record the exposure date because it helps determine the likely stage of pregnancy.

High Concern

The female:

• Is confirmed or strongly suspected to be pregnant

• Is a guinea pig having a first pregnancy at a more advanced age

• Is losing appetite

• Is becoming weak

• Has abnormal vaginal discharge

• Appears painful

• Has stopped gaining expected pregnancy weight

• Is overdue based on a known mating date

Action: Arrange same-day veterinary assessment. Guinea pigs deserve particularly close monitoring because pregnancy toxaemia and dystocia can progress quickly.

Critical

The female has:

• Strong contractions without producing a pup

• A visible pup stuck in the birth canal

• Heavy bleeding

• Green, brown or foul-smelling discharge with no delivery

• Collapse

• Severe weakness

• Open-mouth or laboured breathing

• Seizures

• Minimal responsiveness

• A cold body

• Severe abdominal pain or enlargement

Action: Attend an emergency exotics service immediately.

Normal guinea pig delivery is generally rapid, commonly completing within approximately 30 minutes with only a few minutes between pups. Continuous active straining for approximately 20 minutes without delivery, or prolonged intermittent straining without progress, should be treated as dystocia. (College of Veterinary Medicine)

What Else Can Look Like Pregnancy?

An enlarging abdomen does not prove pregnancy.

Important alternatives include:

• Obesity

• Gastrointestinal gas or bloating

• Fluid within the abdomen

• Enlarged organs

• Urinary retention

• Reproductive tract infection

• Uterine tumours

• Ovarian cysts

• Mammary or abdominal tumours

• Constipation

• Internal parasitic or infectious disease

Ovarian cysts and reproductive tract tumours are important considerations in adult female guinea pigs and may cause abdominal enlargement, hair loss, reduced appetite or lethargy. (merckvetmanual.com)

In rats and mice, abdominal masses, mammary tumours and other age-related conditions may also produce weight gain or changes in body shape.

A veterinarian should confirm pregnancy rather than relying on appearance, behaviour or home abdominal palpation.

When Is This an Emergency?

Seek immediate veterinary care for any pregnant rat, mouse or guinea pig showing:

• Complete food refusal

• Marked reduction in drinking

• Collapse

• Severe weakness

• Open-mouth breathing

• A fetus lodged in the birth canal

• Active contractions with no progress

• Heavy or persistent bleeding

• Foul-smelling discharge

• Seizures or tremors

• Minimal responsiveness

• Severe abdominal distension

• Sudden inability to stand

• A cold body

• Failure to care for newborns combined with maternal illness

For guinea pigs, reduced appetite during late pregnancy is especially urgent because ketosis may already be developing before dramatic neurological signs appear. (PubMed Central (PMC))

What To Do Right Now After Accidental Mating

1. Separate the Animals Immediately

Move the male and female into secure, separate enclosures.

Do not wait for:

• Visible pregnancy

• Another mating attempt

• Enlargement of the abdomen

• Confirmation that the male is fertile

Further mating does not improve the pregnancy and may cause stress or injury.

2. Record the Exposure Window

Write down:

• First possible date of contact

• Last possible date of contact

• Observed mating or mounting

• Whether the male was present during or after a recent birth

• Current body weights

This helps estimate possible delivery dates.

3. Arrange a Veterinary Examination

A veterinarian can:

• Confirm the sex of both animals

• Assess body condition

• Look for concurrent illness

• Discuss pregnancy diagnosis

• Explain reproductive options

• Plan monitoring and emergency care

The earlier this happens, the more useful the discussion is.

4. Begin Weight Monitoring

Use a digital scale and weigh the female at the same time each day or according to veterinary instructions.

Record:

• Body weight

• Appetite

• Water intake

• Stool production

• Activity

• Abdominal shape

• Discharge

• Breathing

Weight alone cannot confirm pregnancy, but a trend is useful.

5. Do Not Squeeze or Repeatedly Palpate the Abdomen

Forceful palpation may injure the mother or fetuses.

Pregnancy palpation should be performed only by someone experienced with the species.

6. Maintain Normal, Species-Appropriate Nutrition

Do not suddenly overload the diet with:

• Calcium

• Protein supplements

• Sugary foods

• Multivitamins

• High-calorie treats

Pregnancy increases nutritional demands, but oversupplementation and obesity can also increase reproductive risk.

Guinea pigs still require unlimited grass hay, fresh water, vitamin C and an appropriately balanced diet. Rats and mice require a complete formulated rodent diet with continuous access to water.

7. Do Not Give Oxytocin or Calcium at Home

Oxytocin can be dangerous when a fetus is obstructing the birth canal or the uterus is not positioned to respond normally. Experimental mouse literature also demonstrates that oxytocin treatment is not risk-free and must be selected according to the cause of the dystocia. (PubMed Central (PMC))

Calcium should not be given blindly either. The veterinarian may need imaging, blood tests and a physical examination before deciding whether medical stimulation of labour is appropriate.

8. Prepare for Delivery Without Constantly Disturbing the Mother

Pregnant rats and mice benefit from:

• A quiet enclosure

• Clean, soft nesting material

• Stable temperature

• Reliable food and water

• Minimal unnecessary disturbance

Excessive noise, lack of nesting material, inadequate food or water and crowding can contribute to poor maternal behaviour or pup loss. (merckvetmanual.com)

Guinea pigs do not normally build a traditional nest. Their enclosure should remain dry, clean, quiet and free from high platforms or trapping hazards.

How Do Vets Diagnose Pregnancy?

History and Examination

The veterinarian will ask about:

• Exposure dates

• Age and sex

• Previous pregnancies

• Body-weight changes

• Appetite

• Discharge

• Current housing

• Diet

• Existing disease

The abdomen may be assessed gently, but palpation alone cannot reliably determine fetal viability or rule out another abdominal condition.

Ultrasound

Ultrasound can:

• Confirm pregnancy

• Assess the uterus

• Identify fetal heartbeats

• Estimate fetal development

• Detect fluid or uterine disease

• Help evaluate fetal distress

It is particularly useful when pregnancy dates are uncertain or the female appears unwell.

Radiographs

Radiographs become more useful once fetal skeletons have mineralised.

They may help determine:

• Approximate number of fetuses

• Fetal size

• Fetal position

• Pelvic dimensions

• Whether a fetus is obstructing the birth canal

• Whether fetuses remain after labour appears to stop

Radiographs and ultrasound are commonly combined when dystocia is suspected.

Blood and Urine Testing

Testing may be recommended to assess:

• Hydration

• Blood glucose

• Ketones

• Calcium

• Electrolytes

• Liver and kidney function

• Anaemia

• Infection

These tests are especially important in a pregnant guinea pig with appetite loss, weakness or breathing changes.

Common Reproductive Mistakes

Trusting One Sex Check

Young rodents are frequently misidentified. Have the sex confirmed by an experienced veterinarian or rescue.

Waiting Until the Listed Age of Sexual Maturity

Published ages are averages. Individual animals may become fertile earlier.

Leaving the Male With the Female Until Birth

Postpartum mating can occur within hours.

Treating Laboratory “Breeding Life” as a Welfare Recommendation

Efficient reproduction does not mean repeated breeding is safe or humane.

Breeding an Older First-Time Guinea Pig

Age does not create one guaranteed anatomical outcome, but later first pregnancies are associated with more concern and should not be undertaken casually. (PubMed Central (PMC))

Assuming a Large Abdomen Proves Pregnancy

Tumours, ovarian cysts, obesity and fluid accumulation may look similar.

Giving Oxytocin Without Imaging

A uterotonic drug can worsen an obstruction.

Ignoring Appetite Loss in Pregnancy

This may be the first sign of pain, dystocia, ketosis or another serious illness.

Disturbing the Mother and Litter Repeatedly

Frequent handling and environmental disruption can increase stress, particularly in mice and rats.

How Can Accidental Breeding Be Prevented?

Confirm the Sex Early

Have young animals sexed by someone experienced with that species.

Recheck them as they grow because external anatomy becomes easier to interpret with age.

Separate Opposite Sexes Before Puberty

Do not wait for sexual behaviour.

The separation plan should be based on the earliest plausible fertility for the species, not the average age at which a laboratory colony reaches peak reproductive performance.

Use Secure Enclosures

Check:

• Door latches

• Bar spacing

• Connecting tunnels

• Shared exercise areas

• Temporary carriers

• Supervised play spaces

A determined male does not require a lengthy romantic courtship. He requires one insecure cage door.

Consider Neutering

Neutering may allow mixed-sex companionship without pregnancy, but the benefit and risk differ by species and individual.

Guinea pig castration is generally less invasive than spaying a female but still requires an exotics-experienced surgeon. Males may remain fertile temporarily after surgery, so postoperative separation instructions must be followed.

Do Not Breed Without a Medical and Welfare Plan

Before planned breeding, you need:

• Correct sex and age

• Appropriate body condition

• Good genetic and medical history

• Species-appropriate nutrition

• Separate housing

• A plan for every offspring

• Access to an emergency exotics veterinarian

• Funds for imaging, hospitalisation or caesarean surgery

• A plan to prevent immediate postpartum rebreeding

“Letting them have one litter” is still deliberately accepting every pregnancy and neonatal risk.

Frequently Asked Questions

Can sibling rats, mice or guinea pigs breed?

Yes. Related animals do not avoid mating simply because they are siblings. Opposite-sex littermates must be separated before sexual maturity.

Can a female become pregnant immediately after giving birth?

Yes. Mice may conceive within 24 hours, rats return to fertility rapidly and guinea pigs commonly have fertile postpartum estrus within approximately 2 to 10 hours. (merckvetmanual.com)

How long are rats, mice and guinea pigs pregnant?

Rat gestation is approximately 21 to 23 days, mouse gestation 19 to 21 days and guinea pig gestation 59 to 72 days. (merckvetmanual.com)

Is a first guinea pig pregnancy after six months always impossible?

No. The traditional explanation based solely on permanent pubic symphysis fusion is too simplistic. Maternal age, parity, fetal size, obesity, uterine function and other pelvic factors all influence dystocia risk. A later first pregnancy remains concerning and should never be planned without specialist veterinary advice. (PubMed Central (PMC))

Can I tell whether mating was successful by watching the animals?

No. Mating can be brief or occur when nobody is present, and mounting does not prove fertilisation. Treat any unprotected opposite-sex contact as a possible pregnancy.

Final Thoughts

Rats, mice and guinea pigs reproduce quickly, but they do not reproduce in the same way.

The most important distinctions are:

1. Rats and mice have four to five-day reproductive cycles.

2. Their pregnancies last only around three weeks.

3. Their pups are born blind, deaf and dependent.

4. Guinea pig pregnancy lasts approximately two months.

5. Guinea pig pups are born fully furred, mobile and developmentally advanced.

6. Guinea pigs may become fertile earlier than a simple 10 to 12-week table suggests.

7. All three species may return to fertility shortly after giving birth.

8. Back-to-back pregnancy places substantial strain on the mother.

9. Guinea pigs face particular risks from dystocia and pregnancy toxaemia.

10. A laboratory breeding-life range is not a recommendation for continuous breeding.

11. An enlarging abdomen does not confirm pregnancy.

12. Prolonged labour, bleeding, weakness, breathing difficulty or food refusal requires urgent veterinary care.

The safest rule is simple: if breeding is not deliberately planned, professionally confirm the sex of every animal and separate opposite sexes before the earliest possible fertility window.

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ASK A VET™ can help you review photographs for sex identification, calculate possible pregnancy dates and organise weight, appetite and delivery records while you arrange care with an exotics veterinarian. A pregnant rodent with unproductive contractions, heavy bleeding, collapse, breathing difficulty or complete food refusal still requires immediate hands-on veterinary treatment.