How to Determine Pregnancy in a Rat

Early Indicators of Pregnancy

Behavioral Changes

Increased Nesting Behavior

Increased nesting behavior serves as a reliable physiological sign of gestation in laboratory rats. Females exhibit a marked rise in the construction and maintenance of a nest shortly after mating, typically appearing within 48–72 hours post‑coitus. The behavior includes gathering bedding material, arranging it into a compact structure, and repeatedly re‑shaping the nest throughout the dark phase.

Observation guidelines:

Monitor each cage twice daily, focusing on the evening period when rats are most active.
Record the number of bedding pieces collected and the degree of compaction, using a simple scoring system (0 = no nest, 1 = scattered material, 2 = partial nest, 3 = well‑formed nest).
Compare scores with baseline data from non‑pregnant control females to identify significant deviations.

Physiological correlation:

Elevated prolactin levels stimulate nest‑building activity, linking hormonal changes to the observed behavior.
The onset of consistent nesting aligns with the implantation phase, providing an early indicator before abdominal enlargement becomes apparent.

Practical application:

Incorporate nesting assessments into routine health checks to reduce reliance on invasive procedures.
Use nest‑score thresholds to prioritize individuals for further confirmation methods, such as ultrasound or palpation, thereby optimizing resource allocation.

Overall, systematic evaluation of nesting activity offers an objective, non‑intrusive metric for detecting pregnancy in rats, enhancing experimental accuracy and animal welfare.

Changes in Appetite and Water Intake

Pregnant rats exhibit measurable alterations in both food consumption and fluid intake, providing reliable cues for gestational assessment.

During early gestation, daily food intake typically rises by 10‑15 % compared to non‑pregnant controls. The increase becomes more pronounced in mid‑gestation, reaching 20‑30 % above baseline. Consumption of high‑energy components, such as protein‑rich pellets, often escalates, reflecting the metabolic demands of fetal development.

Water consumption follows a similar upward trend. Average fluid intake rises by approximately 15 % in the first week of pregnancy and may double by the third week. Elevated drinking frequency accompanies the growth of the uterine mass and the associated increase in plasma volume.

Practical monitoring protocol:

Record individual food weight before and after a 24‑hour period; a consistent rise of ≥10 % suggests gestational onset.
Measure water bottle volume daily; an increase of ≥15 % supports the same inference.
Compare recorded values against established baseline data for the specific strain and housing conditions.
Confirm findings with secondary indicators such as abdominal palpation or ultrasound when precise dating is required.

Consistent documentation of these parameters enables early detection of pregnancy, facilitates appropriate husbandry adjustments, and supports experimental reliability.

Reduced Activity Levels

Reduced activity levels constitute a reliable indicator of gestation in laboratory rats. Pregnant females typically display a measurable decline in spontaneous locomotion compared with non‑pregnant controls. This decrease becomes apparent during the second week after conception and intensifies as embryonic development progresses.

Observations should focus on the following parameters:

Frequency of cage exploration: marked reduction in the number of trips across the enclosure.
Time spent in sedentary postures: prolonged periods of resting on the nest material.
Response to handling: diminished reactivity and slower movement when disturbed.
Wheel‑running activity (if provided): noticeable drop in revolutions per hour.

Quantitative assessment can be achieved by recording baseline activity levels in a pre‑mating cohort, then comparing weekly measurements after pairing. A reduction of 30 % or more relative to baseline strongly suggests pregnancy, especially when accompanied by other physiological changes such as abdominal enlargement and altered hormonal profiles.

Consistent monitoring of these behavioral shifts, combined with established physical markers, enhances the accuracy of gestational detection without invasive procedures.

Physical Signs

Weight Gain

Weight gain provides a reliable physiological marker for detecting gestation in laboratory rats. During early gestation, a female typically gains 5–10 % of her pre‑mating body mass, with a more pronounced increase of 15–20 % by mid‑gestation. The pattern differs from normal growth cycles; non‑pregnant females maintain a relatively stable weight when housed under consistent feeding regimes.

Accurate assessment requires regular weighing with a precision scale (±0.1 g). Recommended schedule: weigh the subject daily for at least seven days before mating, then continue daily measurements throughout the expected gestation period. Plotting individual weight trajectories highlights the inflection point where rapid gain begins, indicating successful conception.

Key considerations for interpreting weight data:

Consistent diet: identical caloric content and feeding times minimize variability unrelated to pregnancy.
Environmental control: stable temperature and humidity reduce stress‑induced weight fluctuations.
Baseline establishment: a minimum of three consecutive pre‑mating weights establishes a reliable reference.
Exclusion of pathological weight loss: monitor for signs of illness that could mask gestational gain.

When weight gain aligns with the described timeline and magnitude, it strongly suggests pregnancy, allowing researchers to proceed with further reproductive assessments without invasive procedures.

Palpation of the Abdomen

Palpation of the abdomen is a reliable technique for confirming gestation in laboratory rats. The procedure requires gentle, systematic pressure applied to the ventral surface of the animal, allowing detection of developing embryos through tactile cues.

The optimal time window for effective palpation ranges from day 12 to day 18 of gestation. Prior to day 12, embryonic structures are too small to be distinguished from surrounding tissues; after day 18, the uterine contents become less distinct due to increased size and mobility of fetuses.

Technique steps:

Restrain the rat in a dorsal recumbent position using a soft cloth or a specialized restraining device.
Warm the examiner’s hands to prevent vasoconstriction and ensure consistent sensitivity.
Apply light, circular pressure with the fingertips along the midline of the abdomen, moving caudally toward the pelvis.
Identify a series of firm, rounded masses approximately 2–4 mm in diameter; these correspond to the gestational sacs.
Note the number and distribution of palpable masses, which provide an estimate of litter size and fetal positioning.

Key considerations:

Conduct palpation in a quiet environment to reduce stress, which can affect uterine tone.
Use a magnifying lens if necessary to enhance tactile discrimination.
Record findings immediately, documenting the date, gestational day estimate, and observed litter count.

Repeated examinations at two‑day intervals improve accuracy, allowing confirmation of pregnancy progression and early detection of potential complications such as resorption or fetal demise.

Vaginal Plug Observation

Vaginal plug observation provides a reliable early indicator of successful mating in laboratory rats. The plug forms when the male deposits a coagulated secretion in the female’s vagina shortly after copulation. Its presence confirms that sperm transfer has occurred and that the estrous cycle has progressed to the fertile phase.

The plug typically appears within 12–24 hours after pairing and remains visible for 24–48 hours. Removal of the plug by gentle flushing can be performed, but preservation of the intact structure is preferred for accurate assessment. Recording the exact time of plug detection enables calculation of gestational age, as embryonic development advances predictably from the moment of copulation.

Practical steps for reliable observation:

Pair female and male rats in the evening; check females the following morning.
Inspect the vaginal opening with a magnifying lens or low‑power dissecting microscope.
Identify the opaque, gelatinous mass adhering to the vaginal epithelium; distinguish it from normal secretions by its consistency and location.
Note the date and hour of detection in the animal log.
Return the female to the home cage; avoid handling that could dislodge the plug prematurely.

Interpretation of findings:

Presence of a plug confirms mating; absence does not necessarily indicate infertility, as copulation may have failed or occurred outside the observation window.
Re‑examination after 24 hours can capture delayed plug formation.
Consistent plug detection across multiple cycles validates the breeding protocol and supports downstream experimental timelines.

By integrating systematic plug monitoring into breeding schedules, researchers obtain a precise temporal marker for gestation, facilitating accurate planning of embryological or pharmacological studies.

Confirmatory Methods for Pregnancy Detection

Hormonal Testing

Progesterone Levels

Progesterone is the primary steroid hormone indicating gestational status in female rats. During the estrous cycle, serum concentrations remain low, typically below 5 ng/mL. After successful mating, luteal activity elevates progesterone to 15–30 ng/mL within 48 hours, reaching a plateau of 30–50 ng/mL throughout early pregnancy. Persistent elevation beyond the expected luteal phase strongly suggests implantation.

Blood collection is performed via tail vein or retro‑orbital sinus, using heparinized microtubes to prevent clotting. Serum separation requires centrifugation at 2 000 g for 10 minutes. Quantification employs enzyme‑linked immunosorbent assay (ELISA) kits validated for rodent samples; assay sensitivity of 0.5 ng/mL ensures detection of early hormonal shifts.

Interpretation guidelines:

< 5 ng/mL – non‑pregnant, estrous phase.
5–15 ng/mL – post‑ovulatory luteal phase without conception.
≥ 15 ng/mL – probable pregnancy; values above 30 ng/mL confirm gestation.

Potential confounders include stress‑induced adrenal progesterone release and exogenous hormone administration. Repeating measurements on consecutive days reduces false‑positive identification caused by transient spikes.

Integrating progesterone profiling with vaginal cytology enhances diagnostic accuracy. Cytology confirms mating (presence of spermatozoa) while progesterone quantifies luteal response, together providing a reliable method for confirming pregnancy in laboratory rats.

Relaxin Assays

Relaxin, a peptide hormone secreted by the corpus luteum, rises markedly after implantation and remains elevated throughout gestation in rodents. Measurement of serum relaxin therefore provides a reliable biochemical indicator of pregnancy in laboratory rats.

The assay typically employs a sandwich enzyme‑linked immunosorbent format. Capture antibodies specific for rat relaxin coat microplate wells; after incubation with diluted serum, a biotinylated detection antibody binds the captured hormone. Streptavidin‑horseradish peroxidase and a chromogenic substrate generate a colorimetric signal proportional to hormone concentration. Calibration curves derived from recombinant rat relaxin standards enable quantification in nanograms per milliliter.

Key procedural points:

Collect blood via retro‑orbital sinus or tail vein; allow clotting, centrifuge at 2 000 g for 10 min, store serum at –80 °C.
Thaw samples on ice; avoid repeated freeze‑thaw cycles to preserve antigenicity.
Dilute serum 1:5–1:20 in assay buffer, depending on expected concentration range.
Include duplicate wells for each sample; incorporate negative controls (non‑pregnant serum) and positive controls (late‑gestation serum) on each plate.
Read absorbance at 450 nm; apply the four‑parameter logistic model to interpolate concentrations.

Interpretation guidelines:

Values below 0.5 ng/mL generally indicate non‑pregnant status.
Concentrations above 2 ng/mL reliably confirm gestation, detectable as early as day 5 post‑coitus.
Serial sampling permits monitoring of hormonal dynamics, correlating with embryonic development stages.

Advantages of relaxin assays include early detection, minimal invasiveness, and compatibility with high‑throughput screening. Limitations involve cross‑reactivity with other insulin‑like peptides and the requirement for validated antibodies specific to the rat isoform. Proper assay validation—assessment of precision, accuracy, linearity, and limit of detection—ensures reproducible results across experimental cohorts.

Ultrasound Imaging

Visualizing Fetuses

Visualizing developing offspring provides direct evidence of gestation in laboratory rats. Early‑stage embryos appear as small echogenic structures on high‑frequency ultrasound, while later stages present as distinct, fluid‑filled sacs. Ultrasound transducers operating at 30–40 MHz deliver sufficient resolution to count individual «fetuses», assess crown‑rump length, and detect cardiac activity. Proper coupling gel and gentle restraint minimize stress and maintain image quality.

Necropsy remains the definitive method for confirming pregnancy. After euthanasia, the uterine horns are opened along the mesometrial border. Careful inspection reveals the number and position of each «fetus», the presence of placental tissue, and any resorption sites. Dissection should proceed with fine forceps and scissors to avoid damaging fragile membranes. Recording the weight and developmental stage of each embryo facilitates comparative studies.

Histological evaluation adds microscopic detail. Fixation of uterine tissue in neutral‑buffered formalin, followed by paraffin embedding, permits sectioning at 5 µm. Staining with hematoxylin–eosin highlights organogenesis, while immunohistochemical markers such as Ki‑67 identify proliferative zones. Microscopy confirms vascular connections and assesses any pathological alterations.

Key considerations for reliable visualization:

Select imaging modality according to gestational age; ultrasound for early detection, necropsy for definitive counts.
Maintain consistent temperature (37 °C) during procedures to preserve tissue integrity.
Document each observation with calibrated measurements to ensure reproducibility.
Apply sterile technique when handling uterine tissue to prevent contamination.

Collectively, these approaches enable accurate determination of pregnancy status and provide essential data for reproductive research.

Confirming Heartbeats

Confirming fetal cardiac activity provides unequivocal evidence of gestation in laboratory rats. Detection of a heartbeat distinguishes viable embryos from non‑viable or pre‑implantation stages and eliminates ambiguity inherent in external palpation or weight gain assessments.

Heartbeats become detectable between embryonic day 12 and day 14, coinciding with the formation of a functional myocardial tube. Prior to this window, ultrasonic imaging may reveal gestational sacs, but the presence of a pulsatile signal confirms embryonic development.

Typical techniques for heartbeat confirmation include:

Doppler ultrasound: high‑frequency transducer applied to the abdominal wall; a characteristic systolic‑diastolic waveform indicates cardiac motion.
Auscultation with a miniature stethoscope: feasible in larger strains; rhythmic sounds correspond to fetal heart rate.
Electrocardiographic recording: needle electrodes inserted subcutaneously near the uterine horns capture embryonic ECG peaks.
Direct visual inspection: after humane euthanasia, embryos are examined under a stereomicroscope; spontaneous contractions of the yolk sac or heart tube confirm activity.

Procedural steps for Doppler assessment:

Anesthetize the animal using an inhalant agent (e.g., isoflurane) at 1–2 % concentration; maintain respiratory rate within normal limits.
Position the rat supine on a heated platform; apply a coupling gel to the ventral abdomen.
Align the transducer over each uterine horn; adjust gain and depth until a clear pulsatile signal appears.
Record the fetal heart rate for at least 30 seconds; rates between 300 and 400 beats per minute are typical for mid‑gestation embryos.
Document findings and compare with established reference values to assess embryonic viability.

Interpretation of results requires correlation with gestational age. A sustained heartbeat within the expected range confirms pregnancy and indicates healthy embryonic development. Absence of cardiac activity in the specified window suggests either early embryonic loss or a false‑positive result from other diagnostic methods.

Radiography (X-rays)

Detecting Fetal Skeletons

Detecting fetal skeletons provides definitive evidence of gestation in laboratory rats. Skeletal ossification becomes visible after embryonic day 14, allowing reliable confirmation of pregnancy without relying on behavioral or hormonal indicators.

Common techniques include:

Radiographic imaging of the abdomen; X‑ray exposure reveals mineralized bones in developing fetuses.
Alizarin red S staining after fixation; the dye binds to calcium deposits, producing a vivid contrast of skeletal structures.
Micro‑computed tomography (micro‑CT); high‑resolution three‑dimensional reconstructions display individual vertebrae, ribs, and limb bones.
Whole‑mount skeletal preparation; maceration in potassium hydroxide followed by staining highlights the complete ossified framework.

Critical parameters for each method:

Timing: perform detection no earlier than embryonic day 14 to ensure sufficient ossification.
Dose: limit radiation exposure to ≤0.1 Gy for radiography to avoid embryotoxic effects.
Fixation: use 10 % neutral‑buffered formalin for at least 24 h before staining to preserve tissue integrity.
Imaging settings: set micro‑CT voxel size to ≤30 µm for clear delineation of skeletal elements.

Interpretation relies on identifying characteristic bones such as cranial vault, vertebral column, and limb long bones. Presence of these structures confirms pregnancy, while their absence suggests either early gestation or non‑pregnant status.

Estimating Litter Size

Estimating the number of pups in a pregnant rat requires direct observation and measurement techniques that provide reliable data for breeding programs and research protocols.

Common approaches include:

Palpation of the abdomen between days 12 and 15 of gestation; experienced personnel can feel the developing uterine horns and count individual embryos.
Ultrasonography performed with a high‑frequency transducer; images reveal fetal silhouettes, allowing precise counting without invasive handling.
Radiography after administration of a contrast agent; the resulting silhouettes outline each fetus, facilitating accurate enumeration.
Dissection at scheduled sacrifice; direct visual inspection of the uterine contents yields the definitive litter size.

When using palpation, record the count on the day of assessment and repeat after 24 hours to confirm consistency. Ultrasonographic and radiographic results should be corroborated with a second imaging session to reduce false negatives. Final litter size is confirmed at parturition, providing a benchmark for evaluating the accuracy of pre‑birth estimates.

Differentiating from Pseudopregnancy

Understanding Pseudopregnancy

Pseudopregnancy, also called false pregnancy, occurs when a female rat exhibits physiological and behavioral changes typical of gestation despite the absence of embryos. Hormonal stimulation, commonly induced by mating with a sterile male or by exposure to male pheromones, triggers luteal activity and progesterone secretion comparable to that of a true pregnancy.

Key characteristics of pseudopregnancy include:

Elevated plasma progesterone levels sustained for 15–20 days.
Development of mammary gland enlargement and milk secretion.
Abdominal distension caused by uterine hypertrophy.
Nest‑building behavior and maternal instincts directed toward non‑existent offspring.

Distinguishing pseudopregnancy from genuine gestation relies on diagnostic criteria:

Ultrasound examination – Absence of fetal vesicles or embryonic structures confirms false pregnancy.
Palpation – Lack of palpable embryos or fetal movements differentiates the condition.
Serum hormone profiling – Progesterone peaks in pseudopregnancy often exceed those of early true gestation but lack the biphasic pattern observed in actual pregnancy.
Vaginal cytology – Persistent diestrus‑type cells without the cyclic changes associated with ovulation indicate luteal maintenance without conception.

Recognition of pseudopregnancy is critical for experimental accuracy. Misinterpretation can lead to erroneous conclusions regarding fertility, embryonic development, or the efficacy of reproductive interventions. Researchers should incorporate routine ultrasound screening and hormonal assays when assessing reproductive status in laboratory rats to ensure reliable data.

Management strategies include:

Removing the male stimulus to terminate luteal support.
Administering prostaglandin analogs to induce luteolysis and restore normal estrous cycles.
Monitoring subsequent estrus to confirm return to baseline reproductive function.

Understanding the mechanisms and diagnostic markers of pseudopregnancy enhances the precision of reproductive studies and prevents confounding effects in experimental outcomes.

Key Differences in Symptoms

Pregnancy in laboratory rats produces distinct physiological and behavioral alterations that separate pregnant individuals from non‑pregnant controls. Recognizing these differences enables reliable detection of gestation without invasive procedures.

Observable changes fall into three categories:

Behavioral modifications – increased nesting activity, frequent rearrangement of bedding, heightened aggression toward cage mates, and reduced locomotor activity during the latter half of gestation.
Physical signs – progressive abdominal enlargement detectable by palpation after day 10, visible mammary gland development, and a noticeable increase in body weight that exceeds normal growth curves.
Physiological indicators – elevated serum progesterone levels, altered estrous cycle pattern (cessation of regular cycling), and changes in urinary hormone metabolites detectable by immunoassay.

Each symptom appears at a specific gestational stage, allowing staged assessment. Early nesting behavior may emerge as soon as day 4, whereas abdominal distension becomes reliable after day 12. Combining behavioral observation with physical palpation and hormonal testing yields the highest accuracy for confirming gestation in rats.

Diagnostic Approaches

Diagnostic approaches for confirming gestation in laboratory rats rely on observable physiological changes, laboratory analyses, and imaging techniques. Direct observation of abdominal enlargement provides a rapid, albeit approximate, indication of pregnancy. Consistent weight gain of 5–10 percent of baseline body mass over a two‑week period typically corresponds with embryonic development.

Laboratory methods augment visual assessment:

Vaginal cytology: presence of corpora lutea‑derived cells and absence of estrous‑phase epithelial cells indicate a non‑estrous state compatible with pregnancy.
Serum hormone measurement: elevated prolactin and progesterone concentrations, quantified by immunoassay, correlate with gestational status.
Urinary hormone detection: increased levels of luteinizing hormone metabolites serve as supplementary markers.

Imaging modalities offer definitive confirmation:

High‑resolution ultrasonography: detection of fetal sacs and cardiac activity as early as day 10 post‑coitus provides unequivocal evidence.
Magnetic resonance imaging: detailed anatomical visualization without ionizing radiation, suitable for longitudinal studies.
Computed tomography: applicable for late‑stage gestation when skeletal ossification becomes apparent.

Combining physical examination with hormonal profiling and imaging yields a robust diagnostic framework, reducing false‑positive rates and enabling precise timing of gestational stages.

Care for Pregnant Rats

Nutritional Requirements

Nutritional adjustments provide reliable indicators of gestation in laboratory rats because physiological changes alter food intake and body composition.

During the early stages of pregnancy, rats require increased energy, protein, and micronutrients to support embryo development and maternal tissue growth.

Energy: 15‑20 % higher caloric intake than non‑pregnant controls; concentrate on carbohydrate‑rich diets that maintain steady blood glucose.
Protein: minimum 20 % of total diet, with high‑quality sources such as casein or soy isolate to supply essential amino acids.
Essential fatty acids: inclusion of omega‑3 and omega‑6 ratios of approximately 1:5 supports fetal neural development.
Calcium and phosphorus: maintain a Ca : P ratio of 1.2 : 1; supplement with calcium carbonate and dicalcium phosphate to prevent skeletal deficiencies.
Vitamin A: 5 000 IU kg⁻¹ of diet to sustain visual and immune function.
Vitamin D₃: 1 000 IU kg⁻¹ to facilitate calcium absorption.
B‑complex vitamins: provide adequate thiamine, riboflavin, and pyridoxine for metabolic demands.
Trace minerals: zinc, selenium, and iron at levels recommended for gestating rodents to avoid anemia and oxidative stress.
Water: unrestricted access; pregnant rats increase fluid consumption by 30‑40 % to support amniotic fluid production.

Implement a feeding schedule that offers fresh diet twice daily, records daily food consumption, and monitors weight gain of at least 2 g per week. Sudden reductions in intake or failure to achieve expected weight trajectories may indicate reproductive failure or health issues.

Commercial gestation chow formulated to meet the above specifications simplifies diet management; however, standard laboratory chow can be modified with calculated supplements to achieve comparable nutrient profiles. Regular analysis of diet composition ensures consistency across breeding cycles.

Environmental Considerations

Environmental variables directly affect the reliability of gestation assessment in laboratory rats. Temperature fluctuations can mask subtle body‑weight changes; maintaining a stable ambient range of 20‑24 °C reduces metabolic noise. Humidity levels above 60 % increase respiratory stress, potentially altering behavior used as pregnancy indicators.

Lighting cycles regulate hormonal rhythms; a consistent 12 h light/12 h dark schedule prevents estrous‑cycle disruption that might confound detection of implantation signs. Cage density influences stress; limiting occupants to no more than three adults per standard cage minimizes aggressive interactions and preserves normal nesting patterns.

Dietary composition shapes body‑weight trajectories; providing a nutritionally balanced pellet diet with constant protein (≈20 %) and fat (≈5 %) content ensures weight gain reflects fetal development rather than dietary excess. Water availability must remain unrestricted; dehydration accelerates weight loss, obscuring pregnancy‑related gain.

Bedding material contributes to insulation and odor control; using low‑dust, absorbent substrate reduces respiratory irritation and prevents olfactory cues that could alter maternal behavior. Regular cage cleaning, performed at 48‑hour intervals, removes waste without disturbing nest integrity, preserving observable changes in nest building.

Noise exposure above 70 dB elevates cortisol levels, suppressing gestational markers; housing rooms should be sound‑attenuated and equipment operated on low‑noise settings. Ventilation rates of 15–20 air changes per hour maintain air quality while avoiding drafts that could cause temperature stress.

Implementing these environmental controls creates a stable background against which physiological and behavioral signs of pregnancy become discernible, enhancing the accuracy of gestational determination in rat models.

Monitoring for Complications

Confirm gestation in a rat, then initiate systematic observation to identify maternal or fetal complications. Early detection reduces loss rates and improves experimental outcomes.

Typical complications include:

Excessive weight loss or failure to gain expected weight.
Persistent vaginal bleeding or abnormal discharge.
Lethargy, reduced grooming, or marked changes in activity.
Abnormal abdominal distension suggesting uterine rupture or fluid accumulation.
Elevated body temperature beyond normal gestational range.

Monitoring procedures:

Record body weight daily; a gain of 2–3 g per day indicates normal progression, while stagnation or decline signals potential issues.
Inspect the ventral abdomen for swelling, asymmetry, or palpable masses; gentle palpation detects fetal movement and uterine tone.
Observe behavior for reduced nesting, food intake, or water consumption; deviations from baseline warrant further evaluation.
Collect vaginal swabs when discharge appears; microscopic examination distinguishes normal secretions from hemorrhage or infection.
Perform transabdominal ultrasonography at mid‑gestation (days 10–12); imaging confirms fetal viability and identifies abnormal fluid collections.
Measure serum progesterone; a sharp decline may precede miscarriage.

Intervention guidelines:

Immediate veterinary consultation for any sign of hemorrhage, severe weight loss, or abnormal temperature.
Adjust housing conditions (temperature, bedding) to reduce stress if behavioral changes emerge.
Administer appropriate antibiotics only after confirming bacterial infection; avoid prophylactic use to prevent resistance.
Consider terminating the pregnancy ethically if fetal viability is compromised and maternal health deteriorates.

Consistent application of these monitoring steps ensures timely identification of complications and supports reliable reproductive research.