Mycoplasma in Rats: Infection and Treatment Methods for Rodents

Understanding Mycoplasma Infection

What is Mycoplasma pulmonis?

Mycoplasma pulmonis is a cell‑wall‑deficient bacterium belonging to the genus Mycoplasma, family Mycoplasmataceae. It is the primary etiologic agent of murine respiratory mycoplasmosis, a chronic infection that predominantly affects rats and other laboratory rodents.

The organism measures 0.2–0.3 µm in diameter, lacks a rigid peptidoglycan layer, and possesses a sterol‑rich plasma membrane that confers flexibility and resistance to osmotic stress. Its genome is approximately 1 Mb, encoding essential metabolic pathways and surface lipoproteins that facilitate adherence to respiratory epithelium.

Infected rats display a spectrum of clinical manifestations, including sneezing, nasal discharge, conjunctivitis, and interstitial pneumonia. Subclinical carriers often harbor the pathogen in the upper respiratory tract, serving as reservoirs for horizontal spread through aerosol droplets, direct contact, and contaminated bedding.

Laboratory diagnosis relies on:

Culture on specialized mycoplasma media (e.g., SP4 broth) under microaerophilic conditions.
Polymerase chain reaction targeting species‑specific 16S rRNA sequences.
Serologic testing for antibodies using enzyme‑linked immunosorbent assay (ELISA).

Therapeutic interventions focus on antimicrobial agents effective against mycoplasmas:

Tetracyclines (e.g., doxycycline) administered in drinking water or feed.
Macrolides (e.g., tylosin) delivered orally.
Fluoroquinolones (e.g., enrofloxacin) reserved for refractory cases.

Treatment regimens typically span 7–14 days, with dosages adjusted for age and weight. Eradication requires concurrent environmental decontamination, including autoclaving of cage components, replacement of bedding, and strict quarantine of affected colonies.

Preventive strategies emphasize:

Routine screening of breeding stock.
Maintenance of specific pathogen‑free (SPF) colonies.
Implementation of barrier housing and filtered airflow systems.

Understanding the biology, transmission dynamics, and control measures for Mycoplasma pulmonis is essential for managing respiratory infections in rodent research facilities.

How Mycoplasma Affects Rats

Mycoplasma infection in laboratory rats compromises respiratory, urogenital, and systemic health. The organisms lack a cell wall, allowing them to persist on mucosal surfaces and evade standard bactericidal agents. Colonization begins in the upper respiratory tract, spreads via direct contact or aerosol, and may reach the reproductive tract, causing subclinical carriage or overt disease.

Key physiological disruptions include:

Impaired mucociliary clearance, leading to chronic rhinitis and sinusitis.
Altered immune regulation, manifested as lymphoid hyperplasia, reduced antibody production, and increased susceptibility to secondary pathogens.
Reproductive disturbances such as reduced fertility, embryonic loss, and placental inflammation.
Systemic effects like weight loss, decreased feed efficiency, and intermittent fever.

These alterations affect experimental outcomes by introducing variability in immunological assays, pharmacokinetic measurements, and behavioral studies. Routine screening, strict quarantine, and targeted antimicrobial protocols are essential to maintain colony integrity and data reliability.

Transmission Routes

Mycoplasma spreads among rats through several well‑documented pathways. Direct physical contact between animals permits transfer of organisms present on mucosal surfaces and skin. Aerosolized particles generated by sneezing, grooming, or cage cleaning can be inhaled, leading to respiratory colonisation. The fecal‑oral route operates when contaminated bedding, feed, or water is ingested, especially in high‑density housing. Vertical transmission occurs when infected dams pass the pathogen to offspring during gestation or through milk. Indirect spread via contaminated equipment, gloves, or personnel—known as fomite transmission—contributes to outbreaks when biosecurity measures are insufficient.

Key factors influencing these routes include:

High stocking density, which increases direct and aerosol exposure.
Inadequate cage sanitation, fostering fecal‑oral dissemination.
Use of shared feeding devices, facilitating fomite transfer.
Presence of asymptomatic carriers, sustaining vertical and environmental spread.

Effective control relies on isolating infected colonies, implementing rigorous cage change protocols, and employing barrier techniques for personnel. Regular screening of breeding stock detects vertical carriers before dissemination.

Direct Contact

Direct contact between rats provides the most efficient route for Mycoplasma transmission. The organism adheres to epithelial surfaces and spreads through grooming, mating, and aggressive encounters. Saliva, nasal secretions, and skin lesions serve as carriers, allowing rapid colonization of susceptible individuals housed in the same cage or enclosure.

Effective control of contact‑mediated spread relies on strict husbandry practices:

Separate infected and healthy animals; maintain individual or ventilated cages.
Implement routine health monitoring with PCR or culture of oropharyngeal swabs.
Enforce daily cleaning of bedding, feeding devices, and water bottles to remove residual secretions.
Limit group sizes to reduce the frequency of physical interactions.

Therapeutic intervention must address both the pathogen and the conditions that facilitate transmission. Recommended regimens include:

Oral administration of tetracycline-class antibiotics for 7–10 days, adjusted for body weight.
Adjunctive anti‑inflammatory agents to mitigate tissue damage caused by persistent infection.
Post‑treatment re‑testing to confirm eradication before re‑introduction into the colony.

Preventive strategies focus on minimizing direct physical exchange. Use of barrier systems, such as mesh partitions, reduces nose‑to‑nose contact while preserving airflow. Regular personnel training on handling techniques further limits inadvertent transmission during cage changes or experimental procedures.

Airborne Transmission

Airborne transmission represents a primary route by which mycoplasma spreads among laboratory rats. Aerosolized particles generated during cage cleaning, animal handling, and respiratory secretions can remain suspended long enough to infect susceptible individuals within the same enclosure or adjacent cages.

Experimental studies have demonstrated that Mycoplasma pulmonis, the most common species in rodents, can be recovered from air samples collected in animal facilities. Inoculation of naïve rats with filtered air containing these particles results in colonization of the upper respiratory tract, confirming the infectious potential of aerosolized organisms.

Environmental factors influencing aerosol stability include temperature, relative humidity, and airflow patterns. Low humidity and moderate temperatures extend particle viability, while turbulent airflow promotes wider distribution. Ventilation systems that recirculate unfiltered air increase the risk of cross‑contamination.

Effective mitigation relies on engineering and procedural controls:

Install high‑efficiency particulate air (HEPA) filters on all supply and exhaust vents.
Maintain negative pressure in quarantine and animal holding rooms.
Use sealed, individually ventilated cages (IVCs) to limit particle escape.
Implement strict cage change schedules with biosafety cabinets and disposable PPE.
Conduct regular air sampling for mycoplasma DNA to detect early contamination.

Treatment protocols must account for the possibility of reinfection via aerosols. Continuous antimicrobial therapy is less effective when environmental re‑exposure persists; therefore, prophylactic measures accompany drug regimens. Selection of antibiotics with proven pulmonary penetration, such as macrolides, improves therapeutic outcomes, but success depends on simultaneous reduction of airborne load.

Monitoring programs that combine serology, PCR of respiratory swabs, and air sampling provide comprehensive surveillance. Early identification of airborne spread enables rapid containment, preserving the health of rodent colonies and the integrity of experimental data.

Vertical Transmission

Mycoplasma species capable of colonizing laboratory rats can be transmitted from dam to offspring through the placenta, amniotic fluid, or milk. Transplacental passage occurs when mycoplasmas breach the maternal‑fetal barrier during gestation, leading to infection of embryos before birth. Lactational transmission results from bacterial shedding into the mammary glands, contaminating milk and exposing neonates during nursing.

Evidence for vertical spread includes detection of mycoplasmal DNA in fetal tissues, positive cultures from newborn pups before environmental exposure, and higher prevalence in litters born to infected dams compared with those born to pathogen‑free mothers. Experimental infection models demonstrate that inoculation of pregnant females produces consistent infection in their progeny, confirming the efficiency of maternal‑to‑offspring passage.

Vertical transmission influences colony health by establishing persistent infection cycles that are difficult to eradicate. Infected litters may exhibit reduced growth rates, respiratory signs, or subclinical carrier status, which can compromise experimental outcomes. Early identification of maternal infection therefore becomes essential for colony management.

Practical measures to control maternal transmission include:

Routine screening of breeding females by PCR or culture of uterine and vaginal samples.
Segregation of confirmed carriers from the main colony.
Use of pathogen‑free breeding stock sourced from certified vendors.
Implementation of embryo transfer or cesarean rederivation to obtain mycoplasma‑free offspring.

When infection is confirmed, antimicrobial therapy must consider the pharmacokinetics in pregnant and lactating rats. Tetracyclines and macrolides penetrate the placenta and milk, reducing bacterial load in both dam and offspring, but dosage regimens should avoid embryotoxicity. Post‑treatment monitoring through repeated testing ensures that vertical transmission has been interrupted and that subsequent generations remain free of infection.

Recognizing Symptoms of Mycoplasmosis

Respiratory Signs

Respiratory manifestations of mycoplasma infection in laboratory rats are typically subtle but progress rapidly under stressful conditions. Nasal discharge appears first, often serous to muco‑purulent, and may be accompanied by sneezing. Subsequent signs include:

Labored thoracic movements
Increased respiratory rate (tachypnea)
Audible wheezes or crackles on auscultation
Cyanosis of the extremities in severe cases

These clinical features often coincide with reduced activity, weight loss, and poor grooming. Early detection relies on routine health monitoring, including visual inspection for nasal secretions and periodic auscultation of the thorax. Radiographic evaluation reveals interstitial infiltrates and bronchial thickening, confirming lower‑respiratory involvement. Laboratory confirmation employs polymerase chain reaction or culture of respiratory swabs, distinguishing mycoplasma from secondary bacterial agents.

Prompt antimicrobial therapy, typically tetracycline‑based regimens, mitigates progression and reduces mortality. Supportive care—humidified environment, nutritional supplementation, and reduction of cage density—enhances recovery. Continuous observation of respiratory signs remains essential for evaluating treatment efficacy and preventing outbreak spread within rodent colonies.

Sneezing and Nasal Discharge

Sneezing and nasal discharge are the most frequent external indicators of Mycoplasma infection in laboratory rats. The organisms colonize the upper respiratory epithelium, causing inflammation that disrupts mucociliary clearance and stimulates reflexive sneezing. Nasal exudate varies from clear serous fluid to mucopurulent material, reflecting the stage of infection and the host’s immune response. Persistent sneezing, especially when accompanied by bilateral nasal discharge, often precedes lower‑respiratory involvement and should prompt immediate diagnostic evaluation.

Diagnostic procedures include:

Direct observation of clinical signs in a controlled environment.
Collection of nasal swabs for polymerase chain reaction or culture to confirm Mycoplasma spp. presence.
Hematological analysis for leukocytosis or neutrophilia, supporting an active infection.
Radiographic or micro‑CT imaging when pulmonary extension is suspected.

Therapeutic strategies focus on reducing respiratory irritation and eliminating the pathogen. Recommended measures are:

Administration of macrolide antibiotics (e.g., tylosin or tilmicosin) at species‑specific dosages for a minimum of 10 days.
Environmental modification: enhancement of ventilation, reduction of humidity, and removal of bedding that retains moisture.
Supportive care: isotonic saline nasal drops to thin secretions and improve clearance, combined with monitoring of weight and hydration status.
Isolation of affected animals to prevent aerosol transmission to the colony.

Effective control of sneezing and nasal discharge minimizes the risk of secondary bacterial pneumonia and preserves the integrity of experimental data derived from rat models. Regular health surveillance and prompt treatment remain essential components of colony management.

Labored Breathing and Wheezing

Labored breathing and wheezing are frequent respiratory manifestations in rats infected with Mycoplasma spp. The organisms colonize the upper and lower airways, producing inflammation and mucus hypersecretion that obstruct airflow. Resulting increased airway resistance forces the animal to exert additional muscular effort during inspiration, which appears as visible chest wall retractions and audible wheezes.

Key clinical observations include:

Rapid, shallow respiration with visible intercostal muscle contraction.
Audible high‑pitched wheeze during both inspiration and expiration.
Nasal discharge that may become serous or purulent.
Reduced activity and weight loss secondary to compromised oxygen intake.

Diagnostic confirmation relies on:

Respiratory auscultation to detect wheeze patterns.
Radiographic imaging showing peribronchial infiltrates or lung consolidation.
Polymerase chain reaction or culture of tracheal swabs to identify Mycoplasma DNA.

Therapeutic measures focus on alleviating airway obstruction and eliminating the pathogen:

Administration of macrolide antibiotics (e.g., tylosin or tilmicosin) at dosages validated for rodent models.
Nebulized bronchodilators (e.g., albuterol) to relax smooth muscle and reduce wheeze intensity.
Supportive oxygen therapy for severe hypoxemia.
Environmental control: humidity optimization, reduction of dust and ammonia levels to prevent secondary irritation.

Monitoring protocols require daily assessment of respiratory rate, wheeze severity, and body condition. Persistent labored breathing despite treatment indicates possible secondary bacterial infection or irreversible lung damage, necessitating reevaluation of antimicrobial regimen and consideration of humane endpoints.

Other Clinical Manifestations

Mycoplasma infection in laboratory rats frequently presents with respiratory signs, yet the pathogen also produces a range of systemic and localized manifestations that may be overlooked without targeted observation.

Neurological involvement appears as tremors, ataxia, or seizures, often reflecting encephalitis or meningitis secondary to hematogenous spread. Ocular lesions include conjunctivitis, keratitis, and corneal ulceration, sometimes accompanied by lacrimation and photophobia. Dermatological signs consist of alopecia, erythema, and ulcerative dermatitis, particularly on the ventral abdomen and tail base, indicating cutaneous colonization or immune‑mediated reactions.

Gastrointestinal disturbances manifest as reduced feed intake, weight loss, and occasional diarrhea, suggestive of enteric colonization. Hematologic abnormalities may involve anemia, leukopenia, or thrombocytopenia, detectable through routine blood counts. Reproductive effects include reduced fertility, irregular estrous cycles, and embryonic resorption, highlighting the pathogen’s capacity to impair gonadal function.

Additional clinical signs:
- Polyuria and polydipsia indicating renal involvement
- Lymphadenopathy of cervical and mesenteric nodes
- Joint swelling and lameness suggestive of septic arthritis
- Behavioral changes such as lethargy or hyperactivity

Recognition of these diverse presentations is essential for accurate diagnosis, appropriate therapeutic intervention, and effective colony management.

Lethargy and Weight Loss

Mycoplasma infection in laboratory rats frequently presents with reduced activity and a progressive decline in body mass. The organism colonizes the respiratory and urogenital tracts, impairing nutrient absorption and inducing systemic inflammation that diminishes energy reserves. Affected animals display:

Persistent sluggishness, reluctance to explore or engage with conspecifics
Decreased food intake, often accompanied by selective feeding patterns
Measurable loss of body weight over days to weeks, despite unchanged housing conditions

Pathophysiological mechanisms include cytokine‑mediated anorexia, altered gut microbiota, and impaired mitochondrial function in skeletal muscle. These factors collectively reduce caloric efficiency and promote catabolism of lean tissue.

Diagnostic confirmation relies on polymerase chain reaction or culture of respiratory swabs, supplemented by serology to differentiate acute from chronic infection. Baseline weight and activity scores should be recorded before treatment initiation to assess therapeutic impact.

Effective management combines antimicrobial therapy with supportive care:

Administration of macrolides (e.g., tylosin, azithromycin) at species‑specific dosages for a minimum of 10 days
Provision of high‑calorie diets, preferably pelleted formulations enriched with protein and lipids
Monitoring of weight gain and activity levels daily; adjust dosage if clinical response stalls

Failure to intervene promptly results in prolonged morbidity, increased susceptibility to secondary infections, and potential loss of experimental validity. Regular health surveillance and immediate treatment of identified cases mitigate the risk of lethargy and weight loss becoming chronic conditions in rodent colonies.

Head Tilts and Inner Ear Infections

Head tilting in rats often signals vestibular dysfunction, and Mycoplasma spp. are recognized contributors to inner‑ear pathology. The organisms can invade the cochlear and semicircular canal tissues, provoking inflammation, edema, and bacterial proliferation that disrupt vestibular hair cells. Resulting asymmetry in neural input produces the characteristic lateral or dorsal head tilt observed in affected rodents.

Clinical assessment should include:

Observation of persistent head deviation, circling, or loss of balance.
Otoscopic examination for serous or purulent discharge.
Auditory brainstem response testing to evaluate hearing thresholds.
Necropsy of the temporal bone with histopathology and PCR to confirm Mycoplasma presence.

Therapeutic protocols rely on antimicrobial agents with proven efficacy against mollicutes. First‑line treatment commonly employs a macrolide (e.g., tylosin) administered orally at 25 mg/kg twice daily for 7–10 days. Fluoroquinolones (enrofloxacin 10 mg/kg once daily) serve as alternatives when macrolide resistance is suspected. Adjunctive anti‑inflammatory therapy, such as meloxicam at 0.2 mg/kg, reduces edema and accelerates vestibular recovery.

Preventive measures include strict quarantine of new arrivals, routine screening of breeding colonies with PCR assays, and maintenance of low‑density housing to limit aerosol transmission. Regular monitoring for early vestibular signs enables prompt intervention, minimizing morbidity and preserving experimental integrity.

Reproductive Issues

Mycoplasma infection in laboratory rats frequently interferes with reproductive performance. Colonization of the genital tract disrupts the estrous cycle, leading to irregular or prolonged phases that reduce mating efficiency. Female rats exhibit decreased implantation rates and increased early embryonic loss, while infected males show reduced sperm motility and abnormal morphology.

Transmission between breeding pairs occurs through direct contact, contaminated bedding, and aerosolized particles. Neonatal pups acquire the organism from dam’s milk or during birth, which can cause respiratory distress and lower survival rates. Persistent infection in a colony compromises long‑term breeding productivity and may necessitate culling of affected lines.

Effective management requires coordinated diagnostic and therapeutic actions:

Screening: Perform PCR or culture on vaginal swabs and semen samples before initiating breeding programs.
Treatment timing: Administer macrolide antibiotics (e.g., tylosin, tilmicosin) at least two weeks prior to mating to allow clearance from reproductive tissues.
Verification: Re‑test animals after a full treatment cycle to confirm eradication before re‑introduction to the breeding cohort.
Biosecurity: Isolate treated individuals, use sterilized equipment, and replace bedding to prevent re‑contamination.

Failure to address Mycoplasma presence in breeding colonies leads to reduced litter size, increased variability in experimental outcomes, and higher animal welfare concerns. Prompt detection and appropriate antimicrobial regimens restore normal reproductive function and sustain colony stability.

Diagnosing Mycoplasma Infection

Clinical Examination

Clinical examination of laboratory rats suspected of Mycoplasma infection relies on systematic observation and targeted diagnostic procedures. The evaluator should begin with a thorough external inspection, noting any signs of respiratory distress, nasal discharge, or ocular secretions. Body condition scoring provides a quick assessment of weight loss or muscle wasting, which often accompanies chronic infection.

Key examination steps include:

Palpation of the thoracic cavity to detect abnormal lung sounds; auscultation may reveal crackles or reduced breath sounds.
Measurement of rectal temperature; febrile responses are common in acute cases.
Assessment of mucous membranes for pallor or congestion, indicating systemic involvement.
Collection of oropharyngeal swabs and nasal washes for polymerase chain reaction or culture, confirming pathogen presence.
Radiographic imaging of the thorax to identify interstitial infiltrates or pleural effusion.

Interpretation of findings must integrate clinical signs with laboratory results. A positive PCR or culture combined with respiratory abnormalities confirms active infection, guiding subsequent therapeutic decisions.

Laboratory Tests

Accurate diagnosis of mycoplasma infections in laboratory rats relies on a defined set of laboratory examinations. Specimens typically include oropharyngeal swabs, lung tissue, and serum, collected under aseptic conditions to prevent cross‑contamination. Primary diagnostic modalities are:

Polymerase chain reaction (PCR) targeting species‑specific 16S rRNA sequences; provides rapid detection with high sensitivity.
Culture on specialized mycoplasma media; confirms viability and allows antimicrobial susceptibility testing, though requires 2–4 weeks for colony formation.
Enzyme‑linked immunosorbent assay (ELISA) for IgG/IgM antibodies; indicates exposure history and seroconversion dynamics.
Histopathology of lung sections stained with hematoxylin‑eosin or Grocott’s methenamine silver; reveals characteristic lesions such as interstitial pneumonia and peribronchiolar infiltrates.
Quantitative real‑time PCR (qPCR); supplies bacterial load estimates useful for monitoring treatment efficacy.

Interpretation of results must consider the infection stage. Early acute infection often yields positive PCR with negative serology, whereas chronic carriers may present low bacterial loads but detectable antibodies. Culture positivity confirms active infection and guides selection of effective antimicrobials based on in‑vitro susceptibility patterns.

Laboratory data integrate directly into therapeutic protocols. Positive PCR or culture results trigger immediate administration of approved antimicrobials (e.g., macrolides, tetracyclines) at dosages validated for rodents. Follow‑up testing—typically PCR or culture performed 7–14 days post‑treatment—verifies eradication. Persistent seropositivity without PCR detection suggests resolved infection but warrants continued observation for potential recrudescence.

PCR Testing

Polymerase chain reaction (PCR) provides rapid, sensitive detection of Mycoplasma species in laboratory rats, enabling early intervention and containment within breeding colonies. The method amplifies specific DNA fragments, allowing identification of low‑level infections that may be missed by culture or serology.

Sample collection typically involves oropharyngeal swabs, fecal pellets, or tissue homogenates from euthanized animals. After collection, nucleic acids are extracted using silica‑column kits or magnetic‑bead protocols that remove inhibitors common in rodent specimens. Quality of the extract is verified by spectrophotometric ratios (A260/A280) before amplification.

Primer sets target conserved regions of the 16S rRNA gene or species‑specific loci such as the P1 adhesin gene. A standard reaction mix contains:

DNA template (10–100 ng)
Forward and reverse primers (0.2–0.5 µM each)
dNTPs (200 µM)
MgCl₂ (1.5–2.5 mM)
Thermostable DNA polymerase (0.5–1 U)
Buffer (provided with enzyme)

Thermal cycling follows an initial denaturation (95 °C, 3 min), 30–35 cycles of denaturation (95 °C, 15 s), annealing (55–60 °C, 30 s), and extension (72 °C, 30 s), concluding with a final extension (72 °C, 5 min). Amplified products are visualized by agarose‑gel electrophoresis or quantified with real‑time fluorescence detection.

Interpretation hinges on the presence of a correctly sized amplicon and, for quantitative assays, cycle‑threshold values below established limits of detection (typically 10–100 copies per reaction). Positive controls containing known Mycoplasma DNA and negative controls lacking template verify assay integrity. Repeating tests on duplicate samples reduces false‑negative risk.

Advantages of PCR include:

Detection of subclinical carriers
Turnaround time of 24–48 h
Compatibility with high‑throughput platforms
Capability to differentiate Mycoplasma species through melt‑curve analysis or sequencing

Limitations involve susceptibility to contamination, requirement for specialized equipment, and inability to assess organism viability. To mitigate these issues, laboratories implement unidirectional workflow, use aerosol‑resistant tips, and regularly calibrate instruments.

Incorporating PCR into routine health‑monitoring programs aligns with guidelines from the National Institutes of Health and the Federation of European Laboratory Animal Science Associations. Recommended frequency is quarterly screening for breeding colonies and biannual testing for non‑breeding groups. Positive findings trigger quarantine, antimicrobial therapy, or depopulation, depending on infection severity and experimental impact.

Overall, PCR serves as a cornerstone technique for reliable surveillance of mycoplasma infections in rat colonies, supporting both animal welfare and experimental integrity.

Serology

Serological testing provides a quantitative measure of the host immune response to mycoplasmal infection in laboratory rats. Blood samples collected from the tail vein or retro-orbital sinus are centrifuged to obtain serum, which must be stored at –20 °C or lower to preserve antibody integrity. Proper labeling of specimens with animal ID, collection date, and strain prevents misidentification during analysis.

Common serological assays include:

Enzyme‑linked immunosorbent assay (ELISA) – detects IgG and IgM antibodies with high sensitivity; results expressed as optical density or calculated titers.
Indirect immunofluorescence assay (IFA) – visualizes antibody binding on fixed mycoplasma antigens; provides qualitative confirmation of ELISA positives.
Complement fixation test (CFT) – measures the ability of serum antibodies to fix complement in the presence of antigen; useful for monitoring seroconversion over time.

Interpretation of results depends on the infection stage. Early exposure yields low‑titer IgM, which may rise to high‑titer IgG during chronic infection. A four‑fold increase in titer between paired samples collected 2–3 weeks apart indicates active seroconversion. Cross‑reactivity with related Mycoplasma species can produce false‑positive signals; confirmatory testing with a species‑specific antigen reduces this risk.

Serology supports colony health management by identifying asymptomatic carriers, guiding quarantine decisions, and evaluating the efficacy of antimicrobial regimens. Routine screening schedules—monthly for high‑density facilities and quarterly for low‑density colonies—provide early detection and enable timely therapeutic intervention.

Culture

Culturing Mycoplasma from laboratory rats requires selective media, strict incubation parameters, and careful handling to prevent cross‑contamination. The organism’s lack of a cell wall mandates use of osmotic stabilizers and cholesterol‑enriched supplements. Standard formulation includes:

10 % horse or fetal bovine serum as a cholesterol source
0.5 % yeast extract for growth factors
0.05 % glucose as an energy substrate
Antibiotic mix (e.g., tetracycline, lincomycin) to suppress bacterial flora

Incubation proceeds at 37 °C in a humidified atmosphere with 5 % CO₂. Mycoplasma colonies appear as “fried‑egg”‑shaped growth on solid agar after 3–7 days; broth cultures become turbid within 24–48 hours. Verification employs PCR targeting the 16S rRNA gene or fluorometric DNA staining, providing rapid confirmation without reliance on visual inspection alone.

Subculturing should follow a 1:10 dilution into fresh medium every 48 hours to maintain exponential growth and avoid nutrient depletion. Cryopreservation employs 10 % glycerol in broth, stored at –80 °C; recovery requires gradual thawing and immediate inoculation into pre‑warmed selective medium.

Quality control includes routine testing of all reagents for Mycoplasma contamination, use of laminar flow hoods, and regular sterility checks of incubators. Documentation of passage number, incubation times, and colony morphology ensures reproducibility across experimental batches.

Treatment Approaches for Mycoplasmosis

Antibiotic Therapy

Antibiotic therapy remains the primary pharmacological approach for controlling Mycoplasma infections in laboratory and pet rats. Mycoplasma species lack a cell wall, rendering β‑lactam antibiotics ineffective; treatment relies on agents that inhibit protein synthesis or DNA replication.

Effective agents
1. Tetracyclines (doxycycline, oxytetracycline) – bacteriostatic, broad spectrum against Mycoplasma spp.
2. Macrolides (azithromycin, tylosin) – bacteriostatic, suitable for oral administration.
3. Fluoroquinolones (enrofloxacin, ciprofloxacin) – bactericidal, reserved for severe cases due to resistance risk.
Dosage guidelines (average adult rat, 250 g)
- Doxycycline: 5 mg/kg body weight, orally, twice daily for 7–10 days.
- Azithromycin: 10 mg/kg, orally, once daily for 5 days.
- Enrofloxacin: 2.5 mg/kg, orally, once daily for 5 days.
Administration routes – oral gavage or medicated drinking water; subcutaneous injection reserved for agents lacking palatable formulations.
Resistance considerations – Mycoplasma can develop rapid resistance to macrolides and fluoroquinolones; susceptibility testing recommended before initiating therapy.
Monitoring – clinical signs (respiratory distress, nasal discharge) and periodic PCR assays of oropharyngeal swabs assess treatment efficacy; repeat testing 2 weeks post‑therapy confirms eradication.
Withdrawal periods – for research colonies, adhere to institutional guidelines; typical withdrawal for tetracyclines is 7 days, for macrolides 5 days, to prevent drug residues in subsequent studies.

Successful antibiotic therapy requires accurate species identification, appropriate drug selection, and strict adherence to dosing schedules. Failure to observe these parameters leads to persistent infection and potential colony-wide outbreaks.

Common Antibiotics Used

Mycoplasma infections in laboratory rats require antimicrobial therapy that penetrates the cell‑wall‑deficient organism and achieves therapeutic concentrations in respiratory and systemic tissues. The antibiotics most frequently employed are listed below with recommended regimens and critical considerations.

Tetracyclines (e.g., doxycycline, oxytetracycline)
- Dosage: 10–20 mg/kg body weight, administered orally or via drinking water.
- Treatment length: 7–14 days, depending on clinical response.
- Considerations: Bacteriostatic; effectiveness reduced by concurrent calcium‑rich diets; avoid use in pregnant females due to embryotoxicity.
Macrolides (e.g., tylosin, erythromycin)
- Dosage: 50–100 mg/kg, delivered in feed or water.
- Treatment length: 5–10 days.
- Considerations: Bacteriostatic; may cause gastrointestinal disturbance; resistance reported in some Mycoplasma strains.
Fluoroquinolones (e.g., enrofloxacin, ciprofloxacin)
- Dosage: 5–10 mg/kg, administered subcutaneously or orally.
- Treatment length: 5 days minimum.
- Considerations: Bactericidal; high tissue penetration; potential for cartilage toxicity in young animals; monitor for selection of resistant organisms.
Lincosamides (e.g., clindamycin)
- Dosage: 10 mg/kg, given orally.
- Treatment length: 7 days.
- Considerations: Effective against certain Mycoplasma species; risk of Clostridioides difficile overgrowth; limited data in rodents.
Pleuromutilins (e.g., tiamulin)
- Dosage: 20 mg/kg, incorporated into feed.
- Treatment length: 5–7 days.
- Considerations: Bacteriostatic; low incidence of resistance; not widely available in all regions.

Selection of an antimicrobial agent should reflect susceptibility testing, the severity of infection, and the physiological status of the animal cohort. Combination therapy is generally avoided to prevent antagonistic interactions, unless guided by culture results. Monitoring of clinical signs and periodic PCR testing confirm therapeutic success and help detect recrudescence.

Duration of Treatment

Mycoplasma infection in laboratory rats requires antimicrobial therapy whose length determines therapeutic success and limits recurrence.

Typical regimens employ tetracyclines, fluoroquinolones, or macrolides. Reported treatment periods are:

Tetracycline (oral or subcutaneous): 7–14 days, extended to 21 days for severe respiratory involvement.
Enrofloxacin (injected or administered via drinking water): 5–10 days; longer courses (up to 14 days) when systemic spread is documented.
Azithromycin (or other macrolides): 10–14 days, with a minimum of 7 days if only mild enteric colonization is present.

Duration adjustments depend on several variables. High bacterial load, multi‑organ involvement, or infection with resistant strains generally mandate prolonged therapy. Young, immunocompromised, or pregnant animals may require extended courses to achieve clearance. Route of administration influences drug bioavailability; water‑borne delivery often necessitates longer exposure to maintain effective plasma concentrations.

Therapeutic cessation is justified when:

Clinical signs (nasal discharge, sneezing, weight loss) have resolved for at least 48 hours.
Two consecutive cultures or PCR assays, spaced 48 hours apart, return negative.
Hematological parameters (elevated neutrophils, lymphocytosis) revert to baseline.

After completing antimicrobial treatment, a monitoring interval of 2–4 weeks is recommended. Re‑evaluation during this period identifies latent carriers and prevents re‑establishment of infection within the colony.

Potential Side Effects

Mycoplasma infection in laboratory rats can produce a range of adverse reactions that may confound experimental outcomes and compromise animal welfare. Clinical manifestations include respiratory distress, reduced weight gain, and altered behavior such as lethargy or increased aggression. Hematological changes often involve lymphocytosis or neutropenia, while histopathology may reveal pulmonary inflammation and epithelial degeneration.

Therapeutic interventions, particularly antimicrobial agents, introduce additional risks. Commonly used drugs such as tetracyclines, macrolides, and fluoroquinolones can cause:

Gastrointestinal irritation, leading to diarrhea or reduced feed intake.
Hepatotoxicity, reflected in elevated liver enzymes and potential hepatic necrosis.
Nephrotoxicity, indicated by increased serum creatinine and impaired renal function.
Disruption of normal microbiota, predisposing to opportunistic infections or dysbiosis.
Phototoxic reactions, especially with tetracycline derivatives, causing skin lesions under bright lighting.

Repeated dosing or high concentrations may exacerbate these effects, resulting in cumulative organ damage. Drug interactions, for example between macrolides and anesthetic agents, can prolong sedation or alter cardiovascular stability. Monitoring protocols should include regular assessment of body weight, feed consumption, blood chemistry, and behavioral observations to detect early signs of toxicity.

Preventive measures, such as dose optimization, rotating antimicrobial classes, and employing supportive care (e.g., fluid therapy, hepatic protectants), can mitigate side effects while maintaining therapeutic efficacy.

Supportive Care

Supportive care maximizes recovery chances for rats afflicted with mycoplasma infections and complements antimicrobial therapy. Adequate hydration prevents dehydration from fever‑induced tachypnea and reduced water intake. Provide sterile, palatable fluids through automatic dispensers or syringe feeding; monitor consumption at least twice daily and replace water bottles to avoid biofilm formation.

Nutritional support addresses anorexia and weight loss common in infected rodents. Offer high‑calorie, easily digestible diets such as pelleted mash enriched with vitamins and minerals. Supplement with soft, nutrient‑dense gels or syringe‑delivered emulsified formulas when oral intake declines. Record body weight every 24 hours to detect rapid loss.

Environmental management reduces stress and secondary complications. Maintain cage temperature within the thermoneutral zone (22–26 °C) and humidity between 45–55 %. Use low‑dust bedding, replace it frequently, and ensure adequate ventilation without drafts. Isolate affected animals in a dedicated rack equipped with HEPA filtration to limit pathogen spread.

Pain and discomfort control improves overall condition. Administer analgesics (e.g., meloxicam 1 mg/kg subcutaneously every 24 h) according to veterinary guidelines, adjusting dosage based on clinical signs. Monitor respiratory rate, nasal discharge, and ocular secretions to gauge disease progression.

Regular clinical assessment guides supportive interventions. Implement a checklist for each animal:

Body weight and condition score
Water and food consumption
Respiratory pattern and temperature
Presence of mucosal secretions
Response to analgesics and antibiotics

Document findings in a centralized log to identify trends and adjust care promptly. Together, these measures create a comprehensive supportive framework that enhances the efficacy of antimicrobial regimens and facilitates recovery in mycoplasma‑infected rats.

Improving Environmental Conditions

Optimizing the environment of laboratory rats directly influences the incidence and severity of Mycoplasma infections. Clean, well‑ventilated cages reduce aerosol transmission, while maintaining temperature between 20 °C and 24 °C and relative humidity of 40–60 % stabilizes mucosal barriers. Regular replacement of bedding material eliminates reservoirs of organisms; low‑dust, autoclaved substrates are preferred.

Key environmental measures include:

Ventilation: At least 15 air changes per hour with HEPA filtration to remove airborne pathogens.
Sanitation: Daily removal of waste, weekly deep cleaning of cage racks, and routine disinfection of surfaces with agents proven effective against Mycoplasma species.
Bedding management: Use of sterile, absorbent bedding; replace at intervals not exceeding three days to prevent moisture buildup.
Temperature and humidity control: Continuous monitoring with calibrated devices; adjust HVAC settings to maintain stable ranges.
Quarantine facilities: Isolate new arrivals for a minimum of two weeks, providing separate airflow and dedicated equipment to prevent cross‑contamination.
Stress reduction: Provide nesting material, enrichment objects, and consistent lighting cycles (12 h light/12 h dark) to minimize immunosuppression linked to chronic stress.

Implementing these practices creates a barrier that limits pathogen spread, supports the efficacy of antimicrobial regimens, and promotes overall animal welfare during experimental protocols.

Nutritional Support

Nutritional management is a critical component of therapeutic protocols for rats infected with Mycoplasma species. Adequate caloric intake supports immune function, reduces catabolism, and promotes recovery from respiratory and systemic manifestations.

A balanced diet should emphasize high-quality protein sources (e.g., casein, soy isolate) to compensate for increased nitrogen loss. Energy density can be raised by incorporating 10–15 % corn oil or medium‑chain triglycerides, which are readily oxidized and do not exacerbate hepatic strain. Fiber content must remain moderate (3–5 % crude fiber) to prevent gastrointestinal stasis while maintaining gut motility.

Micronutrient supplementation addresses deficiencies commonly observed during infection:

Vitamin C (50–100 mg kg⁻¹ day⁻¹) enhances neutrophil activity.
Vitamin E (20–30 IU kg⁻¹ day⁻¹) provides antioxidant protection.
Zinc (10–15 mg kg⁻¹ day⁻¹) supports epithelial repair.
Selenium (0.1 mg kg⁻¹ day⁻¹) contributes to oxidative stress mitigation.

Fluid therapy complements dietary measures. Subcutaneous administration of sterile isotonic saline (10 ml kg⁻¹) restores hydration and facilitates nutrient transport. In severe cases, oral rehydration solutions enriched with electrolytes and glucose (2 % dextrose, 0.9 % NaCl) may be offered via gavage.

Feeding frequency should increase to three to four small meals per day, reducing the burden of large bolus ingestion and maintaining steady nutrient absorption. Palatable, soft formulations (e.g., gelatin‑based blocks) improve intake in animals experiencing oral discomfort or reduced appetite.

Monitoring body weight, food consumption, and serum biochemical parameters (total protein, albumin, electrolyte balance) allows timely adjustment of the nutritional plan, ensuring optimal support throughout the treatment course.

Pain Management

Effective pain control is essential when treating mycoplasma infections in laboratory rats. Analgesic selection must consider the pathogen’s impact on respiratory and musculoskeletal systems, the experimental endpoints, and potential drug interactions.

Non‑steroidal anti‑inflammatory drugs (NSAIDs) such as meloxicam (1–2 mg kg⁻¹ subcutaneously, once daily) or carprofen (5 mg kg⁻¹ oral, every 12 h) provide anti‑inflammatory and analgesic effects. Use is limited by possible gastrointestinal irritation and interference with immune responses.
Opioids, including buprenorphine (0.05–0.1 mg kg⁻¹ subcutaneously, every 8–12 h) and fentanyl patches (0.018 mg kg⁻¹ day⁻¹), deliver strong analgesia without significant anti‑inflammatory activity. Monitor respiratory rate and sedation, especially in animals with compromised lung function.
Local anesthetics (e.g., lidocaine 2 % topical or bupivacaine 0.25 % infiltrative) can be applied for procedural pain, reducing systemic drug load.

Administration routes should match the study design: subcutaneous injections minimize stress, while oral dosing integrates with feed or water when long‑term analgesia is required. Drug stability in drinking water must be verified to avoid degradation.

Pain assessment relies on objective scoring systems: facial expression scales, hind‑limb grip strength, and locomotor activity tracking. Baseline measurements before infection establish reference values and enable detection of analgesic efficacy.

When analgesics are combined with antimicrobials such as doxycycline (10 mg kg⁻¹ oral, twice daily), verify that pharmacokinetic profiles do not diminish therapeutic concentrations. Adjust dosing intervals if drug‑drug interactions are documented.

Documentation of analgesic protocols, dosing schedules, and observed side effects is mandatory for reproducibility and ethical compliance. Regular review of pain management practices ensures alignment with institutional animal care standards and minimizes confounding variables in mycoplasma research.

Preventing Secondary Infections

Effective prevention of secondary infections in rodents suffering from Mycoplasma requires strict biosecurity, vigilant monitoring, and targeted therapeutic strategies.

First, isolate newly acquired or symptomatic animals in a dedicated quarantine area for at least two weeks. During quarantine, conduct daily clinical examinations and collect nasal, tracheal, and fecal samples for culture or PCR to detect opportunistic pathogens such as Streptococcus spp., Pseudomonas spp., and Clostridium spp. Early identification allows prompt intervention before organisms spread to the main colony.

Second, maintain a clean environment. Implement a routine disinfection schedule using agents proven effective against Mycoplasma and Gram‑negative bacteria (e.g., 0.1 % sodium hypochlorite, 70 % ethanol, or quaternary ammonium compounds). Replace bedding, water bottles, and feed containers weekly, and ensure ventilation rates of at least 15 air changes per hour to reduce aerosolized pathogen load.

Third, control stressors that compromise immunity. Provide consistent temperature (20‑22 °C), humidity (45‑55 %), and light cycles (12 h light/12 h dark). Offer a balanced diet enriched with vitamin C, zinc, and omega‑3 fatty acids to support mucosal barriers.

Fourth, apply antimicrobial stewardship. When Mycoplasma infection necessitates treatment, select agents with narrow spectra (e.g., tetracyclines) and avoid broad‑spectrum antibiotics that may disrupt normal flora and promote overgrowth of resistant organisms. Monitor drug levels and adjust dosages based on serum concentrations to minimize sub‑therapeutic exposure.

Fifth, consider prophylactic measures for high‑risk groups:

Administer prophylactic macrolides to breeding pairs during peak breeding season.
Use immunostimulants (e.g., bacterial lysates) to enhance innate defenses.
Employ sentinel animals to detect emerging secondary pathogens early.

Finally, document all interventions in a centralized health‑record system. Record quarantine dates, diagnostic results, treatment regimens, and environmental parameters. Regular audit of this database highlights trends, enabling preemptive adjustments to husbandry practices.

By integrating isolation, sanitation, stress reduction, judicious antimicrobial use, and systematic record‑keeping, secondary infections in Mycoplasma‑affected rodent colonies can be substantially reduced, preserving animal welfare and experimental integrity.

Management and Prevention Strategies

Biosecurity Measures

Biosecurity protocols are indispensable for preventing and controlling mycoplasma infections in laboratory rat colonies. Effective measures reduce pathogen introduction, limit spread, and protect research integrity.

Implement a strict quarantine for all new arrivals; isolate animals for a minimum of four weeks while conducting PCR screening for mycoplasma.
Enforce dedicated personnel and equipment for infected and non‑infected rooms; use separate cages, feeding devices, and transport carts.
Require personal protective equipment (gloves, lab coats, shoe covers) for anyone entering animal rooms; disinfect hands and clothing before and after contact.
Apply routine environmental cleaning with agents proven to inactivate mycoplasma, such as 70 % ethanol or quaternary ammonium compounds; focus on cage racks, work surfaces, and ventilation ducts.
Conduct regular health monitoring; schedule monthly serological and molecular tests on sentinel animals and a random sample of the colony.
Maintain a documented record of all biosecurity actions; include dates of quarantine, test results, cleaning logs, and personnel access.

Adherence to these practices sustains a pathogen‑free environment, safeguards experimental outcomes, and complies with institutional animal care standards.

Quarantine Protocols

Effective quarantine of rodents suspected of mycoplasma infection limits pathogen spread and safeguards research integrity. Upon arrival, each animal should be placed in a sealed isolation cage within a dedicated biosafety cabinet. Access to the cage is restricted to personnel wearing disposable gloves, gowns, and shoe covers; all handling occurs inside a laminar flow hood to prevent aerosol dissemination.

Standard quarantine duration extends to 30 days, during which the following procedures are mandatory:

Daily health monitoring, including observation for respiratory distress, ocular discharge, and weight loss.
Serial sampling of oropharyngeal swabs on days 7, 14, and 28 for PCR detection of mycoplasma DNA.
Serological testing on day 28 to confirm seroconversion status.
Immediate removal of any animal showing clinical signs, followed by necropsy and culture to identify the specific mycoplasma strain.

Environmental controls complement animal-level measures. Airflow within the quarantine room must be unidirectional, with HEPA filtration at both supply and exhaust points. Surfaces are disinfected twice daily using a 0.5 % sodium hypochlorite solution, and all waste is autoclaved before disposal. Records of temperature, humidity, and ventilation rates are logged continuously to ensure conditions remain within validated parameters (20–22 °C, 45–55 % relative humidity).

If PCR or serology indicates infection, the entire cohort undergoes treatment according to established antimicrobial regimens, and quarantine is extended until two consecutive negative test results are obtained at least 7 days apart. Upon clearance, animals may be transferred to the main animal facility following a final health assessment and documentation of quarantine completion.

Regular Cleaning and Disinfection

Regular cleaning and disinfection are fundamental components of a mycoplasma control program for laboratory rats. Contaminated bedding, cage surfaces, and feeding equipment provide reservoirs for the pathogen, facilitating transmission among animals and compromising experimental outcomes.

Effective protocols include:

Daily removal of soiled bedding and immediate disposal in biohazard containers.
Weekly deep cleaning of cages with a detergent solution followed by a rinse with distilled water.
Disinfection of cage interiors, water bottles, and feeders using agents proven to inactivate mycoplasma, such as 0.1 % sodium hypochlorite, 70 % ethanol, or quaternary ammonium compounds with validated efficacy.
Sterilization of reusable equipment (e.g., metal cages, metal trays) by autoclaving at 121 °C for 30 minutes.
Periodic fumigation of animal rooms with vaporized hydrogen peroxide or chlorine dioxide to reduce environmental load.

Selection of disinfectants must consider compatibility with cage materials and the absence of residual toxicity. Validation procedures, such as swab sampling followed by PCR or culture, confirm the elimination of mycoplasma after each cleaning cycle.

Personnel hygiene reinforces environmental measures. Handwashing with antimicrobial soap before and after handling cages, use of disposable gloves, and routine changing of lab coats limit cross‑contamination. Training programs that emphasize correct dilution, contact time, and thorough coverage of surfaces ensure consistent application of the disinfection regimen.

Integration of these practices into a documented standard operating procedure enables reproducible control of mycoplasma in rat colonies, supporting reliable research data.

Reducing Stress Factors

Stress reduction is essential for controlling Mycoplasma infections in laboratory rats and enhancing the efficacy of therapeutic protocols. Elevated cortisol levels impair immune function, increase pathogen shedding, and interfere with antibiotic absorption, thereby compromising treatment outcomes.

Key environmental measures include:

Maintaining temperature within the species‑specific optimal range (20‑24 °C) and humidity at 45–55 %.
Providing consistent light cycles (12 h light/12 h dark) with minimal flicker.
Ensuring cage ventilation without drafts and limiting noise below 70 dB.
Using low‑density bedding and avoiding scented enrichment that may trigger anxiety.

Handling practices that minimize stress:

Acclimating rats to the handling area for at least 30 minutes before procedures.
Employing gentle, two‑hand scooping techniques rather than tail lifts.
Limiting the duration of restraint to the shortest possible period.
Conducting all manipulations by the same trained personnel to reduce novelty.

Nutritional and social strategies:

Supplying a balanced diet enriched with omega‑3 fatty acids to support anti‑inflammatory pathways.
Offering chewable objects and nesting material to promote natural foraging behavior.
Housing compatible individuals in groups of 3–5 to satisfy social needs while preventing overcrowding.

Implementing these stress‑mitigation tactics creates a stable physiological baseline, thereby decreasing Mycoplasma transmission risk and improving the reliability of treatment regimens.

Genetic Predisposition and Breeding Considerations

Genetic factors influence the likelihood that a rat will acquire and maintain Mycoplasma infection. Specific major histocompatibility complex (MHC) alleles correlate with higher bacterial load, while other haplotypes exhibit reduced colonization. Studies comparing commonly used inbred strains reveal that Sprague‑Dawley rats often display greater susceptibility than Fischer 344 or Wistar rats, suggesting strain‑dependent immune responsiveness.

Breeding programs can mitigate infection risk through several practical measures:

Maintain colonies under specific pathogen‑free (SPF) conditions; regular microbiological testing identifies asymptomatic carriers before breeding.
Prefer strains with documented lower prevalence of Mycoplasma colonization for long‑term projects.
Implement embryo transfer or cesarean rederivation when introducing new genetic lines to avoid vertical transmission.
Apply selective breeding to enhance resistance; track MHC haplotypes and exclude individuals carrying high‑risk alleles.
Separate breeding pairs by health status; avoid mixing infected and uninfected groups to prevent horizontal spread.

When establishing new colonies, the initial health screen should include polymerase chain reaction (PCR) assays for Mycoplasma species. Positive results mandate culling or decontamination before any breeding occurs. Continuous monitoring of offspring, combined with genetic record‑keeping, ensures that resistance traits are retained while eliminating persistent infection sources.

Long-Term Prognosis and Quality of Life

Mycoplasma infections in laboratory rats produce chronic respiratory and systemic effects that shape long‑term health outcomes. Persistent colonization often leads to reduced growth rates, diminished reproductive performance, and shortened lifespan, especially when initial infection occurs in young or immunocompromised individuals. Successful antimicrobial therapy during the acute phase markedly improves survival probability, yet subclinical persistence can still compromise future vitality.

Key determinants of prognosis include:

Pathogen virulence and strain specificity
Age and immunological status at infection onset
Completeness of antimicrobial course and drug susceptibility
Environmental hygiene and biosecurity measures

Quality‑of‑life assessments focus on measurable parameters rather than subjective judgments. Primary indicators are:

Body weight trajectory and feed conversion efficiency
Activity levels recorded via motion sensors or observational scoring
Reproductive output: litter size, pup survival, and breeding interval
Clinical signs: respiratory rate, nasal discharge, and ocular involvement

Optimizing long‑term welfare requires integrated management:

Administer a full course of a mycoplasma‑effective antibiotic (e.g., tylosin or enrofloxacin) based on susceptibility testing.
Implement rigorous cage sanitation, HEPA filtration, and quarantine of affected cohorts.
Conduct periodic health monitoring using PCR or culture to detect low‑level carriage.
Adjust nutrition to support immune recovery, emphasizing high‑quality protein and essential micronutrients.

When these practices are applied consistently, affected rats can achieve near‑normal growth curves, maintain reproductive competence, and exhibit life spans comparable to uninfected controls. Continuous surveillance ensures early detection of recrudescence, preserving both health status and experimental reliability.