How do you correctly perform inhalation therapy for rats? - briefly
Place the rat in a sealed exposure chamber, deliver the aerosolized medication using a calibrated nebulizer at 0.5–1 L/min for 5–15 minutes while monitoring breathing, then return the animal to its cage, observe for adverse reactions, and document the administered dose.
How do you correctly perform inhalation therapy for rats? - in detail
Inhalation therapy in laboratory rats requires precise control of aerosol generation, exposure conditions, and animal handling to achieve reproducible therapeutic outcomes.
Equipment and setup
- Nebulizer capable of producing particles 1–5 µm, calibrated for the chosen drug.
- Exposure chamber with airtight seals, inlet and outlet ports, and a flowmeter to maintain a constant air velocity of 0.5–1 L/min.
- Exhaust system with high‑efficiency particulate air (HEPA) filter to prevent environmental contamination.
- Temperature and humidity sensors to keep conditions at 22 ± 2 °C and 50 ± 10 % relative humidity.
Animal preparation
- Acclimate rats to the laboratory environment for at least 48 h.
- Fast animals for 4 h prior to exposure to reduce gastric content aspiration.
- Anesthetize with an injectable agent (e.g., ketamine 80 mg/kg + xylazine 10 mg/kg) to minimize stress and ensure steady breathing.
- Position each rat in a restraining tube that allows unrestricted airflow through the nose and mouth while preventing escape.
Dose calculation and aerosol generation
- Determine the required dose in mg/kg; multiply by the animal’s weight to obtain the absolute amount.
- Dissolve the drug in a suitable solvent (e.g., sterile saline) at a concentration that yields the target dose within the planned exposure time.
- Prime the nebulizer with the solution, purge air lines, and verify aerosol output using a cascade impactor or laser diffraction device.
Exposure procedure
- Start the airflow and confirm stable chamber pressure.
- Introduce the nebulizer; begin aerosolization for the predetermined duration (typically 5–15 min).
- Monitor particle size distribution and aerosol concentration with an inline photometer.
- Record respiratory rate and tidal volume of each rat using a plethysmograph attached to the restraining tube.
Monitoring and safety
- Observe animals continuously for signs of distress, apnea, or abnormal breathing patterns.
- Maintain a log of chamber temperature, humidity, and aerosol concentration at 1‑minute intervals.
- If any rat exhibits severe respiratory compromise, terminate exposure and provide supplemental oxygen.
Post‑exposure care
- Transfer rats to a recovery cage with warmed bedding; monitor until the righting reflex returns.
- Administer analgesics (e.g., buprenorphine 0.05 mg/kg SC) if invasive procedures were performed.
- Return animals to their home cages after full recovery, typically within 30‑60 min.
Troubleshooting common issues
- Low aerosol output: check nebulizer membrane for clogging, replace if necessary.
- Particle size drift: recalibrate the nebulizer or adjust the carrier gas flow rate.
- Variable dosing among subjects: verify uniform airflow distribution across the chamber; consider using individual exposure ports for each animal.
Adhering to these steps ensures consistent delivery of inhaled therapeutics to rats, minimizes variability, and upholds animal welfare standards.