How much doxycycline should be given to a rat? - briefly
Administer doxycycline to a rat at 5–10 mg per kilogram of body weight per day, delivered orally (e.g., via gavage) or mixed in drinking water at approximately 0.5 mg/mL to achieve the same dose. Adjust the concentration based on the animal’s weight and water consumption to maintain the target dosage.
How much doxycycline should be given to a rat? - in detail
Doxycycline is administered to rats based on body weight, with the therapeutic range generally set at 5–10 mg per kilogram each day. The exact amount depends on the intended purpose—treatment of bacterial infection, prophylaxis, or experimental modulation of the microbiome.
For a rat weighing 250 g, the calculation is straightforward:
- 5 mg kg⁻¹ × 0.25 kg = 1.25 mg per day
- 10 mg kg⁻¹ × 0.25 kg = 2.5 mg per day
When delivering the drug by oral gavage, dissolve the required milligrams in sterile water and administer a volume of 1 mL per 100 g of body weight. For the 250‑g example, a 2 mL dose containing 2.5 mg of doxycycline provides the upper end of the recommended range.
If the medication is supplied in drinking water, adjust the concentration to match average intake. Rats of this size consume roughly 30–40 mL of water daily. To achieve a daily dose of 2 mg, prepare water with a concentration of 0.05–0.07 mg mL⁻¹ (2 mg ÷ 30–40 mL). A concentration of 0.2–0.5 mg mL⁻¹ is often used in research protocols to ensure adequate intake despite variations in consumption.
Safety considerations include:
- Monitoring for signs of gastrointestinal irritation or reduced feed intake
- Limiting continuous exposure to 7–14 days unless a longer course is justified
- Reducing dose for pregnant, lactating, or neonatal animals, as doxycycline crosses the placenta and is secreted in milk
Guidelines from the National Research Council, veterinary pharmacology references, and institutional animal care committees support these dosage parameters. Adjustments should be made based on specific strain characteristics, health status, and experimental objectives.