What rat route limits does the planner enforce?

Per Diehl et al. (2001) Table 1: PO ≤10 mL/kg, IP ≤10 mL/kg, SC ≤5 mL/kg, IV bolus ≤5 mL/kg, IM ≤0.1 mL per site. Note that the rat IP limit (10 mL/kg) is *half* the mouse IP limit (20 mL/kg) — a common source of error when scaling protocols across species.

How does this differ from the general rodent dosing calculator?

The general rodent dosing calculator covers both mice and rats with a species toggle. This rat-specific planner adds strain presets (Sprague-Dawley, Wistar, Long-Evans, F344, Lewis, Brown Norway) with typical adult body weights, and surfaces only the rat route limits in the UI. Use the general calculator for mouse studies or for one-off mixed-species reference work.

What strain presets are included?

Six common laboratory rat strains: Sprague-Dawley (~300 g adult), Wistar (~280 g), Long-Evans (~320 g), Lewis (~250 g), F344/Fischer (~250 g), and Brown Norway (~290 g). Numbers are mid-range adult means from Charles River and Envigo husbandry guides; individual animals vary by ±25%.

Why is the rat IP limit only half the mouse limit?

Adult rats have proportionally less abdominal cavity volume relative to body weight than adult mice, and they tolerate large IP volumes less well — especially repeated dosing. Diehl et al. (2001) recommends 10 mL/kg as the good-practice ceiling for rats vs 20 mL/kg for mice. Exceeding this limit is sometimes justified for single-dose tolerability studies, but always requires explicit IACUC review.

Can I use this for repeated-dose pharmacology studies?

Yes for the per-dose math, but the planner does not model accumulation, induction, or tolerance. For chronic dosing, multiply the cohort stock volume by the number of doses, add a 10-20% margin for waste and missed injections, and verify drug stability over the storage window.

ToolsConductScience tool

Rat Colony ManagementFree in-browser calculator

Rat Dose Planner.

Plan rat injection volumes from body weight, dose, and stock concentration. Strain presets for Sprague-Dawley, Wistar, Long-Evans, F344. Enforces Diehl et al. (2001) rat route limits.

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Animal & Drug

Strain

Body weight (g)

Dose (mg/kg)

Stock concentration (mg/mL)

Route

Cohort size

Volume & Cohort Stock

Total dose

3.00 mg

10.0 mg/kg × 300 g

Injection volume

300 µL

0.300 mL per rat

Volume per kg

1.00 mL/kg

Diehl IP limit 10 mL/kg

Cohort stock

2.40 mL

8 rats — add 10-20% margin

When to use

Building a rat dosing sheet for an individual animal or cohort
Verifying a planned rat dose stays within Diehl rat route limits
Computing total stock volume needed for a daily rat dosing study
Porting a mouse protocol to a rat study (re-check the volume limits!)
Sanity-checking a published rat dose against the Diehl ceiling

Do not use for

For mouse studies — use the rodent dosing calculator with the mouse toggle
For accumulating-dose studies (multiply manually for total drug exposure)
For non-injection routes (inhalation, dermal, ocular)
For weanling rats under ~50 g — verify with veterinary staff first

Rat IP limit is half the mouse limit

When porting a mouse protocol to a rat study, the IP volume that worked for mice (up to 20 mL/kg) is over the rat ceiling (10 mL/kg). Adjust by either lowering the dose or increasing the stock concentration.

Tail-vein IV is technique-limited well below the Diehl ceiling

A 5 mL/kg IV limit gives ~1.5 mL for a 300 g rat — but practical tail-vein injection is usually limited to ~0.5–1 mL because of vein back-pressure and warming-required dilation.

Use strain-typical body weights for cohort stock volume

A Sprague-Dawley study budgeted at 250 g/rat will under-prep stock when the actual animals arrive at 300 g. Use the strain preset defaults as the floor and add 10-20% margin.

Group housing matters for repeated dosing

Stress from individual handling reduces drug uptake variance, but repeated handling of group-housed rats stresses cage-mates. For chronic studies, plan handling order to minimize cage-mate stress.

Method

Total dose (mg) = body_weight_kg $\times$ dose_mg_per_kg. Injection volume (mL) = total_dose / stock_concentration. Volume per kg = volume / body_weight_kg, compared against the rat entry in Diehl et al. (2001) Table 1. Rat strain presets carry typical adult body weights from Charles River and Envigo husbandry guides.

Validated

Last validated 2026-04-06. Calculations are designed for planning and documentation support; verify procurement decisions against manufacturer specifications or institutional SOPs.

How to cite

How to Cite

ConductScience Rat Dose Planner (v0.91.0). ConductScience, Inc. 2026. Available at: https://conductscience.com/tools/rat-dose-planner

Diehl KH, Hull R, Morton D, et al. A good practice guide to the administration of substances and removal of blood, including routes and volumes. J Appl Toxicol. 2001;21(1):15-23.

Turner PV, Brabb T, Pekow C, Vasbinder MA. Administration of substances to laboratory animals: routes of administration and factors to consider. JAALAS. 2011;50(5):600-613.

Common Laboratory Rat Strains

The choice of rat strain has major implications for dosing math, drug metabolism, and study interpretation. The most commonly used strains in US biomedical research:

Sprague-Dawley (SD)

Outbred white rat. Adult males ~300–500 g, females ~225–325 g. The default rat strain at most US academic vivariums and the most common rat in pharmacology, toxicology, and behavior studies. Heterogeneous response is a feature for some studies and a confound for others.

Wistar

Outbred white rat, slightly smaller and more docile than SD. Adult ~250–350 g. The most widely used rat strain in Europe and Asia. Often interchangeable with SD for routine pharmacology.

Long-Evans

Outbred hooded rat (white body, dark head). Adult ~300–400 g. The most common rat strain in behavioral neuroscience because the pigmented eyes give better visual acuity than albino strains.

Lewis (LEW)

Inbred. Adult ~225–325 g. Widely used in autoimmunity, transplantation, and stress research. More sensitive to pain stimuli than SD and Wistar.

F344 / Fischer 344

Inbred. Adult ~225–325 g. The historical NIA aging colony strain. Used heavily in carcinogenicity studies and longevity research.

Brown Norway (BN)

Inbred. Adult ~250–350 g. Used in respiratory allergy models and as the genetic background for several disease models.

Diehl et al. (2001) Rat Route Limits

The Diehl guide is the most cited source for rodent injection volumes in IACUC and AAALAC documentation. Rat-specific limits:

Maximum injection volumes (mL/kg) — adult rat

PO (oral gavage): 10
IP (intraperitoneal): 10
SC (subcutaneous, single site): 5
IV bolus (lateral tail vein): 5
IM (intramuscular, single site): 0.1 — very small per site

Notable contrast with mouse limits

The rat IP limit is half the mouse IP limit (10 vs 20 mL/kg). The rat SC limit is half the mouse SC limit (5 vs 10 mL/kg). The rat IM limit is 2× the mouse IM limit (0.1 vs 0.05 mL) — but rats also have larger muscle masses, so the absolute volume that fits is much larger.

When porting a mouse protocol to a rat study, do NOT just scale the dose by mg/kg — re-check the volume against the rat-specific limit, because the rat ceiling is more restrictive on most routes.

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