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Stresnil (Canada)

This page contains information on Stresnil for veterinary use.
The information provided typically includes the following:
  • Stresnil Indications
  • Warnings and cautions for Stresnil
  • Direction and dosage information for Stresnil


This treatment applies to the following species:
Company: Elanco


Injection 40 mg/mL




DIN 00755710

Active Ingredient

Each mL of STRESNIL injection contains 40 mg azaperone.


Azaperone, the active ingredient of STRESNIL (azaperone) injection, is a sedative-tranquilizer of the butyrophenone series, a major class of tranquilizers. Chemically, it is 4’-fluoro-4-(4-(2 pyridyl)-1-piperazinyl]butyrophenone.


STRESNIL (azaperone) injection is a potent sedative-tranquilizer which produces a predictable and consistent response in pigs. The drug is fast-acting; the onset of action is approximately 5-10 minutes after intramuscular injection. After injection, the pigs should be left undisturbed in a quiet environment for about 20 minutes. The peak effect is reached in approximately 15 minutes in young animals and 30 minutes in mature animals and generally lasts for one to six hours. The animal remains conscious but is quiet and indifferent to the environment.


STRESNIL (azaperone) injection is indicated for the prevention of aggressiveness when mixing or regrouping pigs. The drug is recommended for use when pigs from different litters or pens are brought together, since they often fight in an attempt to establish a social order. Following a single dose of STRESNIL, pigs may be mixed; fighting is eliminated or greatly reduced.

Dosage and Administration

The recommended dose of azaperone for the pig is 2.2 mg/kg (1 mg/lb) of body weight. One mL of STRESNIL (azaperone) injection will treat 18.2 kg (40 lbs) of body weight. Inject STRESNIL intramuscularly just behind the ear (into the muscle above the wing of the atlas) or into the rump (semitendinosus and semimembranosus muscle). The hypodermic needle should be sufficiently long (2.5 to 5 cm) and held perpendicular to the surface of the skin to insure intramuscular deposition of STRESNIL.

All animals must be treated. Retreatment is necessary each time mixing or regrouping occurs.


Do not use in conjunction with castration because the hemorrhaging period may be extended. Do not use in breeding stock because the effects on reproduction have not been fully explored.

Stresnil Caution

Do not inject subcutaneously. If too short a needle is used the drug may not be deposited intramuscularly. When injecting behind the ear, the farther from the ear the greater the possibility of injection into the fat of the neck.

Adverse effects:

STRESNIL (azaperone) injection is generally well-tolerated. With the recommended dose possible side effects which may occur include incoordination, salivation, lethargy, piling, shivering and temporary anorexia. These reactions are of short duration and leave no lasting effects. At doses greater than recommended, these same reactions may occur in a more profound manner and will be of longer duration.


Treated animals must not be slaughtered for use in food for at least 24 hours after the latest treatment with this drug. This drug is not to be used in pigs in transit to slaughter.

How Supplied

STRESNIL (azaperone) injection, 40 mg/mL, is available in 100 mL vials.


Store between 15 to 25°C. Protect from light.

Stresnil, Elanco and the diagonal bar logo are trademarks of Elanco or affiliates.

© 2022 Elanco or its affiliates.

Manufactured by:

Elanco Canada Limited, 1919 Minnesota Court, Suite 401, Mississauga, Ontario L5N 0C9


CPN: 1231134.4

Customer Service:   800-265-5475
Fax:   519-821-7831
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Copyright © 2023 Animalytix LLC. Updated: 2023-02-28