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Stresnil 40mg Solution for Injection 100ml


Stresnil is a neuroleptic sedative for pigs, to be used for the treatment of: 1.Aggression -prevention of fighting; -treatment of aggression in sows.
Prescription Medicine

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Clear, pale yellow sterile, aqueous solution for injection containing 40 mg azaperone per ml.

Excipients include:

Methyl parahydroxybenzoate (E218) (antimicrobial preservative) 0.5 mg/ml

Propyl parahydroxybenzoate (E216) (antimicrobial preservatives) 0.05 mg/ml

Sodium metabisulphite (E223) (antioxidant) 2.0 mg/ml


Stresnil is a neuroleptic sedative for pigs, to be used for the treatment of:


-prevention of fighting;

-treatment of aggression in sows.

2.Stress, including transport-related stress.

3.Obstetric conditions e.g. cessation of parturition due to excitation, as an obstetric aid in manual delivery, inversion of the vagina, prolapse of the uterus, pathological straining.

4.Premedication in local and general anaesthesia.

Dosage and administration

Mode of administration

To be given strictly by intramuscular injection behind the ear. A long hypodermic needle should be used and the injection given as closely behind the ear as possible and perpendicularly to the skin. There is a risk of injecting part of the drug into the fat, if heavy animals are injected with a short needle into the neck. In this case, the injection may have insignificant effect.

An appropriately graduated syringe must be used to allow accurate administration of the required dose volume. This is particularly important when injecting small volumes.


It is important to adhere to the recommended dose. Aggression may only be curbed temporarily or not at all if the dose is too low. If the dose is too high, aggression may recur after awakening.

1. Aggression

i) Prevention and cure of fighting (including regrouping of piglets, porkers or fattening pigs)

1 ml/20 kg (2 mg/kg)

Pigs from different litters or pens may be brought together into one pen immediately after administration. All animals should be treated. After a few minutes, they lie down together for about two hours, irrespective of their origin. Afterwards, violent fights are unlikely to occur.

During the time of treatment, untreated animals should not be admitted to the run. the product will not prevent aggressiveness in non-castrated adult boars. Newly weaned piglets may be treated together with other routine treatments on arrival at the fattening unit.

Fighting animals become quiet shortly after the injection. The animals are unlikely to fight even after the effect of the drug has worn off.

ii) Treatment of aggression in sows i.e. in sows that do not accept their new-born piglets, or bite them

1 ml/20 kg (2 mg/kg)

The sow will accept her piglets ½ to 1 hour after administration and will also accept piglets from other litters.

2. Stress

i) Restlessness, anxiety, nervousness, excitation, e.g. because of pain

0.5–1 ml/20 kg (1–2 mg/kg)

The dosage should be adapted to the degree of excitation. If the animal is very nervous, the product may be given in divided doses at 15 minute intervals.

ii) Transport of boars

0.5 ml/20 kg (1 mg/kg)

The animals should not be brought together within the first half hour following injection because they are still likely to be aggressive; they should be left alone in a quiet environment during the induction period (approximately 30 minutes). The dose of 0.5 ml/20 kg (1 mg/kg) should not be exceeded as a higher dose may cause the penis to be extruded, which may then be damaged.

iii) Transport of weaners

1 ml/100 kg to 1 ml/20 kg (0.4–2 mg/kg)

Administer 15–30 minutes before transport to reduce mortality and weight loss during transport. The dose can be increased up to 1 ml/20 kg (2 mg/kg) in order to prevent fighting during transport. Allow adequate space for animals to lie down and ensure that the lorry is adequately ventilated.

3. Obstetrics

1 ml/20 kg (2 mg/kg)

For use in cessation of parturition due to excitation, as an obstetric aid during manual delivery, inversion of the vagina, prolapse of the uterus, pathological straining.

4. Premedication in local and general anaesthesia

0.5–1 ml/20 kg (1–2 mg/kg)

For example in blood sampling, diagnostic examination and minor therapeutic interventions under local anaesthesia (castration, cryptorchidism and prolapse of the rectum, inguinal hernia, wound treatment, insertion of nose rings in boars and sows, etc).

Exact dosage will depend on the type and duration of the procedure and concomitant medication.

Contra-indications, warnings, etc


Stresnil is contraindicated for use in transport or for regrouping of pigs which will be slaughtered prior to the end of the 10 day withdrawal period.

The use of Stresnil should be avoided in very cold conditions because of a possible risk of cardiovascular collapse due to peripheral vasodilation.

In boars, a dose of 0.5 ml/20 kg should not be exceeded, as a higher dose may cause the penis to be extruded, which may then be damaged.

Precautions and warnings

After treatment, the animal should be left alone in a quiet environment. Insufficient results may be obtained if the animal is disturbed or chased during the induction period.

Occasional deaths have been observed in Vietnamese Pot Bellied Pigs. It is thought this may be caused by injection into the fat leading to slow induction and tendency to use additional doses, leading to overdosage. It is important with this breed not to exceed the stated dose. If the initial dose does not appear to have an effect, allow complete recovery before re-injecting on a different day.

Can be used in pregnant and lactating animals, and in particular obstetric conditions e.g., cessation of parturition due to excitation or as an obstetric aid to manual delivery.

Salivation and panting may occur at high doses. These side effects disappear spontaneously and leave no lasting damage.


When given as premedication for general anaesthesia, the dosage of the anaesthetic should be reduced because of the potentiating effect of azaparone.


If the dose exceeds that recommended, aggression may result on reawakening. In boars overdosing (>1 mg/kg) may cause the penis to be extruded, which may then be damaged. Salivation and panting may occur at high doses.

Repeat dosing in Vietnamese Pot Bellied pigs too soon because of absorption of the initial dose in fat has resulted in death.

Withdrawal period

Pigs meat: 10 days.

Operator warnings

This is a potent drug. Particular care should be taken to avoid accidental self-administration. It is recommended that, once the required dose is withdrawn from the vial, the needle should be kept guarded until the product is administered. Alternatively, it should be removed from the syringe and immediately inserted into the injection site and the syringe should be connected to it.

Wash off splashes from skin and eyes immediately. In the case of accidental self-injection, seek medical advice immediately, and show the package leaflet or label to the physician. Wash hands after use.


Any unused product and empty containers should be disposed of in accordance with any guidance from your local waste regulation authority.

Shipping charges mainland UK zone1

Value Weight Delivery Charge
Over £49.00 Any Weight FREE
Under £49.00 No weight limit £4.50
Under £49.00 Under 250g £2.99

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*Due to legal requirements medicines may not be returned except to correct an error in despatch or in response to an "official recall". If an item is believed to be faulty it should be returned for inspection and it may be necessary to forward it to the manufacturers for testing before replacements or refunds can be authorised. This does not infringe legal rights. Please contact our customer services for a "Returns Number" which must appear on the outside of the package or it will not be accepted. We advise customers to use an insured method of shipping and to retain proof of despatch. We may refuse returns on products specially obtained or manufactured to order. Items must be returned unsoiled and unused and sent adequately packed and carriage paid.

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