Alizin Dosage Guide for Dogs: How Much Does Your Dog Need? (Weight-Based Chart)
Complete Alizin Dosage Guide for Dogs by Weight
If your dog has had an accidental mating and you’re looking into Alizin (aglepristone) as a solution, one of the first questions you’ll have is: how much Alizin does my dog actually need? This guide covers everything you need to know about Alizin dosing, how the injection works, what to expect afterwards, and answers to the most common questions dog owners ask.
Important: Alizin is a prescription veterinary medicine. Always consult your veterinarian before use.
What is Alizin?
Alizin is an injectable veterinary medication manufactured by Virbac containing aglepristone at a concentration of 30mg per ml. It is a synthetic progesterone antagonist — meaning it blocks the hormone progesterone, which is essential for maintaining pregnancy in dogs.
Alizin is licensed to terminate unwanted pregnancies in bitches (female dogs) from day 0 to day 45 after mating. It works by competitively binding to the progesterone receptors in the uterus with 3 times the affinity of the body’s own progesterone, effectively preventing embryo implantation or causing resorption/abortion of existing pregnancies.
You can buy Alizin injection online at PetShopBoss.com with worldwide shipping.
Alizin Dosage: The Basic Formula
The standard dose of Alizin for pregnancy termination in dogs is:
- 10mg aglepristone per kg of body weight
- This equals 0.33ml of Alizin per kg of body weight (since the concentration is 30mg/ml)
- Given as TWO subcutaneous injections, exactly 24 hours apart
The timing between the two injections is critical for efficacy. Both injections are the same dose.
Alizin Dosage Chart by Dog Weight
Use this chart to quickly determine how much Alizin your dog needs per injection:
| Dog Weight | Weight in lbs | Alizin per Injection | Total for 2 Injections | Vials Needed (10ml) |
|---|---|---|---|---|
| 3 kg | 6.6 lbs | 1.0 ml | 2.0 ml | 1 vial |
| 5 kg | 11 lbs | 1.65 ml | 3.3 ml | 1 vial |
| 7 kg | 15.4 lbs | 2.3 ml | 4.6 ml | 1 vial |
| 10 kg | 22 lbs | 3.3 ml | 6.6 ml | 1 vial |
| 15 kg | 33 lbs | 5.0 ml | 10.0 ml | 1 vial |
| 20 kg | 44 lbs | 6.6 ml | 13.2 ml | 2 vials |
| 25 kg | 55 lbs | 8.25 ml | 16.5 ml | 2 vials |
| 30 kg | 66 lbs | 9.9 ml | 19.8 ml | 2 vials |
| 40 kg | 88 lbs | 13.2 ml | 26.4 ml | 3 vials |
| 50 kg | 110 lbs | 16.5 ml | 33.0 ml | 4 vials |
Remember: If the injection volume exceeds 5ml, you must split the dose across multiple injection sites.
How to Administer Alizin
Alizin should be administered by a veterinarian or under veterinary supervision:
- Route: Subcutaneous injection only (under the skin)
- Preferred site: Scruff of the neck
- Preparation: Use strict aseptic technique — clean the vial septum before drawing each dose, use a sterile needle and syringe
- After injection: Lightly massage the injection site
- Volume limit: Maximum 5ml per injection site — split larger doses across multiple sites
- Schedule: Two injections, 24 hours apart. Timing is essential for success
When to Use Alizin: Timing Matters
Alizin can be used from day 0 to day 45 post mating, but timing affects efficacy:
- Day 0–21 (first trimester): Efficacy is approximately 99%. The pregnancy is terminated through embryo resorption — usually with minimal visible signs
- Day 22–45 (second trimester): Efficacy is approximately 95%. Abortion occurs with visible signs similar to whelping (fetal expulsion, vaginal discharge, reduced appetite)
Virbac recommends waiting until after the end of oestrus (heat) before using Alizin, typically 10–14 days post mating. This avoids the need for repeat courses if the bitch is re-mated during the same heat cycle.
What to Expect After Alizin Treatment
If treated before day 20: The embryos are resorbed by the body. You may notice little to no external signs. Mild appetite changes or restlessness may occur for a day or two.
If treated after day 20: Abortion will occur with signs similar to natural birth — fetal expulsion, brownish vaginal discharge, reduced appetite, and possible mammary congestion or mild lactation.
The abortion/resorption process typically starts within a few days and is complete within 7 days.
Follow-up: A veterinary examination (ideally ultrasound) is recommended approximately 10 days after treatment to confirm the pregnancy has been fully terminated. If partial abortion or treatment failure is detected, a repeat course may be given between days 30–45.
Alizin for Pyometra Treatment
Beyond pregnancy termination, Alizin is increasingly used off-label for the medical management of pyometra (uterine infection) in dogs and cats. This is particularly relevant for breeding animals where preserving fertility is important.
How it works for pyometra: By blocking progesterone, Alizin promotes cervical opening and uterine contractions, helping the uterus expel infectious material.
Typical protocol for dogs:
- 10mg/kg subcutaneously on Days 1, 2, 8 (and sometimes Day 15)
- Combined with broad-spectrum antibiotics
- Sometimes combined with prostaglandins (e.g., cloprostenol)
This approach is best suited for open-cervix pyometra in animals that are systemically stable. Closed-cervix pyometra or severely ill animals typically require emergency spay surgery, which remains the gold-standard treatment.
Side Effects of Alizin
Based on clinical field trials, the following side effects have been reported:
- Injection site pain: ~17% of dogs
- Local inflammation at injection site: ~23% (resolves within 28 days)
- Anorexia (loss of appetite): ~25%
- Excitation/restlessness: ~23%
- Depression: ~21%
- Diarrhoea: ~13%
- Vomiting: ~2%
- Early return to oestrus: heat interval shortened by 1–3 months
Contact your veterinarian immediately if you notice persistent vaginal discharge (especially if purulent or bloody), prolonged illness, or if your dog seems severely unwell after treatment.
Who Should NOT Use Alizin?
Alizin is contraindicated in dogs with:
- Known allergy to aglepristone or peanut oil
- Impaired liver or kidney function
- Diabetes
- Addison’s disease (hypoadrenocorticism)
- Poor general health
Do not use after 45 days post mating. Do not administer to pregnant bitches unless termination is intended.
Alizin for Cats
Although not officially licensed for cats, Alizin is used off-label by veterinarians for pregnancy termination and pyometra treatment in cats. The typical feline dose is 10–15mg/kg, with the same two-injection protocol 24 hours apart. Aglepristone’s binding affinity in cats is 9 times higher than progesterone, making it particularly effective.
Cats may experience haemorrhagic vaginal discharge after treatment — this is a known species-specific effect. Always consult your veterinarian before using Alizin in cats.
Where to Buy Alizin Online
You can purchase genuine Virbac Alizin (aglepristone 30mg/ml, 10ml vial) from PetShopBoss.com with worldwide delivery. We offer competitive pricing and ship internationally.
Summary
Alizin is one of the safest and most effective options available for managing unwanted pregnancy in dogs. With a straightforward two-dose protocol, high efficacy rates (95–99%), and an established safety profile backed by extensive clinical trials, it remains the treatment of choice recommended by veterinarians worldwide. Whether you’re dealing with an accidental mating or exploring medical pyometra management, Alizin provides a reliable, non-surgical solution.
Always consult your veterinarian before administering Alizin to ensure it is appropriate for your dog’s specific situation.
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