12/12/2025
Here is a simple and practical guide on how to administer PRRS (Porcine Reproductive and Respiratory Syndrome) vaccine on a farm.
✅ HOW TO ADMINISTER PRRS VACCINE
PRRS vaccines come in two types:
1. MLV – Modified Live Vaccine (most commonly used)accine
2. KV – Killed Vaccine (less common)
Below is the standard method used for MLV PRRS vaccines, which is likely what you are using.
⭐ 1. Prepare the Materials
• PRRS vaccine vial
• Sterile diluent (if your vaccine needs reconstitution)
• 3–5 mL syringe
• 20–22 gauge needle (½–1 inch)
• Alcohol or disinfectant
• Cooler with ice pack to maintain 2–8°C
⭐ 2. Reconstitution (for MLV vaccines)
Most MLV PRRS vaccines come as freeze-dried powder.
1. Shake the diluent gently.
2. Inject all diluent into the vaccine vial.
3. Shake until fully dissolved.
4. Use within 2 hours only (MLV dies fast).
⭐ 3. Correct Dosage
Typical dose:
• 2 mL per pig (standard for most PRRS MLV brands)
Always check the label because some brands use 1 mL.
⭐ 4. Injection Site
PRRS vaccine is given IM or SC, depending on brand:
Intramuscular (IM)
• Inject in the neck area (not the ham)
• Needle: 20–22 gauge, 1 inch
Subcutaneous (SC)
• Lift the skin in the neck behind the ear
• Needle: 20–22 gauge, ½ inch
Most farms use IM administration.
⭐ 5. Pig Handling
• Pigs should be healthy, no fever, no heavy stress.
• Avoid vaccination during extreme heat.
• Handle pigs calmly to avoid stress-related reactions.
⭐ 6. Post-Vaccination Monitoring
For 1–3 days, observe for:
• Fever
• Off-feed
• Mild cough
• Swelling at injection site
These are normal reactions for MLV PRRS.
🐷 SPECIAL REMINDERS
✔ Vaccinate ALL pigs in the group
Do NOT vaccinate only a few pigs — this increases virus circulation and makes the outbreak worse.
✔ Do NOT mix PRRS vaccination with:
• Deworming (at least 5–7 days interval)
• Other live vaccines on the same day (unless allowed by label)
✔ Biosecurity is critical
PRRS spreads through:
• Air
• Vehicles
• People
• Needles
Use one needle per litter or change frequently.
If you want, you can send a picture of your PRRS vaccine vial and I’ll confirm:
• Type (MLV or killed)
• Correct dose
• Correct route
• Correct age for pigs
Just upload the picture.
PRRS stands for Porcine Reproductive and Respiratory Syndrome — a highly contagious viral disease that affects pigs of all ages.
It is one of the most economically damaging diseases in the swine industry.
🦠 CAUSE
PRRS is caused by the PRRS virus (PRRSV) — an RNA virus that affects:
• Lungs (respiratory system)
• Immune system
• Reproductive organs
🐖 SYMPTOMS
✅ In Sows / Pregnant Gilts
• Abortion (3rd trimester)
• Early farrowing
• Mummified fetuses
• Weak-born piglets
• Increased stillbirths
• Retained placenta or metritis
✅ In Piglets
• Difficulty breathing (“thumping”)
• High mortality
• Fever
• Weak, poor sucklers
• Blue ears in severe cases
✅ In Growers / Finishers
• Coughing
• Fever
• Slow growth
• Rough hair coat
• Secondary infections (because PRRS weakens the immune system)
🔥 HOW PRRS SPREADS
Very easily:
• Airborne (up to several kilometers depending on wind)
• Semen from infected boars
• Contaminated needles or equipment
• Trucks, shoes, clothes
• Sick pigs mixing with healthy pigs
🩺 DIAGNOSIS
Confirmed through:
• PCR test (gold standard)
• Blood sampling
• Lung tissue testing
🛡️ PREVENTION
• Strict biosecurity
• Using PRRS vaccines (MLV or killed)
• Quarantine new pigs 30 days
• Needle change every litter or group
• Disinfection of equipment and vehicles
• Air filtration (for large farms)
💉 VACCINATION
PRRS vaccines do not eliminate the virus but:
• Reduce severity of disease
• Reduce shedding
• Improve sow reproductive performance
• Improve piglet survivability
❗WHY PRRS IS HARD TO CONTROL
• Virus mutates quickly
• Many strains
• Can hide inside the immune cells
• Can circulate silently without symptoms
Here is a simple, clear, and correct guide for the proper handling of PRRS (Porcine Reproductive and Respiratory Syndrome) vaccines to avoid vaccine failure and protect the herd.
✅ PRRS Vaccine – Proper Handling Guide
PRRS vaccines (usually MLV—Modified Live Virus) are very sensitive. Incorrect handling easily kills the virus and makes the vaccine useless. Follow these guidelines strictly:
1. Storage Requirements
✔ Keep the vaccine refrigerated at 2–8°C
• Never freeze the vaccine.
• Never expose it to heat or direct sunlight.
✔ Maintain cold chain
• Use an icebox during transport.
• Keep vials cold but not touching the ice directly.
2. Before Vaccination
✔ Use only CLEAN, DRY syringes and needles
• Do NOT use syringes washed with disinfectant. Disinfectant kills the live PRRS virus in the vaccine.
✔ Use ONLY sterile equipment
• Disinfect the skin, not the needle.
• Let the skin dry before injecting.
✔ Reconstitute (mix) properly
• Add diluent to the vaccine vial, not the other way around.
• Mix gently.
• Use immediately after mixing. PRRS MLV loses potency within 2 hours after reconstitution.
3. During Vaccination
✔ Follow the correct dose
• Usually 2 mL IM or 1 mL IM/SC, depending on brand.
✔ Avoid stress in pigs
Stress weakens immune response.
• Do not vaccinate sick pigs.
• Avoid vaccinating during extremely hot weather.
✔ Separate vaccine and chemicals
• Never mix the vaccine with antibiotics, multivitamins, or iron injectables in the same syringe.
• PRRS vaccine must stay pure.
4. After Vaccination
✔ Observe animals for reactions
Mild fever is normal for 1–2 days.
✔ Maintain good biosecurity
PRRS vaccine does not protect if the farm has poor hygiene, infected visitors, or contaminated equipment.
5. Important DO NOTs
❌ Do NOT shake the vaccine violently ❌ Do NOT expose it to sunlight ❌ Do NOT use expired vaccines ❌ Do NOT split 1 vial for multiple days ❌ Do NOT vaccinate during heavy stress or illness ❌ Do NOT vaccinate pigs with high fever, pneumonia, or diarrhea
