• Prevention of Respiratory Disease: The most common indication is to aid in the prevention of upper respiratory tract disease, which can manifest as rhinitis (“red nose”), conjunctivitis (red, watery eyes), fever, coughing, and difficulty breathing.
• Reduction of Clinical Signs and Viral Shedding: Vaccination helps reduce the severity of clinical signs and the amount of field virus excreted by infected animals, which limits disease transmission within and between herds.
• Prevention of Reproductive Disorders: IBR virus can cause reproductive issues, including infectious pustular vulvovaginitis (IPV), balanoposthitis in bulls, and abortions in pregnant cows. Certain vaccines are specifically indicated to prevent these outcomes, particularly in breeding stock.
• Use During Outbreaks: Modified-live virus (MLV) vaccines may be recommended for use during an IBR outbreak due to their rapid onset of immunity.
• Differentiation of Infected from Vaccinated Animals (DIVA): “Marker” vaccines are indicated for use in herds participating in IBR control or eradication programs, as they allow veterinarians to differentiate between an animal that has been vaccinated and one that has been naturally infected with the field virus. 

ADMINISTRATION

• Subcutaneous (SC): The most common method, injecting under the loose skin in the neck, away from major lymph nodes.
• Intramuscular (IM): Administered into the muscle, often in the neck, for some vaccine types.
• Intranasal (IN): A less common method for IBR, administered directly into the nostrils for local immunity. 

1. Reconstitution: A sterile diluent is aseptically mixed with the freeze-dried vaccine powder.
2. Injection: A 2 mL (or specific dose) injection is given, often in the neck.
3. Technique: For SC, lift a fold of skin to create a “tent” and inject under it; for IM, inject into the muscle. 

• Primary Series: Calves vaccinated young (under 6 months) often need a booster later, as maternal antibodies can interfere.
• Revaccination: Annual boosters are usually recommended.