- Swelling and pain at the injection site
- Lethargy
- Loss of appetite
- Slight fever
- Increased heart rate
- Difficulty breathing
- Urticaria (hives)
- Anaphylaxis (a severe, potentially life-threatening allergic reaction)
These reactions are typically mild and transient, resolving within a few days. However, if you observe any of these reactions in your horse, it's important to contact your veterinarian immediately.