Chances are, if you have given enough injections over time, you have run across an anaphylactic reaction. Whether you have seen one before or not, this event is a scary one. Be sure to act fast — anaphylactic reactions are a true emergency.
Anaphylaxis is a type of hypersensitivity disease where an immune response goes uncontrolled and is not self-limited. We generally see this type of hypersensitivity shortly after injections are given. There are other means of causing this systemic reaction like insect stings, administration of blood or blood products, or skin absorption. This occurs when the animal has been previously exposed to an antigen or a foreign substance. Once this happens, the immune system "remembers" this substance is foreign and, on the subsequent exposure, hypersensitivity occurs.
The degree to which an animal is affected can vary from swelling of the injection site to difficulty breathing. Other signs include muscle tremors, anxiety, salivation, bloat, nasal discharge, vocalization, edema, diarrhea and dilation of blood vessels. This dilation of blood vessels then drops blood pressure. Between the blood pressure change and the difficulty breathing, death can easily occur without immediate action.
Epinephrine is the drug of choice to counter the reaction. The problem is that very few of us carry epinephrine with us. By the time we run back to the supply room and dig to the back of the refrigerator, look up the dose and go back to the animal, it may be too late. Now is a good time to discuss dosage with your veterinarian. Commit this one to memory. Be sure to carry it in your vaccine and treatment cooler. Buy a new bottle or two when your other ones expire, even if you have not opened them. It is money well spent if you can save a life.
There are certain breeds of cattle and genetic lines that have higher reported incidences of anaphylaxis. If you are able to ascertain the cause of the reaction, avoid repeated exposure to the same antigen because similar reactions are very likely. Animals should be monitored for 24 hours and additional supportive care may be prescribed by your veterinarian. Most animals will recover and return to normal within 24 to 48 hours. Pregnant animals may spontaneously abort and emphysema may result in animals that had severe problems breathing, along with muscle spasms.
Now is a good time to change your routine. Always walk back through the group after giving injections. Give one injection per pass in a headlock situation if possible. This will help you pinpoint reactions to the cause if you have any problems. Then, after 10-15 minutes, start back on the first animal with a different product if multiple injections are to be given. Work in the cool part of the day. More reactions are seen in hot weather.
Anaphylactic reactions occur when you least expect them. It is best to be prepared and act fast. With this advice, you may just be able to save a life.
Angela M. Daniels is a veterinarian with Circle H Headquarters LLC, a dairy and swine veterinary practice, food safety laboratory and DHIA milk-testing and contract research organization in Dalhart, Texas.