Use of Emergency Medications (Epinephrine and Atropine)

ImmunityQ&AMeongsiljang Veterinary Advisory Board

We’ve summarized the roles, timing of administration, and key precautions pet owners should know about epinephrine and atropine, which are used in cases of cardiac arrest or shock in dogs and cats.

What Are Emergency Medications?

A veterinarian preparing medications in an emergency situation

Emergency medications are essential drugs administered immediately in life-threatening situations such as cardiac arrest, shock, or bradycardia to restore heart rate and breathing. The most important point to remember is that assessment and administration must be performed exclusively by a veterinarian. While pet owners should be familiar with the names and functions of these medications, the fastest way to save a life in an emergency is to transport your pet immediately to a 24-hour animal hospital. The primary medications used are epinephrine and atropine.

When Are These Two Medications Used?

Epinephrine and atropine serve different purposes. Epinephrine is used in situations where the heart has stopped, such as in cardiac arrest (asystole or pulseless electrical activity), or when maintaining blood pressure during cardiopulmonary resuscitation (CPR). It is a key vasopressor administered every two cycles in the RECOVER guideline-based CPR protocol. Atropine, on the other hand, is used for bradycardia—an abnormally slow heart rate—or when the heart rate drops due to poisoning or vagal overactivity. However, bradycardia may not always respond well to atropine. Veterinary emergency medicine textbooks classify both of these medications as essential drugs that must be included in a standard crash cart (emergency medication cart).

Epinephrine vs. Atropine: A Quick Comparison

Item	Epinephrine	Atropine
Main use	Cardiac arrest (asystole, pulseless electrical activity)	Severe bradycardia, bradycardia due to poisoning
Mechanism of action	Increases cardiac contractility and blood pressure	Increases heart rate, suppresses parasympathetic nerves
Route of administration	Intravenous, intratracheal, intraosseous	Intravenous, intramuscular, subcutaneous, intratracheal
Onset of effect	Rapid onset (within a few minutes)	Within a few minutes (IV basis)
Direct use by guardian	False	False

Neither drug is administered directly by the guardian. They are used only under veterinary judgment.

Epinephrine: A Medication to Restart the Heart

Epinephrine is a medication that strongly stimulates the sympathetic nervous system to restart the heart and constrict blood vessels, thereby raising blood pressure. According to the RECOVER guidelines (international standards for veterinary cardiopulmonary resuscitation), it is the first-line vasopressor used in cases of cardiac arrest, including pulseless electrical activity and asystole. It is administered repeatedly every two cycles of CPR, and depending on the situation, it may be alternated with or combined with vasopressin. The veterinarian determines the dosage and dosing interval based on the patient’s body weight.

A veterinarian's hand preparing epinephrine in a syringe

Head Straight to the Emergency Room If You See These Signs

If you notice any of the following symptoms, do not hesitate and head straight to a 24-hour emergency animal hospital. - Severe difficulty breathing: The tongue or gums turn blue. - Collapse or loss of consciousness: No response when called. - Rapid facial swelling: Occurs within minutes to tens of minutes after vaccination, medication, or an insect sting. - Slow or undetectable pulse: The heartbeat sounds weak even when listening closely to the chest. - Lethargy following persistent vomiting and diarrhea: This can progress to shock. In such cases, crash cart medications may be required. Calling ahead to describe the situation allows treatment to begin immediately upon arrival at the hospital.

Atropine: A Medication to Wake Up a Slowed Heart

Atropine is a medication that blocks the effects of the parasympathetic nervous system (specifically the vagus nerve), which helps raise a slowed heart rate and reduces excessive salivation and bronchial secretions. It is used in situations such as bradycardia during anesthesia, bradycardia caused by poisoning or vagal hyperactivity, and certain types of bradyarrhythmias. While veterinary textbooks note that atropine may be considered for bradycardia in poisoned patients, it often responds poorly to atropine, and its use in certain poisonings can be controversial, so it must be administered with caution. As with atropine, determining the appropriate dosage based on body weight and condition is the responsibility of the veterinarian.

A cat being monitored for heart rate at the veterinary clinic

What Pet Owners Can and Cannot Do

Emergency medications are not meant to be stocked or administered by pet owners. Incorrect dosages or administration routes can lead to arrhythmias, seizures, or even death. - What you can do: Monitor symptoms, contact your vet in advance, ensure safe transport, and keep a record of any ingested medications or foods. - What you should not do: Administer emergency injections at home, use medications purchased online, or share human medications with your pet. The most important emergency action for pet owners is to make a quick decision and get your pet to a 24-hour veterinary hospital as soon as possible.

Precautions by Breed and Condition

Emergency medications do not affect all animals in the same way. - Breed- and individual-specific drug responses: Even with the same medication, reactions can vary depending on breed or individual characteristics. Always inform the clinic of any past adverse drug reactions. - Elderly patients with heart disease: The sympathetic nervous system stimulation caused by epinephrine may worsen existing arrhythmias, so dosage adjustment is necessary. - Pregnant or nursing animals: Medications can affect the fetus or offspring, so the veterinarian will carefully weigh the risks and benefits before making a decision. - Glaucoma or severe tachycardia: Atropine can further increase heart rate, so its use may be restricted in these cases. Preparing a list of all medications and supplements your pet is currently taking can be extremely helpful in an emergency.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Can I keep epinephrine at home?

This isn’t a medication that pet owners should keep at home or administer on their own—both prescribing and administering it fall strictly within the veterinarian’s scope of practice. Instead, it’s far more practical to save the location and phone number of a nearby 24-hour emergency animal hospital in advance.

My face swelled up after being stung by a bee. Should I get an epinephrine injection right away?

If your pet is experiencing systemic symptoms such as difficulty breathing or collapse, it could be a life-threatening emergency, so you should seek immediate veterinary care. Even if there is facial swelling, the condition can deteriorate rapidly, so it is safest to have a veterinarian examine your pet without delay. The treatment plan and choice of medications must be determined by a veterinarian based on a thorough assessment of your pet’s condition.

Does atropine have no side effects?

Possible side effects include a rapid heart rate (tachycardia), ventricular arrhythmias, and reduced airway and salivary secretions. Extra caution is needed in patients with glaucoma or an already elevated heart rate. Therefore, the dosage and dosing interval are carefully adjusted based on the patient’s weight and cardiac condition.

Why is atropine given before anesthesia?

This is used to prevent a sudden drop in heart rate or excessive salivation during anesthesia. It is not administered to all patients; instead, veterinarians selectively prescribe it based on the pet’s breed and overall health status.

What should pet owners definitely do before arriving at the emergency room?

Call the clinic ahead of time to let them know what’s going on, then securely fasten your pet in a carrier and transport them quickly and quietly. Bring a written note listing any food, medications, or toxic substances ingested, when the symptoms started, and all current medications—this will help the veterinary team make faster, more accurate assessments on arrival.