- Atropine is administered to block the effect of certain nervous system impulses (acetylcholine) on receptors throughout the body. In animals, like dogs and cats, it is most often used when an animal is undergoing anesthesia for surgery to block the undesirable effects of nervous system stimulation.
- The involuntary nervous system is divided into the sympathetic (flight or fight response) and parasympathetic branches. In general, these two systems oppose each other.
- When stimulated, the sympathetic system increases heart rate, blood pressure, and cardiac activity. The pupils dilate and gastrointestinal function reduces.
- The parasympathetic system, working largely through a nerve called the vagus nerve, slows heart rate, reduces blood pressure, and stimulates gastrointestinal function, salivation, and digestion.
- Cells contain targets, called receptors, that are stimulated by chemicals released from nerves. In the parasympathetic system, the chemical transmitter released by nerves is acetylcholine and the receptors are called muscarinic receptors.
- Atropine blocks the muscarinic receptor and thereby inhibits the effect of acetylcholine, reducing the parasympathetic activity of this chemical.
- Therefore, atropine belongs to the class of drugs known as anti-muscarinic agents. Sometimes they are also called “anti-cholinergics” or “parasympatholytics,” terms that also describe the actions.
- When the muscarinic part of the parasympathetic nervous system is blocked, the sympathetic system becomes more prominent.
- Atropine is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.
Brand Names and Other Names of Atropine
- This drug is registered for use in humans and animals.
- Atropine is known by the generic name only. There are both human and veterinary formulations available.
Uses of Atropine for Dogs and Cats
- Atropine is used prior to anesthesia for surgery to reduce drooling and respiratory tract secretions.
- Atropine is often administered with many anesthetic agents to prevent slowing of the heart rate.
- It is also used to treat dangerously slow heart rates and is an important drug in CPR.
- Atropine is an antidote for some insecticide (e.g. cholinesterase inhibitors) and mushroom poisonings.
- Atropine is also used to reduce drooling (salivation), vomiting and nausea.
- Atropine-like compounds have been used to treat vomiting caused by motion sickness.
- Atropine-like compounds have been used to treat acute bouts of diarrhea in animals.
- Atropine is used in the eye to dilate pupils. This can reduce eye pain and prevent complications in various eye diseases.
- Atropine will antagonize compounds that constrict the airways and cause coughing. Therefore, atropine, and similar compounds can be used in animals that may have difficulty breathing (such as asthma – like conditions).
Precautions and Side Effects
- While generally safe and effective when prescribed by a veterinarian, atropine can cause side effects in some animals.
- Atropine should not be used in animals with known hypersensitivity or allergy to the drug.
- It should also not be used if a gastrointestinal obstruction or infection is suspected.
- Do not use atropine if inflammation of the large bowel is present.
- Never give atropine to an animal that has been diagnosed as having glaucoma.
- Atropine may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with atropine. Such drugs include certain antihistamines, meperidine, diazepam, metoclopramide and procainamide.
- Atropine should be used with caution in animals with rapid heart rates or with impaired kidney, heart or liver function.
- When the eye formulation for atropine is given, the animal, especially cats, may profusely drool due to the bitter taste of the drug.
- Some side effects include dry mouth, constipation, central nervous system stimulation (excitement), blurred vision, drowsiness or ataxia (a wobbly walking pattern or gait). Because of the dry mouth, atropine may cause some animals to drink excess water.
How Atropine Is Supplied
- Atropine is available in various injectable concentrations.
- Atropine is also available in 0.4 mg tablets.
- Atropine is also available as 1 percent or 2 percent ophthalmic preparation.
Dosing Information of Atropine for Dogs and Cats
- Medication should never be administered without first consulting your veterinarian.
- The typical dose for atropine is 0.01 to 0.02 mg per pound (0.022 to 0.044 mg/kg). Usually, atropine is given only by injection.
- If used as an antidote for certain poisonings, doses up to 1 mg per pound (2 mg/kg) may be required.
- If used as a treatment for eye disease, one drop in the affected eye every 2 to 24 hours may be prescribed.
- The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your pet feels better, the entire treatment plan should be completed to prevent relapse or prevent the development of resistance.