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Erythromycin (brand names: Gallimycin®, Ery-Tab®, Ery-Ped®, E.E.S., ERYC®, Emycin®, Erybid®, Erythro®, Erythrocin®, PCE®) is a macrolide antibiotic used to treat certain bacterial infections, most commonly Rhodococcus equi infections in foals. It also acts as a prokinetic used to increase the movement of the gastrointestinal tract. Today, it is not commonly used in species other than horses.
Its use in horses, cats, dogs, ferrets, and birds to treat infections or gastrointestinal mobility problems is off label (extra label). Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.
This medication will take effect quickly, in about 1 to 2 hours, but effects may not be visible for a few days.
If you miss a dose, give it when you remember, but if it is close to the time for the next dose, skip the dose you missed and give it at the next scheduled time, and return to the regular dosing schedule. Never give your pet two doses at once or give extra doses.
Side effects of the oral forms of erythromycin include:
Side effects of erythromycin in foals may include:
Side effects of erythromycin in adult horses may include:
This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.
DO NOT USE erythromycin in:
USE WITH CAUTION in:
Some breeds of dogs (e.g., collies, sheepdogs, and collie- or sheepdog-cross breeds) are more sensitive than others to medications. This is typically due to a specific genetic mutation (MDR1/ABCB1) that makes them less able to tolerate high doses of certain medications. Use erythromycin cautiously in these cases.
Certain medications may interact with erythromycin and so it is important to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your dog is taking before starting any new treatment.
The following medications should be used with caution when given with erythromycin:
Erythromycin may also interact with the liver parameters AST and ALT and could cause falsely elevated values.
If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet's weight and symptoms.
© Copyright 2025 LifeLearn Inc. Used and/or modified with permission under license. This content written by LifeLearn Animal Health (LifeLearn Inc.) is licensed to this practice for the personal use of our clients. Any copying, printing or further distribution is prohibited without the express written consent of LifeLearn. This content does not contain all available information for any referenced medications and has not been reviewed by the FDA Center for Veterinary Medicine, or Health Canada Veterinary Drugs Directorate. This content may help answer commonly asked questions, but is not a substitute for medical advice, or a proper consultation and/or clinical examination of your pet by a veterinarian. Please contact your veterinarian if you have any questions or concerns about your pet’s health. Last updated on Mar 19, 2025.
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