Major Uses

Propionibacterium acnes is a slow-growing, gram-positive bacterium that is sometimes used as part of immunotherapy in animals to treat conditions that are otherwise difficult to control. It works by stimulating the immune system to fight existing infections.

Propionibacterium acnes is generally used as an adjunct to other therapies in the treatment of equine respiratory disease complex, a condition that causes cough, fever, enlarged lymph nodes, loss of appetite, nasal discharge, lethargy, and slow recovery from exertion. It may also be used in the treatment of chronic recurrent pyoderma in dogs.

Common Precautions

Propionibacterium acnes is known to cause a temporary loss of appetite, rise in temperature, sluggishness, or tremors in the first few hours following injection.

Propionibacterium acnes is not for use in food-producing animals unless discontinued at least 21 days before slaughter. The drug is not for use in pregnant horses.

Propionibacterium acnes is known to interact with other medications and supplements and should not be used along with glucocorticoids or other immune suppressants. Use of steroids should be stopped at least 7 days prior to beginning therapy with propionibacterium acnes.

Propionibacterium acnes should not be used in animals with a known allergy or hypersensitivity to the drug. Any known or suspected overdose should be reported to a veterinarian right away.


Propionibacterium acnes should be stored at room temperature until first used, and then at 35-35°F. This product should not be frozen.


Propionibacterium acnes is available as a solution for intravenous use only.

In foals, the typical dose of propionibacterium acnes (Eqstim) is 1 ml. In older horses, the typical dose is 1 ml/250 lb (1 ml/113 kg) of body weight. The dose should be repeated on day 3 or 4 and again on day 7. Thereafter, once weekly dosing is acceptable. In dogs, the dosing and schedule of administration are different.

Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

If a dose of propionibacterium acnes is missed, it should be taken as soon as possible. If it is almost time for the next dose, the missed dose should be skipped and the normal schedule resumed. Two doses of this medication should not be taken at once.

This information is for general reference only and should not be used for the diagnosis or treatment of any condition of your pet. It's intended as a general reference, this information may not include all possible uses, precautions, directions, reactions (including allergic), drug interactions, or withdrawal times. Always consult your local veterinarian and have your pet examined for any advice concerning the diagnosis and treatment of your pet, including which products and doses are most appropriate. Any trademarks are the property of their respective owners. VetDepot is not a pharmacy. All prescription products are dispensed by our Pharmacy Partner. Article last updated 2/2014.