Yes, goats can have penicillin, and it is one of the most commonly used antibiotics in goat care. Penicillin G procaine is the form most frequently given to goats, typically by intramuscular injection. However, as of 2024, penicillin for animals is no longer available over the counter in the United States and requires a prescription from a licensed veterinarian.
Types of Penicillin Used in Goats
Two forms of penicillin are relevant to goat owners. Penicillin G procaine is the short-acting version, designed to reach effective levels in the bloodstream quickly and requiring daily injections. The other is a combination product that blends penicillin G procaine with penicillin G benzathine, a longer-acting form that releases the drug more slowly over several days. Most goat owners and veterinarians rely on the procaine form because it produces more predictable blood levels at the doses commonly used in small ruminants.
At standard label doses, the combination product produces relatively low blood concentrations after the first 12 hours. Research in cattle showed that plasma levels dropped below a therapeutically meaningful threshold within half a day at approved doses. This matters for goats too: a penicillin injection that sounds like it should last for days may not actually maintain useful drug levels long enough to clear an infection unless the dose is significantly increased, which creates its own complications.
What Penicillin Treats in Goats
Penicillin is effective against a range of bacterial infections in goats. It is commonly used for pneumonia, mastitis (udder infection), foot rot, wound infections, and abscesses. The FDA lists it among the medications relevant to treating conditions like abortion caused by Campylobacter and mastitis caused by Staphylococcus bacteria in sheep and goats. Veterinarians also reach for penicillin when treating listeriosis, a serious brain infection goats can pick up from spoiled silage or feed, though listeriosis typically requires higher doses and more frequent administration than the label specifies.
Dosage and How to Give It
The labeled dose for penicillin G procaine is 3,000 units per pound of body weight, given intramuscularly once daily. In practical terms, that works out to 1 mL per 100 pounds of body weight for the standard concentration product. Many veterinarians prescribe higher doses for goats because small ruminants metabolize the drug faster than cattle, for which most penicillin products were originally formulated. Your vet will determine the correct dose for your goat’s weight and condition.
Treatment typically continues until the goat shows clear improvement and for at least one day after symptoms disappear. Most courses run two to three days, and treatment should not exceed four consecutive days at the label dose. If the infection hasn’t responded by then, the problem may require a different antibiotic or a reassessment of the diagnosis.
Where and How to Inject
Penicillin G procaine is given as an intramuscular injection, meaning it goes into the muscle rather than under the skin. For meat-producing goats, all injections should be given in the neck to avoid damaging cuts of meat in the hindquarters. The target area is a triangle of muscle in front of the shoulder, above the spine, and below the ligament that runs along the top of the neck.
Insert the needle perpendicular to the skin’s surface. Use an 18- or 20-gauge needle, 1 to 1.5 inches long, depending on the size of the goat. No more than 10 mL should go into a single injection site. If your goat needs a larger volume, split it between two sites spaced at least a hand’s width apart. Rotate sites with each daily injection to reduce soreness and tissue damage.
Before injecting, warm the bottle to room temperature and shake it well. Penicillin G procaine is a thick suspension, and cold product drawn straight from the refrigerator is harder to inject and more painful for the goat.
Allergic Reactions to Watch For
Penicillin allergy is uncommon in goats, but anaphylaxis (a severe allergic reaction) can happen with any injectable antibiotic in any species. Signs develop within seconds to minutes of the injection and include sudden difficulty breathing, swelling of the face and eyelids, hives, drooling, wobbliness, and collapse. In documented cases in cattle, the swelling is often described as doughy, leaving a visible dent when you press it with a finger.
If your goat shows these signs, epinephrine given intramuscularly is the emergency treatment. Many goat owners keep a bottle of epinephrine on hand specifically for this reason, especially if they give injections regularly. Recovery from a reaction can take a couple of hours even with treatment. A goat that has had a reaction to penicillin should never receive it again.
Meat and Milk Withdrawal Times
If you raise goats for meat or milk, withdrawal periods are critical. Penicillin residues must clear the animal’s tissues and milk before either can enter the food supply. For sheep, the labeled slaughter withdrawal after intramuscular penicillin G procaine at the standard dose is 8 to 9 days. Goats metabolize drugs differently from sheep, and specific tissue-depletion data for goats at higher-than-label doses are limited.
Milk residues are a particular concern. Research has shown that after a moderate intramuscular dose of penicillin G procaine in goats, measurable drug residues persisted in milk for at least 72 hours. At higher doses in sheep, residues were detectable for up to 8 days. The Food Animal Residue Avoidance Databank (FARAD) has noted that the data in small ruminants are limited enough that confident withdrawal recommendations for off-label use are difficult to make. If you’re using penicillin at doses above the label, testing milk or urine before selling is a practical safeguard.
Prescription Requirements Since 2024
Penicillin for livestock used to be available at farm supply stores without a prescription. That changed under FDA Guidance for Industry #263, which moved all medically important antimicrobials for animals to prescription-only status. This includes penicillin G procaine and all combination penicillin products. You now need a valid veterinary prescription to purchase these drugs, which means you need an established relationship with a veterinarian who knows your herd.
Storing Penicillin Properly
Penicillin G procaine and combination penicillin products should be stored in the refrigerator at 36 to 46°F (2 to 8°C). Do not freeze them, as freezing damages the suspension and can make the drug less effective or cause it to clump. Discard any product past its expiration date. Once you’ve punctured the rubber stopper with a needle multiple times, the risk of contamination increases, so using a clean needle each time you draw from the bottle helps extend its usable life.