Horses and Off-Label Drug Use: What Every Owner Should Know A veterinarian was found negligent in the death of the reining horse Hard Rock Siemon, after using a drug off-label.   

Horses and Off-Label Drug Use: What Every Owner Should Know

Reining horse death

by Amy Ganci, Esq

Recently, my firm assisted an owner whose horse died after being given a shot of Procaine G Penicillin (“PPG”).

The horse bumped his head near his eye two days earlier and there was some swelling on the boney area above his eye socket. There was some hair missing, but no broken skin. The horse had a normal temperature, appetite and was perky and otherwise normal in every regard. The treating veterinarian determined there was no injury to the eyeball itself.

Despite these findings, and without determining whether the swelling was blood from trauma or pus from infection, the veterinarian prescribed Bute for a couple days, and then, without any medical explanation injected the horse with PPG. Immediately, the horse began suffering the effects of an anaphylactic reaction. He fell to the ground and died in front of his young owner.


Veterinary negligence

At trial, the veterinarian was found negligent. Subsequently, the case settled confidentially. In finding the veterinarian liable, the jury was greatly influenced by the fact that the vet disregarded federal law governing his use of PPG.

The Animal Medicinal Drug Use Clarification Act (AMDUCA) regulates veterinarians’ off-label – or extra-label use of controlled substances.

In short, AMDUCA requires that veterinarians comply with certain preliminary requirements before using a drug off-label, which means for diseases or conditions for which the drug is not indicated by the drug manufacturer. For instance, in our case, PPG was only indicated for the treatment of strangles caused by Streptococcus equi.

For those of us who own horses, but are untrained in veterinary or other medical fields, understanding AMDUCA’s extra-label algorithm could help protect the health and lives of our beloved horses. The reason is simple, drugs are dangerous, not only for the animal, but drug residuals are proving dangerous to humans.


Veterinary considerations for Off-Label Rx

In short, the steps a veterinarian must meet before giving a drug off-label to a non-food animal include the following:

  1. First and foremost, the veterinarian needs to determine that the animal’s health is suffering or threatened.
  2. Then, establish the presence of a valid veterinarian/client/patient relationship.
  3. Determine whether an animal drug exists which fulfills all of the following:

– Contains the needed ingredient,

– In the proper dosage form,

– Labeled for the indication,

– And is clinically effective.


Then proceed with extra-label use of an animal drug, if available, and

a. Maintain required records and

b. Label the drug appropriately.




Proceed with extra-label use of a human drug, even when an animal drug exists, after determining the economic reasons are valid, and

a. Maintain required records and

b. Label the drug appropriately.


The recordkeeping requirements include the following:

– Identify the animals, either as individuals or a group.

– Animal species treated.

– Numbers of animals treated.

– Conditions being treated.

– The established name of the drug and active ingredient.

– The dosage prescribed or used.

– Duration of treatment.

– Specified withdrawal, withholding, or discard time(s), if applicable, for meat, milk, eggs, or animal-derived food.

– Keep records for 2 years.

– FDA may have access to these records to estimate risk to public health.


The labeling requirements include:

– Name and address of the prescribing veterinarian.

– Established name of the drug.

– Any specified direction for use including the class/species or identification of the animal or herd, flock, pen, a lot, or other groups; the dosage frequency, and route of administration; and the duration of therapy.

– Any cautionary statements.

– Your specified withdrawal, withholding, or discard time for meat, milk, eggs, or any other food.


Hard Rock Siemon Case

Veterinary negligence caused the death of the reining horse Hard Rock Siemon.
Hard Rock Siemon

In the PPG case, the veterinarian had not diagnosed a condition which would ever respond to the PPG.

He likewise had not determined that the horse’s health was suffering or threatened. In fact, the veterinarian told the owner he felt the swelling (which was not bothering the horse) would resolve on its own in the next day or two and it was simply bruising.

The vet stated he was giving the PPG “just to be safe.”


Anaphylaxis to penicillin in horses

What is the occurrence of anaphylaxis to penicillin in horses?

The problem is no one knows what the true occurrence of anaphylaxis to penicillin is in horses. That’s because veterinarians are not required, and therefore, routinely do not report adverse drug events.

Unless the horse is famous, like the racehorse stallion Spend A Buck, who succumbed to an anaphylactic reaction to penicillin while standing at stud in Brazil, most deaths or near death reactions are wholly unreported.

Anaphylaxis is the number one warning associated with the use of penicillin. Similarly, adverse drug events from other animal and human drugs used in horses are not required to be reported.

As we would with our personal physicians, as responsible horse owners, we should question when a drug is being given to our horse. What is the drug? Google it and see for what conditions the manufacturer says the drug is indicated. Check out the dosage. Learn more about the dosing recommendations from the manufacturer. If the drug is not indicated for what ails your mount, ask the vet why he recommends the drug.

In my client’s case, we all learned too late that “just to be safe” with a double dosage of one of the world’s most powerful systemic antibiotics was a bad idea.

Don’t let it happen to you.