OTHER DIAGNOSES CONSIDERED
Other conditions or ailments that might also need to be ruled out by a vet.
Diagnosis
Conditions or ailments that are the cause of a problem that you see - your observation.
Your vet may diagnose
Procaine Penicillin G Reaction
Summary
Procaine penicillin G is commonly given to horses intramuscularly (IM) with no adverse effects. It is a useful antibiotic for many equine infections. However, if it is accidentally administered into a blood vessel, a violent reaction may occur.
A horse experiencing this reaction appears hyper-alert or spooked. This progresses into a seizure-like fit, with the horse scrambling and sometimes falling down. Horses may spin around or lurch backwards with their eyes wide, and nostrils flared, sneezing, or blowing. The reaction lasts 2-5 minutes, but it seems like much longer. In many cases, the signs are much more mild, just snorting and spinning for a few moments.
Horses generally quiet down after 5-10 minutes. This reaction is not allergic in nature, but is caused by the procaine additive. It is more likely to occur after multiple injections in the same site. We think that this is because of the development of inflammation and increased blood supply to the area from repetitive trauma.
When it happens in our presence (yes, it can rarely happen to a vet too), we may use sedatives to try to slow the horse down until the reaction passes. A confident handler may be able to manage a horse through this reactive fit by circling the horse around them, but when in doubt get out of the stall and call your vet.
Diagnosis is obvious because of timing with respect to Penicillin G Procaine injection, and characteristics of fit.
The only treatment might be sedation with xylazine or similar sedative, to prevent injury during fit. But this is not always practical or safe to do. Always use caution!
A horse experiencing this reaction appears hyper-alert or spooked. This progresses into a seizure-like fit, with the horse scrambling and sometimes falling down. Horses may spin around or lurch backwards with their eyes wide, and nostrils flared, sneezing, or blowing. The reaction lasts 2-5 minutes, but it seems like much longer. In many cases, the signs are much more mild, just snorting and spinning for a few moments.
Horses generally quiet down after 5-10 minutes. This reaction is not allergic in nature, but is caused by the procaine additive. It is more likely to occur after multiple injections in the same site. We think that this is because of the development of inflammation and increased blood supply to the area from repetitive trauma.
When it happens in our presence (yes, it can rarely happen to a vet too), we may use sedatives to try to slow the horse down until the reaction passes. A confident handler may be able to manage a horse through this reactive fit by circling the horse around them, but when in doubt get out of the stall and call your vet.
Diagnosis is obvious because of timing with respect to Penicillin G Procaine injection, and characteristics of fit.
The only treatment might be sedation with xylazine or similar sedative, to prevent injury during fit. But this is not always practical or safe to do. Always use caution!
my vet's role
Diagnostics Used
These are tests that might be helpful to make this diagnosis or further characterize the condition.
Treatments May Include
These treatments might be used to help resolve or improve this condition.
PROGNOSIS AND RELEVANT FACTORS
Prognosis is usually good if the horse does not injure itself during the reactive fit. A horse that has had a procaine reaction in the past will not necessarily have one in the future. That said, most people that have witnessed this reaction firsthand are hesitant to use penicillin again in that horse.my role
I might observe
You might make these observations when a horse has this condition.
Skills I Might Need
I might need these skills if my horse has this diagnosis.
Questions To Ask Your Vet:
- Will this happen again?
- Does this mean my horse is allergic to penicillin?
- Do I continue to use procaine penicillin or is there another antibiotic I can use?
Prevention
Use good IM injection technique. Be prepared for a reaction by performing this injection in a spacious and safe environment, where a horse is less likely to cause injury to itself during a reaction. Use procaine penicillin only when it is indicated, not every time an antibiotic is needed. Safer oral antibiotics are often preferable.