I recently received a forwarded newsgroup message from a friend and horse professional about a ranch owner who accidently overdosed five of her horses on Bimectin an Ivermectin dewormer paste for horses. Four of the horses died and the fifth at the time of the email was not expected to live.
My first reaction was sorrow for the owner and then I felt that the owner had a hand in this due to assumptions that all of us can fall victim to. The times we live in cause us to assume that medications are safe and reactions and side effects are a remote possibility.
I would be grief stricken beyond a level that would be safe for me to continue functioning in daily life if I had allowed this to happen to my horses. Having been raised by a doctor and having worked in his office as a medical assistant, I learned in my childhood about the serious and potentially lethal effects of any type of drug reaction. This did not stop me from making a mistake of allowing one of my dogs to lick some horse wormer one day long ago, while I was worming some of my horses. As the worming was completed, only minutes later, I noticed my dog looking very sick. I realized that she had consumed some of the paste wormer after I had put the discarded tube down where she was able to sniff it and lick.
I was so angry with myself for being negligent about disposing of the worming paste tubes but fortunately I did notice her eyes bulging and red and her demeanor changing rapidly to one of grave discomfort. I rushed her to an emergency veterinary care clinic, where they administered stomach pumping and other therapy. The dog lived but would have died had I not acted within the first few hours of ingestion.
Ivermectin(Bimectin is an Ivermetctin) has no antidote. A horse will die after over dose from Ivermectin after the paste is absorbed. Complete absorbtion takes about 12 to 16 hours. The vital organs will fail or be damaged over about 24 to 72 hours. There is time between dosing and 12 hours to attempt to pump the stomach contents out of the system by veterinary medical procedure if the vet is contacted early enough.
The sad case mentioned above was a case of assuming things were fine after the paste wormers were administered and just forgetting about the horses for more than 12 hours. It is a best practice to assume that all medical treatments, including routine deworming pastes are potentially lethal or damaging to the health by way of overdose or other adverse reactions. The overdose was apparently due to a packaging error on the part of the manufacturer.
Bimectin is not an FDA approved equine paste wormer. I consulted a vet after I learned about this incident to see if treatment was available for dewormer overdoses. The vet said it would depend on how long the paste wormer was in the horse’s system and other factors such as contents of the stomach if any. The best practice is also to never use horse dewormers that are NOT FDA approved. This approval is on the box or wrapper of the paste wormers. If it is not, don’t use it.
Most importantly is it always the best practice to assume that any medical drug including anti inflamatories can cause a reaction so if you have given any drug, you should watch your horse for at least five hours to note any signs adverse reaction. With horses the eyes, breathing, movement, heart rate and deameanor are very good indicators.
We do read this on most labels for over the counter drugs. Tylenol is very easy to overdose on. It happens often and patients end up in the Emergency Room with a charcoal stomach pump and liver damage if they get the treatment sooner than later.
Know your horse and it should not be difficult to notice when your horse is not feeling well. If you know your horse, you will notice when they are sick or reacting adversely to any kind of drug.
