What could have caused a dewormer to kill my dog?

[TWRichards]

We have used liquid dewormer many times in the past with various dogs we have had with no problems, and twice before on "Bandit" our Jack Russell terrier, [he was two years 3 months old] we adopted him about 2 years ago when we found him barely able to walk from starvation and took him in and made him a healthy and happy dog, and part of the family. Three days ago we checked his stool and he had worms again and we administered the dosage by his weight as before, he threw up his food and layed down, somewhat unsteady on his feet when he got up to move, gradually his started to breathe heavier and was visibly not reacting well to the medicine. We contacted a vet via the internet for advice on this, he said basically discomfort and a bad reaction to wormer is not uncommon, and piperazine has a very low toxicity, it should wear off, he suggested keeping the dog warm and try to get him to drink water to flush things out, and also take him in the next day as it was past hours. We did this but he would not take the water and seemed to be getting worse, we went looking for a 24 hour clinic found one in our county, and we were getting the address and ready to go when he stopped breathing while my wife was holding him about 2:30 in the morning, he went downhill so fast in the last 30 minutes, his breathing became laborious.
Needless to say we are devastated and heartbroken and so are the kids. The dewormer was petgold, piperazine described as "safe" for pets, and upon researching I have seen that more dogs are killed by dewormers than by worms, we had no idea that this could happen. I have recently read that worms can cause damage to a dogs the GI tract when in contact with dewormer or something to that effect? clearly our dog had a severe reaction to the drug on this occasion but never before, same medicine, same bottle, 2008 exp. date, we checked his weight/dosage ratio. We are at a loss as to why the severe reaction resulting in death within 5 hours, needless to say we will only have a vet administer dewormer on any other pets in the future, a very safe and comfortable one for the animal. The fact that we administered our pet dewormer and it killed him before we realised he was in serious trouble to get him into a vet in time is weighing very heavy on us.
I have read piperazine is being banned as unsafe in many countries, causes nerve damage etc., in humans and animals. If someone here could offer a possible reason that a dog could have such an extreme reaction to this medication please post. -Thank you, TWRichards

[LittleMissLevi]

As in humans it could be that he had an allergy to start when you first gave it to him but it was so mild that you didn't notice. If you give someone (human or animal) something they have a "mild" allergic reaction to the subsequent ones can than be fatal causing anaphylatic shock. This may be what happened or it could have been completely unpredictable reaction that is never forseen.

Sorry about your lose and I hope your family is doing okay.

[TWRichards]

Because his symptoms seemed extreme and he never exhibited them before with the previous dosages, we did not think it was an allergy, but it probably was an allergic shock then as you say. Thank you for the reply and we are doing a little better everyday.

[hazelrunpack]

I am so sorry for your loss, TW. It sounds like Bandit was very lucky to have found you. He was loved and cared for--and his life may have been short, but he appreciated all you did for him.

Let the second-guessing go...there was no way you could have known that he'd react so to a medicine you'd given him before. You did the best you could. He understands and wouldn't want you to be unhappy.

[Love4himies]

So sorry for your loss. Please don't feel guilty, he was loved and knew it.

Have you considered contacting the manufacturer to report this?

[Prin]

I'm so sorry. :sad::sad:

There are websites out there with horror stories of petstore de-wormers and anti-flea meds. It's always best to get everything from the vet.