A client injected his 2 dogs with a multivitamin prep Modvit®, it's not indicated for dogs` but he thought it's just vitamins so it was fine to do so. A few minutes later the dogs had a strong skin hypersensitivity reaction with lumps allover the body, the groins were hyperemic, the dogs were salivating, scratching and panting excessively. The vet decided to inject an antihistamine at 2mg/kg of body weight IV. Just before injecting the second dog the already injected one had a strong episode of seizures but the skin reaction also started to disappear just following the injection. About an hour later, the dog stabilised and was able to go home.
My question is on the seizures, what could have really caused these them?