If the virus is in its early stages it's not uncommon for the test to come out negative and then as the symptoms continue if the pet is tested again it comes positive. We still prescribe medications if the test comes out negative and often recommend coming back to retest. Because of the symptoms which often includes not eating/drinking you need to syringe feed and keep the pet hydrated even if that means giving fluids (and pedialyte) via syringe. Sometimes it's not enough and the pet is unable to fight off the Parvo virus or whatever else may be ailing them. It's a sad situation but we see it fairly often. I'm sorry for your loss.
Sorry about your dog.
I guess it's possible. Sorry about your dog
I haven't however parvo tests aren't perfect. Sometimes they do have false negatives. Also there could be another cause aside from parvo that can cause death too. For instance there has been issues with certain breeds with certain foods. Also liver problems and allergic reactions can present like parvo too.
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