I'm sorry to hear this happened to your siblings dog.
Blood parasite is a bit of a vague term. It could mean ticks, leaches, fleas ect (external). Or it could mean a internal parasite which is different. Do you hapen to know what it is your siblings dog has? If it is a internal parasite I don't think you can personally go out and by it. There are many different kinds of parasites which means there will be variations in what is needed to treat them (internally speaking) and I don't think you can get something like a antiparacitic drug or what ever else they need to treat over the counter (I could be wrong though). The vet is the one that's going to know the correct medical cocktail for treatment and what treatment the dog needs.
I'm not sure were your sibling is located, but is it possible to find a emergency vet/ vet hospital that is more eqiped for dealing with this?
Blood parasite is a bit of a vague term. It could mean ticks, leaches, fleas ect (external). Or it could mean a internal parasite which is different. Do you hapen to know what it is your siblings dog has? If it is a internal parasite I don't think you can personally go out and by it. There are many different kinds of parasites which means there will be variations in what is needed to treat them (internally speaking) and I don't think you can get something like a antiparacitic drug or what ever else they need to treat over the counter (I could be wrong though). The vet is the one that's going to know the correct medical cocktail for treatment and what treatment the dog needs.
I'm not sure were your sibling is located, but is it possible to find a emergency vet/ vet hospital that is more eqiped for dealing with this?