I don't know how long this will last, but I literally noticed yesterday that our shepherd dog has ac…

I don't know how long this will last, but I literally noticed yesterday that our shepherd dog has active discharge from her mammary glands. It looks like a mix of blood and milk: both blood and the fluid itself are flowing, not from one spot but from all at once. We've already made an appointment with the vet, but we still have to wait until the fourth. Has anyone else experienced something like this? I'd love to know what this might mean... A familiar vet gave me a few tips, but I decided to ask here anyway—maybe someone has been through this and it all turned out fine, so to speak, with little trouble. The dog is eight and a half years old, she hasn't been spayed, and she hasn't given birth.