Thoughts:
A) I am leaning towards this being slobber/shaking related, might be brown because she's nosing up the dirt or something. That just seems more likely than someone who happens to walk by at the right time multiple times, gets the dog to come close, and then spits on her. Watch the dog and or get a camera that can't run out of power. This will confirm/deny, so find out for sure.
B) If it IS a person doing this, you have to confront them sternly. That won't be fun, but probably someone who picks on a dog is going to be a pathetic insecure bully. They will deny deny but you will have to be firm. And then watch more that they don't come back and try to do worse - plenty of evil people out there. Dognap, poison, shoot, etc. Really, if there is any way to get the dog in the backyard then do that, or else you may just have to sit out there with her while she is out there.
C) don't leave your dog outside unattended, unless you want it to escape, be kidnapped, or get injured. GF is very involved in animal rescue and veterinary, and have seen countless stories that started with unattended dog "but there's a fence!" and ended very badly.
D) people saying to "unleash the Rott!" - you must not know many Rotts. They are frigging babies. We have a 14 lb terrier mix with diabetes who is more dangerous. Rotts look scary af, and there are a few that have been abused or trained to be vicious, but 95% of them are just teddy bears.
A) I am leaning towards this being slobber/shaking related, might be brown because she's nosing up the dirt or something. That just seems more likely than someone who happens to walk by at the right time multiple times, gets the dog to come close, and then spits on her. Watch the dog and or get a camera that can't run out of power. This will confirm/deny, so find out for sure.
B) If it IS a person doing this, you have to confront them sternly. That won't be fun, but probably someone who picks on a dog is going to be a pathetic insecure bully. They will deny deny but you will have to be firm. And then watch more that they don't come back and try to do worse - plenty of evil people out there. Dognap, poison, shoot, etc. Really, if there is any way to get the dog in the backyard then do that, or else you may just have to sit out there with her while she is out there.
C) don't leave your dog outside unattended, unless you want it to escape, be kidnapped, or get injured. GF is very involved in animal rescue and veterinary, and have seen countless stories that started with unattended dog "but there's a fence!" and ended very badly.
D) people saying to "unleash the Rott!" - you must not know many Rotts. They are frigging babies. We have a 14 lb terrier mix with diabetes who is more dangerous. Rotts look scary af, and there are a few that have been abused or trained to be vicious, but 95% of them are just teddy bears.