Hello & welcome, I am Dr. B, a licensed veterinarian & I would like to help you with your wee one today.
Given that the mating was 10 weeks ago (which she'd be due to have pups already if pregnant), a false pregnancy is a concern.
As you may know, this is a benign hormonal condition where an entire non-pregnant female dog produces milk despite not having gone through a pregnancy. It is a phenomena that is actually used to ensure pup survival in wolf packs (so that pups are not without milk if mum were to die). In regards ***** ***** this, aspirin is of no benefit and should be discontinued. Instead, we tend to need to use supportive care +/- Galastop (a hormonal treatment from her vet) to settle this.
In regards ***** ***** care, we'd want to make sure she is not licking or nursing herself. When dogs do this, they just confuse their body more (as it thinks it is making milk for a purpose) and will prevent her mammary glands from settling down. Furthermore, you do want to keep general mammary gland stimulus to a minimum. This means you don't want to over handle them and if she is bothering them then consider putting an e-collar on her (from the pet store or the vets) and/or covering the glands with a t-shirt +/- reversed boxer shorts (reversed so there is a hole for her tail).
Next, we want to make sure we aren't letting her carry out maternal behaviors that may confuse her body further. Specifically, we want to remove access to any nests she may have made and remove any toys she may be mothering. This has to be done carefully because if she is very attached to a toy (though you have not mentioned this is the case) then she may become distressed when you remove it. For very anxious dogs, we do sometime have to delay removal of "babies" and focus on our other steps to avoid distress.
Once stimulus of the glands and any "babies/nests" are addressed, we do have a few choices on how to address this. Many dogs will settle on their own (as the hormones wane) after a few weeks. In some cases, we can help speed up this procedure via lifestyle and/or medical management. In regards ***** ***** changes, we do find that some dogs respond to us 'simulating winter' (a time when resources are scarce and therefore not a time to be feeding pups). To do so, we half their daily ration of food and double exercise. Typically, this only needs to be done for a few weeks but can help those stubborn false pregnancies to subside. I appreciate that Bella is older so the exercise increase may not be something she would handle, therefore you may keep this option in reserve for her.
Further to this, there are a range of hormonal therapies on the market for treating false pregnancies. If required, your vet will be able to dispense this for you. Often these are not necessary but you find that she doesn't settle over the next few weeks or you are struggling to keep her from stimulating her glands, then this may be an option to consider. At the same time, they can double check that she hasn't a uterine infection (a common issue for older females though doesn't tend to affect mammary development).
Overall, to see swollen mammary glands of a female unneutered dog that may not be pregnant, false pregnancy would be our top concern and the above would be our course of action.
Please take care,
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