I'm sorry that your question wasn't answered in a timely manner and I regret that my state board of veterinary examiners doesn't allow me to speak to customers by phone in this venue but other experts in this category may be able to assist you in this regard. Please let me know if you'd like another expert to do so and I'll opt out of this conversation. Please stay in the conversation if you wish.
As Bella's pregnancy progresses, her mammary glands are going to become more dense and engorged with blood. This is going to result in the perceived heat and firmness you're feeling particularly in the most caudal (toward the tail) mammary glands. Unless there are other symptoms of concern, there's no reason to be worried at this time. Please respond with further questions or concerns if you wish.