Dog rectal temp is 98.6 F

It's cold out, 61 F, but her temp last night was 99.4 so it's dropped. She's a little less playful than normal. My vet doesn't seem concerned, but I'm unsure if I should be.

Hello!  The normal temperature for a dog in Farenheight is often suggested to be 99.5 - 102.5.  Out of context, I am wondering things like, was the temperature taken correctly?  How accurate is the implement used for the temperature measurement?  Does the vet have all the information they needed to triage the case properly / an up to date examination of the patient?  We are never evaluating just a number and in this case it sounds as though the patient appears to be ill in themselves.  We therefore recommend that you call your vet or their emergency counterparts and ask them to triage your dogs' case, in context, based on the most recent information so that a decision can be made about this problem.  The way that you said it was cold outside made me wonder whether this was a yard dog and you were checking whether they could maintain their temperature outside?  If so, you should let your vet know when you make the call.  Please will you let us know what happens next?

Thank you! She is an inside only dog, I did a rectal temp at home and the vet did one at their office. They said since she was alert at the office, they weren't too worried but to monitor. I'm a worry wart and thought it was low, but wasn't sure.

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