METS for walking the dog
is about 3.0, for a comparison of standing versus sitting in an office work setting
METS is 1.8 to 2.3 while standing and 1.3 to 1.8 while sitting (which gives a difference of about 0.5 comparing sedentary sit-down jobs to standing jobs). For sitting down watching the television at home
METS is about 1.0.
So comparing the differences between what you are talking about and a sedentary lifestyle:
Standing 7 hours per day: 0.5 * 7 = 3.5
Walking the dog for one hour per day: (3.0 - 1.0) * 1 = 2.0
The TDEE for sedentary is (I think, you can check) about 120% of BMR. So, figure sedentary TDEE averages a METS of 1.2 (as a reference, sitting quietly is 1.0 and sleeping is 0.9). If you take 1.2 times 24 hours you get 28.8. Add the 3.5 for standing 7 hours and the 2.0 for walking the dog for an hour and you get to 34.3, which is an average of 1.43. Take your BMR first by 1.20 and then by 1.43 and then compare those numbers to what you get by selecting "sedentary" or "light" or "moderate" and that might help you decide.
Hope this helps!
ETA: @kencc had this post
which was helpful, a snip from the relevant part:
kencc wrote: One of the issues is that the Mifflin-St Jeor equation gives a reasonably accurate BMR for an 'average' person but tends to over-estimate BMR for over-weight people with a body fat percentage greater than, say, 30%. For those with a high BF%, it's usually found that the Katch-McArdle equation gives a lower but more accurate BMR figure than Mifflin.
I'm pretty sure the BMR calculation on this site is Mifflin-St. Jeor, so you might want to factor that into your figures, maybe search for the Katch-McArdle equation and see how different it is.