Hadn't felt any difference in temp and we haven't changed shampoo or anything.
We do live on a property and they are forever getting into mud patches and things, we just hose them down, let them dry off and give them a proper bath once eveyr couple of months, over summer once every month as it's warmer and helps cool them down.
As soon as we have a nice warm day i might empty out the old bathtub and put it out the front where i can chain them up and give her a good scrub.