We had planned a 3.5 mile hike today, but the temp. is 20 degrees with 15 mph winds. "Feels like" 2 degrees. She is 5 months old. We know that goldens are cold weather dogs, but is this too cold?
First of all, your dog is too young for that length of hike.
Large breed dogs need more time for their joints to develop and harden. If you take them on long hikes or runs, they are likely to damage their joints and have problems later in life.
Secondly, yes, I think it is too cold - especially for a dog so young.
