Australian Shepherd

The Australian Shepherd is a mountain hiker's dog: athletic, 16 to 32 kg, sure-footed on scree and keen to cover ground all day. Its thick double coat is an asset at altitude and in cold weather, but it is a liability on hot, exposed runs, so shift summer mileage to early mornings. One safety point matters for active owners: the breed is commonly affected by an MDR1 gene mutation that makes some common drugs dangerous. A simple DNA test tells your vet what to avoid if the dog is ever treated after a trail injury.