Are my dogs catching something?

We have two shelties (nine and ten), a labrador and just got a new aussie shepard puppy (3 months). Recently, they all seem to be fatigued a few times they have gone to the bathroom in the house, which is a rare occurence even for the puppy. The female sheltie has a lot of secretion from her eyes now the labrador does also. She also has a lack of appetite. Are they getting sick?