Hi,
I think your concepts are nice. The proportions are correct, and they do look like real creatures. Some of the colours are a bit bright, could try reducing saturation a bit. Creature's faces are important; humans identify each other, and also their pets, through facial features. Thus, if you want to create a being that looks alien, make one with strange face.

I think this is also the case in your first and second pets: people identify them as familiar animals due to their faces.
Here's an example:

I hope you don't mind me using your pet as subject. I changed the face of your creature a bit. Also reduced the colour saturation. With the tapir nose, it's not nearly as identifyable as a canine. However, try moving your finger on top of the nose, to hide it, and you'll see the dog again.

Keep it up, and add something from yourself in each pet.
- Cherppow