Hmm. Hate to say it, but it needs a fair amount of improvement.
A couple tips: Don't make the neck to head transition so abrupt, and maybe make the head a bit more proportionate to the real-life equivalent of your subject. i.e. If the head is big, make the facial features big and maybe make the body look like it belongs with that head.
The paws need a bit of work too. The toes on most animals with paws are more square than circular, and the toes are slightly thin when seen from a forward angle.
If you look closely at an animal's legs/shoulder/hips area, you'll notice that the legs don't taper towards the paws that steeply. Usually it stays moderately consistent, and if the leg is big, the paw should be sized accordingly.
Animals' chests are usually bigger than the head and slightly protrude from between the front legs. When comparing the chest to the head, the head should usually be slightly smaller than the chest.
For reference, canine heads are longer than feline heads (except for in pugs), likely to accommodate for all that smelling power. Dog noses are also usually square compared to cat noses, which are more triangular. In a lot of types of dogs, the head takes a dip towards the snout from the forehead compared to that of a cat, which stays more consistent.
TL:DR, dog heads are longer than cat heads and it should be fairly clear between the two different kinds of animals.
To continue the statement in the TL;DR bit, cats usually have longer tails than dogs do and are typically rounded at the tip. They only poof out when the feline is intimidated (not angry as many think), and otherwise the tail should look slimmer. Canine tails are usually shorter but fluffier than that of cats, with wolves coming closest to cat tail length compared to their body size. However, a wolf tail is still shorter than a cat's is compared to the respective species' body sizes.
TL;DR, you have a lot to learn and a long way to go.
I'm not saying your art is bad. It just shows lack of experience. The shading on the last one is pretty good, but other than that, it needs a good deal of work.
It's a long road ahead, and it's not getting any shorter and it's not gonna get any less bumpy.
