Hiya c:
Shaded Haddock's picture ^-^
As you can see, the light source is very important. For, if it were to be around midday, the sun would be right above the dog and shadows would be underneath his face, belly, etc. Also, you can have a look at muscles/anatomy of an animal and shade according to that - but I didn't do that. I've used regular shading, darker shading and lighter shading [very hardly visible]. I told you it'd be very rough, so here it is ^-^
Blu