The nature of dogs is to be obsessive and compulsive so the 'D' is not really applicable as it's not a disorder, it's just how they're made.
OCD in people manifests in recurring thoughts and repetitive behaviours that cannot be controlled.
Obviously when we use the term in relation to dogs, we're using it loosely and as short hand for a behavioural approach. In the video below you'll see some examples of behaviour which are obsessive and compulsive....they're also quite common place.
The first dog is absolutely fascinated by a water drip and she just cannot leave it alone. She has to investigate each drip and is totally immersed in this activity. You might say, 'well she's a collie cross', that's how they are. Yes, so just bear with me on this.
The second dog is so fixated on the ball that she can't move away from it even when other another dog crosses right in front of her. It's as if she's hypnotised by it....until she reaches out and breaks the spell. She features in the next video doing much the same compulsive thing. Her guardian thinks she's 'OCD'.
Interestingly, in this video, there's a retriever sitting just behind her, as if in a queue. Notice how the retriever doesn't make any attempt to get the ball. Not only does she not attempt to get the ball but, she doesn't attempt to move away. She too is captivated by what is happening.
She does however move when it comes to her turn to feature! She's fixated in a different way but fixated none the less. Her energy is trying to will the ball to be thrown. She's almost leaping out at you in her desire/determination to make something change. The smaller dog beside her also really wants the ball however her energy isn't quite so strong and she could be persuaded elsewhere.
What does being this way mean for these dogs? Is it good, bad or indifferent? What does this mean in human terms...is it a problem?
If you look at any dog sport/agility/flyball activities, you'll see dogs exhibiting exactly the same sort of behaviour. They're extremely focused upon what they're doing and they do it with every ounce of their being, until, in some cases, someone picks them up and carries them away/disengages them from that activity.
Many people don't appreciate their dogs obsessive and/or compulsive nature as, in the human view, it comes across as an unatural behaviour or one that is outwith their ability to control. It can also be tiring, physically and mentally, trying to keep up with that seemingly endless supply of energy and zest! It's all about 'What are we doing next?', over and over again.
Yet people will throw a ball for their dogs, over and over again....takes the element of 'next' out of the equation. Dogs can end up with a repetitive strain injury doing this kind of activity.
What is going on is that dogs create their world based upon patterns...and patterns repeat. This is how a dog comes to feel safe and why people need to understand the dog's reliance upon consistency. If you want your dog to learn something you have to teach it consistently....over and over again....not just once or twenty times.....over and over and everywhere, obsessively!
Dogs are not born with impulse control. This means they will do things for instant gratification. It has to be 'now'! We can all relate to that!
Dogs have to be taught impulse control.
Compulsion is a driver that seemingly serves no logical purpose......why stand staring at the ball? Obviously compusive behaviour has to provide some form of gratification as otherwise it wouldn't happen. There would simply be no point to it. The point being that what is gratificaction for a dog can be difficult to 'see' from a human prespective.
What we do know is that these expressions of behaviour make for dogs that are quite trainable; collies being the 'go to' when people think about 'trainable dogs'. 
From working with hundres and hundreds of dogs over the years, we see dogs who are more 'managed' than 'trained'. This doesn't do justice to the dog as his/her potential is never being fully explored. Thus the dog seldom gets to experience that 'I did it!' feeling...which they love. The 'reward' for doing well is a huge expression of positive emotion in which both guardian and dog participate. It's very bonding!
Of course, training and manageability are not just down to the dog. The relationship you develop with your dog is a reflection of your mutual relevance.
All of the dogs featured here are very responsive to 'training'. Their pattern reliance is quite high and, if you recognise and fulfill that need, you'll have an easy to handle dog - a biddable dog. These are all quite 'biddable' - they will follow direction.
Not all dogs are 'biddable'.....but that's another discussion!