
Yes apart frominhibition sue to training errors a dog may have low libido for good health reasons that should exclude it from breeding.
I imagine this is one reason why the Kennel Club will not allow litters by AI from dogs that have not sired pups naturally or from bitches that have not had pups naturally before.
One such condition is underactive thyroid which affects Libido and fertility.
A reluctant male can be brought around to the job with patience and an experienced bitch.
I have recently managed to get a dog I bred going as a stud at 6 1/2 years old after he had been put off by my own bitch a couple of years ago, and this with a maiden bitch. His pups are now 5 weeks old and a second litter is hopefully due.