Infertility in male dogs refers to diminshed or absent fertility but does not imply sterility. Infertility in a dog can be due to a number of different problems including injury or infection.
In this condition, the dog is either not able to mate or if it does, fertilization does not occur as expected. In most cases, the dog's inability to pregnant a female dog is due to bad mating timing. Other various causes can also play a part in the infertility of a male dog.
The main symptom of infertility in male dogs is the inability to make a female dog pregnant. Other common symptoms include
Loss of libido (sex drive)
Bloody urine (hematuria)
Difficulty urinating (dysuria)
Straining to defecate (tenesmus)
Enlarged, inflamed, painful testicles (orchitis; one or both can be affected)
Reluctance to sit
Stiff, stilted gait
Increased frequency and volume of urination (polyuria)
Increased thirst and water intake (polydipsia)
Small testicles (one or both)
Enlarged testicles (one or both)