Canine semen question

Dear Colleagues,

I have a case that is frustrating me. 

I have a 3 year old Leonberger male, intact and never been bred. He had semen collected at a dog show in October 2018 which showed high numbers of immotile sperm. He was then referred to me. The dog had great libido and gave a very white second fraction, with clear first and third fractions. Sperm count was over 2 billion, but 99% immotile. Morphology showed about 4% normal, 40% distal droplets, 20% proximal droplets, 18% bent mid pieces, 13% abnormal head shapes, and 3% coiled tails. Viability measured by PI on NucleoCounter was 19%. Aerobic culture of semen (manual collection) yielded no growth. Mycoplasma/Ureaplasma culture at Cornell yielded no growth. SCSA testing at Texas A&M was within normal ranges. Male is brucellosis negative on RSAT. He is not on a grain-free diet. 

We gave the dog 4 months of rest and rechecked his semen. No appreciable change 

I have now collected him 3 days in a row (and slated to continue tomorrow), with only a slight change in motility (0.4% to 2.5% motility) and no appreciable change in morphology. Overall sperm numbers have remained high (dropping from 2 billion to 1.2 billion).

The male reportedly had retained testes until he was 13 weeks old. The testes now are uniformly shaped, slightly soft, appropriate size, with no lesions on ultrasound. 

Any thoughts?

Thank you!