It sounds as if Boobie may have a urinary tract infection (UTI). Since he's been neutered, issues with his prostate seem less likely although they can't entirely be ruled out.
Minocycline can be given to dogs and can actually be used for urinary tract issues especially if a culture and sensitivity indicates that the particular bacteria growing in the bladder is sensitive to it.
My only hesitation about its use is that it may affect a urinalysis if one is done by your vet when/if Boogie is seen. If a culture and sensitivity is done while the patient is taking antibiotics, then the results can definitely be affected and can, thus, be difficult to interpret for some patients.
But, to specifically answer your question: The dose of Minocycline that I'd use for a dog this size would be 100 mg twice a day, with food to avoid stomach upset. If this drug is given on an empty stomach, most patients will vomit so be sure to make sure he's had a good meal when it's given.
I should mention that it would be illegal for me to advise the use of a drug for whom it wasn't prescribed (human or pet) but I can provide the dosage information which is what I've done.
I would also encourage increased fluid consumption to help flush out the bladder.
I hope this helps. Deb