ATTACHED is PDF that should be helpful. My experience with Brucella in cattle encompassed the entire phase of eradication of Brucellosis in the USA. The PDF gives several testing schemes. I hope it is useful.

• Isolation of Brucella from semen.
• Serological tests (RBPT, STAT and ELISA).

Isolation of Brucella

PCR 

If you want to diagnose from semen than culture and staining is proffered because  B. abortus can be cultured from semen. If you want to diagnose by serology than serum is preferred.

The least amount of semen required for diagnosis of brucellosis is 2ml  that should be free from bacterial, mycotic, and particulate contamination to separate 1ml of seminal plasma upon which the serological tests will be performed. 30µl of sodium azide 1% (w/v) should be added per each ml of semen and then semen should be centrifuged at 900 xg for 10 min. to separate seminal plasma. The serological tests done on seminal plasma as reported by research articles are RBPT (Rose Bengal test), BAPA (Buffered acidified plate antigen test) and iELISA as screening tests. CFT (complement fixation test), SAT, 2-ME (mercapto-ethanol tube agglutination test), PCR and Real Time PCR as confirmatory tests. the best method ever used in diagnosis of brucellosis is isolation and identification of brucella micro-organisms which is the only gold standard but this method has some limitations of being difficult to be applied on large scales, low sensitivity, slow growing nature of brucella spp. 

Hello

take a look at these too, 

they could help maybe

In canids and in Ovines 

Good luck

https://www.ncbi.nlm.nih.gov/pubmed/17343907

https://www.ncbi.nlm.nih.gov/pubmed/12488071

By isolation . This my research