as a veterinarian,first of all if they have a doubt for this pigs(general term-swine),they must do the nessecary procedure to make sure,that they are not infected by the virus,the word culling is seperation of undesirable animals,therefore their goverment will give the order to the higher veterinarian who is in charge to their goverment.as you say islam teach not to harm animals.so for this modern world we are facing now,we have all the technologies to determine this kind of virus,