beagle brothers fighting

Question
I have 2 six year old beagles that are brothers. They have been best friend right from the start. They have had a few small fights over years, but nothing major. 2 Days ago i took them to vet for their yearly ckup and shots. Everything went fine & normally. About 1am that night i took them out to pee & my 1 dog went into street. I have shock collars on them and the street is only time i zap them-after i did the 1 dog went after his brother. They had a brutal fight and bit each other bad.My neighbor had to come out to grab the 1 dog so i could move them into house. 2 days later they still want to attack each other when in same room..i am not sure how to get them past this..the instigator dog doesn't want to fight anymore, but his brother does. I am taking the victim dog to vet now to see if he got an infection from the bites..I'll take any suggestions for help..

Answer
Sounds like there may have been some trama between the shots that day and the shock collar that night. Regardless, if this has continued and they seem to be on the verge of fighting more you need to seek out the help of a one to one trainer who will come to your house and do it fast. Aggression seldom dissapates, it almost always escalates! Two dogs fighting can cause severe damage to each other.