Totally agree with Karla. Could be a number of things including stones
Welcome.....Any blood from any area is NOT normal (Unless it's a heat cycle in a female).....So, yes there is cause for concern......Panting hard is usually associated w/pain!
My first thought is your guy has a UTI and needs to be treated....Left unattended, these infections can migrate to the Bladder & Kidneys which are harder to treat....Oral antibiotics will be given & a recheck of urine in a couple of weeks to make sure the infection is cleared......
It's also possible that your guy is experiencing A Bladder/Kidney Stone....These seem to be common and will also cause bleeding.......
Either way, you need to have him seen by a Vet ASAP.....Neither of these issues will get better on their own, they will only get worse......
Let us know what you find out & good luck! Karla
P.S. Both conditions described above are extremely PAINFUL!