Hi looking for any bright ideas. My grey hound has been ill for 3 weeks. Suddenly became lethargic, not eating vet gave anti biotic jab and he rallied for 2 days. Then went down hill again, apart from a temperature vet could find nothing we suspected teeth as he has always had problems. Vet took out some and found an abscess on one. He recovered from the surgery after a week eating normally, but he's still lethargic, panting and had a temperature. On third course of anti biotics. Blood test shows infection but can't locate the source seems a long time to have an infection, and he's not responding to anti biotics