doxycycline

Can someone please explain to me how to measure doxycycline POWDER? I need it for my 587g rat. How do I mix it? Thanks.

One of my boys was recently on baytril, doxy and a bronchodilator (Theophylline) but his symptoms improved. They've come back, but I realized his medications were in my car for several days and it's been extremely hot here. Are these medications ineffective now? Are they dangerous from heat...