Someone Poisoned My Rott

My rottie Omar had been throwing up, became very weak, unable to walk, breathing heavily and somewhat disoriented. I took him to the vet on Tuesday and my vet at first diagnosised him w/Upper Respitory Infection and mild case of worms.. Gave him 2 shots sent us home w/meds.. throughout the nite Omar was vomiting constantly.. took him back yesterday.. I told her that I notice "chunks" of blood in his vomit. She said she would do some test for poison.. This morning I found out that he had been poisoned w/ rat poison or mole poison and he has internal bleeding.. .. I adopt Omar, (3 yr old rottie)just 2 months ago. I had a rottie before him that I had for almost 4 years. His name was Bobo.. he had been abused as a pup and my friend ask me if I would take him in.. I did.. It was the best thing I could have ever done. My husband and I just moved into our home 3 years ago.. never had any major problems w/our dogs. They are fenced in and I also have pens that I put them in when they are eating.. cause my Doberman is quiet the pig.. BUT... BOBO died back in Oct..BROKE my heart.. and he too had been poisoned and I also had a Chow-chow pup to die.. Maverick.. he died on a friday nite and Bobo died on a SATURDAY NITE.. what I don't understand is why.. why poison an animal that has no way of bothering you or harming you in any way.. WELL, I would like for you all to be thinking of us.. my vet .. said she couldn't tell me if he(Omar) would be alright or not.. its too soon to tell .. I just don't think I could handle another loss.. .. But for my other animals.. My dobie and chocolate lab.. their fine.. its just been my rotties that have been targeted. How can people be so cruel?!