It depends on the locality, for example in Nigeria the Mongrels were found to be resistant to haemoparasites more than the other breeds because they were found to be more immune to this disease. Though not scientifically proven but the statistics of dogs presented to the clinic proved this to be so.
No, because they are not a common breed here in Nigeria, we have breeds like the German Sheperd, Rottweiler, Labrador Retriever, Great Dane, Dalmatian, Terrier, Samoyed e.t.c.