Why isn't Rh disease present in other mammals?
Rh is just a proteinous(antigenic) factor in red blood cells; not a DISEASE.If it is present in blood you are Rh positive. If not Rh negative.An Rh negative person if exposed to Rh positive blood will form specific antibodies against the Rh antigens. In case of pregnancy, Rh antigens of the foetus do not get exposed to the Rh negative blood of the mother during first pregnancyas the two bloods are well separated by the placenta.

However during the delivery of the first child there is a possibility of the exposure of maternal blood to small amounts of Rh positive blood of the foetus.In such cases the mother starts preparing antibodies against Rh antigens in her blood.

In case of her subsequent pregnancies, the Rh antibodies from the Rh negative mother can leak into the blood of the Rh positive foetus and destroy the foetal RBCs. THis could be fatal to the foetus or could cause severe anaemia and jaundice to the baby.A condition called erythroblastosis foetalis arises.

This condition can be avoided by administering ant- Rh antibodies to the mother immediately after her first delivery.

This is not a disease but is just as a result of antigen- antibody reaction.As far as Rhesus monkeys are concerned, it is an innate factor in them, common to all.It is quite similar to the case of Bacillus thuringiensis in biotechnology. When inserted into plant cells these bacterial phytotoxins cause havoc as an insecticidal agent; whereas they seem to have exactly no effect inside bacteria.You may also consider the case of Penicillium notatum.These organisms are capable of causing harm to other living organisms but are not affected themselves.

Similar is the case with Rhesus monkeys.