Sadqah removes troubles, so there is no harm if animal is given in charity with the intention that Almighty Allah shall make him healthy with its blessings. It should be noted that while doing sadqah the specification of animal in this way that it shall make healthy is not correct rather you can give money etc with the same intention instead of animal. In some places animal is slaughtered or given in sadqah with the intention that the exchange of life is life. It is baseless. Hadhrat Maulana Ashraf Ali Thanavi (رحمة الله) writes: “Likewise, it is a particular custom among commoners rather prominent ones that they slaughter animal on behalf of a sick person, they do it to remove evil etc. So it is learnt with established sings that slaughtering is intended and it is considered as effective in removing evil in the state of illness, therefore it seems to be unlawful.
لما مر من قوله أن الإراقة فى غير محال وارادة”. (امداد الفتاوى: 3/ 570)
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband