Shalom, would animals be allowed to euthanize, like a dog or horse that is suffering and will die, can you sacrifice them so they don’t feel pain?
It is permitted to kill an animal that is suffering. To euthanize them is best as it doesn’t cause them any pain, but killing it in a way that isn’t very painful, and will alleviate it’s pain is also permitted. The Chazon Ish was once asked what to do
with a fly that was wounded and suffering, and he said that it should be killed in order to minimize its suffering.
Please see the following post https://dinonline.org/2018/05/31/sick-pet-fish/
Dinim v’Hanhagos chazon Ish 2-pg. 40, Noda B’yihuda Y:D 83