in ancient societys what happened to slaves when they got sick or old ?

It probably varied depending on the owners, some treated their slaves better than others. But in America, old slaves often would look after the slave babies and young children while their parents worked, and I imagine that this was probably common in ancient societies as well, someone had to care for the young ones. A sick slave might be nursed back to health, but there were a lot of diseases in ancient times for which there was no cure, and a slave might be likely to die if it was something serious (so was a free person come to that.) In general, far fewer people than nowadays lived to old age, you were much more likely to die at a younger age than you would be now, so there would be far fewer old people generally than there are nowadays. Old people are common nowadays, but in past times they were relatively rare, only a minority made it to old age.

if they had insurance they had medi- care if they didn't they were thrown on the waste dump nothing changes

It depended on the owner. Some loyal house slaves in Roman times were actually treated quite well if they had been loyal life long slaves. I am sure others were not so lucky and likely were killed when of no further use or thrown out to fend for themselves. Maybe they were sold cheaply while they were still of at least a little use.

They would treat them the same as they would a racehorse with a broken leg.

It's on a case by case basis.

Slaves were a commodity so it was in the best interest of the slave owner for the slaves to be healthy. Although an aged slave becomes physically limited, his job description could be modified to facilitate that. It can become about cost effectiveness but not all owners were heartless. It was not unusual for some relationships to develop an affinity for each other.

Depended on the slave’s job. If he was a tutor, he would be a regular part of a household and would be cared for as a skilled slave.

A slave in a mine was simply a tool to be used until broken. They didn’t have sick days and no one in the mine had to worry about old age. They were worked to death.

Killed through exposure.

It depends on which society you are talking about.

Different societies had different policies for the elderly (though most slaves did not live that long).

They were often killed.

if they had insurance they had medi- care if they didn't they were thrown on the waste dump nothing changes