Call them first and tell them of your situation. As long as you are sure of their ages and they are in good and healthy the BHS will find homes for them. The first thing they do there is give them physical and spay and neuter, if not already done. I understand they take cats up to 5 years of age.
Sorry to hear you have to give up your pets. If there isn't a friend or co-worker to take them the BHS can take and rehome, you can drop off but best to call ahead
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