i agree above

the clot could move

my dog as a kid we let her out one night when she didnt come back right away we found her outside on her side whimpering

she had a stroke we put her down

13 is a good age but you cant make a animal suffer because its like your child

i have a 18 year old cat had a good scare last month but she my kid i got her at two i couldn't loose her but id she was sick in anyway like that where its to expensive to fix

i highly recommend with the list you gave putting her to sleep

BUT there may be a option to make your mom more happy in my town a funeral home started cremating pets with all kinds of holders angles animals

my wife's mom dies and her and her 2 sisters got angels with ashes in them

its a option if it dont creep yall our to much a nice way to remember it

good luck and very sorry to here pets are the hardest choice in life

have a good one