This is where I think tinies can be more expensive.
I have 1 here that is 15 weeks old and still under 1.5 pounds. She will get a good vet check, bile acid tested and if needed x-rays of her hips or knees. I'm waiting on her to get a bit larger first. Its not happening very fast though.
I spent her first 2 weeks tube feeding her because she was only 1.5 oz at birth and not strong enough to suckle. She still has her tail because she was to small and fragile to even try to dock it. I've never been one to let nature take its course and this time I'm glad I didn't she is a doll.