“in the past 2 years my Belle has gotten into fights with the boys, and caused vet bills”
Taking her for a blood panel is more feasible and cheaper than continuing vet bills from the fights. If her thyroid is low, the meds are inexpensive and she needs them. There are also other medical problems that can lead to aggression.
Vet bills are always feasible, it is part of the responsibility of owning dogs, so I don’t understand why you would say it is not feasible. If you mean you don’t have the money, try talking to the vet and setting up a payment plan.