here are some sites i found for vet bill help in Maryland 
hope it helps.
American Animal Hospital Association
http://www.aahahelpingpets.org/home /
" Through the AAHA Helping Pets Fund, veterinary care is possible for sick or injured pets even if they have been abandoned or if their owner is experiencing financial hardship."
Angels 4 Animals
www.Angels4Animals.org (
http://www.Angels4Animals.org)
"Our services range from financial aid to complete treatment to those pets and pet owners in need."
Care Credit
www.carecredit.com (
http://www.carecredit.com)
A credit card company for health care, including veterinary care. "With a comprehensive range of plan options, for treatment or procedure fees from $1 to over $25,000, we offer a plan and a low monthly payment to fit comfortably into almost every budget."
God's Creatures Ministry
http://www.all-creatures.org/gcm/help-cf.html
"This fund helps pay for veterinarian bills for those who need help."
Help-A-Pet
http://www.help-a-pet.org/home.html
"Our efforts focus on serving the elderly, the disabled, and the working poor."
IMOM
http://www.imom.org
"We are dedicated to insure that no companion animal has to be euthanized simply because their caretaker is financially challenged."
The Pet Fund
http://thepetfund.com/
"The Pet Fund is a registered 501(c)3 nonprofit association that provides financial assistance to owners of domestic animals who need urgent veterinary care."
United Animal Nations
http://www.uan.org/lifeline/index.html
"The m ission of LifeLine is to help homeless or recently rescued animals suffering from life-threatening conditions that require specific and immediate emergency veterinary care. We strive to serve Good Samaritans and rescue groups who take in sick or injured animals. In certain cases, LifeLine can also assist senior citizens and low-income families pay for immediate emergency veterinary care."
HandicappedPets.com
http://www.handicappedpets.com/Articles/help/
"From time to time, HandicappedPets.com recognizes a caretaker of handicapped pets that need some special attention, and a little extra help. There are those who are so selflessly dedicated to their animal families that they give up a little more than they can afford."