A friend of mine owns and runs a boarding kennel called Catered Canine Care (or possibly Canine Catered Care- sorry, I am losing my mind these days- comes up if you google it) in the Frederick/Jefferson area.
Never used her as a kennel (don't own a dog) but given what I know about her as a person and horseperson, I am sure the care is good.
There is something about the outside of a horse that is good for the inside of a man.(Churchill)
Buckeystown Vet Hospital has a fantastic kennel. I did some relief work for them several years ago and the facility and the care was top notch. I have referred several friends there and they have always been very pleased. It's the only kennel in the area that I recommend. I will PM you about the ones that I advise friends to steer clear of.
Life would be infinitely better if pinatas suddenly appeared throughout the day.
I second Buckeystown Vet. I take my 2 dogs, 3 cats and I trailer in my horse there for all routine vet care. I also use their grooming services several times a year and their boarding at least once a year.
If your friends have horses, I would be happy to send you some horse info about the area. Feel free to PM me.