You might need to adjust the photos by editing them on a calibrated monitor and through a photo editor software that has print profiles or print display capabilities...or find someone or some printing lab that might do this for you. Many times, this has to do with the settings of your monitor - if the brightness is high, saturation or contrast adjusted too much where a photo that actually is darker or less colorful 'looks' bright and vibrant on that computer screen, but when printing with the settings as they came out of the camera, they look poor.
I am not familiar with printing from those facilities you mention, but are any of them willing to 'fix' photos to improve them before printing? If not, the best way would be to find someone who is very proficient with computers and photo editing, with software like Photoshop or Lightroom, with a decently calibrated monitor, and see if they can edit your photos from the disk for you, then re-save them to another disk or memory card that you can then bring to the printer.
You can also check with some of the online printing companies, like Shutterfly and MPix - some of them let you upload your photos and can determine if they need a little 'boost' to improve them before printing.
Best of luck - sorry to hear of the passing of your dog.
