I want to make my dog's birthday special.
Is it okay to give her just one McDonald's hamburger (and no more after that)?
Better safe than sorry and don't give it, lots of grease in these burgers! All that grease can cause a number of problems such as diarrhea or acute pancreatitis - which has a possibility of turning into a long term issue (most commonly seen in our small dogs). These burgers also contain onions which are toxic to dogs.
The other poster mentioned going to the pet store for a nice treat which is a good idea however stay away from bones:
A vet I work with had a case not too long ago with a bull pizzle that punctured the dogs esophagus and went into his chest cavity, the dog unfortunately passed away. Even though it's not technically a bone it's one of those scenarios to be weary of.
Add to the current answers, a stock burger there has onions on it. If not ordered special, the "treat" could be less than pleasant. The amount on the burger may not be enough to be deadly, but I suspect that the volume is enough to ensure it's actually not a treat.
Net effect, you may like their burgers (I'll skip passing judgment on that), but there are plenty of dog-safe treats that are sure to be as big a hit, if not bigger, than anything McDonald's is going to put out for them.
Not safe, it has sugar and onions, dogs can't deal with any of them! Onions will cause anemia, directly affecting the red blood cells, onions are toxic for dogs, while sugar will definitely cause liver failure.
Well somebody asked for a reference, in the US you should read what the American Kennel Club published on its website, all you need to know about dog nutrition is right there:
http://www.akc.org/content/health/dog-nutrition/
And regarding to onions:
http://www.akc.org/content/health/articles/can-dogs-eat-onions/
How big is your dog?
A McDonald's hamburger is not the best thing to feed a dog - even as a treat. It won't kill her, but depending on her size, the salt, the bun, the ketchup, mustard and especially the onions will upset her digestion, possibly causing uncomfortable gas and diarrhea. I recommend that you only feed her the meat patty if at all. Likely it was cooked with salt or salt is ground in the beef, so make sure she drinks plenty of water afterwards. If she is under 40lbs (18 kg), I would avoid it altogether.
Remember, with treats for your pet, it's not how much you give them but that you are giving them a treat. Smile as you talk to her, give her affection, gently massage her legs and muscles - stay engaged with her, she'll LOVE that :)
As an alternative suggestion for your dog's birthday maybe take a trip to a dog park or a dog friendly hike or beach? Dogs love being social, with people, other animals or other dogs - that way she can catch up on the latest news and gossip. Maybe just a fun walk around the neighborhood? She doesn't know it's her birthday. She just loves doing stuff with you!
Lastly, I would also recommend against feeding her raw hamburger. Raw hamburger may contain Salmonella or E. coli which can cause disease in your dog and which your dog may pass on to you. Instead talk to her as you cook her a plain and lean ground beef hamburger patty (no salt or seasonings). Let her sniff at the objects you are cooking with - that way she'll feel like a part of the process. When you are done cooking and the pan has cooled off you could wipe the pan to remove excess fats and let her lick the pan - but don't make this a habit, especially if it is a small dog.
I hope you and your dog have lots of special occasions for a long time to come!
There is lots of sugar in a McDonalds burger. That would be really bad for your dog. Why don't you make your own burger using ingredients that you're sure that are good for the dog to eat?
It's probably as safe and healthy as it would be for you.
And it would probably also make him happy, but not more happy then with any other treat you give him. So my advice: go to the pet shop and buy an actual dog treat. Like a big bone or something like that. At least that will be more healthy and suitable for a dog.
Get a plain double burger. When you get home, take the bun off and pat both pattys down with a paper towel, then cut them down to the size that fits your dog.
I have had 3 German Shepherd Dogs. All purebred and they all ate plenty of McDonald's throughout their long lives, including the odd soft serve cone. Never caused them one iota of an issue ever. Fear-mongering is at an all time high these days. It's a dog... it can and will eat just about anything. My dogs die from old age at about 12 years old and when I could their last meal would be a cheeseburger and a cone before going to see the vet for the final visit.