To be honest, this does look somewhat worrying. The rest of the incision healed very well, but the dark dot near the bruising could be a spot that didn't heal properly.
In my oppinion, you don't need to rush to an emergency vet, unless one of the following occurs:
- Your dog is lethargic, sleeping all the time and avoiding physical activities.
- Your dog eats or drinks much less than usual.
- The bruise turns dark blue or black.
- The gums of your dog turn pale.
You must keep an eye on this and documenting the progress with regular photos is a good idea. If it keeps spreading, turns a blueish or black color or if your dog gets a fever, go to the vet on monday.
If your dog starts excessively licking the bruise, put the e-collar (collar of shame) back on.
If your dog gets a fever or is having pain you can give her a weight-appropriate dose of ibuprophen as a first aid measure. Cut one tablet into 2 parts for a dog of more than 25 kg, 4 parts for a dog of 10 - 25 kg and even smaller parts for smaller dogs. Give one part of a tablet up to 3 times a day, but only after the dog ate something (ibuprophen causes discomfort and loss of appetite if taken on an empty stomach). If there are no signs of fever or pain, this is not neccessary and could even prolong the healing.