Good Morning Christine and welcome to Just answer. I am Dr. Loretta, a licensed veterinarian and I am happy to answer your question.
I feel your pain, Christine and this is very difficult for you and for your girl.
It is not unusual for something to happen after this procedure is done that makes your girl seem foreign to Max....almost as if they do not know each other. This cause anxiety between the 2 dogs and depression for your girl. It may also be that your girl is acting depressed due to the chemical imbalance caused by this procedure and this depression can be serious and cause Max to stay away. This LINK may help.
It will take time, but Max will eventually get over this anxiety and become buddies again with your girl. There are aids, Christine that will help them past this.
Purchase a DAP Collar (Dog Appeasement Pheromone) at the pet store. This is a canine pheromone that acts as a calming agent and will decrease anxiety. Place this on both dogs. Also, purchase Rescue REmedy which is a holistic anti anxiety medication available at the pet store and give this to both dogs.
After this, take them for walks together , play ball with them together and talk to both of them in soft voices. Make sure to pay attention to both dogs equally. Give them treats together and give a treat when they act or play together.
If this is not enough, your vet will have anti anxiety medications to help that are stronger Christine and will help them past this.
Don't worry Christine....there are ways around this but you have ot take some time and be patient.
Does that make sense to you, Christine?
Please let me know if you have ANY other questions. My goal is to give you 100% satisfaction and if you are not yet satisfied, please Reply so I can clarify for you
Sincerely, XXXXX XXXXX