Spaying the female can change the temperment but I don't foresee it causing the male to fight with the female. If anything, it will either make the female have a calmer temperment or it will make the female's temperment some what better because she no longer has to deal with the pain of going through a cycle plus she has no chances of some of the cancers and other problems that come along with the reproductive organs as female dogs get older. For the male, it may also calm him as well be cause the female will no longer go into "heat" and so the male will no longer go crazy trying to get at her.
I hope this helps, let me know if you have anymore questions. :)
*According to Dogs Obedience Training. com...
American research has shown that there is a 70% improvement in behavior after castration.
* According to Veterinary Partner.com...
Spay/neuter helps produce healthy and good-tempered purebred dogs. An in tact male will have hormone-related behaviors, including urine marking in your house, aggression toward other male dogs, territorial aggression, and escape-oriented behavior in order to roam. A female with estrus, may show erratic behavior, signs of pain that may be similar to cramping in humans, and a greatly increased propensity to get out of the house or fenced yard. Spaying the dog prior to ever getting pregnant can spare both her health and her temperament from sometimes dramatic deterioration.
*According to Peninsula Humane Society & SPCA Resorce Library
*According to InfoVets.com
Behavior problems are generally reduced, including roaming, interdog aggression, and anxiety or fear-related problems.
*According to Cuhumane.com
Reduces or eliminates intermale fighting, irritable aggression of females in heat, and dominance aggression. *Neutering does not affect guarding behavior.
*According to Angelfire.com
Some undesirable behaviors may also be avoided or improved by spaying and neutering. There is quite a lot of individual variation in this, because other factors (training, socialization and so on) are at work here. Neutered males are less likely to roam off in search of female companionship, less likely to fight with other dogs.
*According to Program For Companion Animals Behavior, School of Veterinary Medicine......
One study showed that male intact cats exhibited less affection to humans than neutered cats.
There are plenty others. Let me know if this is not what you are looking for and I will see what I can do. Thanks again.