The answer to whether a neutered or spayed dachshund calms down after recovery from the procedure to eliminate its reproductive capabilities truly depends on how its human companions define appropriate behavior.
Just Removing Sex Drive
Having a dachshund spayed, which is the surgical removal of the female sexual organs, or neutered, which is castration or removal of the male testes, takes away the dog's ability to reproduce. A "fixed" dog usually ceases to have a drive for mating and mating behavior. A male will no longer go on the prowl for available females; a fixed female won't be going into heat and therefore won't be "available."
More Interest in Humans
Once a dog's hormonal drive to reproduce is gone, he or she appears to human companions to be more interested in what people are doing. This may or may not be true. It is, however, the way pet owners often intrepret a dog's lack of interest in seeking mates. It is often viewed as an increased interest toward interacting with humans, which is seen as a "settling down" or calming behavior when it may be that the dog just has one less thing on his or her to-do list.
Most canines are fixed at about 6 months of age. By this point, they are well into the doggie version of puberty. Any mammal -- human or canine -- going through puberty is going to behave erratically at times. When hormonal levels fluctuate, so does behavior. As hormones stabilize, what is again interpreted as a calming trend begins to emerge. The fact is, as any dog ages he tends to be less energetic.
Dachshunds as a breed are busy dogs. They are constantly curious regarding their environment; they are talkative to those around them and full of spunk regardless of age if they're healthy. Simply losing their sexual capabilities does not change their breed characteristics or individual personalities. If your dachshund was excitable prior to surgery, he most likely will still get worked up when a stranger invades your backyard or when you toss a ball.
- running dachshund image by Diana Mastepanova from Fotolia.com