Sexual-Aggression towards dog

Question
The situation is this:

I moved in with my roommate about 7 months ago. She has a 1.5 year old, unaltered male cat. I have a 1 year old unaltered female mini-dachshund. The two have gotten along beautifully, but after my dog went into and out of heat about 3 months ago Melvin, the cat, has started biting the back of my dog's neck and tries to mount her. My dog, Pooky, doesn't really understand the behavior and he always ends up hurting her, which I feel is damaging their relationship, since she no longer wants to play with him. Whenever she would initiate playtime he always tries the same thing and this is now what she associates playtime with, usually running away or coming to cower in my lap. My roommate is going to get him fixed eventually, but there's no set date and time, and this puts it out of my hands. Is there a way to curb this behavior, other than through neutering?

Also, if it has any bearing, my roommate also has a fixed female cat, which does not get along at all with the male, and a fixed, large-breed, female dog. Both of these animals are much older.

Answer
Sarah,

There are low-cost clinics around. I would find one as soon as possible. That is Mother Nature causing the animals to behave like that, not a behavior problem. You can't punish them because they are not doing anything wrong, just following their basic instinct.

You are not doing them any favors by not getting both of them fixed. You are just confusing them and you can see that it causes behavior problems that may become permanent.

If your roommate is not going to fix her cat then I would do it. If nothing else for the sake of your dog.

Tabbi