horse trekking in Bolivia

Hi,

I'm currently travelling in Bolivia and would really like to do some trekking in the mountains but am not able to walk much at the moment due to an injury - so was planning to do some treks by horse.

Does anyone have suggestions on who to contact for 2 - 4 day rides, maybe in the following areas of Bolivia:

-Near La Paz (maybe something similar to the Yunga Cruz trek - don't know if this can be done by horse)?
-Parque Nacional Sajama?
-Parque Nacional Torotoro?

Thanks a lot for any suggestions!

Rob

the place to go to do horse riding is Tupiza

- Yunga Cruz - the second part is too overgrown and steep for a horseride

- Sajama - they have donkeys and guess mules in "town" , so you might be able to organize something on your own - bring all food you need form somewhere else-