Here is a (non-comprehensive) list of Tierschutzvereine in Switzerland:
http://www.tierdatenbank.ch/cms/adre...utzverein.html
And a list of Tierheime in Luzern, again not necessarily comprehensive:
http://www.tierdatenbank.ch/cms/adre...rheime-lu.html
Call around, see if volunteer help is needed.
Not all Tierheime are rescues, in the sense that the sole activity is taking in homeless animals - some are private kennels that also take in strays. Nonetheless, you can always ask if volunteers are needed.
And a list of Tierheime (again, not all-inclusive) in Switzerland, in case you want to look a bit farther afield:
http://www.tierdatenbank.ch/cms/adre...-tierheim.html
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There are also private animal welfare groups, pursuing various missions. Google terms like 'Tierheim' Tierschutz' 'Tierhilfe' 'Tiere In Not', 'Hunde In Not,' 'Katze (Bussi) In Not', etc.
FYI, the Tierdatenbank site is a good starting point for information on the broader animal protection topic. This is a Switzerland-wide database of animals in need of homes, of animals lost and found, and of information for animal owners. A good resource.