No, they work to better protect animals.

Copied from http://www.hsus.org/about_us/faqs/#What_does_The_HSUS_do:

What does the HSUS do?

The HSUS is the nation's largest animal protection organization with more
than seven million members and constituents. The HSUS is a mainstream voice
for animals, with active programs in companion animals, wildlife and habitat
protection, animals in research, and farm animals. The HSUS protects all
animals through legislation, litigation, investigation, education, advocacy
and field work. A non-profit organization, The HSUS celebrated its 50th
anniversary in 2004, is based in Washington, D.C. and has seven regional
offices across the country.