Saffron-robed Hindu monks served legal papers on the RSPCA as part of an ongoing dispute over the slaughter of a sacred cow.
The six-strong group marched into the charity's headquarters in Horsham to deliver notice of their intention to sue over the death of Gangotri.
The 13-year-old Belgian blue-jersey cross was put down on welfare grounds on December 13, 2007 by vets from the Royal Society for the Protection of Animals (RSPCA).
However, campaigners claim the "mercy killing" was illegal and took place while members at Bhaktivedanta Manor in Hertfordshire, Europe's largest Hindu temple, were at worship.
The RSPCA refutes this allegation, stating that they informed staff on site "exactly" what would happen, and avoided killing the cow during prayer hours.
At the time of her death, Gangotri had been injured for more than a year and suffered from bed sores because she could no longer stand.
But Hindu groups in the UK reacted angrily to the measure taken by the RSPCA.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article