Police say the case of the chocolate coloured Labrador found dead at Sulby Reservoir in February is far from closed.
They are making a new appeal for information from the public, six months after the animal was found.
Acting Inspector Phil Shimmin says officers would especially like to hear to someone who wrote an anonymous letter to the investigating team in April.
But he is stressing any and all information would be welcome and the case will not close until those responsible have been found (audio file attached):
If you have any information, you can contact police on 631212 or call Crimestoppers anonymously on 0800 555111.