Police are investigating reports that a puppy was bludgeoned with a hammer then put into a microwave.
The 11-week-old animal was killed in the Ailsbury Park area of Lurgan, Co Armagh on Saturday.
Two men aged 23 and 16 have been arrested on suspicion of causing unnecessary suffering to an animal.
They remain in police custody.
It is believed footage of the alleged attack was shared on social media platforms including Snapchat.
The Police Service of Northern Ireland (PSNI) has appealed for any information.
Detectives have called for anyone who has seen the footage or has photographs of the incident to come forward.
A spokesman said: "Whatever happened, it is obvious that little Sparky suffered a horrendous death. We want to get to the bottom of that and make sure that whoever is responsible is held to account.
"We have two in custody, but need the evidence to be able to take that further."
Anyone with information is asked to contact the PSNI on 101.