Cat owners in the Horsham Downs Rd, Rototuna, area are being warned to be on the alert after the remains of two cats were found on the roadside.
Waikato SPCA animal welfare inspector Georgina Higgins was called to a scene she described as "probably the most gruesome thing that I'd seen in a while".
The dead cats had serious injuries which vets believed were from a dog attack, and were thought to have been killed overnight on Boxing Day.
The SPCA has warned residents in the area to keep cats inside if possible and watch for roaming dogs, which could be reported to the Waikato District Council.
Any injured cats should be seen by a veterinarian, and the SPCA was happy to assist with injured stray cats.
The contact number for Waikato SPCA is 07 847 4868.