RSPCA Cymru has now launched an appeal for information, and called for cat owners in the community to be vigilant and to know the symptoms of a suspected poisoning.
The animal welfare charity was alerted after two cats were found last week, not walking properly and appearing severely uncoordinated.
Fluffy, a brown and white rescue cat, aged approximately three, was soon unable to walk; while another cat – Twmws – aged 18 months – was exhibiting similar symptoms.
Veterinary diagnosis confirmed the cat had been poisoned by anti-freeze.
Karen Louise Jones, owner of Fluffy and Twmws, said: “We’re absolutely devastated. Watching what both cats went through after being poisoned was so horrible to see. We have three children – and the whole experience has been heartbreaking for them, and the whole family.
“Fluffy was a rescue cat – and it has taken a long-time to build up her confidence, but he was a wonderful cat who had settled in so well. The loss of them both has left a big void in our house.”
There are concerns in the local area that two stray cats also found dead may have also ingested anti-freeze.
RSPCA Cymru has called on anyone in the local area with information to get in touch, and urged households with cats to be cautious and understand the symptoms of a potential poisoning.
Paula Milton, RSPCA animal welfare officer, said: “Our heart goes out to the owners of Fluffy and Twmws. They were such young cats – and it is heartbreaking to hear of them losing their lives in such an awful way.
“We do not know if this poisoning was intentional or deliberate – but for multiple cats to have potentially been impacted, including two other strays, is a serious concern.
“Anyone with information about what could have happened in Cwmllynfell is urged to contact our inspectorate appeal line on 0300 123 8018.
“We’re urging people in the local area to know the signs of a possible cat poisoning. Vomiting, a depressed or sleepy demeanour, appearing drunk or uncoordinated, seizures, and breathing difficulties could all be symptoms.
“Anyone fearing their cat may have been poisoned should try and remain calm, move the moggy away from the source and contact a vet immediately.”