The RSPCA is investigating the deaths of two cats after the animals drank anti-freeze.
The cats, both eight-months-old, belonged to the same owner from Brithdir near New Tredegar.
The pets, who belonged to Sue Burris, had to be taken to a vet to be put down after they both collapsed.
The vet confirmed they had both ingested anti-freeze and the RSPCA is appealing for information.
Mrs Burris has now lost five cats in the last year. She found one cat dead in a shed at Christmas and another two went missing.
She said: “I have three children and they are very upset. The cats died a terrible death and I would hope that no one is doing this on purpose.”
RSPCA inspector Rebecca Rees said: “It could be that these cats were targeted maliciously or it’s possible that someone was simply unaware of the potential hazard to cats when they poured the anti-freeze away.
“Whatever the circumstances we want to warn all cat owners of the dangers of anti-freeze poisoning.
“Anti-freeze is very toxic to cats and sadly once ingested they suffer from kidney failure within a few days. Cats like its sweet taste and don’t have to ingest much for them to become seriously ill.
“Effective treatment is only available if caught within the first 24 hours but this is not normally possible, as the cat shows no sign of being unwell within this time.
“By the time the cats show signs of illness there is nothing that can be done to save them.”
Anyone convicted of causing unnecessary suffering to an animal could face a maximum six-month prison sentence, as well as a £20,000 fine.
Anyone with information about the incident should contact the RSPCA on 0300 1234999.