The Scottish SPCA said that there were two incidents on cat poisoning on the same street and issued an appeal for information following the poisonings on Taylor Place in Dalkeith.
One cat had to be put to sleep and another took ill after ingesting anti-freeze.
Inspector Stephanie McCrossan said, “The poisoning of domestic animals is a huge issue and we deal with a large number of complaints regarding poisonings and they are incredibly difficult to solve due to the nature of the crime.
“Antifreeze (ethylene glycol) is one of the most common causes of cat poisoning, particularly in the winter months.
“The liquid is usually colourless and odourless, but it has a sweet taste that appeals to dogs in particular, but cats will also ingest it.
“By the time symptoms occur, such as vomiting, lethargy and, in the latter stages, head shaking and coma, it is normally too late to treat.
“Renal failure is most often the cause of death, with irreparable damage to the kidneys.
“Pet owners in the area should be vigilant when letting their cats out of the house, and should supervise their animals where possible.”
Anyone with information is being urged to contact the Scottish SPCA animal helpline on 03000 999 999.
Anyone found guilty of deliberately poisoning an animal can face penalties of up to six months in prison, a £5,000 fine or both.