VET Mark Kallman was left to ponder the motive of thieves, who broke into Coffs Harbour's Blue and White veterinary clinic and stole $10,000 worth of drugs - most of which are harmful to humans.
The offenders smashed a hole in the glass door and gained access to the Argyll St clinic overnight.
"They were systematic stealing all of our vaccines, tick and snake bite serum and all of the anti-cancer drugs, which is a major concern," Mark said.
The anti-cancer drugs are cytotoxic and in humans can actually have the side effect of causing cancer.
"My concern is a social one that the thieves may dispose of the brightly coloured anti-cancer drugs in a public place and put other people at risk.
"Patients of ours have been greatly affected by this break-in.
"A lot of the cancer drugs are specially adapted to particular pets, so the poor old dog or cat which has contracted cancer is now without treatment."
The clinic was forced to cancel multiple appointments throughout the day.
Mark said the drugs the thieves have stolen are of virtually no use for drug manufacture or human consumption.
"These drugs can't be broken down to reproduce anything.
"Drug manufacturers are usually not the brightest sparks, but they know what they need to make drugs
"These guys have stolen $10,000 worth of drugs that are virtually useless unless they are used on animals, which need specific treatment.
The break-in happened sometime between 8pm on Wednesday and 7.30am today.
Passing motorists who may have seen people acting suspiciously in Argyll St overnight should call Coffs Harbour Police on 02 66520299 or Crimestoppers on 1800 333 000.