Ukraine International Airlines (UIA) said Tuesday that it has opened an investigation and suspended a senior employee after 38 dead puppies were discovered on one of its planes.
"UIA has opened its own internal enquiry during which the head of freight transportation will remain suspended," the group said in a statement.
UIA, the main Ukraine airline, said it had also suspended the transportation of all animals on its Boeing-767s.
Canada has also opened an investigation as the dead French bulldog puppies were found aboard a UIA plane in Toronto on June 13.
In all there were around 500 of the puppies on the flight.
The surviving French bulldogs, a popular breed in Canada, were suffering from symptoms including dehydration, weakness and vomiting.
A dog handler who was picking up another animal from the airport cargo area where the puppies were discovered earlier spoke of a "horror scene".
"Unfortunately the animals' cause of death remains to be established," UIA said Tuesday.
In all the flight which landed in Toronto had 550 dogs and 89 cats aboard. UIA ruled out any problem of a lack of air in the cargo hold.
"The transportation of such pedigree breeds ... carry a certain risk" which breeders and those who transport the animals by plane understand, the airline said.
In January a UIA Boeing 737 was accidentally downed by an Iranian missile, while landing at Tehran, killing all 176 people on board.