There have been 18 complaints from the public about livestock being transported in unsuitably hot weather over the last two months, says the Ministry for Primary Industries (MPI).
During December and January, the ministry said it also received five referrals from MPI veterinarians based at meat processing plants about stock suffering from heat stress-related symptoms.
MPI animal welfare acting national manager Murray Pridham said many of the complaints from the public were able to be quickly resolved by the ministry contacting the transport company, and sometimes it involved asking them to move trailers parked on the roadside.
But Pridham said seven cases were still under investigation.