Council compliance operations manager Jason Shailer said it was not something he had dealt with before.
"It seems that most young dogs that are registered for the first time are old enough to have been desexed.
"That's probably because there is a kind of dog-breeding 'season' where the majority of pups are born earlier in the year."
Whanganui veterinarian Dr Hein Stoop said although dogs can breed at any time, most tend to arrive earlier in the year.
"It's an evolutionary adaptation that goes back to wolves.
"In the wild, wolf cubs would be born in spring when food was plentiful and they would be more likely to survive. Over time, with artificial lighting and heat available, dogs have evolved to breed more often but they do tend to still follow that evolutionary pattern of breeding more often in spring."
Stoop said the recommended age for desexing male and female dogs is between six and nine months although veterinarians have differing views.
"It also depends on the breed and size of the dog but neutering and spaying operations require general anesthetic and the older they are, the better they will cope with the operation."
Shailer said although Malcolm would not qualify for the neutering discount for Teddy until next year, he could be eligible for the $24 responsible dog owner status discount.
"To qualify for responsible dog owner status, new owners need to attend a free training session offered by the council.
"Once they have that status, it rolls over to the following year unless their dog has been causing problems."
Under the council's current dog control policy and bylaw adopted in 2021, new owners and those who don't have responsible dog owner status can qualify by doing the course.
Owners who had already qualified are not required to complete the training.
Owners who complete their dog registrations by July 31, qualify for a 10 per cent discount on the $120 fee.