medium sized dogs,such as spaniels, may begin to show signs of aging around 7 or 8 years of age. Giant breeds may do this as early as 5 or 6 while smalltoy breeds may wait around until 9 or so. Keep in mind dogs are as individual as people theres no hard-and-fast rule for what shell do and when shell do it. Sexual maturity in puppies can happen before your puppy is fully grown, which can be dangerous for females. Therefore, the akc recommends waiting until after your females first heat to breed her. rats become sexually mature at age 6 weeks, but reach social maturity several months later. He is not obease or under wieght, do you think he will get much bigger? They say there are 3 size types for rats, and i was trying to see how big he will be. To use, enter his current weight, age, and breed size, and the interactive tool will do the rest. If you have a mix-breed dog, see our puppy weight charts to see which breed category your puppy falls into based on his current weight and age. Breeding age standards most fancy breeders tend to wait until the female is at least 4 months old (usually 4-5 months) or until they have reached a certain weight (usually 9-12 ounces). At times breeding is delayed, 10-12 months, to evaluate the health and temperament of the potential mother. My rat terrier was 1yr when she had her puppy, it depends on when they are in heat. Asked in rat terriers how long can a rat terrier live? If they are fixed they can live longer. Early spaying and neutering i do not believe in spaying and neutering at an early age. I believe that the dogs should be allowed to mature before they are spayed or neutered. Yes, it makes it more difficult when keeping intact dogs, but it can be managed if handled properly. Gallery baby rat growth from rat guide baby rat growth photos.