In the United States, most dogs and cats are spayed/neutered between 5 and 8 months of age. To try to control pet overpopulation, many animal shelters have started to spay/neuter all animals before they are adopted. This means they are spaying/neutering animals at a younger age, even 6-14 weeks of age. Many veterinarians in private practice have started early spaying/neutering as well.
Questions have arisen regarding the safety of this procedure and possible effects on the animals when they become older. Some people were especially concerned that early neutering could make cats more prone to urinary tract disease. As more studies have been done, and veterinarians have followed early spayed/neutered animals into older age, these concerns have been shown to be unfounded.
Groups of cats spayed/neutered at 7 weeks of age, 7 months of age, and after 12 months of age were followed in a large study. The cats were all placed in homes and followed for years. When comparing the groups of cats it was found that:
Cats spayed/neutered before 12 months of age were generally longer and taller than those spayed/neutered at 12 months.
Cats who were not spayed/neutered until 12 months of age or older were noticeably less affectionate and more aggressive.
There were no significant differences in the development of the urinary tract among the three age groups.
A similar study was performed with dogs. There were no significant differences in growth rate, food intake, or weight gain in the three groups of dogs spayed/neutered at different ages.
Early spaying/neutering has been shown to be safe in multiple studies. It must be remembered that younger animals may need different anesthetics and are more prone to hypothermia (lower than normal body temperature) during surgery. But as long as procedures are modified to account for these differences, early spaying/neutering is very safe. In fact, animals spayed/neutered at a younger age, often have faster recoveries than those spayed/neutered when they are older.