Wolves and dogs can interbreed and produce offspring. These offspring are usually fertile and are known as wolf hybrids. Wolves can be crossed with any breed of dog. The most common hybrids are wolf bred with malamute, husky, or German shepherd. Although wolf hybrids can occur naturally in the wild, this happens very infrequently due to the territorial nature of the wolf. Most hybrids are the result of deliberate breeding in captivity.

Wolves and dogs mature at different rates, which can make the physical development of the hybrid unpredictable. The female dog reaches sexual maturity at 6-8 months of age, and has two estrus cycles per year. The female wolf reaches sexual maturity at 2-4 years and has one estrus cycle per year, in February or March. The female hybrid can reach sexual maturity at any time between these two extremes, and can have one or two estrus cycles per year.

The male dog matures sexually around 8 months, and usually exhibits raised leg urination (RLU). The male wolf matures sexually between 2 and 3 years depending on pack status, and may or may not exhibit RLU. Male hybrids can mature anywhere between these two extremes and may or may not exhibit RLU.