The first time a Golden Retriever goes into heat is when she reaches approximately 10 to 14 months old. There are circumstances where a dog can go into heat at a younger age, but this usually happens when she is around other dogs who are in heat.
While most Golden Retrievers go into heat on a regular cycle, determining how long this cycle lasts is based on each particular dog. Some Golden Retrievers go into heat every seven to eight months, while others can go as long as 10 months without going into heat. Their heat cycle lasts approximately three weeks.