Here's why:
* Hormonal Control: Heat cycles are controlled by hormones, and these hormones are regulated by the dog's endocrine system. While size can influence overall hormone levels, it doesn't directly impact the duration of a heat cycle.
* Breed Variations: Different dog breeds have evolved with varying reproductive cycles. Some breeds may experience heat cycles lasting a few weeks, while others might have shorter cycles.
* Individual Differences: Even within the same breed, individual dogs can have slightly different heat cycle lengths due to their unique genetic makeup.
So, while a large dog might have more overall hormones circulating in their body, it doesn't mean they will have a longer heat cycle than a smaller dog.