Amazon’s (AMZN) work culture is well-known for several qualities — tough, hard-working, innovative, even bruising. But it’s not necessarily known as being one of the largest dog-friendly tech companies.

According to the Seattle-based e-commerce giant, Amazon has 4,000 registered canines — 500 of which on average come to the offices everyday with their employee owners. Indeed, Amazon caters heavily to employee-owned dogs with dog-oriented activities, beyond simply offering dog treats at the reception desk.

In July 2016, for instance, the company held a screening for the film “The Secret Life of Pets,” in which dogs that attended also received customizable dog tags. And last October, Amazon hosted a Halloween dog costume contest, in partnership with the Downtown Dog Lounge, a Seattle-based business. The winner? A 5-year-old greater Swiss mountain dog named Charlie, dressed as one of Santa’s reindeer, pulling a two-wheeled cart designed to look like Santa’s sleigh.

Amazon also built facilities aimed at keeping employees’ dogs entertained. This April, the company opened a 1,000 square-foot dog park at the intersection of Lenora Street and Sixth Avenue in Seattle as part of the company’s larger $4 billion effort to build and expand its urban campus.

Located next to Amazon’s dome-like glass Spheres, which will house an array of tended greenery and foliage when they officially open in early 2018, the so-called “Spheres dog park” is within walking distance to many of the company’s offices. Some of dog park’s features include rocks and platforms to play on, as well as a drinking fountain.

Dogs have played an integral part of Amazon’s company culture since the very beginning, an Amazon spokesperson told Yahoo Finance. The practice stems from two former Amazon employees — a husband and wife team — who brought their corgi Rufus to work.

Rufus played a ceremonial role, of sorts, during those early Amazon days. Between 1998 and 1999, when Amazon was still just an online marketplace, employees lifted the corgi up and used his paw to click the computer mouse to mark the launch of various online pages going live on the Amazon.com website.

Amazon eventually named an office building at its Seattle headquarters after Rufus, and photos of the corgi remained peppered around the company campus.

Amazon is hardly the only tech company to allow employees to bring their pets work, but it is one of the tech companies with the largest number of registered pets. Yahoo Finance’s Company of the Year Nvidia (NVDA), for instance, also allows pets to roam its Santa Clara, Calif. Campus. But Nvidia Senior Director of Human Resources Nilufer Koechlin told me recently the chipmaker has “several hundred” registered canines, which falls short of Amazon’s whopping 4,000-plus.