Professor Frederick Marius, who invented the first K9 in the year 5000 while working on the asteroid K4067, described him as "my best friend and constant companion." Marius had a dog on Earth, but weight requirements did not allow him to bring his real dog into space, so he built K9. (TV: The Invisible Enemy) He built K9 by using the latest technology. Marius used his own medical computer, a state-of-the-art intraresponsive brain app, protective anti-radiation cladding, probes, a laser scapel, a vision and voice box and two scanning antennas. He put these parts together and created K9. (PROSE: One Man and His Dog) According to one account, the Professor copied the remnants of one of the versions of K9 created by the Doctor and given to Sarah Jane Smith. (PROSE: Tautology)
Solid K9 Training, founded by award-winning, internationally-acclaimed dog trainer Jeff Gellman, is one of the nations most effective and respected dog training services providing no-nonsense, "Real World" training methods throughout New England. Serving dog owners from Hartford, CT to Boston, MA in our multifaceted, secure and 24/7 staffed Solid K9 Training Center in Providence, RI, as well as all throughout the nation with Jeff's wildly successful RV Dog Trainer Tour. We will train any dog, regardless of breed, shape, size or history. We work to fix all dog behavior issues including excessive barking, growling, snapping, nipping, dog aggression (fighting), human aggression (biting), child aggression, pulling on leash, leash aggression, leash reactivity, skateboard reactivity, resource guarding, jumping on people, fear issues, anxiety issues, separation anxiety, chewing and destroying household items, running away, not listening, door bolting, stealing food, getting into the trash, cat aggression, chasing game, and killing animals/game. We also have a renowned reputation specializing in obedience training, which includes heeling and walking properly on a leash, sit/stay, down/stay, place, recall training (come to owner), and crate training. Our Training services include Board and Train behavioral modification, 1 on 1 Training, Obedience Classes, Puppy Training programs, Boarding / Board & Play, Daycare, and many free dog training resources including Dog training advice videos, dog training webinars, and Dog Training Q and A videos on Periscope on Monday and Wednesday nights. Our behavior modification training is cutting edge, using techniques like modern low level E-collar (remote collar) training and food and clicker training. Solid K9 Training has a worldwide reputation of being able to handle the most challenging dog behaviors and often times other dog trainers will refer their more serious cases to us. For more information on our services offered, as well as free dog training tutorial videos, please see my website and other social media pages:
On August 1, 2016, Blue Coat, Inc. (K9’s parent company) was acquired by cybersecurity leader Symantec™.  As can be imagined Blue Coat and Symantec had a handful of similar products and unfortunately, it didn’t make sense to maintain two competing products. it was decided to “end-of-life” K9 Web Protection and focus corporate and customer attention on Symantec’s line of Norton™ products.

In early 2007, K9 was reactivated by the Tenth Doctor; Sarah Jane was unable to go to any humans for repairs prior as the parts inside K9 could change history. K9's repairs were short lived. In battling Lucas Finch and his Krillitane invasion at the school the next day, Mark III blew up a vat of Krillitane oil, which was now lethal to the Krillitanes destroying himself and the Krillitanes in the process. (TV: School Reunion)
Dallas K-9 Academy is the best and the most effective dog training available. Your dog is trained in your home (or place of business). We also offer board and train programs. Our effective techniques developed through more than 18 years of experience help you teach your dog to understand how he should behave in day-to-day situations. At the completion of training, we deliver your dog to your home and work diligently with all family members to assure you he will continue his newly learned behaviors.
Solid K9 Training, founded by award-winning, internationally-acclaimed dog trainer Jeff Gellman, is one of the nations most effective and respected dog training services providing no-nonsense, "Real World" training methods throughout New England. Serving dog owners from Hartford, CT to Boston, MA in our multifaceted, secure and 24/7 staffed Solid K9 Training Center in Providence, RI, as well as all throughout the nation with Jeff's wildly successful RV Dog Trainer Tour. We will train any dog, regardless of breed, shape, size or history. We work to fix all dog behavior issues including excessive barking, growling, snapping, nipping, dog aggression (fighting), human aggression (biting), child aggression, pulling on leash, leash aggression, leash reactivity, skateboard reactivity, resource guarding, jumping on people, fear issues, anxiety issues, separation anxiety, chewing and destroying household items, running away, not listening, door bolting, stealing food, getting into the trash, cat aggression, chasing game, and killing animals/game. We also have a renowned reputation specializing in obedience training, which includes heeling and walking properly on a leash, sit/stay, down/stay, place, recall training (come to owner), and crate training. Our Training services include Board and Train behavioral modification, 1 on 1 Training, Obedience Classes, Puppy Training programs, Boarding / Board & Play, Daycare, and many free dog training resources including Dog training advice videos, dog training webinars, and Dog Training Q and A videos on Periscope on Monday and Wednesday nights. Our behavior modification training is cutting edge, using techniques like modern low level E-collar (remote collar) training and food and clicker training. Solid K9 Training has a worldwide reputation of being able to handle the most challenging dog behaviors and often times other dog trainers will refer their more serious cases to us. For more information on our services offered, as well as free dog training tutorial videos, please see my website and other social media pages:
Introduced into the plot in The Invasion of Time, K9 Mark II first actually appear on-screen in The Ribos Operation (1978). More mobile than his predecessor, Mark II exhibited the ability to sense and warn others of danger. He travels as a companion alongside the Doctor and Romana. Around the time of Romana's regeneration (the transition from actress Mary Tamm to Lalla Ward), the K9 character was explained as suffering from "laryngitis" to accommodate Leeson's departure from the series at the start of the 1979–80 season; for this time, he was portrayed by David Brierley, until Leeson's return for the 1980–81 season. When the Doctor and Romana travel to the parallel universe of E-Space, K9 is severely damaged, in Warriors' Gate (1981). The damage was such that K9 could only function in E-Space; when Romana decided to stay and forge her own path, the Doctor gave K9 to her. The character makes subsequent appearances in remakes of the unfinished serial Shada, alongside the Eighth Doctor (Paul McGann); the 2003 Shada audio play and webcast depict K9 Mark II as having returned to Gallifrey with Romana, now Lady President of the Time Lords, where the Doctor visits them. It is not clear if either of these audio appearances are considered canonical in relation to the continuity of the TV series.
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