What the federation's sheet records
Two Boerboel littermates, CR's Sun Wukong (164 lb) and CR's Mr. Wednesday (186 lb), each pulled 22,039 lb on rails at a Unified Pulling Federation (UPF) event in Pittsburgh, Pennsylvania, on 9 May 2026. It is the heaviest single-dog figure on any federation's published result sheet the editorial team has read. Both pulls were on rails, the lowest-friction system in the sport: UKC's rulebook expects two to three times the load from a rail cart that it expects from a sled on snow, so the figure compares only with other rails results. The numbers below come from UPF's results sheet for the event, run as Spring Into Bully Max, and from the federation's sheets for Sun Wukong's two earlier pulls, not from a press release or a kennel page.
| Place, 120+ class | Dog | Owner on sheet | Breed | Body weight | Weight pulled | Time | Sheet "Percent" |
|---|---|---|---|---|---|---|---|
| 1 | Conquest | CR | Boerboel | 128 lb | 21,336 lb | 26.82 s | 166.69 |
| 2 | Amarillo | Travis Torrez | Presa Canario | 125 lb | 19,834 lb | 25.03 s | 158.67 |
| 3 | Sun Wukong | CR | Boerboel | 164 lb | 22,039 lb | 23.22 s | 134.38 |
| 4 | Wednesday | CR | Boerboel | 186 lb | 22,039 lb | 25.03 s | 118.49 |
The column UPF labels "Percent" is not a percentage but weight pulled divided by body weight: 22,039 divided by 164 is 134.38, so Sun Wukong moved about 134 times his own weight and Wednesday, at 186 lb, about 118 times his. The two heaviest pulls of the day finished third and fourth because UPF decides a class by the highest multiple of body weight; a 128 lb Boerboel named Conquest, at 21,336 lb and 166.69 times body weight, won it. CR's page describes Conquest as a daughter of Mr. Wednesday. Sun Wukong's remarks column carries MWP, the federation's divisional bonus for most weight pulled; Wednesday's does not: with the weight tied, the bonus went to the faster pull, 23.22 seconds against 25.03. It is the only pull on Wednesday's UPF profile.
UPF lists the dogs as Sun Wukong and Wednesday; their registered names are CR's Sun Wukong and CR's Mr. Wednesday.
Elsewhere on the same 32-line sheet, Hamilton, a 112 lb Presa Canario, won the 110 class with 19,834 lb at 177.09 times body weight, and JT, an American Pit Bull Terrier of 38 lb, pulled 18,332 lb on the same rail cart, 482 times his weight. That is why the sport does not rank dogs by raw pounds.
Sun Wukong's earlier sheets
UPF's sheets record three pulls for Sun Wukong, all on rails in Pittsburgh:
| Date | Body weight | Weight pulled | Time | Multiple of body weight | Place |
|---|---|---|---|---|---|
| 12 April 2025 | 162 lb | 12,142 lb | 13.22 s | 74.95 | 1st |
| 8 November 2025 | 158 lb | 16,917 lb | 19.31 s | 107.07 | 1st |
| 9 May 2026 | 164 lb | 22,039 lb | 23.22 s | 134.38 | 3rd |
Both 2025 first places were uncontested: on both sheets the Heavy division contains a single line, his. The weights stand; the placings were not won against anyone. The same November sheet shows the day's best pound-for-pound pull among the big dogs belonged to Wendy, a 97 lb Presa Canario who moved 16,884 lb, 33 lb less than Sun Wukong, at 174 times her body weight.
The 16,917 lb pull produced the press coverage: a wire release of 24 November 2025 from Bully Max, whose training facility hosted the event, describing the pull as a world record recognized by UPF and naming the owner as Eli Carver of CR.
How organized weight pull is judged
The United Kennel Club's weight-pull rulebook, effective 2016 and revised in 2019, is the most detailed of the public rulebooks.
Under UKC rules a qualifying pull means moving a weighted vehicle 16 feet in 60 seconds or less without a foul. The rulebook recognises three surfaces, natural ground, carpeted artificial surfaces and snow, and three vehicles, a rail cart, a wheeled cart and a sled, with rails scored as a category of their own. Placement goes to the highest multiple of body weight, with ties broken by the faster time, inside weight classes whose top rung, Unlimited, is 101 lb and over, where an adult Boerboel lands.
The welfare rules are detailed. Once the dog is released, the handler may not touch the dog or the equipment until the judge calls the pull complete. Food and lures are banned from the on-deck area and the chute, as are whips and noisemakers, and only a flat buckle, snap or martingale collar may be worn. Females in season, pregnant or lactating may not compete, nor may lame or ill dogs or dogs under one year old. A handler who abuses a dog is excused on the spot, and anyone UKC knows to be involved with dogfighting is barred from its events for life.
UPF's published rules are shorter. Pulls must be completed within 60 seconds on a rail system over carpet or on wheels over dirt or carpet, classes are determined by most weight pulled per pound, a flat collar is required with pinch collars and choke chains barred, touching the dog during a pull is a foul the first time and a disqualification the second, and the chief judge's decisions are final. The rules fix the pull at 16 feet between the start and finish lines, the same distance UKC uses.
The surface ladder
The largest single influence on a weight-pull figure is what the load rides on. UKC's minimum for a qualifying pull is three times body weight on snow, eight times on wheels and ten times on rails. Its automatic-withdrawal caps, the load at which a dog is retired from the pull, scale the same way: for Division B, open to all dogs and mandatory for holders of the Weight Pull Champion Excellent title or higher, 25 times body weight on snow, 28 on wheels over natural ground, 35 on wheels over carpet and 65 on rails. In the federation's own arithmetic a rail cart is worth roughly two and a half to three and a third times a sled on snow (65 against 25 at the Division B cap, 10 against 3 at the qualifying minimum).
The International Weight Pull Association runs wheels on natural ground or carpet and sleds on snow, and has no rail system. Its records are set only at its championships; the heaviest entry in its record table is 6,075 lb by Tank, a Mastiff, on wheels over carpet at Grand Rapids, Michigan, in 2022.
Read against those ladders, the UPF numbers are a surface effect: the heaviest pulls on the 9 May 2026 rails sheet came from dogs moving between about 118 and about 482 times their body weight. A 6,075 lb pull on carpet and a 22,039 lb pull on rails are not measurements of the same thing.
How the two dogs are bred
OFA's pages for CR's Sun Wukong (AKC WS80296527, a brown male) and CR's Mr. Wednesday (WS80296528, a red male) both give a birth date of 18 March 2023, a sire numbered WS79897802 and a dam numbered WS72008704. Each dog's page lists the other in its full-siblings table as a littermate, alongside a third AKC-registered littermate, CR's Breaker of Chains.
The dam's number resolves to a named dog. OFA's record for WS72008704 is Black Iron's The Man Eater of Njombe, a brown female born 19 January 2021, also carried under SABBS number 0000416056, and her offspring table lists both dogs. Black Iron Njombe is the dam of both dogs.
The sire's number does not resolve directly, because OFA holds no record under WS79897802; the link runs through another littermate, registered through SABBS rather than AKC. OFA's record for CR Koda, a female registered through SABBS (442682) and born the same day, 18 March 2023, lists her dam as 416056, Njombe's SABBS number, and her sire as 413160. The dog OFA files under 413160 is Peterbuilt Hakeem, a male Boerboel born 11 July 2021.
CR's page on the pulls does not name either parent. It says that "their sire contributed genetically to the breeding", that he had no competitive weight-pull history and that the dam's line had none either, and that the litter had fourteen puppies, of which the kennel kept seven.
On paper, then: two littermates, whelped 18 March 2023, sired by Peterbuilt Hakeem out of Black Iron Njombe. The littermate relationship, the whelp date and the dam's identity are on the dogs' own OFA pages; the sire's identity is carried by a littermate's OFA page, which lists his registry number, and by his own OFA record under that number.
Why the directory does not call it a world record
Bully Max's video of the 22,039 lb pulls, posted on 10 June 2026, is titled World Record Pull. The directory's own wording is narrower: 22,039 lb is the heaviest single-dog figure in any federation's published results, for four reasons.
UPF publishes no records list, and the word "record" appears nowhere on its results, points-leaders, national-winners or rules pages. World record is the sponsor's phrase, not the federation's.
It is a tie: two dogs moved the identical weight on the same day, so there is no single record holder.
It is a rails figure, and the IWPA, which publishes a formal record table, does not run rails at all. Guinness World Records has no single-dog pulling record on its site that the editorial team could find; its one dog-pulling entry is a team record, 145,302 lb moved by 210 sled dogs in Whitehorse, Yukon, in October 2000. The heaviest figures the editorial team found at other federations, 16,146 lb at a World Wide Weight Pull Organization event in 2015 and 14,445 lb at an American Pulling Alliance event in 2023, are rails results too; each is graded, with its sheet, in dog weight pull records, checked against the result sheets.
Finally, the claim is only as wide as the archive. The editorial team read UPF's published archive, 1,504 event listings from 2014 through 2026; 1,449 of them are weight-pull sheets, and 1,436 could be read (the 13 that could not were twelve events from 2014 to 2017 and one July 2024 pull). Nothing on them is heavier. Until November 2025 the archive's heaviest pull was 14,890 lb, by an American Pit Bull Terrier named Spock at the 2016 national championships in McPherson, Kansas; eleven of the twelve heaviest results were then set at the two Bully Max events of November 2025 and May 2026, by dogs of four breeds. The directory's reading is that the venue's rig and conditions explain those numbers at least as much as any breed does.
Who organized, judged and publicized the event
UPF's event page lists Erica Noseworthy as both organizer, with Bully Max, and chief judge, and the results sheet shows four dogs entered under her name. Bully Max is listed as sponsor and co-presenter and is the company that announced the result as a world record. Carver, the owner named in the press release, appears on UPF's published roster of U.S. judges, under Florida. CR's page states that Eli Carver competed as owner and handler of both dogs, did not run the event or judge his own dogs, that six judges were present, and that both dogs were withdrawn by their handler rather than pulled to failure; that is the kennel's account. The directory sets these facts out because they bear on what kind of claim the figure supports, not because they suggest anything improper.
How much can a Boerboel pull?
There is no single answer, because the surface sets the scale. Using UKC's ladder for a 164 lb dog, a qualifying pull would be about 490 lb on snow, 1,310 lb on wheels and 1,640 lb on rails, and a Division B dog would be withdrawn at about 4,100 lb on snow and 10,660 lb on rails. Those are the federation's arithmetic, not predictions for any dog.
Published Boerboel results are few. In the American Pulling Alliance's profile database, the heaviest Boerboel result is 9,392 lb by a 104 lb dog named Star on rails over carpet at Rakovnik, Czech Republic, in June 2018. UPF's profiles index lists 16 dogs entered as Boerboels, plus one Boerboel mix, under eight handlers; four of them, Sun Wukong, Wednesday, Conquest and Alucard, are entered by CR, and the four heaviest Boerboel pulls in UPF's archive are theirs. A statement of what a Boerboel can pull means nothing unless it names the federation, the surface, the body weight and the date.
What this does and does not say about the breed's strength
A dog of 186 lb moving 22,039 lb on rails is a judged result. It is not evidence of anything unusual in the breed's biology.
The Boerboel is a large, heavy-boned guardian breed; the two dogs on the sheet weighed in at 164 and 186 lb. A dog of that mass, conditioned for the sport, has more body to put into a harness than a 40 lb terrier, which is why the raw-pound figures come from big dogs and the multiples from small ones. The four separate questions hiding inside the word strongest are taken apart in the strongest dog breed, measured four ways.
The evidence against a breed-specific strength trait comes from skull studies. A 2025 study in Science Advances by Hebdon and colleagues analysed 117 canid skulls from 40 breeds and 18 wild subspecies and found near-complete overlap in shape between kennel-club groups, between dogs grouped by the task they were bred for, and with wild canids, short-muzzled dogs excepted. Morphology-based bite-force quotients showed no specialization in breeds bred for biting either. Selective breeding, the authors concluded, has produced extreme variety without producing task specialists.
Strength is also not bite force. No Boerboel bite force has been measured in any published study, and the PSI figures that circulate for the breed are not measurements. A 2018 review of bite-force measurement in dogs and cats reports every result in newtons and contains no breed table; the one awake-dog dataset it summarises, 22 dogs of 7 to 55 kg, ranged from 13 to 1,394 N, with the dog's willingness to bite the sensor the decisive factor. Nothing in that literature supports a number for a Boerboel.
What the sheets support is narrower: two large, related, conditioned dogs, on the rail carts for which UKC's rulebook expects the highest multiples, moved more weight than any dog in that federation's published archive. Everything beyond that is either the sponsor's wording or a claim about the breed that the evidence does not carry.