Four questions hiding inside one
No breed is strongest on every measure. On absolute weight moved, two Boerboels hold the heaviest single-dog figure in any federation's published results, 22,039 lb on a rail cart; pound for pound a 38 lb American Pit Bull Terrier leads at 482 times its own weight; no breed has a measured bite force; and over distance the sled breeds hold the field. Those are four different questions, and the rest of this article takes them one at a time.
Absolute weight: 22,039 lb, twice, on one sheet
UPF's official results sheet for the "Spring Into Bully Max" weight pull, dated 5/9/26 and marked "Type of Pull: Rails", lists four entries in the 120-and-over class of its Heavy division. Two of them, Sun Wukong (164 lb) and Wednesday (186 lb), both Boerboels handled by CR, are recorded at 22,039 lb pulled. The class winner, Conquest, a 128 lb Boerboel from the same kennel, pulled 21,336 lb, and a 125 lb Presa Canario, Amarillo, pulled 19,834 lb.
Two details shape how that number should be read. First, the 22,039 lb dogs placed third and fourth: UPF places dogs within a class by the multiple of body weight (its sheet labels the column "Percent"), and Sun Wukong's 134 times and Wednesday's 118 sit below Conquest's 167 and Amarillo's 159. Second, UPF keeps no all-time records list. The phrase "world record" appears in the sponsor's video and press release and on the kennel's website, not in any UPF document.
That is why this article uses a narrower phrase. The editorial team went through all 1,504 result sheets in UPF's published archive, thirteen seasons from 2014 through 2026. Of those, 1,449 are weight-pull sheets (the rest cover mill race, wall climb and lure coursing), and the 1,436 that could be read contain nothing heavier than 22,039 lb; the 13 that could not be read are rails sheets from 2014 to 2017 and one from 2024.
The surface sets the scale. The UKC rulebook asks three times body weight on snow, eight times on a wheeled cart and ten times on a rail cart for the same qualifying title, so a rail figure and a wheel figure are not the same measurement, and every pull in this section is a rail pull unless it says otherwise. The heaviest American Pulling Alliance (APA) figure read for this article is 14,445 lb, by a 100 lb Greater Swiss Mountain Dog on rails over carpet in 2023, and the International Weight Pull Association (IWPA), which sanctions no rail carts, has 6,075 lb at the top of its record table, by a 187 lb Mastiff on wheels over carpet in 2022.
UPF's event page lists Erica Noseworthy as both organizer and chief judge, and four of her own dogs placed in lighter classes on the sheet. Bully Max, the sponsor and co-presenter, is the party that publicized the result. The dogs' owner, named in the sponsor's 2025 press release as Eli Carver of CR (the kennel's page says he owned and handled both dogs), appears on UPF's published roster of U.S. judges; the kennel's page adds that he did not judge his own dogs. The Boerboel weight-pull article covers this in full.
Who the two dogs are
Sun Wukong and Wednesday are littermates. OFA's public registry pages record CR's Sun Wukong (AKC WS80296527) and CR's Mr. Wednesday (WS80296528) as male Boerboels whelped 18 March 2023 out of the same sire number, WS79897802, and the same dam number, WS72008704, and each page lists the other as a littermate. The dam is Black Iron's The Man Eater of Njombe, Black Iron Njombe for short, a brown female whelped 19 January 2021 whose OFA page carries that AKC number alongside her SABBS number, 416056.
The sire is Peterbuilt Hakeem. OFA holds no record under the AKC number WS79897802, so the two dogs' own pages give a number rather than a name, and the link is made by a third registry page: OFA records a SABBS-registered littermate of the same litter, CR Koda, whelped 18 March 2023, with sire 413160 and dam 416056. SABBS 413160 is the registration under which Peterbuilt Hakeem's own OFA record is filed, and 416056 is Black Iron Njombe's SABBS number. The dogs' breeder, CR, says on its page about the pull that one sire produced the litter of fourteen and that he had no weight-pull history, but does not name him there. So: littermate status, whelp date and dam are on the two dogs' own OFA pages; the sire rests on CR Koda's SABBS record on OFA (sire 413160, dam 416056), which is checkable on OFA's public search.
Pound for pound: the bully breeds win, and it is not close
The same 9 May 2026 sheet answers the ratio question on the same afternoon and the same rails. JT, an American Pit Bull Terrier weighing 38 lb, pulled 18,332 lb, 482.42 times his weight on the sheet's own column, and Stitch, a 26 lb dog of that breed, pulled 12,540 lb at 482.31 times. Among the Boerboels the best ratio was Alucard's, a 97 lb female the kennel describes as a maternal half-sister of the two 22,039 lb dogs, at 17,076 lb and 176 times; Sun Wukong's 22,039 lb was 134 times his 164 lb and Wednesday's 118. A 112 lb Presa Canario, Hamilton, pulled 19,834 lb at 177 times and took the Heavy division's per-pound bonus.
The earlier UPF event showed the same pattern. On 8 November 2025 Sun Wukong pulled 16,917 lb at 158 lb, the figure the sponsor first billed as a world record, as the only entry in the 120-and-over class; on the same sheet a 97 lb Presa Canario, Wendy, pulled 16,884 lb at 174 times body weight against his 107. Lighter dogs hold the ratio column and heavier dogs the absolute column in every sheet and record table the editorial team read, and a heavy dog's pounds say nothing about a light dog's multiple, or the reverse. A ranking that mixes pounds with multiples is answering two questions at once and neither clearly.
Bite force: no breed has a measurement
Most strongest-breed rankings rest on a bite-force table. The Kangal's circulating figure is 743 PSI; ManyPets, one example, gives the Kangal that number and cites no study for it, and the editorial team could find no published measurement of a Kangal's bite anywhere.
Ellis, Thomason, Kebreab and France (Journal of Anatomy, 2008) measured bite force in 20 dogs of mixed breed weighing 5 to 40 kg, roughly 11 to 88 lb, by electrically stimulating the jaw muscles of anesthetized animals: 147 to 946 newtons at the canine teeth, 524 to 3,417 at the second molar. The purpose was to calibrate skull-based estimates, not to compare breeds, and no dog in the sample was near Boerboel size. The 2018 review by Kim, Arzi, Garcia and Verstraete in Frontiers in Veterinary Science gives every value in newtons and has no breed table; the awake-dog study it summarizes, 22 dogs of 7 to 55 kg with no breed stated, ranged from 13 to 1,394 newtons with a mean of 256, and its decisive variable was how eager each dog was to chew the sensor. It names body weight and skull size and shape, not breed, as the main factors.
Two things follow. PSI is a pressure, so it needs a contact area that none of these studies reports, and a breed PSI figure cannot be derived from the data that exist. And no Boerboel bite force has ever been measured. Any PSI figure attached to the breed is not a measurement.
A 2025 skull study cuts against the whole framing. Hebdon and colleagues, in Science Advances, analyzed 117 canid skulls representing 40 domestic breeds (per the abstract) and 18 wild subspecies and found near-complete overlap in skull shape whether breeds were grouped by kennel-club category or by original task. Bite-force quotients computed from skull geometry showed no specialization in breeds with bite work in their origin stories; the only anatomically distinct group was the flat-faced companion breeds. The authors list the "locking jaw" belief about pit bull terriers among the ideas the result undercuts.
Sustained draft: a different sport with different dogs
Weight pull is a short contest: the UKC rulebook defines a qualifying pull as 16 feet in 60 seconds or less, and its higher division withdraws a dog automatically once it reaches 25 times body weight on snow or 65 times on rails. Tank's 6,075 lb at the top of IWPA's record table is about 32 times his 187 lb, on wheels over carpet; at the same 2022 Championships the median completed pull across 49 dogs was about 25 times body weight.
None of that measures endurance. Hauling a loaded sled for hours in cold is a different job, and the northern sled breeds were kept for it; the AKC breed page gives the Alaskan Malamute a single weight, 85 lb for males, rather than a range. The only dog-pulling weight record on the Guinness World Records website that the editorial team could find is a team entry: on 22 October 2000 in Whitehorse, Yukon, 210 dogs pulled a truck tractor, rail trailer and track-mounted drill, 65,910 kg (145,302 lb) in all, over six blocks. That is about 692 lb per dog. Guinness's website, as far as the editorial team could find, lists no single-dog pull and no strongest-dog title; the single-dog figures its printed editions carried through the 1980s are traced in the dog weight-pull records article.
The sixteen-breed table
Every pull figure below was read from the federation's own document: UPF's 9 May 2026 sheet, or the career record APA publishes for each dog in its database. All of them were rail pulls (APA labels the surface "Rails/Carpet"). Weights are the male figures where the registry splits them. No breed in this table has a published bite-force measurement; the Kangal's 743 PSI cites no study.
| Breed | Typical male weight | Heaviest pull read from a federation sheet | Ratio on that pull |
|---|---|---|---|
| Boerboel | 150-200 lb (AKC page, no sex split; the standard lists height only) | 22,039 lb (UPF 2026; two dogs, 164 and 186 lb) | 134x and 118x (176x by a 97 lb Boerboel, same event) |
| English Mastiff (AKC "Mastiff") | 160-230 lb | 7,592 lb (APA 2007) | 58x (132 lb dog) |
| Cane Corso | AKC gives no figure (proportionate to height) | 10,425 lb (APA 2006) | 85x (123 lb dog) |
| Rottweiler | 95-135 lb | 6,425 lb (APA 2017) | 92x (70 lb dog) |
| American Pit Bull Terrier | 35-60 lb (UKC) | 18,332 lb (UPF 2026) | 482x (38 lb dog) |
| American Staffordshire Terrier | 55-70 lb | 11,304 lb (APA 2018, Czech Republic) | 159x (71 lb dog) |
| Presa Canario | 100-125 lb (UKC) | 19,834 lb (UPF 2026) | 177x (112 lb dog) |
| Greater Swiss Mountain Dog | 115-140 lb | 14,445 lb (APA 2023) | 144x (100 lb dog) |
| Alaskan Malamute | 85 lb (AKC single figure) | 12,979 lb (APA 2018) | 183x (71 lb dog) |
| Newfoundland | 130-150 lb | 6,632 lb (APA 2013; one dog) | 50x (132 lb dog) |
| Saint Bernard | 140-180 lb | 7,125 lb (APA 2006) | 48x (147 lb dog) |
| Kangal | 110-145 lb (UKC) | None found; the 743 PSI bite figure cites no study | None found |
| Great Dane | 140-175 lb | 11,716 lb (APA 2018) | 83x (141 lb dog) |
| Dogo Argentino | 80-100 lb (AKC, no sex split) | 10,784 lb (APA 2018, Czech Republic) | 154x (70 lb dog) |
| Tibetan Mastiff | 90-150 lb | 1,950 lb (APA 2026; two dogs, one pulled) | 17x (116 lb dog) |
| German Shepherd Dog | 65-90 lb | 7,122 lb (APA 2018) | 113x (63 lb dog) |
How to read the table
The ratio column is the multiple printed beside each breed's heaviest pull; a lighter dog of the same breed may hold a higher multiple that this article did not search for. Each best-ever cell is the top value of a very different-sized pool. APA's database of 6,253 named dogs holds 2,875 entered as APBT and 1,317 as American Bulldog, roughly two thirds of the whole, against one Newfoundland, two Tibetan Mastiffs, 17 Boerboels and no Kangal or Anatolian at all. A breed that never enters cannot appear; an empty cell records the absence of testing, not weakness.
Venue matters too. The UKC rulebook sets only a minimum load rating for a rail cart, not a design, and the American Staffordshire Terrier, Dogo Argentino and Boerboel maxima in APA's records were all set at Czech events. Part of what a best-ever column measures is where each breed's top dogs happened to compete, and the Boerboel row is no exception.
What the Boerboel row shows
One column of four, then, from a single event in May 2026 at which one kennel entered four Boerboels. In APA's database, where 17 Boerboels have competed, the breed's best pull on file is 9,392 lb, by a 104 lb dog in 2018. For the breed's working profile, growth and size, or how it compares with the other mastiff types, start with the breed overview, size and growth and Boerboel versus the other mastiff breeds. How this directory checks and cites material like this is set out in its editorial standards.