A Frenchton is a cross between a French Bulldog and a Boston Terrier. It is not a recognized breed, and no study has yet measured Frenchton health or lifespan. What we do know comes from its two parent breeds, and both are flat-faced, screw-tailed dogs with well-documented health risks.

What is a Frenchton?

"Frenchton" is the name sellers use for a puppy with one French Bulldog parent and one Boston Terrier parent, or for later generations of those crosses. Because it is a cross, it would fit in the American Kennel Club's Canine Partners program, which the AKC describes as "an enrollment program for mixed breeds", not in breed registration.[1]

Because there is no standard, there is no "correct" Frenchton size, coat or look. Puppies in the same litter can look more like one parent or the other.

Frenchton vs Frenchie: how the parent breeds compare

The two parent breeds look alike, which is part of why the cross is popular. Their breed standards give a rough idea of the size range you might expect:

French BulldogBoston Terrier
Weight in the standardNot over 28 lb (12.7 kg); heavier is a disqualification (AKC)[5]Three classes, from under 15 lb up to 25 lb (6.8 to 11.4 kg) (Royal Kennel Club)[6]
TailShort, straight or screwed[5]Short, straight or curled[6]
FaceFlat-faced (brachycephalic)Flat-faced (brachycephalic)
EyesLarge, roundLarge, round; "excessively prominent eyes" are listed as highly undesirable[6]

So how big do Frenchtons get? Most will land somewhere inside the parents' ranges, but no one has published Frenchton weights. The best predictor is the size of the actual parents. For temperament, see our guide to French Bulldog temperament; with a cross, expect a mix rather than a fixed personality.

Frenchton health issues

Here is what the parent breeds bring to a Frenchton.

  • Breathing problems (BOAS). Both breeds have short skulls. In a 2024 Cambridge study of 104 Boston Terriers, 37.5% had no signs of brachycephalic obstructive airway syndrome (BOAS), compared with 10% of French Bulldogs in earlier data. Severe cases were rare in Bostons.[3] That is good news for Bostons, but it does not tell you how a mixed puppy will breathe. Learn what to listen for in our guide to noisy breathing in French Bulldogs.
  • Screw tail and spine malformations. A gene variant in DVL2 is strongly linked to the screw tail. It is fixed in French Bulldogs (every dog carries it) and present in 94% of Boston Terrier gene copies, and it travels with malformed vertebrae in the chest and tail.[2] A Frenchton is very likely to inherit it. Read more in French Bulldog tail and spine problems.
  • Eye injuries. Flat-faced dogs have prominent eyes. In a UK study, brachycephalic breeds had about 11 times the odds of corneal ulcers compared with crossbreds.[7]
  • Juvenile cataracts. The UC Davis HSF4 DNA test for juvenile hereditary cataracts covers both the French Bulldog and the Boston Terrier. The condition is recessive, so a puppy is affected only if it inherits the variant from both parents.[8]

Heat is a shared risk too: treat a Frenchton like any flat-faced dog on hot days.

Is a Frenchton healthier than a French Bulldog?

Many listings say crosses are healthier thanks to "hybrid vigor." The evidence does not support assuming that. In a 2024 UK study of Cockapoos, Labradoodles and Cavapoos, the odds did not differ significantly between the crosses and their parent breeds in 86.6% of the health comparisons. Where there was a difference, it went both ways: higher risk in 7.0% and lower risk in 6.4%.[4]

Frenchtons were not part of that study. But the logic matters even more here: mixing two breeds that share the same flat face and the same screw-tail gene cannot remove problems that both parents carry. A Frenchton may breathe better than some French Bulldogs if its Boston parent has a longer muzzle and open nostrils, but that depends on the individual parents, not on the label.

Frenchton lifespan: what is not known

There is no published Frenchton lifespan. The year ranges quoted on seller websites are not based on any study we could find. What exists is data on the parents. In a 2024 UK study of more than 584,000 dogs, French Bulldogs had a median lifespan of 9.8 years, among the shortest of all breeds, and flat-faced breeds as a group lived shorter lives than dogs with medium-length faces.[9] For details and caveats, see our guide to French Bulldog lifespan.

Also unknown: whether Frenchtons have fewer spine or breathing problems in practice, and how health changes in second-generation crosses.

Before you buy a Frenchton puppy

Because there is no breed club for Frenchtons, the health tests that matter are those of each parent breed. Ask the breeder to show you, for both parents:

  • A breathing assessment, such as the Respiratory Function Grading Scheme, recommended by the French Bull Dog Club of America.[10]
  • A recent eye exam by a board-certified veterinary ophthalmologist (CAER) and the HSF4 (JHC) DNA result.[8][10]
  • Hips, kneecaps and heart screening.[10]
  • Open nostrils, quiet breathing at rest and a dog that can walk and play without struggling.

Be wary of "Frenchton merle" puppies sold at a premium. UC Davis notes that merle dogs "may possess a wide range of auditory and ophthalmologic defects."[11] See our guide to merle French Bulldog health risks. Our checklist of breeder health tests explains what each result means.

Sources and references

  1. American Kennel Club. AKC Canine Partners [Internet]. akc.org; [date unknown] [updated 2026 Sep 29; cited 2026 Nov 3].
  2. Mansour TA, Lucot K, Konopelski SE, Dickinson PJ, Sturges BK, Vernau KL, et al. Whole genome variant association across 100 dogs identifies a frame shift mutation in DISHEVELLED 2 which contributes to Robinow-like syndrome in Bulldogs and related screw tail dog breeds. PLoS Genetics. 2018;14(12):e1007850. doi:10.1371/journal.pgen.1007850.
  3. Tomlinson F, O'Neill E, Liu NC, Sargan DR, Ladlow JF. BOAS in the Boston Terrier: A healthier screw-tailed breed?. PLoS ONE. 2024;19(12):e0315411. doi:10.1371/journal.pone.0315411.
  4. Bryson GT, O'Neill DG, Brand CL, Belshaw Z, Packer RMA. The doodle dilemma: How the physical health of 'Designer-crossbreed' Cockapoo, Labradoodle and Cavapoo dogs' compares to their purebred progenitor breeds. PLoS ONE. 2024;19(8):e0306350. doi:10.1371/journal.pone.0306350.
  5. American Kennel Club. Official Standard of the French Bulldog [Internet]. AKC; 2018 Apr 10 [cited 2026 Nov 3].
  6. The Royal Kennel Club. Boston Terrier [Internet]. The Royal Kennel Club, Breed Standards; [date unknown] [updated 2025 Nov; cited 2026 Nov 3].
  7. O'Neill DG, Lee MM, Brodbelt DC, Church DB, Sanchez RF. Corneal ulcerative disease in dogs under primary veterinary care in England: epidemiology and clinical management. Canine Genetics and Epidemiology. 2017;4(1):5. doi:10.1186/s40575-017-0045-5.
  8. UC Davis Veterinary Genetics Laboratory. Juvenile Hereditary Cataracts (JHC) [Internet]. UC Davis Veterinary Genetics Laboratory; [date unknown] [cited 2026 Nov 3].
  9. McMillan KM, Bielby J, Williams CL, Upjohn MM, Casey RA, Christley RM. Longevity of companion dog breeds: those at risk from early death. Scientific Reports. 2024;14:531. doi:10.1038/s41598-023-50458-w.
  10. French Bull Dog Club of America. Health Testing and Registries [Internet]. FBDCA; [date unknown] [cited 2026 Nov 3].
  11. UC Davis Veterinary Genetics Laboratory. Merle [Internet]. UC Davis Veterinary Genetics Laboratory; [date unknown] [cited 2026 Nov 3].