English Mastiff Rottweiler Cross: Size, Temperament, and Care Guide
Everything about the English Mastiff Rottweiler cross — size ranges, temperament variability, health risks, grooming, costs.
If you've been searching for an English Mastiff Rottweiler cross, you're looking at one of the most physically imposing designer mixes available. This combination pairs two giant guardian breeds, producing dogs that can exceed 150 pounds and stand over 28 inches at the shoulder. But before you commit to a dog of this magnitude, you need a clear picture of what variability looks like, what health screenings matter, and whether your living situation can genuinely accommodate a dog this large.
This guide breaks down the realities of owning a Mastweiler (the most common nickname for this cross) — including the traits you can reasonably predict, the ones you absolutely cannot, and the veterinary costs you should budget for before bringing one home.
Parent Breeds: English Mastiff and Rottweiler
Understanding any mixed breed starts with understanding its parents. The English Mastiff and Rottweiler share a guardian lineage but differ significantly in build, energy, and social behavior. Here's how they compare across the traits that matter most to owners:
| Trait | English Mastiff (AKC Standard) | Rottweiler (AKC Standard) |
|---|---|---|
| Weight Range | 120–230 lb / 54–104 kg | 80–135 lb / 36–61 kg |
| Height at Shoulder | 27.5–30+ in / 70–76+ cm | 22–27 in / 56–69 cm |
| Coat | Short, dense, moderate shedding | Short, coarse, moderate shedding with undercoat |
| Energy Level | Low to moderate (30–45 min exercise/day) | Moderate to high (60–90 min exercise/day) |
| Temperament | Calm, dignified, gentle with family | Confident, alert, loyal, reserved with strangers |
| Trainability | Moderate — willing but slow, sensitive | High — intelligent, responsive, needs mental work |
| Lifespan | 6–10 years | 9–10 years |
| Breed Group | Working Group (AKC) | Working Group (AKC) |
Both breeds belong to the AKC Working Group, meaning they were historically selected for guarding, pulling, and protection tasks. This shared heritage means an English Mastiff Rottweiler cross will almost certainly have protective instincts — the question is how strongly those instincts manifest and whether they lean toward the Mastiff's laid-back watchfulness or the Rottweiler's active territoriality.
How Big Will an English Mastiff Rottweiler Cross Get?
Size is the first thing prospective owners ask about, and with this mix, the range is genuinely wide. Because both parent breeds are large-to-giant, you won't get a small dog — but you could get anything from a "modest" 90-pound dog to a 200-pound giant depending on which parent's genes dominate and the individual's nutrition during growth.
| Measurement | Low End | Typical Range | High End |
|---|---|---|---|
| Weight (adult male) | 100 lb / 45 kg | 130–180 lb / 59–82 kg | 200+ lb / 91+ kg |
| Weight (adult female) | 85 lb / 39 kg | 100–150 lb / 45–68 kg | 170 lb / 77 kg |
| Height (at shoulder) | 24 in / 61 cm | 26–29 in / 66–74 cm | 31 in / 79 cm |
| Full maturity age | 18–24 months (giant breeds mature slowly — do not rush growth) | ||
A critical note on growth: giant-breed puppies must be fed a large-breed puppy formula (look for AAFCO statements specifying "growth" for large-size dogs, meaning 70 lb+ adult weight). Rapid growth from high-calorie diets increases the risk of developmental orthopedic diseases like hip dysplasia and osteochondritis dissecans (OCD). Target a body condition score (BCS) of 4–5 out of 9 throughout puppyhood, even if your dog looks slightly lean — skeletal health matters more than filling out quickly.
Temperament: What to Expect (and What You Can't Predict)
Temperament in any mixed breed is a lottery, but with two guardian breeds, certain baselines are reliable. Your English Mastiff Rottweiler cross will almost certainly be:
- Loyal and bonded to family — both breeds form deep attachments
- Protective of home and people — watchdog barking and wariness of strangers are common
- Physically powerful — even a "calm" individual can pull an adult off their feet on a leash
- Sensitive to household tension — both breeds respond poorly to chaotic or confrontational environments
What varies significantly between individuals:
| Trait | Mastiff-Leaning | Rottweiler-Leaning |
|---|---|---|
| Energy | Couch potato, 30-min walks suffice | Athletic, needs 60–90 min daily activity |
| Stranger Response | Indifferent, barely acknowledges visitors | Alert, positions between owner and stranger |
| Trainability | Slow to respond, needs patience | Eager to work, enjoys structured training |
| Separation Tolerance | Generally fine alone for moderate periods | Prone to distress if left too long without enrichment |
| Play Drive | Low — prefers lounging | Moderate to high — enjoys fetch, tug, scent work |
The challenging scenario for this mix is a dog that inherits the Rottweiler's territorial intensity without the Mastiff's easygoing brake pedal. This can produce a dog that is reactive to strangers, difficult to manage in public, and unsuitable for homes with frequent visitors. Early, structured socialization — exposing the puppy to diverse people, surfaces, sounds, and environments between 8 and 16 weeks — is non-negotiable. Use positive reinforcement methods exclusively; force-free training builds confidence without triggering the defensive responses that aversive tools (shock collars, prong collars) can provoke in guardian breeds.
Consult your veterinarian or a certified applied animal behaviorist (CAAB) if your dog displays fear-based aggression or resource guarding — these behaviors are manageable but require professional guidance in powerful breeds.
Coat, Shedding, and Grooming Requirements
Neither the English Mastiff nor the Rottweiler carries the curly or wire coat genes that produce low-shedding dogs. This means the English Mastiff Rottweiler cross is not hypoallergenic and is not low-shedding. You will deal with year-round moderate shedding and seasonal heavy shedding (typically spring and fall).
Coat possibilities include:
- Short and dense (Mastiff-type) — lies flat, easy to brush, moderate shedding
- Short with a thicker undercoat (Rottweiler-type) — slightly coarser outer coat, heavier seasonal blow
- Color — expect fawn, apricot, brindle (Mastiff genes) or black-and-tan/mahogany markings (Rottweiler genes); some dogs show a blend, such as dark brindle with tan points
Grooming is straightforward but consistent:
- Brush 2–3 times per week with a rubber curry brush or medium-bristle brush (a Kong ZoomGroom or similar tool works well for short coats)
- During shedding season, add a de-shedding tool like the Furminator for short hair — use once weekly to manage undercoat
- Bathe every 6–8 weeks or as needed (over-bathing strips natural oils from short coats)
- Clean facial wrinkles if inherited from the Mastiff parent — use a damp cloth daily and dry thoroughly to prevent yeast and bacterial skin fold infections (intertrigo)
- Nail trims every 2–3 weeks — giant breeds that walk on soft surfaces need regular trimming to prevent splaying and joint stress
Health Considerations: Hybrid Vigor vs. Reality
Let's address the hybrid vigor myth directly. The idea that mixed-breed dogs automatically avoid the health problems of their purebred parents is not supported by veterinary evidence. A 2013 study published in the Journal of the American Veterinary Medical Association found that while mixed breeds have lower rates of some inherited disorders, they share equal or higher risk for others, including hip dysplasia and certain cancers. What crossbreeding can do is reduce the probability of recessive conditions that require two copies of a gene — but both Mastiffs and Rottweiler share several health risks, meaning the overlap is significant.
| Condition | Prevalence in Parent Breeds | Screening Method | Estimated Treatment Cost |
|---|---|---|---|
| Hip Dysplasia | Mastiff: ~25% affected; Rottweiler: ~20% affected (OFA data) | OFA or PennHIP radiographs at 24 months | $3,000–$7,000 per hip (surgical) |
| Elbow Dysplasia | Both breeds: moderate risk | OFA elbow radiographs | $1,500–$4,000 (surgical) |
| Dilated Cardiomyopathy (DCM) | Rottweilers: recognized risk; Mastiffs: documented cases | Echocardiogram by veterinary cardiologist | $400–$800 (diagnostic); $100–$300/month (medication) |
| Gastric Dilatation-Volvulus (Bloat/GDV) | Both deep-chested breeds: HIGH risk | Preventive gastropexy at time of spay/neuter | $400–$800 (preventive); $3,000–$7,000+ (emergency GDV surgery) |
| Osteosarcoma | Rottweilers: significantly elevated risk (one of the highest among all breeds) | No early screening; watch for lameness, swelling | $5,000–$15,000+ (amputation + chemotherapy) |
| Hypothyroidism | Both breeds: moderate prevalence | Full thyroid panel (not just T4) | $20–$50/month (levothyroxine) |
| Entropion/Ectropion | Mastiffs: common eyelid conformational issues | Veterinary ophthalmologic exam | $500–$1,500 (surgical correction) |
Gastric dilatation-volvulus (GDV) is a life-threatening emergency. If your dog shows a distended abdomen, unproductive retching, restlessness, or pale gums — go to an emergency veterinary clinic immediately. Do not wait. Discuss preventive gastropexy (stomach tacking) with your veterinarian, especially if performing spay/neuter. According to the AVMA, deep-chested breeds have a lifetime GDV risk of up to 20–40% without preventive surgery.
Ask any breeder for Orthopedic Foundation for Animals (OFA) health clearances on both parent dogs. Acceptable minimums for this cross: hip scores of Good or Fair (not just "passing"), elbow clearance, cardiac evaluation, and thyroid panel. A responsible breeder will share these openly — if they can't or won't, walk away.
Generations and Predictability: F1, F1B, and Beyond
- F1 (First Generation): One purebred English Mastiff parent × one purebred Rottweiler parent. Maximum genetic diversity, but most unpredictable in appearance and temperament. This is the most common generation for this cross.
- F1B (First Generation Backcross): An F1 Mastweiler × a purebred Mastiff or purebred Rottweiler. Slightly more predictable traits leaning toward the backcross breed. Rare for this specific mix.
- F2 (Second Generation): Two F1 Mastweilers bred together. Greater trait variability due to gene recombination — puppies in the same litter can look and behave very differently.
- Multigen (F3+): Multiple generations of Mastweiler × Mastweiler breeding. Extremely rare for this cross — there is no established breed club or standard, so multigen lines are uncommon.
Unlike Poodle-based designer breeds (Goldendoodles, Labradoodles), the Mastiff-Rottweiler cross has virtually no established multigen breeding programs. Most puppies you'll encounter are F1, and individual variation remains high regardless of generation.
Who Should (and Shouldn't) Own This Mix
This is a dog that requires specific circumstances to thrive. Here's a practical framework for deciding if the English Mastiff Rottweiler cross fits your life:
This mix suits you if:
- You have prior experience with large guardian breeds (Rottweilers, Mastiffs, Cane Corsos, Great Danes)
- You have a securely fenced yard — minimum 6-foot fencing, as both parent breeds can be territorial roamers
- Your home has ground-floor access or minimal stairs (giant breeds develop joint issues that make stairs painful in later years)
- You can commit to structured socialization during the 8–16 week critical period and ongoing positive-reinforcement training through maturity (24 months)
- You budget $3,000–$5,500 annually for food, veterinary care, preventives, and supplies for a giant-breed dog
- You understand local breed-specific legislation (BSL) — Rottweilers are restricted in some jurisdictions, and mixes with Rottweiler heritage may be affected
Reconsider this mix if:
- This would be your first dog, or your first dog over 50 lb
- You live in an apartment or rental with breed/weight restrictions
- You have young children who could be accidentally knocked over by a 150-pound dog
- You travel frequently and need flexible boarding options (many facilities have weight limits or breed restrictions)
- You cannot afford pet insurance ($80–$150/month for a giant-breed mix) or an emergency fund of $5,000+
Cost: Purchase Price and Lifetime Expenses
| Expense Category | Estimated Range |
|---|---|
| Puppy purchase (responsible breeder) | $1,500–$3,500 |
| Adoption/rescue (if available) | $200–$600 |
| Initial veterinary setup (vaccines, microchip, spay/neuter) | $500–$1,200 |
| Giant-breed puppy food (first year, large-breed formula) | $800–$1,400 |
| Adult food (ongoing annual cost) | $900–$1,500/year |
| Preventive medications (heartworm, flea/tick — giant-breed dosing) | $400–$700/year |
| Pet insurance (accident + illness, giant breed) | $80–$150/month |
| Preventive gastropexy (recommended) | $400–$800 (at time of spay/neuter) |
| Supplies (XXL crate, heavy-duty leash/harness, orthopedic bed) | $500–$1,000 initial |
First-year costs for a Mastweiler puppy from a breeder typically total $4,500–$8,000 when all expenses are included. Ongoing annual costs run $2,500–$4,500 excluding emergencies. These numbers are higher than average because everything for a giant-breed dog costs more — food dosing, medication dosing (many preventives are priced by weight), surgical procedures, and even cremation or burial services.
Rescue availability for this specific cross is limited, but Rottweiler and Mastiff breed-specific rescues occasionally have mixed dogs. Check organizations like Rottweiler Rescue or Mastiff Rescue Trust. Adopting an adult mix lets you assess temperament directly rather than guessing from puppy behavior.
Frequently Asked Questions
What two breeds make up the English Mastiff Rottweiler cross?
This mix is a cross between a purebred English Mastiff and a purebred Rottweiler. Both are AKC Working Group breeds with guardian heritage. The resulting mix is sometimes called a "Mastweiler," though this nickname is informal and not recognized by any breed registry.
How big will an English Mastiff Rottweiler cross get?
Most adults fall between 100–180 lb (45–82 kg) and 24–30 inches (61–76 cm) at the shoulder, though individuals outside this range exist. Males tend toward the larger end. Full physical maturity takes 18–24 months, and you should feed a large-breed puppy formula throughout growth to protect developing joints.
What will the temperament of this cross be like?
Expect a loyal, protective dog that bonds deeply with its family. Energy levels and stranger-friendliness vary widely — some individuals are calm and indifferent to visitors (Mastiff-leaning), while others are alert and actively territorial (Rottweiler-leaning). Early socialization and positive-reinforcement training are essential regardless of where your dog falls on this spectrum.
Is the English Mastiff Rottweiler cross hypoallergenic or low-shedding?
No. Neither parent breed carries low-shedding coat genes. This cross will shed moderately year-round with heavier seasonal shedding. If allergies are a concern, this is not a suitable mix — consider consulting an allergist before committing to any high-shedding breed.
What health issues might this mix inherit?
The most significant risks are hip dysplasia, elbow dysplasia, gastric dilatation-volvulus (bloat), dilated cardiomyopathy, osteosarcoma (especially from the Rottweiler side), and eyelid conformational issues like entropion (from the Mastiff side). Require OFA health clearances from any breeder and discuss preventive gastropexy with your veterinarian.
How much does an English Mastiff Rottweiler cross cost?
Expect $1,500–$3,500 for a puppy from a breeder performing health clearances on both parent dogs. Adoption through breed-specific rescues costs $200–$600 when available. First-year total costs (including veterinary care, food, supplies, and preventive surgery) typically range from $4,500–$8,000.
The information in this guide is for educational purposes and does not replace professional veterinary advice. Always consult your veterinarian for health decisions specific to your dog.
Anouk Beaumont
All our authors care for dogs every day — read more of their work on the authors page.
