English Mastiff nutrition, slow growth and bloat

In a 2021 survey of owners of more than 1,000 deceased Mastiff-breed dogs, English Mastiffs and Bullmastiffs among them, the median age at death was 8 years. Cancer caused almost half of those deaths, with osteosarcoma the type recorded most often, followed by old age, heart problems and gastric problems including bloat. The American Kennel Club lists males at 160 to 230 pounds (about 73 to 104 kg) and females at 120 to 170 pounds (about 54 to 77 kg), with a life expectancy of 6 to 10 years. Feeding cannot change a Mastiff's genes. It can, however, influence how fast a puppy grows, how much weight the joints carry and how a dog eats its meals, which are the parts of that picture owners control.

Daily calories

Energy needs rise more slowly than body weight, so a 100 kg Mastiff does not need twice what a 50 kg dog eats. The Merck Veterinary Manual estimates resting energy requirement (RER) as 70 × body weight in kg to the power 0.75, then multiplies it by 1.6 for a neutered adult, 1.8 for an intact adult and 1.4 for a dog that gains weight easily. Figures below are rounded to the nearest 10 kcal.

Treat these as a first estimate. Many Mastiffs are not especially active, and a placid adult that spends most of the day lying down may need less than the table shows. Energy density varies widely between foods, so the amount in the bowl should be worked out from the kcal per cup or per kilogram on the label, then adjusted after regular weigh-ins and body condition checks. At a healthy weight the ribs are easy to feel under a thin layer of fat, and there is a visible tuck behind the ribcage.

Slow, steady growth in puppies

Giant-breed puppies grow for a long time and are genetically inclined to grow fast. A review on feeding large-breed puppies explains the problem with overfeeding them. Extra energy produces a heavier puppy and faster bone growth with abnormal remodeling, which leaves a larger but less dense skeleton carrying more weight than it should. Feeding to a controlled growth rate, with nutrients matched to energy intake, reduces the risk of skeletal problems. Overfeeding speeds growth. It does not build a sounder dog.

Calcium needs particular care. When Great Dane puppies were raised on diets with different calcium and phosphorus levels, their bone mineral content tracked the diet closely until about five to six months of age, after which hormonal control of absorption took over. In those early months, in other words, what goes into the bowl shows up in the skeleton. Two rules follow:

• Use a complete puppy food made for large or giant breeds, fed in measured amounts rather than free choice.
• Add no calcium, bone meal or vitamin D to a complete food, and keep treats and table scraps small enough not to unbalance it.

A Mastiff puppy should look lean, with ribs easy to feel. Plump puppies may look well fed, but this is the time when extra weight does the most damage. Weigh the puppy every week or two and ask the vet to check body condition at each visit. Most Mastiff puppies do well on three meals a day in the early months, and even adults are better on two or more meals than one, for the reason below.

Bloat and gastric dilatation-volvulus

In gastric dilatation-volvulus (GDV), the stomach fills with gas and food and can twist on itself, cutting off its own blood supply and that of the spleen. It is an emergency. The American College of Veterinary Surgeons puts mortality at around 15%, rising when signs have been present for more than six hours.

Deep-chested, large and giant dogs, older dogs, dogs with affected relatives and dogs fed one large meal a day are all at higher risk. In a prospective study of 1,637 large and giant breed dogs, eating quickly and using a raised food bowl both increased the risk, and about 52% of GDV cases in the giant breeds were attributed to the raised bowl. Mastiffs were not among the 11 breeds studied, which included Great Danes, Newfoundlands and Saint Bernards, but the finding is a good reason to keep raised feeders, often sold for big dogs, out of a Mastiff's routine.

• Split the day's food into at least two meals, ideally three.
• Slow down a fast eater with a slow-feeder bowl or by scattering kibble, keeping in mind that the bowls themselves have not been tested as GDV prevention.
• Check the label. ACVS cites a 2006 finding that dry foods listing oils or animal fat among the first four ingredients raised the risk in high-risk dogs.
• Keep the dog quiet around meals. A calm hour before and after eating is a common precaution, although evidence for it is limited.
• Ask about prophylactic gastropexy. Many veterinary surgeons recommend fixing the stomach to the body wall in at-risk breeds, often during spay or neuter surgery, and it can be done by minimally invasive techniques. It prevents the twist, not the bloating.

Joints and body weight

Hip and elbow dysplasia are developmental joint diseases, and a giant dog feels even mild joint problems keenly because of the load involved. Genetics play a large part, but body weight across a lifetime affects how the joints hold up. In a lifetime feeding study of 48 Labrador Retrievers, dogs fed 25% less than their littermates from eight weeks of age stayed leaner, lived significantly longer and showed signs of chronic disease later. Labradors are not Mastiffs, but the direction of the finding is hard to ignore in a breed with a short life expectancy.

Keeping an adult Mastiff lean is the most useful thing diet can do for its joints. Joint supplements such as glucosamine, chondroitin and fish oil are widely used, and the evidence for them varies. If the vet recommends one for a Mastiff with arthritis, the dose needs to be calculated for the dog's actual weight, since products are often sized for much smaller dogs. Stiffness after rest, reluctance to climb stairs or a change in gait are reasons for a joint check.

Cancer and heart disease

No diet has been shown to prevent osteosarcoma, the bone cancer most often reported in the Mastiff survey. What matters is noticing it early. Lameness that does not resolve, or a firm, painful swelling on a leg bone, needs an x-ray rather than a few weeks of rest. Antioxidant-rich foods and particular preservatives are sometimes promoted as cancer protection, but evidence for either in dogs is lacking.

Heart problems accounted for 8% of deaths in the same survey. Taurine, L-carnitine and coenzyme Q10 are often sold for heart support, and a dog diagnosed with heart disease may be prescribed some of them, but there is little evidence they protect a healthy Mastiff. A complete and balanced food and a lean body are the sensible baseline. Coughing, fainting, fast breathing at rest or tiring quickly on walks should prompt a vet visit, where a heart exam and, if needed, an echocardiogram can find disease before it becomes severe.

Sources

1. Mastiff breed mortality: a study of owner experience, dog age and longevity. Veterinary and Animal Science, 2021.
2. Mastiff dog breed information. American Kennel Club.
3. Nutritional requirements of small animals. Merck Veterinary Manual.
4. Feeding large-breed puppies. Compendium: Continuing Education for Veterinarians, 2010.
5. Influence of dietary calcium and phosphorus content in a fixed ratio on growth and development in Great Danes. American Journal of Veterinary Research, 2002.
6. Gastric dilatation-volvulus. American College of Veterinary Surgeons.
7. Non-dietary risk factors for gastric dilatation-volvulus in large and giant breed dogs. Journal of the American Veterinary Medical Association, 2000.
8. Effects of diet restriction on life span and age-related changes in dogs. Journal of the American Veterinary Medical Association, 2002.