Maltese dogs die most often from cardiovascular disease, particularly a progressive heart valve condition that affects the breed at high rates. With a typical lifespan of 12 to 15 years, the Maltese is a long-lived breed, but certain genetic vulnerabilities make heart failure, liver shunts, cancer, and airway problems the primary threats to watch for across their lifetime.
Heart Disease Is the Leading Killer
Large-scale veterinary mortality studies consistently place cardiovascular disease at the top of the list for Maltese. The specific condition driving most of these deaths is degenerative mitral valve disease, where the valve separating two chambers of the heart gradually deteriorates, allowing blood to leak backward with each heartbeat. Over time, the heart has to work harder to compensate, eventually leading to congestive heart failure.
A study published in the Journal of Veterinary Internal Medicine found that among 162 Maltese dogs with no outward signs of heart trouble, 41% already had detectable blood leaking through the mitral valve, and 34% had visible valve changes on imaging. By age 7.5, half of the dogs in the study showed structural valve abnormalities. Because the study only enrolled dogs that appeared healthy, the true prevalence across the entire breed is likely even higher. The condition is slow and progressive. Many Maltese live comfortably for years after early valve changes appear, but once the heart can no longer compensate, the decline can be rapid. Coughing (especially at night), labored breathing, exercise intolerance, and fluid buildup in the lungs are the hallmark signs of heart failure in this breed.
Liver Shunts in Young Maltese
Maltese are significantly overrepresented among dogs born with a portosystemic shunt, an abnormal blood vessel that routes blood around the liver instead of through it. Normally, the liver filters toxins from digestion before they enter general circulation. When a shunt bypasses the liver, those toxins build up in the bloodstream and can affect the brain, kidneys, and other organs.
In one long-running study of 62 dogs diagnosed with congenital liver shunts over 15 years, Maltese accounted for 14 of those cases, making them one of the two most affected breeds. Maltese nearly always have a single shunt located outside the liver, which is actually the more treatable type. Surgical correction was successful in all nine Maltese cases where it was attempted. The condition typically shows up before a dog’s first birthday, with signs like stunted growth, disorientation after meals, excessive thirst, and seizures. Early detection matters enormously here, because untreated shunts can be fatal, while corrected ones often allow a normal or near-normal life.
Cancer, Especially Mammary Tumors
Cancer is a significant cause of death in Maltese, with mammary gland tumors being the most common type in unspayed females. Maltese are among several toy breeds identified as having an elevated risk for these tumors, and roughly half of all mammary tumors in dogs turn out to be malignant. Spaying before the first or second heat cycle dramatically reduces this risk.
Other cancers do occur in the breed, but mammary tumors stand out because of how frequently they appear in intact females and how preventable they are with early spaying. If you notice any lumps along your Maltese’s belly or chest, particularly in middle age and beyond, prompt evaluation gives the best chance of catching a tumor before it spreads.
Tracheal Collapse and Breathing Problems
Maltese are the single most commonly affected breed in studies of tracheal collapse, a condition where the cartilage rings supporting the windpipe weaken and flatten. In a retrospective study of 110 small-breed dogs with tracheal collapse, Maltese made up nearly 31% of all cases. The hallmark sign is a harsh, honking cough that worsens with excitement, exercise, heat, or pressure on the neck from a collar.
While tracheal collapse is rarely an immediate cause of death in milder forms, severe cases can significantly compromise breathing and quality of life. Research has not established a clear link between the radiographic grade of collapse and the severity of symptoms, meaning some dogs with significant structural changes cope reasonably well, while others with apparently mild collapse struggle. Weight management, using a harness instead of a collar, and avoiding extreme heat all help reduce strain on the airway.
Dental Disease and Organ Damage
Maltese are notoriously prone to dental problems, and this is more than a cosmetic issue. Chronic periodontal disease creates a low-grade infection in the mouth that repeatedly seeds bacteria into the bloodstream. Over time, this can cause kidney damage through inflammation and immune complex deposits in the kidney’s filtering units. Bacterial spread from the gums has also been linked to pathologic changes in the heart.
For a breed already predisposed to heart valve disease and with a small body that leaves little margin for kidney decline, dental neglect can quietly accelerate the very conditions most likely to be fatal. Regular dental cleanings and at-home tooth care are among the highest-impact things you can do to extend a Maltese’s life, even though they don’t show up in mortality statistics as a direct cause of death.
Brain Inflammation in Toy Breeds
Maltese are one of several toy breeds genetically susceptible to necrotizing meningoencephalitis (NME), an inflammatory brain disease. The condition progresses rapidly, with symptoms including seizures, behavioral changes, circling, altered awareness, and vision loss. NME is often fatal even with aggressive treatment. Researchers have identified genetic risk factors shared across toy breeds, suggesting an inherited vulnerability in the immune system’s interaction with brain tissue.
NME is not common in absolute numbers, but when it strikes, the prognosis is poor. It tends to appear in young to middle-aged dogs rather than seniors, which makes it particularly devastating for owners who aren’t expecting a serious diagnosis in a seemingly healthy dog.
Puppy Vulnerability to Low Blood Sugar
Maltese puppies face a specific early-life risk that larger breeds don’t: dangerously low blood sugar. Toy breed puppies have very little body mass to draw on for energy reserves, and their small livers store minimal glycogen. Missing even one meal, combined with the energy demands of play or stress, can cause blood sugar to plummet. Symptoms range from weakness and trembling to seizures, collapse, and death if not corrected quickly.
This is primarily a concern in puppies under four months old and in very small adults. Feeding small, frequent meals throughout the day rather than one or two large ones is the simplest way to prevent it. If a Maltese puppy becomes unresponsive or has a seizure, rubbing a small amount of sugar water or corn syrup on the gums while getting to a veterinarian can be lifesaving.