Though much far less common than the preceding reasons for a Maltese having a case of bad breath, there are some diseases that have halitosis as one of the signs. This includes:
Diabetes.
Canine diabetes is linked to bad breath in a number of ways. If blood sugar levels are exceedingly high, this can produce a strong fruity smell. In addition, dogs with diabetes are at greater risk for gum disease and associated infections. Aside from possible bad breath, other signs include changes in appetite, excessive thirst, excessive urination, changes in weight, lethargy, reoccurring urinary tract infections, upset stomach, vomiting, chronic skin issues, and/or vision problems.
Kidney issues.
In the case of kidney stones, kidney infection, or other related conditions that affect the functioning of a dog’s kidneys, breath may develop a strong ammonia-type smell. Other signs may include trouble urinating, blood in the urine, fever, and/or signs of discomfort (odd stance, hunched over appearance).
Lung issues.
Any illness that involves the lungs can involve bad breath. Conditions include canine flu, kennel cough, and bacterial or viral lung infections. Other signs are rather obvious and include coughing,
difficulty breathing, and/or wheezing.
Digestive issues.
An upset stomach may involve burps (silent or audible) that hold strong odors, and regular breathing that holds a sour, acid-type smell. Other signs may include reluctance to eat, lethargy, runny stools, and/or nausea. The cause of digestive issues varies quite a bit, from inferior food with high grain, by-product, or chemical composition, to food intolerance, bacterial infection, and parasitic infection.