Two Pet Health Studies: Heart Stenosis and Behavior Rates
A guide to congenital heart narrowing in dogs and a new analysis challenging high estimates of canine behavior problems.
Two recent studies offer insights for dog owners, one detailing a serious cardiac condition and another reassessing the prevalence of behavioral issues. The first explains the types and management of heart stenosis, while the second questions a prior claim that nearly all U.S. dogs have moderate to serious behavior problems.
Heart Stenosis in Dogs
Heart stenosis is a congenital narrowing within the heart or its vessels, forcing the organ to work harder to pump blood. The condition is usually present from birth. There are several distinct types, each affecting different breeds and requiring specific management.
Subaortic stenosis is the most common form. A fibrous ring forms below the aortic valve, obstructing blood flow from the heart's main pumping chamber. Breeds often affected include Newfoundlands, Golden Retrievers, Rottweilers, Boxers, German Shepherds, and Bullmastiffs. Many dogs with mild cases show no symptoms. Severe cases can lead to lethargy, exercise intolerance, fainting, breathing difficulties, or sudden death. Because it is considered inherited, dogs diagnosed with this condition should not be bred.
Other types include valvular and supravalvular aortic stenosis, which also strain the left ventricle. Pulmonic stenosis affects the right side of the heart, impeding blood flow to the lungs. Breeds frequently impacted are English Bulldogs, Miniature Schnauzers, Beagles, Boxers, West Highland White Terriers, and Labrador Retrievers. Symptoms can include exercise intolerance, fainting, and a bluish tint to the gums in severe cases. A procedure called balloon valvuloplasty, which widens the narrowed valve with a small balloon, is often recommended and has shown good results for this type.
Mitral valve stenosis, which narrows the opening on the left side of the heart, and the rare tricuspid valve stenosis on the right side are less common. They can cause symptoms like rapid breathing, abdominal swelling, and exercise intolerance.
Diagnosis often begins with a veterinarian detecting a heart murmur during a routine exam. Further tests may include chest X-rays, an electrocardiogram, or an echocardiogram. The echocardiogram is a non-invasive ultrasound that visualizes the heart valves and measures blood flow, usually performed without anesthesia.
Treatment depends on severity. Mild cases may only require regular monitoring. Moderate to severe cases often need medications to ease the heart's strain and manage symptoms. Lifestyle changes, such as limiting intense exercise, are commonly advised. Balloon valvuloplasty is a surgical option for pulmonic stenosis. A variant called cutting balloon valvuloplasty has been tried for subaortic stenosis with mixed results and is not routinely recommended. There is no cure for most forms of stenosis, but with proper management, many dogs can live comfortable lives.
Behavior Problem Estimates Challenged
A new study challenges a previous finding that 99% of U.S. Dogs have at least one moderate to serious behavioral issue. Researchers reanalyzing data from the Dog Aging Project found substantially lower rates. They say the original estimates were overstated due to methodological choices in analyzing the survey data.
The reanalysis found prevalence rates for specific problems were far lower. It reported moderate to serious aggression in 1.2% to 30.4% of dogs depending on the type, fear in 14.1% to 28.2%, and separation-related behavior in 9.3%. The original study had suggested these issues were nearly universal and often went unaddressed by veterinarians.
Both studies used owner responses from the mini Canine Behavioral Assessment and Research Questionnaire. The reanalysis authors, James A. Serpell and Lauren R. Powell, argued the original analysis departed from the survey's intended structure in three key ways. It treated individual survey items as independent measures instead of averaging items within established behavioral subscales. It also pooled fear items from distinct categories into a single fear/anxiety group.
The largest discrepancy involved separation-related behavior. The original analysis combined it with an 'attachment/attention-seeking' subscale, which includes behaviors like following owners around. Scores for separation-related behavior were low, while attachment scores were high. Analyzed separately, 9.3% of dogs scored in the problematic range for separation-related behavior, while 88.9% did for attachment. The authors noted that most owners do not see typical attachment behaviors as problematic. The reanalysis also questioned the threshold used to label a behavior as 'moderate' or serious, suggesting it may have been set too low.
