The Longitudinal Outcome of Canine Mitral Valve Disease (LOOK-mitral) - by Dr. Michele Borgarelli, DVM, PhD, DECVIM-CA

This is a study being performed with the collaboration of Virginia-Maryland College of Veterinary Medicine, where Dr. Borgarelli does his research, and one of the largest veterinary cardiology practices in the United States, CVCA. The purpose of the study is to assess the natural history of mitral valve disease (MVD) in a large referred population of dogs, assess the prevalence and effects of co-morbidities on the natural history of the disease, and to identify risk factors for progression and death.  Collected data includes physical exam, radiographic findings, ECG findings, presence of co-morbidity, laboratory results and treatments.

Since October 2015, vets from CVCA have been submitting information from a large population of dogs with MVD to the LOOK Study.  This is strictly an observational study.  Inclusion criteria for study enrollment is a diagnosis of MVD confirmed by echocardiographic exam. Dogs are enrolled in the study at the time the diagnosis is confirmed by a cardiology specialist. 2,053 dogs have been observed as of April 30, 2017, and new dogs can continue to be submitted to the study until September 2017.  Data on the dogs enrolled in the study will continue to be collected until it concludes in October 2020 or until the death of the dog.

The current population of dogs in the study represent 104 different breeds.  The largest segment being mixed breed at more than 300 dogs, second highest is CKC, then Chihuahua.  48% of dogs are female, and 52% are male, and for both male and female, approximately 90% are neutered/spayed.  The median age of all dogs is 10.3 years, but it was noted that the average age for the CKC is much younger than the median.

57% are Stage B (75% of which are B1, 25% are B2), 39% are Stage C, and 4% are Stage D.  During the current 20 months of the study, only 4.5% of dogs have passed.  It was noted that this could be because most dogs being submitted to the study were new cases presented at CVCA which typically occur at the earlier stages.  

Some of the preliminary findings of the study so far are:

• Echocardiogram results are more important than the observation of a heart murmur, as more than 4% of dogs with the disease had zero murmur.  In high risk breeds, this suggests that regular preventative cardiology exams with echocardiogram are warranted rather than waiting until the onset of symptoms.
• Nearly 80% of dogs are referred to cardiologists due to the presence of a cough.  
• Most concomitant disease is chronic respiratory disease.

Additionally, at the conclusion of the conference session, Mighty Hearts Project participants were able to inquire with Dr. Borgarelli on whether dogs who have had an intervention, such as Dr. Uechi's Mitral Valve Repair surgery, were noted and being tracked within the study with this information in mind.  Dr. Borgarelli confirmed that is correct.  One dog that we know of being tracked as part of the LOOK study is Levi, who has had a successful mitral valve repair since his initial diagnosis.  Levi is seen by Dr. Neal Peckens at CVCA in Virginia.