Juvenile Dilated Cardiomyopathy & Xanthinuria Type 2a
Juvenile Dilated Cardiomyopathy
Juvenile dilated cardiomyopathy (JDCM) occurs in Toy Manchester Terriers. It results in sudden cardiac death at a young age, with dogs reported to have passed as early as 10 weeks of age and as late as 1 year of age. Affected dogs usually appear healthy with no signs of heart disease present before the sudden passing. The only external abnormality is that affected male puppies may have unilateral or bilateral cryptorchidism (undescended testicles on one or both sides). For a number of the puppies, their sudden passing occurred within a day of general anesthesia/surgery or exercise. Necropsy (post-mortem examination) may show mild enlargement and dilation of the heart. Microscopic changes include degeneration and scarring of heart tissue and varying degrees of inflammation. Death is presumed to be the result of a sudden fatal arrhythmia (abnormal heart rhythm).
Research performed at the University of Minnesota, in collaboration with University of Pennsylvania and the University of Prince Edward Island, has discovered that JDCM in Toy Manchester Terriers is caused by an autosomal recessive mutation in a cardiac potassium channel. To date, we have tested DNA from 14 Toy Manchester Terriers with JDCM, and all had two copies of the mutation. We have also tested nearly 100 adult healthy Manchester Terriers, and none have had two copies of the mutation. Thus, the disease may be fully penetrant, meaning that all dogs with two copies of the mutation develop JDCM.
We currently estimate that ~15-20% of Toy Manchester Terriers are carriers of the mutation. Carriers do not develop the disease but can produce affected puppies if bred to another carrier. However, this does not mean that carriers need to be taken out of the breeding pool, as that could rapidly reduce breed diversity. As long as carriers are only bred to clear dogs, there is no risk of producing affected puppies.
We do not currently know if the mutation exists in Standard Manchester Terriers. We also do not know the mutation frequency in English Toy Terriers.
Please see the JDCM Result Interpretation document for details on expected outcomes in affected, carrier, and clear dogs as well as breeding guidelines.
Legge CH, et al. Histological characterization of dilated cardiomyopathy in the juvenile Toy Manchester Terrier. Vet Pathol 2013;50:10431052.
Xanthinuria type 2a
Please see the Xanithinuria Result Interpretation document for details on expected outcomes in affected, carrier, and clear dogs as well as breeding guidelines.