>I also was confused about which of his heart rates was the one which was
the problem.
>
>When the infection was discovered 2 weeks ago my vet was hoping that was
>why Mikey's heart did not sound right...
 
Dear X:
 
The heart rate is indeed slow, but I generally would reserve comment
until all of the tests are in.  With a heart rate of 150 and exercise
intolerance, I would expect there to be other significant changes in the
EKG or the X-rays.  If the heart rate is pathologically slow, then I would
expect some marked EKG changes to account for it, such as a heart block or
some electrical disturbance that would account for the dropping of 1 of
every three beats.  Cardiomyopathy, which can attack the very young,
generally shows some radiographic signs which the X-ray would pick up in
an exercise-intolerant animal - fluid in the chest, an enlarged heart, etc.
The ultrasound may show something along these lines if a plain thoracic
film does not.
 
If the value of 150bpm is valid, then there should be other signs to
corroborate the diagnosis of heart disease.  Without such signs, the HR
would have to be considered a low normal for this animal.
 
Another condition that certainly occurred to me, as this animal is young
and exercise intolerant, would be a case of juvenile lymphoma.  In young
animals, this disease manifests as masses in the chest, which may compress
the lungs over time, as well as an enlarged spleen and liver.  You may
want to discuss this possibility with your vet and find out why it is not
currently in the differential list.
 
With kindest regards,
Bruce Williams, DVM
[Posted in FML issue 3457]