DCM – What is all the fuss about?

Presenter: Rachel James, RCVS recognised specialist in Veterinary Cardiology, Nantwich Veteri-nary Hospital

Rachel James took ‘The Webinar Vet’ by storm last week delivering a practical webinar on DCM into which she packed an incredible amount of information. Useful tips and practice relevant advice was given in abundance. For example Rachel offered advice on clinical signs which of course included the obvious pale mucus membranes, tach-yarrhythmias and pulse deficits but in addition Rachel finds the presence of cold extremities such as paws and lips, a really useful indicator of DCM. She also reminded us we will not always necessarily hear a cardiac murmur in these patients and if present at all it is likely to be soft. Rachel also advised dogs with overt DCM are likely to present acutely as early clinical signs tend to be subtle and difficult to spot. Often these dogs will present with syncope, weakness, lethargy, dyspnoea and sometimes sudden death. Cardiac cachexia may also be observed and, if present, is usually severe with some dogs losing several kilograms in 7-10 days.

Occult DCM where no clinical signs are observed is present prior to the development of overt DCM and with the ‘PROTECT’ study showing the treatment of dogs in the occult phase with pimobendan helps to extend the time prior to these dogs going into CHF by 63%, and then goes on to extend their survival time by 34% compared to those dogs not given pimobendan, screening dogs for occult DCM would seem a very wise idea. A study by Wess et Al also showed that a staggering 43.6% of Dobermans between the age of 6-8 years old have DCM and 44.1% of Dobermans over the age of 8 years have DCM, indicating this is a breed we need to seriously focus on and consider screening.

Screening for occult DCM would ideally involve the use of a holter monitor which performs an ECG over a 24 hour period. If there are more than 100 VPCs in a 24 hour period, an echo should be performed where very accurate measurements need to be taken of the left ventricle. The ejection fraction can then be measured and should be greater than 50%, anything less than 50% should raise concern. An end diastolic volume of the left ventricular chamber can also be measured and a volume greater than 95ml/m2 is classically observed in cases of DCM. There is also a 10 fold increase in the risk of sudden death in these patients for every increase of 50ml/m2 in end diastolic volume. The cardiac biomarkers, NT-proBNP has been shown to be significantly higher in dogs which had or developed DCM compared to control dogs. Unfortunately the sensitivity (81.1%) and specificity (75%) is low for this test. However sensitivity does increase to 90% when combined with changes seen with an echo. From a practical perspective Rachel advises screening at risk breeds such as Dobermans yearly from the age of two, however starting from 4 years is acceptable if cost is an issue. Rachel recommends using a holter monitor and biomarkers initially. If these are abnormal it is then worth moving on to perform an echo.

This veterinary webinar was crammed with tips and advice much of which I have not been able to include within this blog but really should not be missed out on by any practising small animal vet. Just as a taster, advice included firstly to always test cases of DCM for thyroid disease as treatment can make a significant difference and secondly if patients are haemodynamically stable, treatment of any arrhythmia should initially be aimed at treating CHF, as once this congestion has resolved many of these arrhythmias will disappear. For more tips and advice on DCM then log in to ‘The Webinar Vet’ and I guarantee you won’t regret it.

The Stethoscope (MRCVS)