Wednesday, January 5, 2011

Heart conditions (part 2: DCM)

Dilated cardiomyopathy is near and dear to my heart, as it affects approximately 50% or more of Dobermans. This is a condition of large breed dogs and occasionally cats. There is thought to be a genetic component because there are very specific breed tendencies. Breeds typically affected include the *Doberman Pinscher, Irish wolfhounds, Great Danes, Newfoundlands, Dalmations, German shepherds, Portuguese water dogs, *Boxers, *Cocker spaniels, and other large or giant breed dogs.

*These have special tendencies to be discussed later.

As with most animal heart diseases, we do not know what starts the disease process or why some breeds seem particularly affected. The heart muscle becomes less efficient at pumping, blood pools, and the left ventricle and left atrium start to dilate. The walls becomes thin, and eventually forward blood flow cannot be maintained. As a result, heart failure occurs (much in the way as with mitral valve disease).

Diagnosis is very similar to that of MVD. Thorough auscultation with concurrent pulse evaluation (usually the femoral pulse), xrays with a VHS, and referral for echocardiogram.

As with MVD, there is no cure for this disease. Treatment is aimed at controlling the signs of heart failure once they occur. Prognosis actually varies with breed.

Some of the specifics:

Cocker spaniels: an association between DCM and taurine levels was found in Cockers. Taurine is an amino acid that is necessary for many important body functions. It was found that supplementing this specific breed with taurine (and L-carnitine, as well) improved contraction of the heart muscle. If you have a cocker spaniel that has been diagnosed with DCM - blood should be submitted to a labratory to have these levels checked, and your pet should be receiving taurine and L-carnitine supplements.

Cats were also found to have a taurine responsive DCM - sometimes due to poor diet. It can be related to canned food diets or homemade diets. Feeding dog food to cats can also cause this. As with dogs, there is an idiopathic form (unknown cause) that takes much the same disease course.

Doberman pinschers: a breed that I love, obviously. Unfortunately, they are the most represented breed to suffer DCM. Also, the course it takes is much nastier in Dobies. They tend to only survive about 2.5 months once heart failure has occurred. Further, they can die quite suddenly and without any advance warning. This is usually due to a fatal arrhythmia. This can occur even if they have never been in heart failure before. Some books and cardiologist recommend yearly screening with a Holter monitor . As with all dogs, there is no preventing or curing this disease. Once heart failure occurs, there are some management options, but Dobies do not do well with this disease.

Boxers: it was recently discovered that Boxers have their own variation of cardiomyopathy that was previously lumped with DCM. It is actually called arrhythmogenic right ventricular cardiomyopathy and also occurs in humans (I think women are more predisposed). It is a totally different disease process and presents usually as syncopal episodes (fainting/collapse). The heart does not necessarily become enlarged, a murmur may be absent, and the only sign might be these fainting episodes. Prognosis is highly varied according to the individual dog.

As a sidenote, there are also secondary dilated cardiomyopathies - specific to some cause. These include chemotherapy induced DCM (notably the drug adriamycin/doxorubicin), nutritional DCM (related to taurine as noted above, also noted in some dogs on Hill's u/d diet for stones), familial DCM in Portuguese water dogs (occurs at a young age and progresses rapidly to death), and infectious DCM (related to tryapanosomiasis (a blood parasite). With the exception of the chemo induced DCM, there are fairly rare. Adriamycin is a very commonly used chemotherapeutic used in the treatment of lymphoma in dogs. As a result, cardiac auscultation and echocardiograms are routinely conducted on dog's undergoing lymphoma treated with adriamycin.

4 comments:

Anonymous said...

Is there any correlation between being a brachicephalic pooch and DCM? I had 3 Japanese Chin dogs- 2 males and 1 female. All developed DCM at some point in their lives, the earliest was at 6 years.
Thanx!

The Homeless Parrot said...

I have never heard of JCs being predisposed to DCM. A quick VIN (veterinary internetwork) search also confirmed that there is no known predisposition. That is very odd, though. Did you live in the same place with all 3? If so, I would be concerned about a toxin of some sort.

Nicki said...

Thanks for the breed specific info. Learned something new today!

Juli said...

My 5 year old English Mastiff had his right front leg amputated because of Osteosarcoma. He has had to two rounds of Adriamycin. One round of Citplatin and one Carboplatin. Citplatin caused elevated creatitine levels so we switched to Carboplatin this last round. Good news there's no signs of lung cancer yet but his heart is enlarged. This Wednesday we see a Cardiologist. In the meantime we decided to start giving him Taurine in hopes of helping his heart. Any idea if the enlarged heart is a death sentence?