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  Discussion on Atrial Fibrillation and Electrolyte Causes.
Author Message
Member:
Redback

Posted on Tuesday, Jan 2, 2007 - 1:55 am:

Dear Dr and Friends:
I have a 5yo standardbred mare. I have just read the article in Hoof beats December 2006 on Atrial Fibrillation. My mare has shown many of the symptoms most prominant being 'hitting the wall in her races'. She goes from on the lead travelling well to slowing to run last everytime around the 400metre mark. It doesn't matter how fast she runs the first part of the race the result is always the same. She is very loose in manure and sweats and shows no other form of distress.
Obviously I would need to do some ecg testing e.t.c. In the meantime would introducing more electrolytes esp potassium either reverse or cure the problem? The article mentions that current drugs are dangerous and of questionable value it would also be hard to use these drugs in Australia in a racehorse due to zero drug laws.
Several other horses in the stable have displayed the same symptoms so prevention is important.
What levels of potassium and salts and minerals would you recommend for pacers in racing condition and work, racing in temperatures of 35 degree celsius centigrade?

Thank you for your help in anticipation.

Geoff
Moderator:
DrO

Posted on Tuesday, Jan 2, 2007 - 10:35 pm:

Hello Geoff,
Unfortunately one horse always has to be last but it will require investigation to discover if there is a medical reason. Atrial fibrillation is not so much a disease but a clinical finding caused by several diseases though often the cause remains unknown. However simple electrolyte abnormalities are not commonly associated with afib and supplementation not likely to help horses with it. For more on how to identify afib (which can be detected with a stethoscope), the treatment, and how to determine prognosis see Diseases of Horses » Cardiovascular, Blood, and Immune System » Atrial Fibrillation.

The article associated with this forum gives specific recommendations on electrolyte supplementation in hot weather.
DrO
Member:
Redback

Posted on Thursday, Jan 4, 2007 - 9:18 pm:

Dear Dr O:
Thank you for your reply. It would appear that the article from Hoofbeats DEC 2006 varies differently in its opinion in regards to potassium as being a probable cause to afib? Are you in a position to review that article and provide a comment on the research behind it?

Regards

Geoff
Moderator:
DrO

Posted on Friday, Jan 5, 2007 - 6:32 am:

Potassium is a critical component of any cell action as the differential concentration of it and sodium across the cell membrane is what creates the potential for muscular contraction, including that which leads to the heart beat. In afib the heart has lost its ability to rhythmically discharge this action potential and recover. So potassium is absolutely involved but what I have no knowledge of is that dietary intake of potassium can effect the condition. Chemical conversion as described in the article is the only practical way I know to deal with the problem and it is often successful. Does the article state something different than this?
DrO
Member:
Redback

Posted on Friday, Jan 5, 2007 - 9:47 pm:

Dear Dr O:
In reading the article I get the clear impression that it is saying that Afib can be caused by a failure to provide sufficient electrolytes particularly potassium to hard working standardbred horses. It was then not really clear about what happens once the Afib occurs. Except that the article then suggests that the operation of placing probes into the heart long term was proving to be a better response than the drug approach due to associated side effects of the drugs. So what I was trying to workout was firstly given the high temperatures that Australian Standardbred horses work in, and that they are now mostly have the same breeding as American horses, what would be suitable levels of potassium and electrolyte intakes. Secondly if a lack of potassium was a cause what would happen in a horse that had suffered afib if they were then given appropriate levels of potassium and electrolytes?
The article indicates that potassium is most likely related to the condition but indicates that the relationship is not clearly understood.
So I guess a third question is: Is there any further studies that consider this relationship?

Thanks for your responses.

Geoff
Moderator:
DrO

Posted on Saturday, Jan 6, 2007 - 8:56 pm:

Geoff, when you first posted the question I went looking, beyond our own article on this disease, for such a relationship and came up with nothing. Mild to moderate hypokalemia does not induce arrythmias and severe hypokalemia induces heart block, premature ventricular contractions, and completely stop the heart.

If you really feel this is a problem for your horse why not have someone listen to his heart as the wandering heart beat is quite distinctive.
DrO
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