Mike "I play a doctor on tv" Sofen :-)
> -----Original Message-----
> From: C.M.Newell [SMTP:reshan@deyr.ultranet.com]
> Sent: Wednesday, April 30, 1997 9:44 AM
> To: ridecamp@endurance.net
> Subject: Re: Missing Heart Beats
>
> At 09:59 AM 4/30/97 MDT, you wrote:
> >Sue Cunningham wrote:
> >>How common is it for endurance horses to miss heart beats and why do
> >>they do it?
> >>Is there some advantage to missing beats rather than just having a
> >>slower heart beat?
> >
> >Missing heart beats is bad. All animals should have a steady rhythm
> >at all times. A horse that is in good condition will have a slower
> >and "bigger" heart beat. The heart will pump more blood per beat
> >that a horse that is in not so good condition.
>
>
> I disagree. Second degree heart block is quite common in
> horses,
> particularly healthy and fit horses. Dropped beats are not at all
> unusual.
> They are due to vagal tone, and are usually easily abolished by
> startling
> the horse , or by jogging it for a short distance.
>
> In addition, to quote John Bonagura, from "Current Therapy in
> Equine Medicine 4":
>
> "Arterial blood pressure can be regulated durin inappropriate
> periods of sinus tachycardia by blocking impulses in the AV
> node
> even as the
> sinus rate increases. Examples include a horse that has
> suddenly
> stopped submaximal exercise...must be appreciated as variations of
> normal."
>
> Sounds like a distance horse at a vet check, no?
>
> --CMNewell, DVM
>