High Heart Rate

[Dalemma]

I have a horse that has PSSM that was diagnosed via a muscle biopsy. He had a fairly large amount of muscle involvement up to 20% which makes him unrideable.

But the thing regarding his condition that has everyone stumped is his heart rate sky rockets when out on grass to 60 bpm.............this year I have found a way to manage him so his heart rate stays under 48 bpm.......he gets 2 hours in the morning and one hour in the afternoon and then gets brought in and gets a flake of hay while the other horses remain on pasture.........the thing that I have noticed is that his heart rate is slowly dropping(it was down to 40 bpm) as the pasture dries up due to no rain..........I had thought his heart rate was high because of the sugars now I am not so sure as I thought the dry pastures had more sugars due to the stress they were under.........and that the green, fertilized and watered pasture would be lower.

Can anyone think of what might be causing his high heart rate??

I have had his heart ultra sounded by a specialist twice and no abnormalities were found..........Dr. Valberg ran a couple of extra tests at the time of his muscle biopsy but they came back negative.

In the winter when he is hayed 100% his heart rate is 36 bpm

Any insight would be appreciated.

Dalemma

[deltawave]

Is it the work of grazing--walking around constantly--that makes him speed up, maybe?

Certainly a gut-load of starch can cause increased blood flow to the intestines, which demands that the the cardiac output to go up (and heart rate is half of the equation for cardiac output).

Although sugars can be high in stressed grass, they can also be high in rich grass--maybe you could have the pasture tested?

[Dalemma]

You would think if it was the work of grazing that there would not be a difference from early spring grass to late summer of dried grass as his heart rate is down right now.

I have thought of doing testing at Equi-Analytical but I live on Vancouver Island and shipping frozen grass to them is a logistical nightmare and actually may be impossible due to the time it would take....not to mention probably really costly.

Yes to sugars can be high on fresh green grass but I still thought my sugars would be higher on the stressed grass.....which puts a hole in my theory that it would be sugars........unless of course my greens grass is actually higher in sugars.......???

I am hoping Katy Watts will weigh in on this.

Dalemma

PS....could some change my thread title to High Heart Rate/ Sugars in Grass