Haemo-concentrating - any boffins ?

[zsuzsanna04]

Hi all,

I have a couple of 4 YO colts in racing. I've bred and raised them myself. They are impeccably behaved - they are not coltish, aggressive or badly behaved in any way. Easy to work with, take out with mares, etc. No problem.

However, one of the boys put in a disappointing run this week and the jock got off and said he needs gelding.

Trainer has taken bloods and he's come back with a high red blood cell count.

The accepted wisdom here (South Africa) seems to be that a high red blood cell count 'clutters' the blood, making it thick and putting strain on the heart and circulatory system, generally affecting performance.

Which I think I follow.

What I don't understand is what testosterone has to do with red blood cell count?

Also, all the exercise physiology literature I've ever read seems to support the idea that increased red blood cells are a good thing as they enable the body to carry more oxygen (although I understand that the amount of oxygen the body can process will depending on the available surface space in the lungs).

Some experts even recommend giving a horse a hard canter to the start to encourage the spleen to dump stored red blood cells.

So how is a high red blood cell count bad (ie does it really 'clog' the blood) and how does testosterone influence red blood cell levels?

Because if there is no relation, there's not a lot of point in gelding to treat a high red blood cell count (although it obviously has other benefits).

Any boffins out there ?

 

[putasocinit]

gelding does seem to take away the thickness e.g. neck general weight in the male horse, but wouldnt haemo concentrating also be to do with too much protein in the blood i.e. horse has eaten too soon before exercise/racing so you could make this horse eat earlier to be safe.

 

[zsuzsanna04]

Thanks P - nope, the lad isn't exhibiting any of the normal thickening or cresting one might not want, and he's not anaemic, so none of the normal reasons apply.

Our racehorses usually get fed at around 7 or 8 am and then they race in the afternoon (anywhere between about 12 o'clock and 5pm), so I'm not sure about a dietary connection, but will look into that.

I guess I'm just struggling to understand haemo-concentrating as a condition and was wondering whether anyone else had come across it and whether it had been remedied by gelding ?

 

[alsiola]

What was his red blood cell count/PCV? A young TB in race training will have a much higher PCV than the average horse so depending on the lab's normal value your horse may not actually be out of the ordinary. This is because, as you said, extra red blood cells mean extra oxygen carrying capacity.

If he truly does have a high RBC count, then by far the most likely reason is dehydration at the time of sampling. Presence or absence of testicles will not affect it. I would repeat the blood sample 2 weeks later and see what it shows. Or just accept that he had a bad day and see how he runs next.

 

[zsuzsanna04]

Thanks Alsiola, I'm told 'normal' is somewhere between 30-40. My boy was measured at 49 a day or so after his run. Trainer tells me the vet says that means his count on race day could have been as high as 55.

The research I've conducted just not support trstosterone having an influence on RBC count.

I also don't understand why RBC count would fluctuate - it is governed (largely) by the bone marrow & spleen. How would testosterone would influence that? Although I'm always happy to learn of course

Dehydration is a much more likely / believable scenario.

Basically, I'm not against gelding - I understand that long term it makes sense for lots of different reasons & I know it will happen.

But if someone is recommending medical interference (that I have to pay for) I'd like to understand it a bit better

 

[stranger1612]

By far the most common reason for a high pcv in a racehorse is splenic contraction prior to sampling. This could be as simple as the "white coat effect" caused by a needle shy horse or a clumsy attempt at venipuncture. The timing of the taking of sample relative to exercise will also have a profound influence on pcv- try taking a blood sample immediately after hard exercise the pcv might be 70% (but is normal!).

I doubt a high pcv in this instance has any relevance on performance but if the jockey has suggested chopping his balls of I would take his advice seriously.

 

[Ladydragon]

The accepted wisdom here (South Africa) seems to be that a high red blood cell count 'clutters' the blood, making it thick and putting strain on the heart and circulatory system, generally affecting performance.

Which I think I follow.

What I don't understand is what testosterone has to do with red blood cell count?

In humans (and I've no idea how or if it is applicable to equines but would be interested to know ), testosterone can have a direct link to RBC... Testosterone stimulates the kidneys to produce erythropoietin which governs baby RBC production in the marrow... ie, steroid abuse can raise testosterone levels and increase the RBC with the negative health effects - as can testosterone therapy... Too high RBC or 'thick blood' can have the opposite effect of good oxygenation as it flows more slowly - and makes the circulatory system work harder and I would imagine that would be the same for horses too... Testosterone certainly isn't the only potential influence on raised haematocrit levels though...

There are some good explanations here why your boy's reading may be high and vary in an expected way - and I would imagine you need more than one test to determine the reliability of the first - ie, rule in/out dehydration, heightened effect post training etc...

 

[zsuzsanna04]

Hi all,

Thanks so much for the help.

I understand the link now. One test may not be conclusive evidence that he suffers from the condition, but I need to give the op some consideration regardless. My lad is not a stud prospect and entires (even ones as nice as he is) pose all sorts of management problems as people tend to be nervous of them, so I know long-term it's in his best interests.

I still feel horrid about it though !!