Cramping, some thoughts.

[sandymere 8,261]

Cramping, some thoughts on hypocapnia.

Thankfully cramping is not an overly common occurrence in dogs but there are those that seem to suffer unduly and any dog can get cramp. To my mind there are two common types, neither of which are very well understood. The commonest is likely due to over exertion, an example would be me mountain biking on Exmoor and doing a lot more than I'm used to so getting wicked cramp in my quads. A couple of months later
doing the same route at a faster pace no cramp, the difference preparation in the form of two months training, Dogs suffer in much the same way.

The actual cause of the electrical impulse that causes the muscles to
spasm is not well understood but this relatively common form of cramping is, as with EIB and rhabdomyolysis, reduced significantly by appropriate preparation in the form of fitness. There is another circumstance where cramping
is a major problem, this in spite of good fitness, but this tends to be seen in track dogs although lurchers can suffer. In these cases it would seem temperament is a major contributing factor, to examine this particular problem I'll go back to my early days.

Many years ago a fellow brought me a fair little track bitch for a bit of a sort out, her problem was that she would cramp badly if kenneled for any length of time prior to racing. This was a classic example in that she would get herself very het up on the way to the track and in the kennel whilst waiting. There were and still are many causes proposed for
this problem and as many remedies that supposedly help, most of which had already been tried without much improvement in her case.

I started with the basics of road work and gallops to improve fitness and used electrolytes and vitamin E as these were thought to redress an imbalance that was a contributing factor in these cases. After six weeks I took her to a little permission and slipped her behind a hare. She ran like a good un and although had no hope of success she certainly had pace. With no cramping and nothing beyond a little stiffness over the following days we were soon off to the flapping track at Huntingdon for
a trial one Sunday morning. The journey was reasonable short and she was in the traps within a few minutes of arriving, again she flew no cramping and a good time! I was well chuffed and booked a trail at Henlow the next weekend. This time the journey was a little longer and
she was kenneled at the track for a while prior to trapping. For the third time she flew but alas locked after the last bend with a major cramp.

She went on to be a reasonably good flapper but never made it beyond that, the owner took her back and I believe he continued a Huntingdon. A well known trainer had had her prior to being brought to me and they'd tried every supplement known to man but neither they nor I could find a cure. Perhaps with more time we would have been able to better
acclimatise her to the racing experience and so reduced the stress that was at the heart of the problem but the owner didn't wish to invest in a lengthy course of action for what was only ever going to be a middle grader.

Traditionally lactic acid and or an electrolyte imbalance were blamed
in these cases but with the recent change of thought on lactic acid, it's now seem as a positive part of the process of the energy cycle rather than a negative waste product, so unlikely to be a causative factor. Then as these dogs don't seem to have any ongoing electrolyte imbalance, this bitch had had bloods and they showed normal values this theory also seems implausible. The stress response was a major clue but
at that time neither I nor my peers had any idea of the biochemistry involved and just blindly followed a set course of adding electrolytes etc.

Now anyone who has left a stressy dog in a car will have seen the condensation that accumulates on the windows due to the excessive panting. This tells use they are losing water, as this is via vapor from
breath we also know that they will not be losing a largelectrolytes, boils a pan of salt water and the water will evaporate as vapor and the salt will be left behind. Some salts may be lost in drawl
but not an excessive amount. Consider an hours car journey followed by an hour in the kennel and you can imagine how much fluid might be lost, this can also be a couple of hours for a lurcher on the way out lamping etc. So fluid loss must be having an effect but it's hard to put the whole thing down to this.

Next we should look at the electrolytes, muscles work via electrical impulses and electrolyte are the way this is carried out so they must be playing a part. This combined with the pH of blood needing to be in a very narrow band, outside of this electrolytes become unbalanced, we may have a clue as to what is going on. Respiratory alkalosis, in this situation a self limiting short term effect that could easily be missed unless blood was tested directly prior to racing, could be the answer.

In every day terms hyperventilation, breathing to fast, for an extended
time will lead to the body blowing off to much carbon dioxide, as this is an acid in the blood the blood will become less acid, more alkaline, which leads to a reduction in serum potassium and calcium, this could well be the reason for cramping. Add to this the sudden change from alkalosis due to, hypocapnia, to acidosis 2nd to lactic acid and maybe
the buffering systems just can't cope.

Perhaps this is why the remedies don't work in these cases, boosting electrolytes such as potassium etc will not help as the body just excretes the excess, there isn't a true underlying deficit, the same with bicarb, so the serum levels always go back to the set mean. It's the hyperventilation that brings about the imbalance so it's more down to behavioural intervention than supplementation. So proper introduction
to racing/working to reduce the stress response coupled with proper physical training to prepare for the exercise to be performed and one should get a reduction in the incidence of cramp, (in theory).

Edited November 27, 2019 by sandymere