RHABDOMYOLYSIS by Nigel Warner (Nigel)

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Rhabdomyolysis

 

It’s not uncommon for a dog, or ourselves for that matter, to be a little stiff and sore for a few days after a hard run this is often described a delayed onset muscle soreness or DOMS. DOMS is fairly predictable and not usually to serious a problem that is in all likelihood due to inflammation of the muscles from damage to a small proportion of muscle fibers and the resulting pain this causes. More worrying are recently a couple of instances where owners of lurchers have noticed their dogs showing signs of severe muscle soreness and or cramps with urinating what appears to be blood the day after a hard session. This is often followed by a drop in condition for a time after wards to a greater or lesser degree. A common suggestion as to the cause of this seems to be a build up of lactic acid but in light of modern thinking, discounting lactic acid as the bad boy and high-lighting its role as an important energy source, this theory doesn’t seem to hold water. So what could be going on?

 

One idea is that the dark brown/red urine is not due just to blood alone but also the contents of damaged muscle cells, myoglobin and creatine kinase, that are released into the blood stream and this is known as rhabdomyolysis (RMS). When the released myoglobin is excreted by the kidneys it gives the urine a dark brown colour. The difference between DOMS and RMS is the extent of the muscle damage involved and the effect this has on the kidneys. High levels of myoglobin can cause kidney failure to the extent that long term damage or even death is a possibility.

 

So why does this happen? RMS was first described in the blitz when people trapped under fallen buildings suffered extensive crush type injuries which lead to major muscle damage; this led to the release of large amounts of the muscle cell contents. Since then it has been described in a variety of species with a genetic link in some breeds of both horses and dogs. But these lurchers had not suffered any such injuries and sight hounds are rarely prone to genetic faults so how had they come to cause so much damage to their bodies? A strong possibility is suggested by looking at the background. In both cases the hounds had had long hard runs at the beginning of the season when they were at less than optimum preparedness and in truth they were both weekend warriors who may lack true working fitness even when at their best. This lack of fitness may have resulted in over exertion of some off the largest muscles in the body leading to extensive damage/breakdown and so exertional rhabdomyolysis.

 

Conditioned muscles in both humans and dogs are usually able to cope with exercise, unless there is a genetic variance, and the body has a variety of methods to protect itself against over exertion but sight hounds have been bred for generations to push the boundaries of the possible so bringing them nearer to the red line than most breeds. This ability to push the limits may mean that, if the incentive is right, they can cross the line when unfit to the extent that DOMS is extremely likely but also doing serious harm to their own bodies is a possibility. So what can we do to recognise treat and avoids these problems.

 

The main symptoms are severe muscle pain, cramping and altered gait with blood/very dark urine. Early recognition is important in the long term outcome. Your vet can check for chemicals in the urine and blood to confirm the diagnosis. And the vet is the best person to lead the treatment as depending on the extent of the problem intravenous fluids with powerful pain killers may be required. Appropriate management of renal function is the major concern but also the causative muscle breakdown needs to be addressed and a regime to rehabilitation and conditioning the dog to prevent future occurrences should be instigated. Good hydration is always of great importance as dehydration may increases the risk of muscle damage and post exercise will increase the strain on the kidneys. Also concentrated urine may well be very dark in the absence of any illness so muddying the waters some what.

 

Any dog that seems to be suffering exercise intolerance should always have a thorough check out with your veterinary surgeon to exclude any underlying heart, lung or systemic illness and check for any structural problems. A genetic predisposition to RMS may mean an animal needs special consideration as to it’s working ability but for normally fit and healthy dogs without any underlying problems then prevention is so much better than cure. Prevention means good preparation before work after a seasonal or injury enforced lay off plus regular top ups for the weekend warriors.

 

I'm not a vet but I am involved in human health and some problems are cross species to the extent of having a similar presentation and treatment, Rhabdomyolysis is one of these. My interest started some years ago when a number of well respected running dog owners asked my opinion of what was happening when, in the parlance of the time a dog 'ran it back off', the excepted knowledge of the day was that it was due to a build up of lactic acid. This theory did not sit well, lactic doesn't build up to such damaging levels as the muscles reduce their output well before it reaches this stage. Along with the muscle wasting another commonly reported symptom was blood in the urine, this was put down to, amongst other things, bursting a blood vessel in the bladder through over exertion, again this didn't sit well but it was to be the symptom that led to my finding the real answer.

 

A few days later a gentleman had spent the night on the floor having fallen late evening, this had resulted in a condition I knew well, rhabdomyolysis. It was whilst I was discussing the treatment with a junior member of the team that I had a eureka moment, they said "his urine is getting lighter, less like blood". I could have kicked myself, why hadn't I got it straight away, after all how many times had I seem this, especially as another classic presentation with rhabdomyolysis is younger individuals, such as service personal, who have over exerted themselves in hot weather.I did a quick search and found it was well known in horses and documented in greyhounds but seemed to have been passed by in the world of lurchers. With this in mind I decided to try to publicize it better. I admit it was a year before I actually got round to it but in 2008 I did a piece called "A Run to Far" and posted it on a number of forums. It was greeted with some derision at the time, lactic acid was the excepted culprit and many would swear black was white that lactic was the culprit. It took a few years of posting to slowly beat back the nay sayers until today rhabdomyolysis is pretty much accepted in the world of lurchers.

 

I take a little pride that I had helped to get this subject brought to a wider audience but alas there still seems some confusion about why running dogs are prone to this and what to do when it happens. With this in mind it is perhaps time to re visit the subject and challenge a few of today's nay sayers who still cling to the old lactic acid treatments in spite of the general acceptance of the true cause of the problem.When sighthounds run they create heat and  there is a well documented link between exertional hyperthermia (increased body temperature), and rhabdomyolysis, when running greyhound types reach temperatures that would be well into the realms of heat stroke in the average dog. The heat increases the muscles cells use of energy at a time when they are already under stress, basically the hotter the dog the more likely it will develop rhabdomyolysis, link this with what  I said in the original piece, one can see why unfit dogs starting with poor muscle condition are particularly at risk. What I didn't discuss in the original article was that the muscle damage is not just confined to the skeletal muscle of locomotion, the running muscles, but also those used in breathing such as the diaphragm and the intra costal muscle between the ribs along with the heart muscle itself. These unseen effects are potential problems in that owners don't t see a problem so don't allow for it when considering recuperation. The acute phase sees the bodies fluid and electrolytes being shunted out of their normal areas and ranges which causes extra strain on the heart along with the damage to the kidneys. In basic terms fluid gets pushed from the blood stream into the cells so the blood pressure drops causing the heart to work harder to pump the remainder. At the same time chemicals from the cells, potassium being one, get dumped into the blood stream. The result is that the heart muscle having suffered damage to its own structure is having to work harder due to the drop in pressure whilst being poisoned by excess potassium!

 

There is not much the owner can do at this stage other than cooling the dog and getting to the vets asap. The extra fluid in the cells can cause severe side effects whilst as said not enough in the blood stream can also have dire results. Drinking to much can just increase the shift whilst not enough is equally as bad. Thankfully the vet can give appropriate fluids and medications to minimize the damage whilst reducing the side effects of treatment. The good news is that evening those with extremely raised blood markers can, with good care, have very good longer term outcomes. Alas those with a less severe presentation that do not get proper intervention may well go on to suffer longer term harm such as kidney failure.So what to do when a dog has run itself to a standstill and has the potential to suffer with this problem, cool it down and give a small drink, then it's a matter of judgment. If it's severe then straight to vets for emergency help, if not than straight home, a light meal and allow more water to drink as it cools down. Closely monitor urine and water, if drinking excessively or producing dark urine then straight to vets. As ever if the owner doesn't feel experienced enough to make a judgment on the severity then going to the vets is best.

 

If rhabdomyolysis is confirmed and muscle wastage noted then we need to remember the unseen damage to the heart and breathing muscles as well as the kidneys. The internal damage will take time to repair so a very gradual process of re conditioning needs to be undertaken. This can only really commence after a couple of weeks of rest, good food and a bit of luck has brought about recovery from the acute phase. Personally I would hesitate to put the systems under the stress of work until the dog has had at the very least 6 weeks of conditioning during which no further symptoms have been noted and, as stated, the 6 weeks begins after the acute phase has fully passed. To conclude, kidney damage, heart damage, brain damage, death not things to be taken lightly, certainly not things for home made remedies or over the counter treatments for mild dehydration. Rhabdomyolysis is best avoided as far as possible by endeavoring to only run dogs as fit as they need to be, avoid hard running in warm weather, and feed a diet that maintains energy stores at optimum. My last thought, if worried about the cost of a visit to the vets take up flower pressing as your hobby.

 

Nigel Warner