Kidney Failure

The kidneys act as a filter, the filter is made up of nephrons sifting through the body's waste products to form urine.
These nephrons can be damaged over a period of time from many reasons, such as, infection, trauma, cancers, auto-immune disease, poison, genetic predisposition & ageing.
If this happens, the nephron will stop functioning, fortunately the body can compensate by the ability of the other nephrons to enlarge so kidney function continues.
A kidney, according to many of the vet text books, can function on as little as 25 per cent efficiency of its original nephrons. When the number falls below this or when the damage occurs too suddenly for the remaining nephrons to function, kidney failure will result

There are 2 types of Kidney Failure
ACUTE This is sometimes, but not always reversible. ( sudden infections can result in long term kidney damage). Acute failure can occur so suddenly that undamaged nephrons just cannot compensate quickly enough. .Infection, harmful toxic substances, including some medications, trauma with acute circulatory failure leading to a reduction in the flow of blood to the kidneys are possible causes.
Many infections can be treated successfully with antibiotics but the leptospira bacillus can cause not only an acute failure but have long term effect on the kidney.

CHRONIC kidney failure is an irreversible process that occurs over months and years.
Most nephrons are lost slowly over a period of time as dogs AGE.
Many dogs live long lives retaining enough nephrons in reserve to take them through until the very end, whilst others will lose so many as they age that even their reserve is depleted at what seems a relatively early age & this can result in a sudden & rapid decline.

Chronic Kidney failure is the most common form of kidney disease in canines & amongst the most common cause of death in the older animal. If the kidney resources are stretched ANY other disease process may effect the final outcome.

Unfortunately this chronic process over a period of years can often go unnoticed as to all intents the dog seems and behaves in his/her normal way.
When signs are picked up the disease process may be well advanced.*

Dogs with chronic failure produce large amounts of dilute urine (sometimes referred to by vets as POLYURIA) because there are not enough healthy nephrons to filter properly and reabsorb the excess water back into the blood circulation.
You will also notice that these dogs drink much more ( POLYDYPSIA), to maintain the right amount of fluid within their system, otherwise they would become dehydrated and embark on a rapid downward spiral with an elevation of toxic waste products also within the system.
Healthy animals can regulate the amount of water lost, by making urine more or less concentrated as necessary.

The dog with kidney failure may start to feel sick, lose its appeite, the vomiting will increase and its blood red cell count will decrease.
IV fluids may offer temporary relief, some, medications may also be used.
When this failure mechanism kicks into action other major organs will of course also become affected by the increased toxins within the body.

As our dogs age it is often advised to watch their diet intake carefully, many of the signs caused by kidney disease result from an accumulation of waste products produced by the breakdown of protein combined with a loss of calcium and a build up of phosphorous levels, Urea is one of the poisonous substances produced in the body by the breakdown of protein and if this level is very high the term uraemic may be used, all this will damage the kidney further. Sometimes you will notice a certain odour to the dog's breath.
Moderate restriction of protein intake in the older animal is now suggested by many vets together with an occasional monitoring of blood levels.
* An "MOT" for older dogs is often a good idea even if the dog is behaving & acting normally, As soon as my older dogs start peeing large amounts of dilute pee, are at the drinking bowl more frequently or their breath has a characteristic odour ( having once worked as a nurse in a renal unit, I know that particular smell!....but sometimes it may have just been what they have been eating!!). I get a urine sample (testing for protein which should not be present in normal urine & if necessary a blood test by my vet)
Pre-anaesthetic blood testing should be an essential for any older animal, or indeed any animal undergoing any procedure requiring a GA as fluid intake could be most important if the dog is already showing from blood tests any signs of nephron failure.

Much research in the 70s and early 80s have now provided valuable insight into the management of dogs showing early signs of renal failure.

As to diet,  there a can be problems with feeding RAW meat...FRESH! opposed to FROZEN!... ie  Campylobactor contamination to name just one, but in MANY instances it is the complete foods that may carry a greater risk in levels of protein content the amounts vary from product to product, read labels carefully. & it is not just about PROTEIN.... but in restricting the amounts of PHOSPHOROUS & SODIUM in dietary intake too.

Also you have to consider the GENETIC make up too. Some dogs develop RF whilst others do not, or have enough in reserve in the working nephrons as I indicated in my previous post message to take them through to the very end.

Studies have suggested that whilst there may be NO conclusive evidence that LOW PROTEIN diets SLOW DOWN the process of CRF, the dogs seem to feel, and appear much better in themselves on such diets. The low protein diets result in lower levels of nitrogeous waste products and it is the high levels produced from HIGH PROTEIN intake that causes them to feel so sick but ALL dietary intake in a dog diagnosed with signs of RF must be carefully monitored.
The key thing always is in OBSERVATION.
Note any changes in your dog's eating & drinking habits.
With kidney disease the dogs become quieter, less alert, appetite may decrease.
I know such signs may also point to other conditions apart from RF but it is as well to consult a vet EARLY.

Increased thirst & passing MORE urine (usually dilute)
Weight loss
Weakness and exercise intolerance
Tendency to bruise or bleed easily

Dehydration....VERY important,
Stiff leg gait and arched back ( a sign of pain in the lumber region where the kidneys are located) Some Afghans go off their back legs very quickly.
Little or NO urine output.



Many thanks to Sylvia Evans for this article

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