What are Renal Tubular Acidosis?
Renal tubular acidosis in horses is a fairly rare disorder that can be difficult to diagnose. Because the symptoms of renal tubular acidosis are so similar to many other horse conditions and because the usual blood testing doesn’t reveal it, it can sometimes be misdiagnosed which can be a fatal situation for the affected horse. The good news is that if it is properly diagnosed early enough and appropriate treatment is given, it is fixable.
Renal tubular acidosis in horses results when there is a too much acid in the body and may be due to a defect in kidney function. This excess acid upsets the delicate balance of chemicals in the body.
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Symptoms of Renal Tubular Acidosis in Horses
The symptoms that you will likely notice in your horse with regard to renal tubular acidosis are:
- Lack of appetite or even anorexia
- Irregular or rapid heartbeat
- Muscle tremors
These symptoms are very much identical to those forecasting other horse diseases and it is this similarity that makes the disease harder to diagnose.
There are three types of renal tubular acidosis in horses. Keep in mind that this condition of and by itself is rare in horses and this makes the three types rare as well:
- Nephrogenic diabetes insipidus - A disease that is connected to a lack of communication and associated responses between the renal tubules and the antidiuretic hormone (ADH) normally produced by the horse’s body (this is not like diabetes mellitus found in humans)
- Distal renal tubular acidosis (also referred as RTA type I) - This type of renal tubular acidosis involves nephrons (small units within the kidney) that are located in the most periphery of the kidney and are responsible for production of uric acid
- Proximal renal tubular acidosis (also referred as RTA type II) - This type of renal tubular acidosis involves nephrons that are located more centrally in the kidney and are responsible for production of bicarbonate
Causes of Renal Tubular Acidosis in Horses
The causes of renal tubular acidosis in horses are rare and sporadic and are difficult to diagnose. These are the two basic causes:
- Reduced production of bicarbonate in the kidneys
- Excessive production of acid in the kidneys
There is a delicate balance of chemistry in the kidneys which needs to be maintained and when this balance becomes upset, it can affect many other systems in the body.
Diagnosis of Renal Tubular Acidosis in Horses
Diagnosis of this condition can be difficult because many of the symptoms and clinical signs are very similar to many other equine conditions. Of course, your vet will need to do a thorough physical examination of the horse and will likely order blood work. Basic blood work really can’t provide definitive diagnosis but can tell your veterinarian if there is an infection present.
Imaging testing may be utilized to rule out some of the other causes of the symptoms. Serum chemistry testing and urinalysis will be required to identify renal tubular acidosis as the cause for the symptoms being demonstrated by the patient. Many veterinary practices do not have the equipment to run blood gasses testing and this can sometimes delay the ultimate diagnosis of this condition. Any blood gas testing determined to be necessary, in these cases, will have to be sent to a laboratory having the appropriate equipment to process it.
Treatment of Renal Tubular Acidosis in Horses
The treatment for renal tubular acidosis in horses is much easier than some equine conditions. Generally, the lower levels of bicarbonate need to be increased to appropriately deal with the excess acids being produced in the kidneys. The simplest way to accomplish this goal is to provide intravenous and oral sodium bicarbonate for a specific time period. Most horses will improve and the condition can literally resolve in a matter of hours unless the horse is dehydrated. In those cases, it may take several days to rehydrate the horse and infuse it with the sodium bicarbonate. For some horses, this treatment will be sufficient but, for others, supplements may be needed on an ongoing basis.
Recovery of Renal Tubular Acidosis in Horses
As noted above, infusing the equine with sodium bicarbonate via IV as well as by mouth generally resolves most of the rare and sporadic cases of renal tubular acidosis seen by veterinarians. For those who have a diabetic insipidus component, the may be an antidiuretic hormone added to control the polyuria (frequent urination). These steps may be sufficient done one time only but, for some horses, ongoing lifelong supplements may be required. Unless significant kidney damage has occurred, your equine should be able to return to his normal activities and work routines in a fairly short time. It should be noted that close observation will likely be recommended by your veterinarian to monitor the kidney function of the horse to avoid delays in treatment should the condition return.
Renal Tubular Acidosis Questions and Advice from Veterinary Professionals
Have been treating with sodium bicarb but but not holding onto it. Would potassium citrate be better and is there something that can be done/given to optimize/maintain bicarb levels
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