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  Discussion on High ammonium biurate crystals w/o liver disease?
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New Member:
Sbower

Posted on Sunday, Dec 31, 2006 - 10:23 pm:

Is there another reason for a high ammonium biurate crystals in a horses urine other than liver disease? A friend of mine is having great difficulty with her horse and the vet seems stymied.

Here's the history of the horse. Any comments as to how to proceed would be gratefully appreciated.

7.5 Year old Paint gelding 1200 lbs - This year as a 7 y/o, he had one colicky episode after a 2 hour ride in cool weather not violent. He was ridden for several hours in July and again in Sept. in hot, humid weather with no problems.

Everytime he exhibited the Flehmen response.

August 13 - found him lying down that morning which was unusual. He was uncomfortable...Flehmen response, lying down, getting up, trotting around, lying down again, etc. Called the vet but before he arrived, Horse urinated and was acting normally. Vet examined him and really didn't find anything noteworthy. Vitals normal, gut sounds okay.

November 13th - (morning) same symptoms as August and immediate relief after urination

December 18th - (morning) same symptoms but appearing more uncomfortable. He urinated once but still appeared uncomfortable. The 2nd time he urinated I collected a sample which was analyzed. Administered Banamine paste and he relaxed some. He stretched out as if to urinate a couple of times but did not produce urine. He finally did urinate what was a thick dark syrup-like consistency. I did not get a sample. Vet came and all vitals including gut sounds were normal but it had been over 2 hours since the Banamine.

Dec. 30 - (10:30pm) found him lying down again...same symptoms as previously. Administered banamine paste and he relaxed. After urinating began to graze.

Urinalysis (abnormal or high normal readings):

Color- orange; appearance-opaque

specific gravity: 1.049 (1.020-1.050)
pH 8.5 ( 7.0-9.0)
Occult blood 3+ (high)
RBC/HPF 4-10 (high)
Crystals Ammonium biurate (3+)(high)
Calcium Oxalate Dihydrate +4

Blood Panel: NORMAL*
*ALP 167 (50-170)
Moderator:
DrO

Posted on Monday, Jan 1, 2007 - 10:22 am:

Welcome Shelly,
We have a policy of not reviewing non-member cases on the boards so I apologize. The policy has developed for a number of reasons, including the frustration of dealing with second (the owner) and third (the owners veterinarian) hand information and of course simply one limited time to deal with member's topics.

However I would be glad to address your question on the significance of ammonium biurate in the horse's urine. I am assuming this test was done with a standard urine dip stick designed for other species, since I don't know of one designed for horses. There are important differences in the chemistry of the urine of horses and omnivores for which these sticks are designed.

So the first question is how accurate are the results but even if accurate what is the significance of this level in a horse? In other species ammonium biurate forms when there are excessive levels of ammonia in the blood, which occurs during liver failure, and the ammonia is not all oxidized to urea (at least if I remember my physiology correctly). Its presence is associated with hyperammonemia dementia. I have not seen reports of this finding on urinalysis in horses. Neither have I not seen it in cases of liver failure, though I have not looked for it as liver failure is usually obvious long before the need for a urinalysis.

If there are reasons to suspect liver disease I would recommend directly addressing this possibility with a thorough evaluation of the liver, including blood ammonia levels and other liver function tests, for more on this see Diseases of Horses » Colic, Diarrhea, GI Tract » Mouth, Esophagus, and Liver » Liver Disease and Failure.
DrO
New Member:
Sbower

Posted on Monday, Jan 1, 2007 - 1:04 pm:

Dr O Thank you for your kind response, I understand the need for not taking on "third party" cases and I apologize for the assumption.

What you said was very interesting however and as the vet said blood work on the said horse showed normal liver functions I guess it does raise the issue of accuracy of the urinalysis.

I am greatly enjoying your site and the wealth of information here. As an owner of two horses with multiple medical issues. I suspect that I'll visit here more than I might like! Thank you!
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