UPDATE - We now understand research has moved on a stage further with blood and stone supply, samples are no longer required.
A sincere thank you too everyone who has participated!
Cystine is a derivative of one of the twenty amino acids that are the building blocks of life - cysteine.
Residual amino acids are usually filtered out and recycled by the kidneys.
When cystine is not being filtered properly it can form into stones (calculi, uroliths) in the kidneys, ureters and bladder. Small stones may pass out of the bladder and through the urinary tract, this can be very painful and there is a high chance of a blockage occurring.
"If there is any change in behaviour or other sign that your dog's urinary tract is blocked or is having trouble urinating, call your veterinarian immediately or go to an emergency clinic if it's after hours, as this is an emergency situation that cannot wait."
Cystinuria is relatively rare and many vets are not aware of it and mistake it for the much more common stones formed from struvite’s (magnesium ammonium phosphate crystals) caused by a urinary tract infection.
Typically, the type of cystinuria that sometimes affects Irish Terriers is late onset about four years old onward.
A laboratory test can determine the levels of amino acids in urine - Cystine, Ornithine, Lysine, and Arginine (COLA test) - though it's only cystine that causes a problem. Fairly obviously, high COLA levels mean the dog is at risk of Cystinuria.
Cystinuria in humans is a genetic recessive trait and it is often misquoted as being the same in dogs but in fact there are several different defective genes which are now put into three divisions - in some breeds it is indeed recessive - designated type 1 but in some others it's dominant - designated type 2. In Irish Terriers (and Scottish Deerhounds) the condition only occurs in male dogs that have not been neutered - designated type 3, this is thought to be testosterone (male hormone) dependent and genetically autosomal (not on X chromosome in the way that sex linked conditions often are.) It is not yet known if the mode of inheritance is dominant or recessive.
Surgical and medical castration cures type 3 cystinuria (assuming stones have been removed.) Surgical castration is a complete lifetime cure. Hormone implant castration works for as long as the chip is effective. See: http://www.virbac.co.uk/suprelorin. Chemical castration may only reduce testosterone by about half and may not be effective in preventing androgen dependent diseases such as type 3 cystinuria. Medical management is not highly effective. BARF (raw food), high protein diets, chicken and salmon seem to favour stone formation.
Following surgical castration and recovery period of a couple of months and one urinary COLA test there is no need for medical treatment, any special diets or monitoring. A regular canine diet will be fine, just not a high protein diet. (Note a BARF diet is high protein.)
SLC3A1 and SLC7A9 Mutations in Autosomal Recessive or Dominant Canine Cystinuria: A New Classification System
A.-K. Brons, † P. S. Henthorn,† K. Raj,† C. A. Fitzgerald,† J. Liu,† A. C. Sewell,§ and U. Giger†
Scottish Deerhound Club of America -Cystinuria
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