I read the Con Introductory Statement on the DCA website with interest. The
following statement, however, puzzled me:
"The backcross experiment proved only that the Dalmatians that received the
gene for typical canine-uric acid metabolism do convert uric acid to
allantoin before excretion. At the time of the original experiment, it was
commonly assumed that uric acid was the cause or at least the primary cause
of urate stone formation. The leading US canine stone experts, Drs. Bartges
and Osborne, do not support that view. . . ."
This is in conflict with what Drs. Osborne, Bartges, Lulich, Unger,
Thumchai, Koehler, Bird, and Felice wrote:
"Regardless of the theory proposed for nucleation and nidus formation, an
essential requirement is supersaturation of urine with a urolith-forming
crystalloid. A crystal nidus cannot be formed if urine is undersaturated
with the crystalloid in question." from CANINE and FELINE NEPHROLOGY and
UROLOGY, Carl A. Osborne and Delmar R. Finco, editors --Williams & Wilkins,
1995, Chapter 41 -- Canine and Feline Urolithiasis: Relationship of
Etiopathogenesis to Treatment and Prevention (Carl A. Osborne, Jody P.
Lulich, Joseph W. Bartges, Lisa K. Unger, Rosama Thumchai, Lori A. Koehler,
Kathleen A. Bird, Lawrence J. Felice -- Page 809 -
So, according to Osborne, et al, without urine supersaturated with uric
acid, urate stones cannot form. The chapter quoted above does say
elsewhere that other factors may influence the size of the stones, but only
if the stones first form in supersaturated urine.
As the Cons agree with the Pros, the Dalmatians that receive the gene for
typical canine-uric acid metabolism do convert uric acid to harmless
allantoin. This prevents uric acid levels from reaching a state of
supersaturation (except in cases of liver shunts--not common in Dals--or
reaction to medication). No stones can, therefore, start to form. Any
other factors that might affect the size or tendency to block have nothing
to work on.
Yes, other factors may play a part in whether or not a dog might actually
block, but when will they be identified? Will they involve one gene or a
number of genes? Can they be bred out? Not everything can. One genetic
factor that strongly influences whether or not a Dalmatian will block with
stones is whether it is a dog or a bitch. Try breeding away from that one!
We have identified one gene, mutated in the breed, that can be replaced by a
working version. Everyone agrees that doing so does effectively lower the
levels of uric acid. This will avoid the state of supersaturation that
expert opinion says is essential to the formation of urate stones and
We can return an unmutated form of this gene to our Dals without losing
breed type--witness Fiona's success in Britain where she can compete on
equal terms with other Dals! I hope the members of the DCA will agree that
type should be determined in the breed ring where everyone can see it.