What We Test For, and Why — Part 2: Uric Acid, Urate Stones, and the LUA Question

Part 1 covered deafness, the piebald gene, BAER testing, and the patches question.

Every purebred Dalmatian carries, in duplicate, a mutation in a gene called SLC2A9. The result is that Dalmatians handle uric acid differently from every other dog on earth.

In a typical dog, uric acid produced by the breakdown of purines is converted in the liver into a highly soluble compound called allantoin and excreted uneventfully. The Dalmatian's liver does this poorly, and the kidney reabsorbs uric acid poorly as well. The consequence is that Dalmatians excrete uric acid in their urine at roughly ten times the rate of other breeds.

This is not a disease. It is a breed-universal metabolic trait, and your dog's test results at the vet will look abnormal against standard reference ranges when the dog is entirely healthy. It is worth telling any new veterinarian who has not worked with the breed.

What it does create is a meaningful risk of urate stones.

High urinary uric acid can crystallize and form stones in the bladder. The trait is universal; the disease is not. A substantial minority of Dalmatians form clinically significant stones — most estimates land somewhere around a quarter to a third of males — while many others never have a problem in their lives.

The sex difference matters enormously. A female with bladder stones is uncomfortable and needs treatment. A male can obstruct, because the male canine urethra narrows where it passes through the os penis, and a stone lodged there is a surgical emergency within hours. Straining to urinate, producing only drops, or producing nothing at all in a male Dalmatian is an emergency room visit, not a morning-appointment problem. If you take one clinical fact away from this page, make it that one.

A second detail worth knowing: urate stones are radiolucent. They frequently do not appear on a standard x-ray. A vet unfamiliar with the breed may radiograph a straining Dalmatian, see nothing, and look elsewhere. Ultrasound or contrast studies are what find them. Say the words "Dalmatian" and "urate" early in that conversation.

Risk is manageable, and most of the management is unglamorous.

Water. The single most effective intervention, and the least interesting. Dilute urine does not form stones as readily. Multiple water sources, adding water to food, and encouraging drinking throughout the day all matter more than most owners expect.

Frequent opportunities to urinate. Urine held for long periods concentrates. A dog crated ten hours a day is at higher risk than the same dog with a midday break.

Diet. Purine load drives uric acid production. Organ meats — liver, kidney, sweetbreads — are the worst offenders, along with certain fish like sardines and anchovies, and yeast-based supplements. Many owners feed a moderate-protein diet from ordinary quality ingredients and never need more than that. Prescription low-purine diets exist for dogs that have formed stones.

Urine pH. Urate crystallizes more readily in acidic urine. Alkalinizing agents such as potassium citrate are sometimes used in dogs with a stone history.

Allopurinol, a drug that reduces uric acid production, is used in some cases. It carries a specific trap worth flagging: combined with a high-purine diet, it can drive formation of xanthine stones instead. It belongs under veterinary supervision with matching dietary control, not as an independent measure.

One more wrinkle that catches people out. Dogs maintained long-term on restricted low-purine diets have been reported to develop taurine deficiency, which is associated with dilated cardiomyopathy. If your Dalmatian is on a prescription urinary diet for the long haul, taurine status is worth discussing with your vet rather than assuming the diet has it covered.

This is the part of Dalmatian genetics that generates the most argument, and a buyer should understand it rather than be steered past it.

In 1973, Dr. Robert Schaible at Indiana University did something that had never been done in a modern registered breed: he deliberately crossed a Dalmatian to an English Pointer in order to reintroduce the normal, functioning version of the uric acid gene into the Dalmatian population. The offspring were then bred back to Dalmatians, generation after generation.

The genetics cooperate unusually well here. The normal allele is dominant; the Dalmatian mutation is recessive. A dog needs only one working copy to metabolize uric acid normally. So a single outcross, followed by sustained backcrossing, can restore normal function while the Pointer contribution to the pedigree shrinks toward nothing with every generation.

Decades later, the descendants of that Dalmatian/Pointer cross breeding project are accepted as Dalmatians by any meaningful measure — the outcross contribution is a fraction of a percent — and they look and behave like Dalmatians because that is essentially what they are. The Dalmatian Club of America voted to accept their registration in 2011, after a long and genuinely bitter debate within the breed community. The UK Kennel Club had moved in the same direction shortly before.

These dogs are called LUA — Low Uric Acid — as distinct from HUA, high uric acid, which describes every conventionally bred Dalmatian.

Supporters make a straightforward argument, and we want to state it fairly before we explain why we don't follow it. A known, painful, sometimes surgical problem affecting a large share of the breed can be eliminated from a line entirely. There is a cheap, reliable DNA test that makes every breeding decision unambiguous. Declining to use a tool that works, they argue, puts pedigree bookkeeping ahead of dogs' welfare.

We don't think that argument is silly, and we don't think the people making it are acting in bad faith. Stones hurt. Surgery is expensive and frightening. Anyone who has sat in a waiting room with an obstructed male understands the impulse.

Before we set out where we stand, we should disclose something, because it shapes how the rest of this should be read.

In the late 1990s, HatTrick Dalmatians agreed to make our champion stud dog, Ch. HatTrick's Power Play — Dominick — available to Dr. Schaible for the Backcross Project.

The reason was type, and in Dominick's case the request was specific. He came down from English import lines and carried large, distinct, clearly defined spots. The backcross dogs at that point had tiny ones.

That can sound cosmetic. It isn't. Restoring a gene is one thing; restoring a breed is another, and the second takes far longer. The early backcross generations did not look like Dalmatians — they looked like what they were, Pointer-Dalmatian crosses, and small, indistinct spotting was among the most visible evidence of it. Proper spotting is not decoration; it is one of the attributes that defines the breed, and a population that had lost it had drifted from what a Dalmatian is. Those attributes had to be deliberately bred back in over generation after generation by putting sound Dalmatian dogs over the line. Dominick was wanted for exactly that.

It is worth being clear about what that kind of request involves. A project rebuilding breed type does not want whatever a kennel can spare — it wants dogs that carry the thing being restored, which is why what was asked for was a finished champion, and a particularly outstanding representation of breed type.

The breeding never happened. The backcross bitch could not be bred — not to our dog, and not, as it turned out, to anyone else's. Nothing came of it.

We mention it regardless, because the part that matters is not the outcome but the answer we gave. When the project asked for sound Dalmatian stock to help rebuild what the outcross had cost it, we said yes. We would say yes again. Declining to help and then criticizing the results from a safe distance would have been cheap.

So what follows is not an outsider throwing rocks. It is the conclusion of a program that was willing to put a dog behind the project, watched it closely, and came out thinking differently about what belongs in our own breeding decisions.

We breed HUA dogs. Our objection to the backcross is not about purity — it is about population genetics.

There is a distinction here that gets missed, and it is the reason our offering a stud and our declining to breed LUA are not in conflict. Sending a Dalmatian stud out to the backcross line widens that pool. It introduces unrelated Dalmatian genetics into a population that badly needs them. Bringing backcross dogs into our own program would do the opposite — it would narrow ours. Those are two different acts pointing in opposite directions, and supporting the first commits us to nothing about the second.

Every LUA Dalmatian alive traces to a single outcross performed in 1973. One Pointer, one Dalmatian, one event. Everything descending from it shares that recent common ancestry, and the pool has never had another source. That is a narrow founder base by any measure.

It also tends to narrow further rather than broaden, because of how the goal works. A breeder who wants LUA puppies reliably breeds LUA to LUA. Every such decision concentrates the same founder ancestry instead of dispersing it. The harder a subpopulation selects toward fixing one allele, the more tightly it closes in on itself. That is not a criticism of anyone's intentions; it is arithmetic.

And single-trait selection in a narrow pool is precisely the mechanism by which purebred dogs acquire their worst problems. It is not that breeders choose bad traits. It is that when you select hard and consistently on one locus within a limited population, everything else in those genomes rides along — including deleterious alleles nobody was looking at and nobody had a test for. The history of dog breeding is largely a history of exactly this: a defensible goal, pursued single-mindedly through a bottleneck, producing consequences that took two decades to become visible.

We watched a version of this play out at close range. What the early backcross generations lost visibly was type — and type is the part you can see, photograph, and correct by selection. Our concern has always been the part nobody can see. If a narrow, hard-selected population visibly shed the breed's physical character, the reasonable question is what else traveled with it that no one had a test for, and how long it will take before anyone finds out.

That matters here because this breed has problems that actually kill dogs.

Dalmatians carry a juvenile-onset laryngeal paralysis and polyneuropathy complex that presents in young dogs and carries a grim prognosis. The breed has a documented copper-associated liver disease that is progressive and can be fatal. Dilated cardiomyopathy occurs here. So do seizure disorders severe enough to end a dog's life. None of these conditions is managed with a water bowl and a diet sheet. There is no daily routine that makes a polyneuropathy less fatal.

Set that against what HUA actually is.

High uric acid is a management issue. It is lifelong, it requires attention, and it is occasionally an emergency — we have said so plainly on this page and we won't soften it. But it is managed with water, diet, frequent opportunities to urinate, and an owner who knows what straining looks like in a male dog. Most HUA Dalmatians never form a clinically significant stone. The ones that do are, in the overwhelming majority of cases, treated and go on to live full lives. It is a condition you handle. It is not a condition that takes the dog.

We are not willing to trade breadth of genetic diversity — the thing that protects a breed against everything nobody has thought to test for yet — to eliminate a problem that a competent owner manages with a bowl of water and a sensible diet.

There is an asymmetry in that trade that we think gets underweighted. Genetic diversity, once spent, does not come back. You cannot breed it back in. A management problem, by contrast, is managed fresh every generation, at low cost, with tools that already exist. Giving up the irreplaceable thing to solve the manageable one strikes us as the wrong direction.

Everything above concerns a legitimate disagreement between people breeding thoughtfully. What follows is a different problem, and it is the one most likely to cost you money.

"LUA" has become a marketing term among back yard breeders. It appears in advertisements from people with no health testing program of any kind, attached to a higher price and an implication that these puppies are simply healthier than other Dalmatians. Buyers who have read just enough to recognize the acronym pay the premium. Often the seller does not understand what they are claiming any better than the buyer does.

Here is what they are usually leaving out.

The trait is inherited one copy at a time, and most LUA dogs carry only one. The functioning allele is dominant, so a dog needs just one copy to metabolize uric acid normally. But because the backcross line has been bred back to conventional Dalmatians for decades, the large majority of LUA dogs are heterozygous — one working copy, one Dalmatian copy.

Do the arithmetic on what that produces:

• A heterozygous LUA dog bred to a conventional Dalmatian: about half the litter is HUA. Ordinary, conventional, high-uric-acid Dalmatians.
• Two heterozygous LUA dogs bred together: about a quarter of the litter is HUA, and only a quarter carries two working copies.

There is no such thing as an "LUA litter" unless every puppy in it has been individually DNA tested. The phrase is being used to describe a pairing, and a pairing does not determine an individual puppy's genotype — it determines a probability distribution. A buyer paying an LUA premium on the strength of the litter's description, or the parents' status, can very easily be taking home a conventional HUA puppy at a marked-up price.

If you ever intend to breed, the distinction matters more still. A heterozygous dog is LUA itself and will pass HUA to half of its own offspring. Someone sold a "proven LUA line" who does not know whether their dog carries one working copy or two is not in a position to predict anything.

And a single test is not a health program. This is the part that concerns us most. The SLC2A9 test is cheap, fast, and produces a clean binary result that fits nicely in an advertisement. BAER testing every puppy in a litter is not cheap. OFA evaluation of hips, eyes, and thyroid on breeding stock is not cheap. Tracking coefficient of inbreeding across a program, making pairing decisions that sacrifice a show win for genetic breadth, being honest with buyers about a weakness in your own line — none of that is cheap, and none of it photographs well.

So the trait that is easiest to market gets marketed, and the expensive invisible work quietly does not happen. A puppy advertised as LUA by a seller who cannot produce a BAER certificate has been screened for exactly one thing and left unscreened for the condition that affects a third of the breed.

To be clear about who we are describing: there are serious LUA breeders who test every puppy, disclose genotypes honestly, run the full health panel, and think carefully about diversity within the limits of their pool. We disagree with their conclusion, as set out above, and we respect their work. They are not the problem. The problem is the seller who has discovered that three letters raise the asking price.

How to protect yourself, in one sentence: if a breeder claims a puppy is LUA, ask for that individual puppy's SLC2A9 test result, from a named laboratory, identifying the dog by microchip or registration — not the parents' results, not a description of the litter. A breeder doing this properly will have it ready. A breeder using the term as a sales hook will not.

We try not to hold positions we couldn't be argued out of, so here is ours in falsifiable terms.

If the LUA population broadens substantially — more independent lines, measurably lower coefficients of inbreeding, a genuine widening rather than a larger number of closely related dogs — the calculus shifts, and we would look again. If the breed's diversity picture were to change in the other direction, that would matter too. We are watching, not dug in.

What we are not willing to do is treat one testable locus as though it were the whole of a dog's health, and pursue it at the cost of the variation the breed is going to need for the problems nobody has a test for yet.

Ask us about this. It is a conversation we're glad to have, and if you come away preferring an LUA program, we would rather you buy from a good one than from us.

Part 3 covers the rest of the health panel — hips, eyes, thyroid, skin — and how to verify any breeder's claims yourself at ofa.org, including the questions that should end a conversation.

Read Part 3 →