Genetic George’s Monthly Musings: Why Can’t I Genetic Test for That?

Genetic George’s Monthly Musings: Why Can’t I Genetic Test for That?

One of the most frequently asked questions I encounter is: “Can you test for this?” The answer, however, is rarely straightforward. Genetics is an inherently complex and often unpredictable field—as my colleague Charlie, with more than 14 years in the discipline, used to emphasise: There are always more questions than answers.

Similarly, Mary, who spends her days supporting breeders, reminds us that the real challenge often lies in interpreting what a genetic test can (and cannot) tell us. In this month’s article, I will outline why certain conditions can be tested for while others cannot, and what breeders should realistically ask when considering hereditary versus spontaneous disorders.

Whether at a dog show, online forum, or in direct consultation with breeders, the inquiry is consistently the same:

• “Do you test for this?”
• “My dog has been diagnosed with cleft palate—can you test for it?”

In most instances, the answer is no; not because the technology does not exist or because laboratories are unwilling to develop it, but because the biological reality of genetics is far more complex than a binary yes-or-no test.

Why Not Everything Has a Genetic Test

The most critical factor to understand is that not all diseases are controlled by a single gene. Many disorders are polygenic, influenced by numerous genes, each exerting modest effects. Layered on top of this are non-genetic modifiers such as nutritional status, environmental exposure, or infectious triggers. Together, they create a multifactorial landscape. Thus, even a clearly hereditary disease may elude the development of a simple, reliable DNA assay.

Complex Genetic Realities

1. Genetic heterogeneity: What appears as a single condition can actually arise from multiple different mutations. Two dogs may look the same clinically but have entirely different genetic causes.
2. Phenotypic similarity: Different diseases may present almost identically, confusing even the best veterinarians and making test development difficult.
3. Oligogenic inheritance: Some conditions depend on the interaction of a major gene and multiple “modifier” genes that influence age of onset, severity, or even whether a dog develops the condition at all.

This is why two dogs carrying the same “faulty” gene can live very different lives—one developing disease early, another never showing any symptoms.

Hereditary vs. Spontaneous

Another key distinction: hereditary does not always equal testable. Some conditions may be inherited but involve too many genetic and environmental factors to isolate into a single DNA test. Others may arise spontaneously—a developmental accident in utero or an isolated immune response that no genetic screen could have predicted.

Practical Guidance for Breeders

When you see a condition appear in a litter, ask yourself:

• Is this the first mating of the pair? If so, and multiple pups are affected, avoid repeating that combination.
• If the pair has produced healthy litters before, and the condition arises once or only in one pup, it is more likely spontaneous or environmental than genetic.
• Always weigh pedigree, phenotype, and temperament alongside DNA results when planning matings.

The Bigger Picture

Genetic testing has revolutionized modern breeding practices, but it is not yet a crystal ball. Science is advancing, and every year the list of available tests grows. Still, some conditions, such as epilepsy, cleft palate, and immune disorders, remain beyond reach.

At Orivet, our mission is not just to provide tests but to educate breeders, share the latest research, and help to interpret what the science means for your program. As Charlie liked to say: “The more you learn, the more you realize there is still more to understand.”

A Gift for Our Readers

As part of our commitment to breeders, I’m offering a special giveaway: the first five readers to email me at: george@orivet.com, with your breed and the genetic or hereditary issue you’re most concerned about, will receive a complimentary Full Breed Profile (valued at over $130).

This is my way of giving back and encouraging more open conversations about genetics, challenges, and opportunities in your breed.

The Simplicity Behind the Science

Now, I don’t want breeders to feel overwhelmed. Just as Charlie never failed to bring back his ball, even if it took a few detours most of the time, genetic testing is actually very straightforward. For the majority of conditions, results fall into three simple categories: Normal, Carrier, or Positive. These tests are well-validated, easy to interpret, and can be used immediately to guide breeding strategies.

It’s only when we start pushing into the more complex diseases—the “tough throws” in genetics—that the ball doesn’t always come back cleanly. That’s where science is still catching up. But rest assured, technology is advancing rapidly. So, will we bring the ball back eventually? Absolutely. Watch this space; the science is moving forward every year.

Why Some Diseases Aren’t (Yet) Testable

• Too Many Genes Involved
  Many conditions (like epilepsy or immune disorders) are polygenic, meaning several genes—plus the environment—all play a role.
• Different Genes, Same Look
  What looks like “one disease” can actually be caused by multiple different mutations, even within the same breed.
• Modifiers Matter
  Some genes change how another gene behaves. This can affect when symptoms start, how severe they are, or whether the disease shows up at all.
• Hereditary ≠ Testable
  Just because something runs in families doesn’t mean there’s a simple DNA marker for it. Some conditions are spontaneous or influenced by environment.

The Takeaway: DNA testing is powerful, but it’s only one piece of the breeding puzzle. Always combine test results with pedigree, clinical history, and phenotype