McNab Health

The McNab Shepherd is a hardy, intelligent working breed developed for stamina, agility, and versatility. To maintain that legacy, breeders must take health testing seriously. Comprehensive evaluation—including full genetic panels and orthopedic screenings through the Orthopedic Foundation for Animals (OFA)—is essential to ensure dogs remain sound, capable, and free of preventable health concerns.

DNA panels have become a cornerstone of responsible breeding. These tests screen for inherited disorders common in herding breeds, including eye conditions like Collie Eye Anomaly (CEA) and Progressive Retinal Atrophy (PRA), Primary Lens Luxation (PLL), neurological issues such as degenerative myelopathy (DM), and other breed-relevant markers. 

Results identify dogs as clear, carrier, or at risk for each condition.

A crucial concept in breeding is that carriers still have a role. Removing all carriers from breeding programs would drastically shrink the McNab gene pool, leading to inbreeding and loss of important working traits. Instead, responsible breeders pair carriers with clear dogs, ensuring that no affected puppies are produced while preserving diversity and desirable characteristics. Over time, this approach can reduce mutation frequency without sacrificing the health of the breed as a whole. Adding in a non-breeding contract to all puppies sold ensures that accidental and irresponsible breeding practices do not happen.

One of the most discussed markers on modern DNA panels is DCM2, associated with Dilated Cardiomyopathy (DCM). Embark, the leading canine genetic testing company, emphasizes that this mutation is only clinically relevant in the Doberman Pinscher breed. In Dobermans, having one or two copies of this marker correlates with increased risk of developing DCM, a serious heart condition.

It is important to understand that Dilated Cardiomyopathy (DCM) is a general term describing a disease state of the heart muscle. DCM can be caused by multiple factors, including:

• Nutritional deficiencies such as insufficient taurine or carnitine in the diet.
   
• Genetic mutations, which vary from breed to breed. For example, Dobermans and Boxers both suffer from genetic forms of DCM, but the mutations involved are not the same.
   
• Environmental or congenital factors, including toxins or trauma.
   

Any specific genetic test that identifies a correlation between a mutation and DCM must be validated within that breed. At present, there are no herding breeds with a proven genetic relationship between any form of DCM and any identified gene. This means that while McNabs may test as carriers or “at risk” for the DCM2 mutation, there is no evidence that this marker causes disease in McNab Shepherds or other herding breeds【Cornell Vet Reference: Dilated Cardiomyopathy – Cornell Riney Canine Health Center】.

For McNab breeders, the presence of the DCM2 marker should be interpreted as informational only and not as a health disqualification. Transparency in explaining this to buyers is essential, so families understand that the marker has no proven connection to disease in herding breeds.

Another important health condition to consider is Lundehund Syndrome (LS), a severe gastrointestinal disorder most commonly associated with the Norwegian Lundehund but identified in other breeds, including the McNab Shepherd. Lundehund Syndrome is a protein-losing enteropathy (PLE), meaning affected dogs lose protein through their intestines due to chronic digestive malfunction. Symptoms can include vomiting, diarrhea, weight loss, malnutrition, and in severe cases, life-threatening protein deficiency.

Genetic Component
Lundehund Syndrome has a strong genetic basis, and while research is ongoing, it is believed to be caused by a mutation that affects the dog’s ability to properly absorb nutrients. In the McNab Shepherd, this disorder has been confirmed through DNA testing and is considered a dangerous condition to pass through breeding lines.

Why It Matters in McNabs
Because McNabs have historically been bred with multiple herding breeds, they have inherited not only desirable working traits but also genetic vulnerabilities. The presence of Lundehund Syndrome in McNab bloodlines represents a hidden but serious risk. Dogs carrying this mutation may not show symptoms themselves but can pass the condition on to future generations, leading to devastating health outcomes in affected puppies.

Testing Availability
Currently, Embark is the only canine DNA company that tests for Lundehund Syndrome. Other testing services, such as Wisdom Panel, do not include this marker in their panels, meaning breeders who use only partial or alternative genetic testing may miss it entirely. This makes full Embark DNA testing especially critical for the McNab Shepherd, ensuring breeders can identify carriers and prevent the spread of this lethal disorder.

Breeding Implications
As with other genetic concerns, the key is responsible pairing:

• Carriers should only be bred to clear dogs to prevent producing affected offspring.
   
• Any dog found to be affected or producing affected puppies should be removed from breeding programs.
   
• Transparency is essential—breeders should clearly disclose Lundehund Syndrome results to buyers and fellow breeders to protect the health of the breed as a whole.

Another serious concern in herding breeds, including McNabs, is epilepsy. Epilepsy refers to recurrent, unprovoked seizures caused by abnormal electrical activity in the brain. These seizures can range from mild episodes to severe, life-threatening events. In addition to being distressing for both the dog and the owner, epilepsy often requires lifelong medication and management.

The Genetic Component
Idiopathic epilepsy (epilepsy with no known external cause) is widely considered to have a genetic basis. Studies in Border Collies, Australian Shepherds, and related breeds show that epilepsy can be inherited, though its mode of inheritance is complex. A single “epilepsy gene” has not been identified; rather, epilepsy is thought to be polygenic (influenced by multiple genes) and can be influenced by environmental triggers.

Border Collie Connection
Historically, McNabs have been bred with Border Collies to expand working ability and maintain herding instincts. While this cross strengthened many desirable traits, it also introduced the risk of epilepsy, which is more prevalent in Border Collies than in McNabs. As a result, McNab breeders must remain vigilant, as epilepsy has been documented in certain McNab lines.

Inheritance and Skipped Generations
One of the greatest challenges with epilepsy is that it may skip generations. A dog may never show seizures itself but still pass the genetic predisposition to offspring. This makes pedigree analysis and transparency essential in breeding programs. If epilepsy is identified in a line, breeders should take care not to repeat that cross or concentrate those genetics further. Open communication among breeders and long-term health tracking are critical for preventing the silent spread of this condition.

Why Epilepsy Matters
Epilepsy not only impacts quality of life, but also the reputation of the breed. For a working dog like the McNab Shepherd, seizures are particularly devastating, as they interfere with the dog’s ability to perform tasks safely. Responsible breeders must acknowledge the risk, monitor pedigrees closely, and avoid doubling up on lines where epilepsy has been seen.

Beyond genetics, orthopedic health is vital for McNabs, who are often used in herding, agility, and other physically demanding activities. Hip and elbow dysplasia can cause pain and limit performance, reducing both quality of life and working ability.

Two widely recognized screening methods are used to evaluate orthopedic soundness:

• OFA (Orthopedic Foundation for Animals): Provides standardized hip and elbow radiographs, scored by expert radiologists. OFA assigns ratings (Excellent, Good, Fair, Borderline, Mild, Moderate, Severe) that help breeders determine whether a dog is suitable for breeding.
   
• PennHIP (University of Pennsylvania Hip Improvement Program): Uses a different radiographic technique to measure laxity (looseness) in the hip joint, which is one of the strongest predictors of future hip dysplasia. Unlike OFA, PennHIP can be performed as early as 16 weeks of age, giving breeders earlier insight into hip quality.
   

Using one or both of these methods allows breeders to identify sound breeding candidates and reduce the incidence of dysplasia in future generations. Combining PennHIP’s early predictive power with OFA’s standardized grading system provides the most complete picture of joint health. For the McNab Shepherd—a working breed that relies heavily on athleticism—maintaining orthopedic integrity is essential to preserving the breed’s function and quality of life.

The health and well-being of a breeding female is just as critical as genetic and orthopedic testing. Carrying and raising a litter is physically demanding; it taxes a bitch’s body, immune system, and energy reserves. Repeated pregnancies without adequate recovery time can shorten her lifespan and compromise both her health and that of her puppies.

Most veterinary reproductive experts recommend that a female dog should not be bred more than three to four times in her lifetime. Breeding beyond this limit increases the risk of uterine complications, nutritional deficiencies, and long-term health decline. An overbred bitch may also produce weaker litters with lower survival rates. Responsible breeders prioritize the mother’s health, ensuring she has sufficient rest between litters, excellent nutrition, and veterinary care before, during, and after pregnancy. Protecting the bitch is not only an ethical responsibility but also guarantees that puppies are born healthy and strong.

Another often overlooked aspect of responsible breeding is avoiding repeated use of the same male-female pairing. While it might be tempting to repeat a successful cross, doing so repeatedly narrows the gene pool and reduces genetic diversity within the breed.

• Genetic Bottlenecking: Continuously producing litters from the same pair can saturate the population with the same set of genes, increasing the risk of recessive, and often currently untestable, disorders appearing in future generations.
   
• Loss of Diversity: McNabs already have a relatively small breeding population compared to larger AKC-recognized breeds. Overusing the same crosses accelerates the loss of genetic variation, which is essential for long-term breed health and adaptability.
   
• Limited Evaluation: Using multiple pairings with different dogs allows breeders to better evaluate how traits are inherited and to identify strong, consistent producers. Breeding the same pair repeatedly hides that genetic information.
   
• Ethical Concerns: Overbreeding the same pair can also place unnecessary strain on the bitch if done back-to-back without regard to her recovery and long-term health.
   

Responsible breeders instead focus on pairing different combinations of dogs, thoughtfully balancing strengths and weaknesses, while spreading genetic influence across the breed. This practice preserves diversity, avoids overrepresentation of certain lines, and strengthens the overall resilience of the McNab Shepherd.

Maintaining a healthy McNab population means balancing vigilance with perspective:

• Run full DNA panels to identify inherited disorders.
   
• Breed carriers to clears to prevent affected offspring while keeping genetic diversity strong.
   
• Educate about DCM2—clarify that while the marker may appear on McNab DNA tests, that specific marker is only a proven health concern in Dobermans. If there is a genetic basis for DCM in McNabs, the marker for that form has not yet been identified.
   
• Acknowledge epilepsy risk—track pedigrees, communicate openly, and avoid repeating affected lines.
   
• Use OFA hip and elbow screenings to preserve orthopedic soundness.
   
• Protect breeding females—limit to 3–4 litters, allow full recovery, and provide excellent care.
   
• Avoid repeated pairings of the same male and female to preserve diversity and strengthen the breed.
   

The future of the McNab Shepherd depends on careful, informed breeding. Full genetic testing ensures that heritable conditions are identified, while OFA evaluations protect the breed’s working ability. The DCM2 marker, though harmless in McNabs, demonstrates the importance of interpreting DNA results in the correct breed-specific context. Epilepsy, however, represents a more serious inherited concern—especially given McNabs’ shared history with Border Collies—and requires vigilance to prevent its spread. Just as importantly, breeders must protect the health of the breeding bitch and avoid repeating the same pairings, both to ensure the welfare of the parents and to safeguard genetic diversity. By breeding responsibly, McNab breeders can ensure the health, resilience, and working ability of the breed for generations to come.

Even with the best planning, testing, and careful pairings, no breeder can guarantee that every puppy will be free of health problems. Some conditions, such as hip and elbow dysplasia, can occur despite clear parentage and normal OFA results, because these disorders are influenced by both genetics and environment. Factors like diet, growth rate, exercise, and even injury during puppyhood can affect how joints develop. Likewise, non-genetic defects—such as birth defects or developmental irregularities—sometimes occur with no clear explanation.

The Role of Responsible Breeders
What separates a responsible breeder from an irresponsible one is how they handle these situations. A responsible breeder is:

• Transparent with puppy buyers, openly sharing any issues that arise in their litters or breeding program.
   
• Proactive in gathering information, such as requesting updated health results from owners and recording them for long-term evaluation of their lines.
   
• Committed to adjusting breeding plans when necessary. If dysplasia, epilepsy, or other significant issues are identified in offspring, ethical breeders make the difficult choice to remove one or both parents from future breeding programs, even if those dogs are otherwise excellent workers.
   
• Supportive of owners, offering guidance, education, and often financial or replacement considerations when unforeseen health problems occur.
   

This transparency builds trust with the community, strengthens the breed’s health in the long run, and ensures that difficult discoveries lead to better decision-making in the future. Ethical breeders recognize that their responsibility does not end when the puppy leaves their home; it extends across generations, guided by the health of every dog they produce.

1. Embark Veterinary – DCM2 mutation and breed relevance: Embark FAQ on DCM2
    
2. OFA (Orthopedic Foundation for Animals) – Hip and Elbow Dysplasia Testing: OFA Screening Info
    
3. AKC Canine Health Foundation – Genetic testing and breeding strategies: AKC CHF Breeding & Genetics
    
4. The Kennel Club (UK) – Genetic diversity and avoiding the popular sire effect: Kennel Club Genetic Diversity Guide
    
5. Dr. Emmanuel Fontaine, Royal Canin Reproduction Specialist – Limits on breeding bitches: How Many Litters Can a Dog Have?
    
6. PetMD – Responsible breeding and health of the dam: PetMD on Dog Breeding Practices

1. Berendt, M. et al. (2009). Epilepsy in Border Collies: Clinical Manifestation, Mode of Inheritance, and Risk Factors. Journal of Veterinary Internal Medicine. PubMed Abstract
    
2. Canine Health Information Center (CHIC). Canine Epilepsy Resources. canine-epilepsy.net
    
3. American College of Veterinary Internal Medicine (ACVIM). Consensus Statement on Canine Epilepsy Classification, Diagnosis, and Management. ACVIM Consensus Statement PDF
    
4. Hülsmeyer, V.I. et al. (2015). Canine Idiopathic Epilepsy: Clinical Characteristics, Breed Distribution, and Risk Factors. BMC Veterinary Research. Full Text