SAM THE DOG TRAINER'S THOUGHT FOR THE DAY

Some dogs weren’t broken.

They were never built.

- Sam Basso

Large Breed Dog Food Studies

Supporting Healthy Skeletal Development in Large and Giant Breed Puppies: Key Insights from Veterinary Nutrition Research

 

As a professional dog trainer with years of experience working with owners and their companions, I often emphasize the importance of a solid foundation for long-term well-being. Physical comfort and mobility play a significant role in a dog's ability to engage positively with their environment, respond to training cues, and participate in enrichment activities. While my expertise lies in behavioral assessment and structured training pathways, I frequently encounter questions about how early life factors, including nutrition, influence a puppy's development. I also must mention that I had a large breed dog that developed osteochondrosis by 5 months of age and had to be put down at 7 months of age, so this topic is still raw to me even after over 30 years. I don’t know if I caused it by supplementing the dog or feeding him incorrectly, or if this would have happened either way.

 

This article summarizes key findings from established veterinary research on nutrition and skeletal growth in large and giant breed puppies. It focuses on landmark studies and ongoing scholarly consensus regarding developmental orthopedic conditions—issues that can affect joint health and overall mobility. Please note: This is not veterinary or medical advice. I am reporting on published research only. Dietary decisions for your puppy should always be made in consultation with a qualified veterinarian, who can provide personalized guidance based on your dog's specific needs. For complex cases involving health concerns or significant behavioral challenges, owners are encouraged to consult their veterinarian.

 

Landmark Research from the University of Utrecht

 

Much of our current understanding of nutrition's role in skeletal development comes from controlled studies conducted at the University of Utrecht's Faculty of Veterinary Medicine in the Netherlands. Led by researcher Herman A. W. Hazewinkel and colleagues, these experiments used Great Dane puppies as a model for large and giant breeds due to their rapid growth rates and susceptibility to orthopedic issues.

 

Key studies from the 1980s to 2000s examined how varying levels of calcium, phosphorus, energy intake, and feeding methods (e.g., free-choice/ad libitum versus portion-controlled) affect bone and joint development. Findings consistently showed that:

 

• Excess calcium intake, particularly without balanced phosphorus, disrupts calcium homeostasis, leading to disturbances in bone mineralization and increased risk of conditions like osteochondrosis (a precursor to cartilage defects and joint issues).
• High energy intake and ad libitum feeding promote rapid growth, which can exacerbate skeletal remodeling challenges in fast-growing breeds, resulting in higher rates of developmental orthopedic diseases (DOD), including hypertrophic osteodystrophy (HOD) and osteochondrotic lesions.

 

 

For example, in one study, puppies fed high-calcium diets without proportional phosphorus developed hypercalcemia, hypophosphatemia, and rickets-like changes that partially resolved after diet normalization, though some osteochondrotic lesions persisted (Schoenmakers et al., 2000). Another found that restricted feeding on balanced diets reduced DOD incidence compared to ad libitum access, even on nutritionally appropriate food (Hazewinkel et al., 1991).These controlled experiments highlighted that overnutrition and mineral imbalances can interfere with endochondral ossification—the process by which cartilage turns into bone—during critical growth phases.

 

Enduring Consensus in Contemporary Research

 

The Utrecht findings remain foundational and continue to be cited extensively in veterinary literature without major refutation. Recent reviews and guidelines (2020 onward) affirm the core principles: controlled growth through balanced, portion-fed diets supports healthier skeletal outcomes in large and giant breeds.

 

Modern recommendations typically include:

 

• Diets formulated specifically for large/giant breed puppies, with calcium levels around 0.8–1.2% (dry matter basis), balanced calcium-to-phosphorus ratios (approximately 1:1 to 1.5:1), and moderate energy density.
• Avoidance of unrestricted feeding and unnecessary supplementation (e.g., extra calcium or vitamin D), as these can tip the balance toward rapid growth and orthopedic risks.

 

Purina Institute and VCA Animal Hospitals guidelines, among others, reinforce portion-controlled feeding to promote steady growth (Purina Institute, n.d.; VCA Hospitals, n.d.). Observational and clinical data support these approaches, with no large-scale studies overturning the Utrecht model's insights.

 

Additional Considerations: Homemade and Unbalanced Diets

 

Veterinary case reports and diet analyses provide supplemental evidence on the risks of unbalanced nutrition, particularly in homemade or raw feeding regimens that do not account for precise mineral and energy needs. Published evaluations of homemade recipes often reveal frequent imbalances in calcium, phosphorus, and other nutrients essential for growing puppies.

 

Clinical cases document severe outcomes in young large-breed dogs fed unsupplemented homemade or raw diets, including nutritional secondary hyperparathyroidism (leading to bone softening, fractures, and neurological issues), skeletal deformities, and generalized osteopenia (e.g., Kavkova et al., 2024; Krook et al., 2020). These real-world examples illustrate how deficiencies (e.g., low calcium relative to phosphorus in meat-heavy diets) or excesses can mirror or exceed the controlled imbalances studied in Utrecht research.

 

Veterinary organizations caution that self-formulated diets, without professional oversight, carry elevated risks during rapid growth periods. Board-certified veterinary nutritionists are often recommended for customizing any non-commercial diet.

 

Implications for Mobility, Behavior, and Training

 

From a behavioral perspective, healthy skeletal development supports a puppy's capacity for physical activity, which is integral to enrichment recommendations and structured management plans. Research indicates that discomfort from joint or mobility issues can influence activity levels, responsiveness, and overall engagement—factors that trainers consider in risk and readiness profiles.

 

A dog experiencing physical limitations may show reduced enthusiasm for exercise or play, potentially complicating owner implementation plans for positive reinforcement pathways. While nutrition itself is outside my scope, awareness of these research findings underscores the value of veterinary-guided feeding to foster a strong physical foundation for behavioral success.

 

In my experience applying ethological principles—drawing from observers like Konrad Lorenz and Raymond Coppinger—dogs thrive when their basic needs, including physical comfort, are met consistently. This aligns with a holistic view of canine well-being, where mobility enables natural behaviors and effective learning.

 

Final Thoughts

 

The body of research on large and giant breed puppy nutrition emphasizes balance, control, and professional guidance to support healthy development. Commercial foods designed for these breeds incorporate lessons from decades of study, offering a reliable option for many owners.

 

Always prioritize your veterinarian's expertise for dietary choices—they can tailor recommendations to your puppy's breed, age, and health profile.

 

“This article incorporates AI-assisted drafting based on established veterinary research and has been reviewed for accuracy, alignment with ethological principles where relevant, and adherence to professional parameters.”

 

References

1. Hazewinkel, H. A. W., Tryfonidou, M. A., Krook, L., Brom, W. E., & Brom, M. (1991). Calcium metabolism in Great Dane dogs fed diets with various calcium and phosphorus levels. The Journal of Nutrition, 121(11 Suppl), S99–S106. https://doi.org/10.1093/jn/121.suppl_11.S99
2. Kavkova, M., et al. (2024). A case series of four dogs presenting with neurological deficits due to nutritional secondary hyperparathyroidism from a boneless raw meat diet. Veterinary Record Case Reports. https://doi.org/10.1002/vrc2.892
3. Purina Institute. (n.d.). Feeding large and giant breed puppies. Retrieved February 14, 2026, from https://www.purinainstitute.com/centresquare/life-stage-nutrition/feeding-large-and-giant-breed-puppies
4. Schoenmakers, I., Hazewinkel, H. A. W., Voorhout, G., Carlson, C. S., & Richardson, D. (2000). Effects of diets with different calcium and phosphorus contents on the skeletal development and blood chemistry of growing Great Danes. Veterinary Record, 147(23), 652–660. https://doi.org/10.1136/vr.147.23.652
5. VCA Hospitals. (n.d.). Nutritional requirements of large and giant breed puppies. Retrieved February 14, 2026, from https://vcahospitals.com/know-your-pet/nutritional-requirements-of-large-and-giant-breed-puppies
6. This article incorporates AI-assisted drafting based on established veterinary research and has been reviewed for accuracy, alignment with ethological principles where relevant, and adherence to professional parameters.

 

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Why Does My Dog Do This? The Biological Reasons Behind Unpredictable Behavior

As dog owners, we’ve all had those moments: your dog suddenly ignores a well-practiced cue, digs furiously in the yard for no apparent reason, or barks at nothing visible. The immediate question is almost always, “Why does my dog do this?” We often reach for the simplest explanation—more training, a different method, or tighter control—as if the right technique could eliminate every unexpected action. Yet the honest answer is sometimes: there is no single, observable “why” in the environment. Dogs are living organisms, not programmable devices, and some behaviors arise from internal processes we cannot fully see or control.
This doesn’t mean behavior is random or that training is pointless. It means we must replace the “vending machine” idea—insert cue, add reinforcement, get perfect response—with a more accurate, organism-centered view grounded in ethology, learning science, and physiology. Understanding these limits helps us set realistic expectations and build stronger, more compassionate relationships with our dogs.The “Vending Machine” ExpectationMany modern training conversations implicitly treat dogs as stimulus-response machines. If the cue is clear and the reinforcement history strong, the desired behavior should appear reliably, every time. When it doesn’t, the conclusion is often that the dog needs “more reps,” a “better motivator,” or a different approach altogether. This assumes we can eventually program away all variability, as though innate biological processes could be overwritten completely.
Living organisms don’t work that way. Dogs are continuously active, self-regulating systems shaped by evolutionary history, internal motivation, and ongoing physiological needs. Behavior emerges from the interaction of these internal processes with the environment, not as a direct, mechanical output of external inputs alone.Behavior Is Endogenous and ContinuousClassic ethology teaches that much of animal behavior is endogenous—generated from within the organism rather than solely triggered by external stimuli. Dogs explore, sniff, scan, rest, and move through their day even when no obvious “cue” is present. Konrad Lorenz described “vacuum activities,” where species-typical actions (like a dog digging or carrying an imaginary prey item) occur without the usual releasing stimulus, simply because internal motivational systems reach a threshold.
This means many everyday canine actions—sudden zooming around the living room, persistent sniffing on a walk, or brief air-scenting—may have no direct environmental cause we can identify. The behavior originates inside the dog as part of normal, ongoing activity patterns inherited from their canid ancestors. Environmental stimuli guide or channel these tendencies, but they do not create the action from scratch.Learning Shapes Probabilities, Not CertaintiesEven highly trained behaviors remain probabilistic. Reinforcement increases the likelihood and fluency of a response, but it never guarantees it will appear on any specific occasion. Learning theory has long recognized that identical cues can produce different outcomes because of context shifts, competing motivations, and momentary internal states.
A dog who reliably sits at the door 99 times may, on the 100th, choose to watch a squirrel instead. This isn’t defiance or a training failure; it reflects the normal allocation of behavior across competing options. Variability is a functional feature of biological learning systems, not an error to be eliminated.Physiology Sets Momentary BoundariesBefore any cue or learned history can matter, physiology determines what is even possible. Stress, arousal, fatigue, hunger, hormonal fluctuations, and recovery needs constantly adjust a dog’s attentional capacity and behavioral flexibility.
When regulatory demands are high—what physiologists call elevated allostatic load—previously accessible behaviors may temporarily disappear or degrade. A tired, overstimulated, or chronically stressed dog simply cannot perform at peak consistency, regardless of how solid the training foundation is. These shifts are lawful biological adaptations, not refusals to comply.Why Perfect Consistency Is a Biological ImpossibilityExpecting machine-like reliability from a living dog creates frustration for both owner and animal. No method, no matter how sophisticated, can override the fundamental properties of an organism: continuous endogenous activity, probabilistic learning effects, and state-dependent physiological constraints.
Variability and occasional “unexplained” actions are not signs that something is wrong with the dog or the training approach. They are expected features of a healthy, functioning biological system navigating a complex world with incomplete information available to us as observers.A Healthier PerspectiveShifting from a mechanistic to an organism-centered view brings relief and clarity. We stop chasing an unattainable ideal of perfection and instead focus on creating conditions that support behavioral accessibility: adequate rest and recovery, predictable routines, enriched environments, and training that respects natural motivational systems.
When your dog does something unexpected, the kindest and most accurate response is often curiosity rather than correction. Sometimes there truly is no external “why”—just a living being expressing normal internal processes. Accepting this reality deepens our appreciation for dogs as complex, sentient companions rather than programmable tools. ReferencesBouton, M. E. (2007). Learning and behavior: A contemporary synthesis. Sinauer Associates.Dawkins, M. S. (2012). Why animals matter: Animal consciousness, animal welfare, and human well-being. Oxford University Press.Lorenz, K. (1981). The foundations of ethology. Springer.McEwen, B. S., & Wingfield, J. C. (2003). The concept of allostasis in biology and biomedicine. Hormones and Behavior, 43(1), 2–15. https://doi.org/10.1016/S0018-506X(02)00024-7Skinner, B. F. (1953). Science and human behavior. Macmillan.Tinbergen, N. (1963). On aims and methods of ethology. Zeitschrift für Tierpsychologie, 20(4), 410–433. https://doi.org/10.1111/j.1439-0310.1963.tb01161.x This article incorporates AI-assisted drafting