When I caution against using dehydrated or freeze-dried liver as training treats, I’m often met with surprise. After all, these treats are incredibly popular for good reason- most dogs love them. They’re often labeled as “high-value,” making them a go-to for trainers and pet owners alike. But while liver is packed with vital nutrients, it’s because it’s so nutrient-dense that it can pose significant health risks if overused. Understanding these risks is crucial for making smart choices about your dog’s health.

Two major nutrients need attention when discussing liver: copper and retinol (vitamin A).

Retinol is a fat-soluble vitamin, meaning it gets stored in fat tissues, particularly in the liver and kidneys. It plays critical roles in:

• Vision
• Bone development
• Reproductive health
• Immune system regulation
• Maintenance of epithelial tissues (like skin and mucous membranes)

However, because it’s stored rather than excreted quickly, excessive intake over time can cause toxic accumulation. The effects of too much retinol include skeletal abnormalities, weight loss, skin disorders- and in severe cases, even death. Vitamin A toxicity doesn’t happen overnight; it’s the result of chronic overconsumption.

Copper is another essential nutrient stored primarily in the liver. It’s involved in many critical body functions, including:

• Iron transport
• Melanin (pigment) production
• Collagen and elastin synthesis
• Energy production (ATP synthesis)
• Protection against oxidative damage
• Formation of the myelin sheath around nerves
• Histamine breakdown
  

Normally, excess copper is excreted through bile. But when copper accumulates, either due to genetics or overconsumption, it can cause severe liver damage.

Copper storage disease is becoming alarmingly more common in dogs. Traditionally, it was linked to genetic mutations that made certain breeds (like Bedlington Terriers) unable to regulate copper properly. However, a growing number of cases across various breeds suggest that other factors- potentially including diet- could also be playing a role.

Even if your dog doesn’t have a genetic predisposition, feeding diets too high in copper (and retinol) over long periods can still lead to serious health problems.

Quick Facts for a 50lb Dog:

• Daily Copper Requirement: 2.07 mg
  
• Daily Retinol Requirement: 155.84 mcg

• Safe Upper Limit (SUL) for Retinol: 21,807 mcg (very high but still reachable)

   

If your dog is eating a prey model or BARF-style raw diet with 5% liver, you could be pushing close to the safe upper limits, especially if your dog eats a large volume of food daily (more than 3% of body weight).

Notably, while copper doesn’t have a formally established SUL, it is still toxic at high levels. Chronic exposure can cause liver failure and other secondary issues, like zinc deficiency– because copper and zinc compete for absorption in the gut. Zinc deficiency itself leads to symptoms like alopecia (hair loss), skin thickening (parakeratosis), vomiting, hair color changes, and eye inflammation.

 Here’s where things get eye-opening: Just four small pieces of freeze-dried beef liver can meet a 50lb dog’s entire daily copper requirement.

If this were the only source of copper, no problem. But when you consider that most dogs are already eating complete and balanced diets — which often exceed their daily copper needs — adding liver treats can quickly tip the scales toward dangerous territory.

I reviewed seven different kibbles across different brands and proteins. Using the low end of the recommended feeding amounts for a 50lb dog, all seven brands already provided over 170% of the minimum daily copper requirement!

These levels aren’t inherently dangerous. However, when you add liver treats into the mix, your dog could easily be consuming copper at six times (or more) their daily requirement. And remember, most owners give more than just four pieces during a training session!

See the tables below for more detailed information on the data!

If you’re looking for high-value treats without the same nutrient-density risks, there are plenty of safer alternatives. The goal is to find options that your dog still loves without stacking on extra copper and vitamin A.

Here are some smart swaps:

• Use freeze-dried food as treats:
  Many freeze-dried complete foods are irresistible to dogs and much more balanced nutritionally. Just remember to slightly reduce your dog’s daily meal portion to account for the extra calories from training.
  
• Try freeze-dried or dehydrated beef lung:
  Beef lung is usually just as exciting for dogs as liver but with a lower nutrient density. It delivers the “high value” excitement without the same overload risks.

   

• Look for simple single-ingredient proteins:
  Freeze-dried chicken breast, turkey, or even rabbit can all be great choices. They’re leaner, less nutrient-concentrated, and easier to portion throughout the day.

   

• Use soft training treats with moderate nutrition:
  There are also many small, soft, minimally processed training treats made with quality ingredients and balanced nutrient profiles. These are perfect for long training sessions without overloading your dog’s system.

   

Ultimately, the key is to treat strategically: pick lower-risk options, use moderation, and always balance treats with your dog’s overall daily intake. Your dog can still enjoy “high value” rewards — without hidden health risks tagging along.

Alternatively, if you really want to continue to use freeze dried liver as treats, a homemade diet formulated around these treats is an option!

While liver is a powerhouse of nutrition, it’s a classic case of “too much of a good thing.” Freeze-dried liver treats are incredibly enticing for dogs, but without careful moderation, they can quietly push your dog’s copper and retinol intake into risky territory.

If you’re already feeding a balanced commercial diet, it’s crucial to recognize that your dog’s nutritional bases are likely covered and then some. Over-supplementing with liver, even just as treats, can contribute to serious long-term health problems like copper storage disease, vitamin A toxicity, and zinc deficiency.

This doesn’t mean you have to avoid liver completely. Used sparingly and thoughtfully, it can still be part of a healthy training routine. Think of it as a “special occasion” reward rather than an everyday staple. By understanding the risks and balancing your dog’s diet accordingly, you can harness the benefits of liver without courting danger.