Here's why:
* Lactose Intolerance: Puppies, especially young ones, often have difficulty digesting lactose, the sugar in cow's milk. This can lead to diarrhea, gas, and other digestive problems.
* Nutritional Deficiencies: Cow's milk does not have the proper balance of nutrients for growing puppies. It lacks essential vitamins, minerals, and antibodies that are crucial for their development.
* Calcium to Phosphorus Ratio: The calcium to phosphorus ratio in cow's milk is not ideal for puppies, potentially causing bone problems.
Instead of cow's milk:
* Puppy Formula: The best option for a 3-week-old puppy is a high-quality puppy formula. You can find this at pet stores or online.
* Mother's Milk: If possible, the puppy should ideally be nursing from its mother.
* Consult a Veterinarian: If you are unsure about the best way to feed your puppy, consult your veterinarian. They can provide specific guidance based on your puppy's age and needs.
Giving your puppy the right nutrition is crucial for their health and growth. Avoid cow's milk and opt for a formula specifically designed for puppies.