why is my Majorca Shepherd not gaining weight

It sounds like you're worried about Zeus not filling out the way you'd expect — that's a really common concern with young dogs, and it's great that you're paying attention to it.

A quick note: based on the profile we have on file, Zeus is listed as a mixed breed, so I'll share general information that applies to young dogs broadly. If Zeus is actually a Majorca Shepherd (also known as a Ca de Bestiar), some of the same principles apply, though that's a less common breed with its own characteristics.

Here are some of the most common reasons a 1-year-old dog might struggle to gain weight:

• Not enough calories for his activity level. Young, active dogs — especially larger or more energetic breeds — can burn through food quickly. The feeding guidelines on dog food bags are a starting point, not a guarantee.
• Food quality or digestibility. Some foods are harder for dogs to absorb nutrients from. A food with a named protein source (like chicken or beef) listed first is generally a good sign.
• Intestinal parasites (worms). These are very common in young dogs and can quietly steal nutrients before the dog's body can use them. A dog can look healthy on the outside and still have a significant parasite load.
• Picky eating or inconsistent feeding schedule. Some dogs simply don't eat enough if meals aren't structured.
• An underlying health issue. Less commonly, things like digestive conditions or hormonal imbalances can interfere with weight gain.

A few things you can try at home in the short term:

• Make sure Zeus is eating on a consistent schedule (two meals a day works well for most adult dogs).
• Check that the food amount matches his current weight and activity level — your vet or the food manufacturer can help you calculate this.
• Look at his stool — loose, frequent, or unusual-smelling stools can be a sign of a digestive or parasite issue.
• Note whether he's eating eagerly or picking at his food.

It's also worth knowing that some dogs naturally lean out around 1 year old as they transition from puppyhood. That said, if he's visibly thin — ribs very easy to feel or see, a tucked-up belly, no muscle definition — that's worth taking seriously.

When to see your vet: I'd recommend scheduling a visit soon, ideally within the next week or two. At 1 year old, Zeus is due for a wellness check anyway, and a vet can weigh him, check for parasites with a simple stool test, and make sure nothing else is going on. If he's also showing lethargy, vomiting, diarrhea, or seems to be getting thinner quickly, don't wait — call your vet right away.