Weterynarz powiedział, że za dużo smakołyków nie jest zdrowe dla psa.

Powiedział is the past tense form of powiedzieć (to say / to tell).

It also tells us something about the subject:

• powiedział = masculine singular
• powiedziała = feminine singular
• powiedziało = neuter singular

So Weterynarz powiedział means The vet said, with the vet understood as male. If the vet were female, it would be:

Weterynarz powiedziała, że...

Polish past tense agrees with the gender of the subject.

Że means that.

It introduces a subordinate clause:

• Weterynarz powiedział = The vet said
• że za dużo smakołyków nie jest zdrowe dla psa = that too many treats are not healthy for the dog

In English, that is often optional:
The vet said (that) ...

In Polish, że is normally used in this kind of sentence.

Za dużo means too much or too many, depending on context.

In this sentence:

• za dużo smakołyków = too many treats / literally too much of treats

A useful pattern is:

• za dużo + noun in the genitive
• za mało + noun in the genitive

Examples:

• za dużo cukru = too much sugar
• za dużo książek = too many books
• za mało czasu = too little time

So here, za dużo expresses an excessive quantity.

Because after expressions of quantity like dużo, Polish usually uses the genitive.

So:

• dictionary form: smakołyki = treats (nominative plural)
• after za dużo: smakołyków = genitive plural

This is a very common pattern in Polish:

• dużo ludzi = many people
• mało pieniędzy = little money
• kilka książek = a few books
• za dużo smakołyków = too many treats

So even though English says too many treats, Polish uses a structure closer to too much of treats, which is why the genitive appears.

This is one of the most common learner questions.

Even though smakołyków is plural in meaning, the grammatical subject here is really the quantity expression:

• za dużo smakołyków = too many treats / too much of treats

In Polish, expressions like dużo, mało, kilka, sporo, etc. often behave differently from an ordinary plural noun. With dużo, the verb is commonly singular, and the predicate adjective is often neuter singular too.

So:

• za dużo smakołyków nie jest zdrowe = literally something like too much treats is not healthy

That is why you get:

• jest, not są
• zdrowe, not zdrowi / zdrowe plural

This is normal Polish grammar with quantity expressions.

Zdrowe is the neuter singular form of healthy.

It agrees with the whole phrase za dużo smakołyków, which is treated grammatically as a singular neuter quantity expression.

Compare:

• Ten smakołyk jest zdrowy. = This treat is healthy.
  
  • smakołyk is masculine singular, so zdrowy
• Ta karma jest zdrowa. = This food is healthy.
  
  • karma is feminine singular, so zdrowa
• To jedzenie jest zdrowe. = This food is healthy.
  
  • jedzenie is neuter singular, so zdrowe
• Za dużo smakołyków nie jest zdrowe.
  
  • the quantity phrase takes neuter singular agreement, so zdrowe

So the form is not matching smakołyków directly; it is matching the whole quantity idea.

Because dla (for) requires the genitive case.

So:

• pies = dog (dictionary form, nominative)
• psa = of/for a dog (genitive)

That is why:

• dla psa = for the dog

This is a fixed case rule:

• dla kota = for the cat
• dla dziecka = for the child
• dla weterynarza = for the vet

When you see dla, you should expect the next noun to be in the genitive.

Yes. Zbyt dużo smakołyków is correct and means essentially the same thing: too many treats.

The difference is mainly one of style:

• za dużo = very common, everyday
• zbyt dużo = a bit more formal or careful in tone

So both of these work:

• Weterynarz powiedział, że za dużo smakołyków nie jest zdrowe dla psa.
• Weterynarz powiedział, że zbyt dużo smakołyków nie jest zdrowe dla psa.

In normal conversation, za dużo is probably the more common choice.

Yes, Polish word order is fairly flexible, although some versions sound more natural than others.

The original sentence is very natural:

• Weterynarz powiedział, że za dużo smakołyków nie jest zdrowe dla psa.

You could also hear:

• Weterynarz powiedział, że dla psa za dużo smakołyków nie jest zdrowe.

This puts a bit more focus on for the dog.

However, not every rearrangement sounds equally smooth. Polish word order often changes for:

• emphasis
• contrast
• topic/focus
• style

For a learner, the original version is a very good neutral model.

Yes, smakołyki is a good word for treats, especially tasty little snacks.

In the context of a dog, it often means:

• dog treats
• little rewards
• snacks

Depending on context, Polish speakers might also say things like:

• przysmaki = delicacies / treats
• psie przysmaki = dog treats

But smakołyków is completely natural here.

Not perfectly. A word-for-word breakdown would be something like:

• Weterynarz = vet
• powiedział = said
• że = that
• za dużo = too much / too many
• smakołyków = of treats
• nie jest zdrowe = is not healthy
• dla psa = for the dog

So the literal structure is closer to:

The vet said that too much of treats is not healthy for the dog.

But natural English would be:

The vet said that too many treats aren’t healthy for the dog.

This is a good example of why Polish and English often express quantity differently.