Ons behandel die hond volgens die voorskrif en hy sterk aan.

A word-by-word breakdown is:

• Ons = we
• behandel = treat
• die hond = the dog
• volgens = according to
• die voorskrif = the prescription / the instructions
• en = and
• hy = he
• sterk aan = gets stronger / recovers / regains strength

So the structure is:

• Ons behandel die hond = We treat the dog
• volgens die voorskrif = according to the prescription
• en hy sterk aan = and he gets stronger

The last part is especially worth noticing because aansterk is a separable verb in this sentence, so it appears as sterk ... aan.

Afrikaans verbs are much simpler than English verbs in the present tense.

With most verbs, the verb form does not change for different persons:

• ek behandel = I treat
• jy behandel = you treat
• ons behandel = we treat
• hulle behandel = they treat

So behandel stays the same. Afrikaans does not need an extra verb like English am/is/are here.

In Afrikaans, die is the definite article for all nouns in the singular and plural.

So:

• die hond = the dog
• die voorskrif = the prescription
• die honde = the dogs

Unlike English, Afrikaans does not have different forms like the for one thing and another article for plural. It is just die.

Volgens means according to or in accordance with.

In this sentence, volgens die voorskrif means:

• according to the prescription
• according to the instructions
• as prescribed

It is a common formal or neutral way to say that something is being done in the proper instructed way.

Examples:

• volgens die reëls = according to the rules
• volgens die dokter = according to the doctor
• volgens die plan = according to the plan

Voorskrif can mean:

• a prescription, especially a medical one
• an instruction or set of directions
• something that is prescribed

In this sentence, because the dog is being treated, the most natural meaning is prescription or prescribed instructions.

So volgens die voorskrif could mean:

• according to the vet’s prescription
• according to the prescribed directions

This is because aansterk is a separable verb.

In a normal main clause, Afrikaans often puts the conjugated verb in second position, and the separable particle goes to the end:

• infinitive/dictionary form: aansterk
• main clause form: hy sterk aan

This is similar to other separable verbs in Afrikaans.

For example:

• Ek trek my jas aan. = I put on my coat.
• Hy staan vroeg op. = He gets up early.
• Die hond sterk aan. = The dog gets stronger / recovers.

So sterk ... aan is not two unrelated words. Together they belong to the verb aansterk.

Yes, it is related.

The base sterk means strong. As a verb in aansterk, it means something like:

• to gain strength
• to recover
• to improve physically
• to build up strength again

So hy sterk aan means that the dog is recovering or becoming stronger.

It is especially common in contexts involving illness, weakness, or recovery.

Afrikaans can use hy for a male animal, especially when the animal is known, specific, or treated like an individual.

So if the dog is male, hy is perfectly natural.

If the sex were unknown or irrelevant, some speakers might use dit, but with pets and animals people care about, hy or sy is very common.

So here:

• hy = he
• referring back to die hond

Yes. The sentence has two coordinated main clauses joined by en:

1. Ons behandel die hond volgens die voorskrif
2. en hy sterk aan

This is similar to English:

• We treat the dog according to the prescription, and he recovers.

Each part has its own subject and verb:

• Ons ... behandel
• hy ... sterk aan

Yes, it is understandable and basically natural.

It means that the treatment is being given as prescribed, and as a result the dog is recovering.

A speaker might also say similar versions such as:

• Ons behandel die hond volgens die voorskrif, en hy sterk aan.
• Ons behandel die hond soos voorgeskryf, en hy sterk aan.

The original sentence is fine, but many writers would add a comma before en because two full clauses are being joined.

Because it is a separable verb, its forms change in a way that may look unusual at first.

Examples:

• Hy sterk aan. = He is recovering / getting stronger.
• Die hond het aangesterk. = The dog recovered / has regained strength.
• Die hond sal aansterk. = The dog will recover.
• om aan te sterk = to recover / to gain strength

So in a main present-tense clause, you often see it split:

• sterk ... aan

But in the infinitive or with another auxiliary, it is usually written together:

• aansterk
• aangesterk