El perro empezó a cojear ayer.

Empezó is the preterite, which is commonly used for a completed event or a specific starting point in the past. In this sentence, the idea is that the dog started limping yesterday—that beginning happened at a definite moment.

Empezaba is the imperfect, which usually describes background, repeated actions, or actions in progress in the past. It would sound less natural here unless you were setting a scene, for example in a longer story.

• El perro empezó a cojear ayer. = The dog started limping yesterday.
• El perro cojeaba ayer. = The dog was limping yesterday.

So empezó focuses on the moment the limping began.

After empezar, Spanish normally uses a + infinitive to mean to start doing something.

So:

• empezó a cojear = started to limp
• literally: started to limp

This is a very common pattern:

• Empezó a llover. = It started to rain.
• Empecé a estudiar. = I started studying.

So the a is not optional here in normal Spanish.

Cojear means to limp or to walk with difficulty because of pain or injury in a leg or foot.

It is a verb. In this sentence, a cojear means to limp.

Related forms:

• cojear = to limp
• cojea = he/she limps, is limping
• cojeando = limping

Example:

• El perro cojea mucho. = The dog limps a lot.

In Latin American Spanish, cojear is pronounced roughly like ko-HEH-ar.

Key point:

• The j has a strong h-like sound in English, but rougher: co-he-ar
• The last part -ear is usually pronounced in two syllables: e-ar

So it sounds approximately like:

• cojear → ko-heh-AR

Also:

• empezó has stress on the last syllable because of the written accent: em-pe-SO

The accent mark in empezó shows that the stress falls on the last syllable: em-pe-ZÓ.

It also helps distinguish forms in writing. For example:

• empezo would be incorrect
• empezó = he/she/it started

Many preterite third-person singular forms have a written accent:

• habló
• comió
• vivió
• empezó

So the accent is both a spelling rule and a pronunciation guide.

Spanish often uses the definite article more than English does. El perro simply means the dog.

You usually need the article with a singular countable noun unless there is some special reason to leave it out.

• El perro empezó a cojear ayer. = The dog started limping yesterday.

If you said just Perro empezó a cojear ayer, it would sound incomplete or unnatural in standard Spanish.

Yes. Ayer is flexible in Spanish. These are all natural:

• El perro empezó a cojear ayer.
• Ayer el perro empezó a cojear.
• El perro ayer empezó a cojear. (possible, though less neutral in many contexts)

The most neutral versions are usually:

• Ayer el perro empezó a cojear.
• El perro empezó a cojear ayer.

The meaning stays basically the same, but the position can slightly change the emphasis.

Yes. Comenzó a cojear and empezó a cojear mean essentially the same thing: started to limp.

• empezar = to begin / to start
• comenzar = to begin / to start

In everyday speech, empezar is extremely common. Comenzar is also very normal and not especially formal, just a bit different in style.

Yes, that is also possible, but it has a slightly different feel.

• empezó a cojear = started limping
• se puso a cojear = began to limp / started limping

Ponerse a + infinitive often emphasizes the action suddenly beginning.

So:

• El perro empezó a cojear ayer. = neutral
• El perro se puso a cojear ayer. = often feels a little more like the dog suddenly began limping

Both are correct, but empezó a cojear is the most straightforward version.

Because estaba cojeando means was limping, which focuses on the action being in progress, not on its beginning.

Compare:

• El perro empezó a cojear ayer. = The dog started limping yesterday.
• El perro estaba cojeando ayer. = The dog was limping yesterday.

So the original sentence is specifically about when the limping began, not just the fact that it was happening.

Mostly yes, but it has a spelling change in some forms to keep the pronunciation consistent.

Infinitive:

• cojear

Present tense examples:

• cojeo
• cojeas
• cojea
• cojeamos
• cojean

Notice the j stays there so the sound remains the same.

This kind of verb is not highly irregular in meaning or structure; the main thing to remember is the spelling and pronunciation.

The subject is El perro.

Spanish often drops subject pronouns like él, ella, or ellos when the verb already makes the subject clear. But here el perro is a noun, and it is important information, so it is stated.

You could not just say:

• Empezó a cojear ayer.

unless the context already made it very clear who started limping.

So in this sentence:

• El perro = subject
• empezó = verb
• a cojear = infinitive phrase depending on empezó
• ayer = time expression

The sentence already sounds completely natural in Latin American Spanish.

Some conversational alternatives could be:

• El perro empezó a cojear ayer.
• Ayer el perro empezó a cojear.
• Desde ayer el perro cojea. = The dog has been limping since yesterday.
• El perro amaneció cojeando. = The dog woke up limping / seemed to start the day limping.

But the original is simple, correct, and very natural.