Chihuahua Puppy Milestones: What to Expect in the First Year

Bringing home a Chihuahua puppy is both exciting and a little overwhelming. These tiny dogs may be small in size, but they grow and change quickly—especially in their first year of life. From wobbly steps to confident tail wags, your pup will hit several key milestones as they mature physically, emotionally, and behaviorally.

Understanding what to expect during each stage of your Chihuahua’s development can make life easier for both of you. It helps you support their growth, spot any concerns early, and guide them into becoming a happy, confident companion.

In this guide, we’ll walk you through the major Chihuahua puppy milestones, month by month, so you can feel prepared—and even more connected to your pup—as they grow from playful puppy to spirited young adult.

Let’s dive into what the first year with your Chihuahua might look like!

Weeks 0–8: The Newborn Phase

During the first two months of life, your Chihuahua puppy is still in the care of their mother and littermates. This period is all about growth, warmth, and basic development. Their eyes and ears open around 2–3 weeks of age, and they slowly begin to explore their surroundings by crawling, walking, and interacting with their siblings.

What Happens During This Phase:

• Puppies rely entirely on their mother for food, warmth, and cleaning.
• They begin to learn basic social behavior—bite inhibition, communication, and play—from their littermates.
• Around 6–8 weeks, they start eating soft solid food alongside nursing.
• Their personality traits may start to emerge—timid, bold, curious, etc.

Important Note for New Owners:

It may be tempting to bring a puppy home early, but reputable breeders and rescues will not rehome a Chihuahua before 8 weeks of age (ideally 9–10 weeks). Removing a puppy too soon can interfere with their emotional development and make future training more difficult.

Weeks 8–12: The Socialization Window

This is one of the most important stages in your Chihuahua puppy’s entire life. Around 8 weeks old, they’re typically ready to leave their mother and begin adjusting to their new home. During this window, their brain is like a sponge—ready to absorb new experiences, sights, sounds, and routines.

What to Expect During This Phase:

• Your puppy may be shy, excited, or both—it’s a big transition.
• They’re learning who and what is safe, so gentle exposure is key.
• Start potty training, crate training, and name recognition.
• They begin their first round of vaccinations, usually between 6–8 weeks and again at 10–12 weeks.

How to Support Them:

• Keep interactions positive and calm—especially with kids, new people, or other pets.
• Introduce household sounds gradually (vacuum, doorbell, etc.).
• Begin gentle handling: touch paws, ears, belly to prep for grooming and vet visits.
• Use treats and praise to reward curiosity and calm behavior.

This is also a great time to introduce essential tools like a soft harness, chew toys, or a puppy pen for safe play.

Helping your Chihuahua feel secure and confident now will lay the foundation for a well-adjusted, happy dog later.

Months 3–4: Confidence & Curiosity Spike

By now, your Chihuahua puppy is starting to settle into your home—and their personality really begins to shine. At this stage, many puppies become more adventurous, playful, and sometimes… mischievous. Their confidence is growing, and so is their curiosity about the world around them.

What to Expect During This Phase:

• Teething begins, leading to increased chewing and occasional nipping.
• Your puppy may start testing boundaries—chewing shoes, ignoring commands, etc.
• Their energy and independence grow quickly.
• A short “fear period” may appear—where they suddenly act cautious or nervous about things they were previously okay with.

How to Support Them:

• Provide plenty of safe chew toys and redirect unwanted chewing calmly.
• Begin reinforcing basic commands: sit, stay, come, leave it.
• Use short, consistent training sessions (5–10 minutes daily).
• Socialize gently but consistently—positive exposure to people, dogs, and places.

Consistency and patience are key. Your Chihuahua is learning what behaviors get attention, so always reward the good and redirect the rest. This is a fantastic window to start building the routines that will last a lifetime.

Months 5–6: Testing Limits (Adolescence Begins)

Welcome to the teenage phase—yes, even tiny Chihuahuas go through it! Around 5 to 6 months of age, your puppy may start testing boundaries, ignoring commands they previously mastered, or becoming a bit more bold or stubborn. It’s totally normal.

This stage marks the beginning of adolescence, and while it can be challenging, it’s also a crucial time to reinforce the habits and structure you’ve been building.

What to Expect During This Phase:

• Increase in independence and selective listening (“I heard you say come… but I’m busy.”)
• Possible regressions in potty training or obedience
• Continued teething—watch for increased chewing
• Girls may go into their first heat; boys may start marking or showing territorial behavior
• Your vet may recommend spaying or neutering around this time

How to Support Them:

• Stay calm, consistent, and positive with training
• Keep rules clear and routines predictable
• Increase mental stimulation through short walks, training games, or puzzle toys
• Revisit earlier lessons like leash walking, recall, and polite greetings
• Provide plenty of praise and rewards for good choices

Don’t worry if your sweet puppy seems a little rebellious—this is a phase, not a personality flaw. With patience and structure, they’ll come out the other side as a more focused, confident young adult.

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Months 7–9: Maturing Mentally and Physically

At this stage, your Chihuahua is starting to look and act more like a grown dog—but they’re still very much a work in progress. You’ll likely notice bursts of energy mixed with moments of calm, as your pup begins to settle into a more balanced rhythm.

They’re also better able to focus, making this a great time to refine training and reinforce good habits.

What to Expect During This Phase:

• A more predictable energy pattern (though zoomies still happen!)
• Increasing emotional maturity—stronger attachment, more affection
• Potential guarding or protective behaviors as they become more aware of their environment
• Improved understanding of commands and household routines
• Their adult coat may start coming in, especially in long-haired Chihuahuas

How to Support Them:

• Stay consistent with boundaries while giving them more responsibility and freedom
• Practice calm behavior in stimulating environments (parks, walks, new visitors)
• Continue daily training—even just 5 minutes a day keeps their mind sharp
• Introduce more challenging toys, longer walks, or new tricks
• Watch for signs of overprotection or anxiety and gently redirect

This is a great time to really bond deeper with your Chihuahua. They’re learning how to be part of your life in a stable, dependable way—keep showing up with love, guidance, and patience.

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Months 10–12: Transition to Young Adulthood

By 10 to 12 months, your Chihuahua is leaving puppyhood behind and stepping into young adulthood. Their behavior becomes more stable, they’re better at self-regulation, and they’ve likely developed a clearer personality—whether that’s bold and outgoing, or gentle and reserved.

While they may still have bursts of puppy-like energy, most Chihuahuas at this stage have settled into their routines and habits. Now is the time to strengthen the foundation you’ve built during their first year.

What to Expect During This Phase:

• Full set of adult teeth
• More reliable potty habits and training response
• Less mouthing and teething behavior
• Settled sleep and activity patterns
• Reinforcement of learned behaviors—good or bad

How to Support Them:

• Continue positive reinforcement and structured routines
• Address any lingering problem behaviors with training or professional support if needed
• Keep them mentally engaged with interactive toys and occasional new challenges
• Evaluate their diet, grooming routine, and vet care to ensure they’re set for adulthood
• Celebrate how far they’ve come—both of you!

By their first birthday, your Chihuahua will have made huge strides physically, emotionally, and behaviorally. While some puppy traits may still linger, you’ve officially raised a young adult—and laid the groundwork for a happy, healthy life together.

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Conclusion: The First Year is Just the Beginning

Watching your Chihuahua grow through their first year is an unforgettable experience. From their first wobbly steps to confident zoomies, this journey is filled with adorable milestones, learning curves, and countless bonding moments.

Each stage of development brings its own challenges and joys—but with patience, structure, and love, you’re helping your puppy grow into a confident, well-adjusted adult. Whether you’re dealing with teething chaos or celebrating their first successful “stay,” every small win counts.

Just remember: no two Chihuahuas grow exactly the same way. Your pup may reach certain milestones a little earlier or later—and that’s completely okay. What matters most is that you’re showing up with care, attention, and the willingness to learn and grow alongside them.

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Have you recently welcomed a Chihuahua puppy into your life?

We’d love to hear what stage your pup is in and what you’ve learned along the way!

FAQ: Chihuahua Puppy Milestones

1. When do Chihuahua puppies start teething?

Teething usually starts around 3 to 4 months and can last until about 6 months. During this time, you’ll notice more chewing and possibly sore gums—provide safe chew toys to help.

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2. At what age is a Chihuahua considered fully grown?

Chihuahuas typically reach their full adult size by 10 to 12 months, but some may continue to fill out slightly until 18 months, especially in terms of muscle tone and coat.

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3. When should I start training my Chihuahua puppy?

You can begin basic training like name recognition, potty routines, and gentle commands as early as 8 weeks old. Keep sessions short, fun, and consistent.

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4. Are fear periods normal in Chihuahua puppies?

Yes, brief fear periods can happen around 3–4 months and again around 6–9 months. During these times, your puppy may suddenly become cautious or afraid of things they were previously okay with. Stay calm, avoid forcing them, and use positive reinforcement.

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5. Is it okay if my Chihuahua isn’t hitting all the milestones exactly on time?

Yes! Every puppy develops at their own pace. Use the milestones as a general guide, not a strict schedule. If you’re concerned, consult your vet or a certified trainer.