Complete Breed Guide for Prospective Owners
Everything about the Chihuahua Rat Terrier mix — size, temperament, health risks, coat types, cost, and whether this designer blend fits your lifestyle.
If you've spotted a compact, alert little dog with the sass of a Chihuahua and the athletic drive of a Rat Terrier, you've likely encountered the Chihuahua Rat Terrier mix — sometimes called the "Rat-Cha" or "Cha-Rat." This designer cross has quietly gained a following among owners who want a small dog with genuine working-dog intelligence rather than pure lap-dog tendencies.
But mixed breeds come with a built-in wildcard: you can't predict exactly which parent's traits any given puppy will inherit. This guide breaks down what you can reasonably expect — and where the surprises tend to show up — so you can decide whether this mix is the right fit for your household.
Parent Breed Breakdown: Chihuahua Meets Rat Terrier
Understanding the parent breeds is the single most useful tool for predicting what a Chihuahua Rat Terrier mix puppy might grow into. Both breeds are small, but their histories, drives, and personalities diverge significantly.
| Trait | Chihuahua | Rat Terrier |
|---|---|---|
| AKC Group | Toy | Terrier |
| Weight Range | 2–6 lb (0.9–2.7 kg) | 10–25 lb (4.5–11.3 kg) — Miniature & Standard varieties |
| Height | 5–8 in (13–20 cm) | 10–18 in (25–46 cm) |
| Lifespan | 14–16+ years | 12–18 years |
| Original Purpose | Companion (ancient Toltec/Aztec lineage) | Farm ratter, hunting terrier |
| Energy Level | Moderate — short bursts | High — sustained athletic drive |
| Prey Drive | Low to moderate | High — bred to chase and kill small animals |
| Trainability | Moderate — can be stubborn | High — eager, responsive, excels in dog sports |
| Barking | High tendency | Moderate to high |
| Coat | Smooth or long; moderate shedder | Short, smooth; low to moderate shedder |
The Chihuahua traces its roots to the ancient Techichi dogs of Mesoamerica and was refined in the Mexican state of Chihuahua in the 19th century. The Rat Terrier, recognized by the AKC in 2013, descends from Fox Terriers crossed with Beagles, Whippets, and Italian Greyhounds — bred for speed and versatility on American farms.
When you cross these two, you're blending a companion-bred toy dog with a purpose-bred working terrier. That tension shapes everything about the mix.
How Big Will a Chihuahua Rat Terrier Mix Get?
Size is one of the more variable traits in this cross, and it depends heavily on which variety of Rat Terrier was used as the parent — the Miniature (10–13 in, 10–18 lb) or the Standard (13–18 in, 15–25 lb).
| Size Category | Weight | Height at Shoulder |
|---|---|---|
| Small end (Chihuahua-dominant) | 6–10 lb (2.7–4.5 kg) | 8–10 in (20–25 cm) |
| Mid-range (balanced blend) | 10–15 lb (4.5–6.8 kg) | 10–13 in (25–33 cm) |
| Large end (Rat Terrier-dominant) | 15–20 lb (6.8–9.1 kg) | 13–15 in (33–38 cm) |
Most Chihuahua Rat Terrier mixes land in the 8–15 lb (3.6–6.8 kg) range as adults. Males tend toward the upper end. If the breeder used a Miniature Rat Terrier, expect a smaller dog; a Standard Rat Terrier parent pushes the mix larger.
Generation Terminology: What F1, F1B, and F2 Mean
F1 (First Generation): One purebred Chihuahua parent × one purebred Rat Terrier parent. These puppies show the widest trait variation — some look almost entirely Chihuahua, others lean heavily Rat Terrier.
F1B (Backcross): An F1 mix bred back to one of the parent breeds. An F1B crossed to a Rat Terrier will produce a slightly larger, more terrier-like dog. An F1B crossed to a Chihuahua will skew smaller and more companion-oriented.
F2 (Second Generation): Two F1 Chihuahua Rat Terrier mixes bred together. Trait variation remains high — genetics don't "settle" in just two generations.
Multigen (F3+): Multiple generations of the cross bred together. Still not a standardized breed, but trait predictability improves slightly. True consistency requires many generations of selective breeding, which is rare for this particular mix.
Temperament: What to Expect (and What Might Surprise You)
The Chihuahua Rat Terrier mix inherits two strong-willed, intelligent parent breeds. The result is typically a dog that is far more capable and opinionated than its small size suggests.
Best-Case Temperament Scenario
A well-socialized Chihuahua Rat Terrier mix combines the Rat Terrier's eagerness to work with the Chihuahua's devotion to its person. You get a dog that:
- Learns commands quickly and enjoys training sessions
- Forms a deep bond with one or two people without being clingy
- Has an "off switch" indoors but is ready for adventure outdoors
- Alerts you to visitors without excessive, nonstop barking
- Gets along with respectful children and other dogs when properly introduced
Challenging Temperament Scenario
Less socialized individuals, or those that inherit a stronger combination of both breeds' stubborn streaks, may display:
- High prey drive: Chasing cats, squirrels, and small dogs — the Rat Terrier's ratter instinct is powerful and not easily trained away
- Resource guarding: Food, toys, or a favorite person — both breeds can show possessive tendencies
- Reactivity on leash: Barking and lunging at other dogs, especially larger ones
- Separation distress: Vocalizing or destructive behavior when left alone too long
- Wariness of strangers: The Chihuahua's suspicion of unfamiliar people can intensify without early socialization
The key variable is the individual puppy's genetic lottery. Littermates can have dramatically different temperaments. A reputable breeder or foster-based rescue can give you the best read on a specific dog's personality.
Coat, Shedding, and Grooming Needs
Neither the Chihuahua nor the Rat Terrier carries the curly or wiry coat genes associated with low-shedding breeds like Poodles. This means the Chihuahua Rat Terrier mix is not hypoallergenic and will shed to some degree.
Coat Type Possibilities
- Short smooth coat (most common): Inherited from both parents — sleek, close-lying hair similar to a Rat Terrier. Low maintenance but does shed seasonally.
- Slightly longer smooth coat: If the Chihuahua parent is a long-coat variety, puppies may inherit a medium-length coat with feathering on the ears, chest, and tail.
- Apple head vs. deer head: Head shape varies — some inherit the Chihuahua's rounded "apple" skull, others get the Rat Terrier's more elongated muzzle. The apple-head conformation carries a higher risk of molera (open fontanel) and dental crowding.
Grooming Schedule
| Task | Frequency | Notes |
|---|---|---|
| Brushing | 1–2× per week | Rubber curry brush or bristle brush; increase to daily during spring/fall shedding peaks |
| Bathing | Every 4–6 weeks | Use a mild, canine-formulated shampoo; over-bathing strips natural oils |
| Nail trimming | Every 2–3 weeks | Small dogs' nails grow fast — if you hear clicking on floors, they're too long |
| Dental care | Daily brushing ideal | Both parent breeds are prone to dental disease; start early with enzymatic toothpaste |
| Ear cleaning | Every 1–2 weeks | Especially important for erect-eared individuals; check for debris and odor |
Shedding level: expect moderate shedding year-round with heavier seasonal blows in spring and fall. A FURminator deshedding tool (small/short-hair version, approximately $25–$35) works well for the undercoat during peak shedding.
Health Considerations: Hybrid Vigor vs. Reality
One of the most persistent myths in the designer dog world is that mixed breeds automatically enjoy "hybrid vigor" — the idea that crossing two breeds eliminates health problems. The reality, as veterinary geneticists consistently explain, is more nuanced. The Merck Veterinary Manual notes that hybrid vigor (heterosis) primarily applies to traits controlled by many genes, like fertility and overall vitality — it does not erase the risk of inherited conditions that both parent breeds share.
Conditions Inherited From the Chihuahua Side
- Patellar luxation: Kneecap that pops out of place; graded I–IV. Prevalence in Chihuahuas estimated at 15–20%. Surgical correction for Grade III–IV costs $1,500–$3,500 per knee.
- Dental overcrowding and periodontal disease: Small jaws mean teeth crowd and rotate, trapping plaque. By age 3, an estimated 80%+ of toy breeds show some periodontal disease.
- Tracheal collapse: Weakening of the cartilage rings in the windpipe, causing a honking cough. More common in dogs under 10 lb. Management ranges from cough suppressants ($20–$50/month) to surgical stents ($3,000–$5,000+).
- Molera (open fontanel): Soft spot on the skull that may not fully close. Increases risk of hydrocephalus and head trauma vulnerability.
- Hypoglycemia: Low blood sugar, especially in puppies under 6 months. Requires frequent small meals and monitoring.
Conditions Inherited From the Rat Terrier Side
- Patellar luxation: Also prevalent in Rat Terriers — this is a shared risk, meaning the mix does not benefit from hybrid vigor here.
- Legg-Calvé-Perthes disease: Degeneration of the femoral head (hip joint), typically appearing between 4–12 months of age. Surgical removal of the femoral head costs $1,500–$3,000; prognosis is generally good with rehabilitation.
- Primary lens luxation (PLL): A painful eye condition where the lens dislocates. The Rat Terrier breed has a known genetic mutation (ADAMTS17) — a DNA test is available through the AKC Genetic Testing program.
- Allergic skin disease: Rat Terriers are prone to atopic dermatitis and food sensitivities. Manifests as paw licking, ear infections, and itchy skin.
- Cardiac conditions: Mitral valve disease appears in both parent breeds, particularly in older dogs.
When to See the Vet Immediately
- Sudden lameness or "skipping" gait (possible patellar luxation or fracture — small bones are fragile)
- Honking cough or difficulty breathing, especially during exercise or excitement
- Eye redness, cloudiness, or apparent pain (possible lens luxation — this is an emergency)
- Seizures, disorientation, or pressing head against walls
- Refusal to eat for more than 12 hours in a puppy (hypoglycemia risk)
Always consult your veterinarian for diagnosis and treatment. This article does not replace professional veterinary care.
Recommended Health Screening
If you're buying from a breeder, ask for documentation of these tests on both parent dogs:
- Patellar evaluation (OFA or equivalent) — both breeds
- Cardiac exam by a veterinary cardiologist — both breeds
- ADAMTS17 DNA test for PLL — Rat Terrier parent
- Ophthalmologist evaluation (CERF/OFA) — both breeds
- Dental assessment — especially if the Chihuahua parent shows overcrowding
Training, Exercise, and Daily Life
This mix has more mental and physical capacity than many owners initially expect. The Rat Terrier's working-dog heritage means these dogs need jobs — even if the job is a puzzle toy or a 10-minute training session.
Exercise Requirements
- Daily walks: 30–45 minutes total, split into two sessions. This is not a breed that does well with only backyard potty breaks.
- Play sessions: 15–20 minutes of active play (fetch, flirt pole, tug) at least once daily.
- Mental stimulation: Food puzzles, snuffle mats, or short training drills. A bored Chihuahua Rat Terrier mix will invent its own entertainment — usually by chewing something expensive.
Training Approach
Use positive reinforcement methods only — treats, praise, play rewards, and marker-based training (clicker or verbal marker like "yes!"). Both parent breeds are sensitive to harsh corrections. The Chihuahua side may shut down or become defensive; the Rat Terrier side may become conflict-averse or, paradoxically, more reactive.
Priority training goals for this mix:
- Recall (come when called): Essential because the prey drive means they will chase. Practice in fenced areas first; never trust recall around wildlife until it's proofed extensively.
- Leash manners: Start early. A front-clip harness (such as the Ruffwear Front Range, ~$40) reduces pulling without neck pressure — critical for breeds prone to tracheal collapse.
- Socialization window: The critical socialization period closes around 14–16 weeks. Expose puppies to diverse people, surfaces, sounds, and other vaccinated dogs during this window.
- Alone-time training: Build up duration gradually (5 minutes → 15 → 30 → 60) to prevent separation distress. Use a Kong stuffed with frozen peanut butter as a departure cue.
Never use shock collars, prong collars, or alpha-roll techniques on this mix. The combination of small physical size and terrier sensitivity makes aversive methods both harmful and counterproductive.
Cost: Purchase Price, Annual Expenses, and Rescue Options
Puppy Purchase Price
| Source | Price Range | What's Typically Included |
|---|---|---|
| Reputable breeder (health-tested parents, take-back clause) | $600–$1,500 | First vaccinations, deworming, microchip, health guarantee, spay/neuter contract |
| Casual/backyard breeder | $200–$500 | Often nothing beyond the puppy itself — health testing rarely done |
| Breed-specific rescue | $200–$450 adoption fee | Spay/neuter, vaccinations, microchip, behavioral assessment, foster history |
| General shelter | $50–$250 | Spay/neuter, basic vaccinations, microchip |
Rescue is a strong option for this mix. Because both Chihuahuas and Rat Terriers are common in shelters — particularly in the southern and southwestern U.S. — mixed offspring turn up regularly. Search Petfinder.com using both parent breed names, or contact Rat Terrier-specific rescues like Rat Terrier Rescue (national, volunteer-run) and Chihuahua rescues in your region.
Estimated First-Year Costs
- Puppy purchase/adoption: $200–$1,500
- Initial veterinary visit + vaccine series (DHPP, rabies, bordetella): $200–$400
- Spay/neuter (if not included): $300–$600
- Supplies (crate, harness, bed, bowls, toys, grooming tools): $150–$300
- High-quality small-breed kibble (annual): $200–$350
- Preventive medications (heartworm, flea/tick — annual): $150–$300
- Training classes (puppy socialization + basic obedience): $150–$350
- Pet insurance (optional but recommended): $300–$600/year for small breeds (providers like Trupanion, Healthy Paws, or Lemonade)
Realistic first-year total: $1,650–$4,400 depending on source and whether unexpected health issues arise.
Who Is the Chihuahua Rat Terrier Mix Best Suited For?
This mix is not a one-size-fits-all dog. Here's a framework to evaluate fit:
| Factor | Good Fit | Poor Fit |
|---|---|---|
| Experience level | Intermediate to experienced owners who understand terrier drive and small-dog fragility | First-time owners expecting a low-effort lap dog |
| Household composition | Adults, couples, or families with children aged 8+ who understand how to handle small dogs gently | Families with toddlers or very young children (injury risk to the dog) |
| Other pets | Other dogs of similar or larger, calm temperament; cats if raised together from puppyhood | Households with pet rodents, birds, or rabbits (prey drive); intact same-sex dogs (territorial risk) |
| Living space | Apartments or condos with daily outdoor access; houses with fenced yards | Strictly outdoor living (too small for temperature extremes); unfenced properties |
| Activity level | Owners who walk daily and enjoy short hikes, dog sports (agility, rally, nose work) | Sedentary lifestyles; owners away 10+ hours/day with no midday break |
| Noise tolerance | People who don't mind an alert-barking dog | Close-quarters apartment living with noise-sensitive neighbors |
The ideal owner is someone who appreciates a small dog with a big personality — someone who'll enroll in agility classes or nose work rather than expecting the dog to simply sit on the couch all day. Rat Terrier heritage means this mix thrives when it has a purpose, even if that purpose is learning tricks for 10 minutes each morning.
Frequently Asked Questions
What two breeds make up the Chihuahua Rat Terrier mix?
The Chihuahua Rat Terrier mix is a cross between a purebred Chihuahua (Toy Group, 2–6 lb) and a purebred Rat Terrier (Terrier Group, 10–25 lb depending on variety). The mix is not recognized as a standardized breed by the AKC but may be registered with hybrid registries like the ACHC (American Canine Hybrid Club) or DRA (Designer Dogs Kennel Club).
How big will my Chihuahua Rat Terrier mix get?
Most adults fall between 8–15 lb (3.6–6.8 kg) and 8–14 inches (20–36 cm) at the shoulder. The exact size depends on whether the Rat Terrier parent was Miniature or Standard, and which parent's growth genes the puppy inherits. Ask the breeder for the weight of both parents at maturity — the puppy's adult weight typically falls somewhere between the two.
Is the Chihuahua Rat Terrier mix hypoallergenic or low-shedding?
No. Neither parent breed carries the low-shedding coat genes found in breeds like Poodles or Bichon Frises. Expect moderate year-round shedding with seasonal increases. If allergies are a concern, spend time with the specific dog before committing — individual coat types vary, and allergen exposure depends on the specific dog's dander production, not just shedding volume.
Are Chihuahua Rat Terrier mixes good with children?
They can be, with important caveats. Children must be old enough (generally 8+) to handle a small dog gently — a 10-lb dog can be seriously injured by a toddler's accidental drop or squeeze. Supervision is non-negotiable. The mix tends to bond closely with family members, including children it's raised with, but may not tolerate rough handling or ear-pulling.
What health issues might this mix inherit?
Shared risks from both parent breeds include patellar luxation, dental disease, and mitral valve disease. Chihuahua-specific risks include tracheal collapse, molera, and hypoglycemia (in puppies). Rat Terrier-specific risks include Legg-Calvé-Perthes disease, primary lens luxation (PLL), and allergic skin conditions. Health testing of parent dogs significantly reduces — but does not eliminate — these risks.
How much does a Chihuahua Rat Terrier mix cost?
From a reputable breeder, expect $600–$1,500. Rescue adoption fees range from $50–$450. First-year total ownership costs (including veterinary care, supplies, food, and training) typically fall between $1,650–$4,400. Ongoing annual costs after the first year average $800–$1,500 for routine care, food, and preventives.
How long do Chihuahua Rat Terrier mixes live?
Both parent breeds are notably long-lived. A healthy Chihuahua Rat Terrier mix can reasonably be expected to live 13–17 years, with some individuals reaching 18+. Lifespan depends on weight management, dental care, preventive veterinary visits, and avoiding trauma (small dogs are vulnerable to being stepped on or dropped).
Do Chihuahua Rat Terrier mixes bark a lot?
Both parent breeds have moderate-to-high barking tendencies — the Chihuahua as an alert watchdog, the Rat Terrier as a vocal terrier. Expect a dog that barks at doorbells, passersby, and unusual sounds. Consistent training with positive reinforcement can manage excessive barking, but a completely silent version of this mix is unlikely.
This article is for informational purposes only and does not replace professional veterinary advice. Always consult your veterinarian for health decisions regarding your dog. If your dog ingests a toxic substance, contact the ASPCA Animal Poison Control Center at (888) 426-4435 (24/7, consultation fee applies).
Anouk Beaumont
All our authors care for dogs every day — read more of their work on the authors page.
