The Chihuahua is the world’s smallest recognised dog breed — and one of the oldest, with roots tracing back to pre-Columbian Mexico. There are two coat varieties (smooth and long) and two head types (apple head and deer head), which creates more variation in appearance than in most breeds. Despite their tiny size, Chihuahuas possess enormous personalities — bold, alert, fiercely loyal to their chosen person, and often comically self-assured. They are wonderful companion dogs when their specific health vulnerabilities and social needs are properly managed.
Quick Facts
| Characteristic | Detail |
|---|---|
| Size | Toy (15–23 cm; 1.5–3 kg — KC standard does not specify height, only maximum weight of 2.7 kg preferred) |
| Coat | Smooth (short, sleek) or Long (soft, feathered) — any colour or combination |
| Exercise | 30–45 minutes per day — moderate; they are more active than many expect |
| Lifespan | 12–20 years — one of the longest-lived breeds |
| Good for flats? | Excellent |
| Puppy cost (UK 2026) | £500–£2,000 |
| KC group | Toy |
Health — Key Conditions
Hydrocephalus
Congenital hydrocephalus (“water on the brain”) is a build-up of cerebrospinal fluid inside the skull, causing pressure on the brain. Chihuahuas are among the breeds most predisposed:
- Warning signs in puppies: Dome-shaped skull that appears disproportionately large, open fontanel (molera) that remains wide, eyes deviating downward (“sunset eyes”), seizures, abnormal gait, behavioural changes
- Diagnosis: Ultrasound through the open fontanel in puppies; MRI or CT scan in older dogs
- Treatment: Mild cases may be managed with medication (corticosteroids, diuretics to reduce fluid production). Severe cases may require surgical shunt placement
- Not all Chihuahuas with a molera have hydrocephalus — but a large, persistent molera should be monitored
The Molera (Fontanel)
Many Chihuahua puppies are born with an open “soft spot” on the top of their skull — the molera. This is similar to the fontanelle in human infants:
- In most puppies, the molera gradually closes as the skull ossifies. In some Chihuahuas, it remains partially or fully open into adulthood
- A persistent molera does not automatically indicate disease — historically it was even considered a breed characteristic
- However, a large open molera means the brain is protected only by a membrane, not bone — making the dog vulnerable to trauma. Handle gently, avoid rough play around the head area
Heart Disease — Mitral Valve Disease (MVD)
MVD is the most common heart condition in Chihuahuas and small breeds generally. The mitral valve thickens and degenerates, causing blood to leak backward in the heart:
- Often detected as a heart murmur during routine vet checks — starting from mid-life (age 5+)
- Many dogs live years with a mild murmur and no symptoms
- Progressive cases develop to congestive heart failure: coughing (especially at night/early morning), breathlessness, exercise intolerance, fluid accumulation
- Medication (pimobendan, ACE inhibitors, diuretics) can manage symptoms and significantly extend life when started at the right stage
Luxating Patella
Kneecap dislocation is very common in Chihuahuas. Graded 1–4, with Grade 1 (intermittent skip) often managed conservatively and Grade 3–4 requiring surgical correction. Maintain an optimal weight — even 200g of excess weight on a 2kg Chihuahua is proportionally enormous.
Safe Handling
Chihuahuas have extremely fragile bones — a fall from a sofa height, being stepped on, or rough handling by a child can cause fractures:
- Not suitable for households with very young children who cannot understand the need for gentle handling
- Supervise interactions with larger dogs — play that is normal between two Labradors can critically injure a Chihuahua
- Use a harness, not a collar — their small trachea is vulnerable to pressure
- Cold weather: Chihuahuas feel the cold intensely — a dog coat is a welfare necessity, not a fashion accessory
FAQs
Why do Chihuahuas shake?
Chihuahua shaking is one of the most common new-owner concerns. It has multiple causes: cold (their tiny bodies lose heat rapidly), excitement, anxiety, or low blood sugar (hypoglycaemia — more common in puppies and very small adults). Persistent unexplained shaking warrants a vet check to rule out hypoglycaemia, pain, or neurological issues. Occasional shaking from cold or excitement is normal — provide warmth, calm reassurance, and regular small meals.