Chihuahua outdoors - UK breed health guide
on September 07, 2026

Chihuahua Health Issues: A Complete UK Owner's Guide

Most Chihuahua content leads with hydrocephalus ("water on the brain") as the headline scare, but a 2020 UK VetCompass study of primary-care records found the breed's actual most common conditions are periodontal disease (13.5%), obesity (5.9%), and retained baby teeth (5.7%) — and, strikingly, traumatic injury is the third most common cause of death. This guide covers the real, UK-sourced health picture, including a genuine fragility risk most breed guides don't mention at all.

Last updated 7 September 2026. Written by Jamie Sinclair, who writes about canine health, nutrition, and everyday care for Doggy Dailies — focused on translating veterinary research and real ingredient science into practical, honest guidance UK dog owners can use.

Table of Contents

Breed Overview

The Chihuahua is the smallest recognised dog breed, typically weighing 1.5–3kg and standing 15–23cm at the shoulder. Despite their tiny size, Chihuahuas are typically bold, alert, and often fiercely loyal to their owner, sometimes wary of strangers or other dogs. They come in smooth and long coat varieties and a wide range of colours.

What UK Vets Actually Record Most: The 2020 VetCompass Study

Most Chihuahua content online leads with hydrocephalus as the headline health concern — understandably alarming, but not actually representative of what UK vets see most often. A 2020 study by O'Neill and colleagues, using the Royal Veterinary College's VetCompass™ primary-care clinical records from 2016, found the most common specific disorders recorded in UK Chihuahuas were periodontal disease (13.5%), obesity (5.9%), retained deciduous (baby) teeth (5.7%), anal sac impaction (4.9%), and aggression (4.2%). The study also found males had a significantly higher probability than females for several conditions, including aggression, heart murmur, and ear and eye infections. This is a genuinely more representative picture of everyday Chihuahua health than the hydrocephalus-first narrative most content defaults to.

Traumatic Injury — A Genuine Risk Most Guides Don't Mention

This is worth highlighting on its own, because it's a striking finding that's almost entirely absent from generic breed content. The same VetCompass study found the most common grouped causes of death in UK Chihuahuas were heart disease (18.8%), lower respiratory tract disorder (16.3%), and traumatic injury (13.8%) — a genuinely notable finding that reflects real toy-breed fragility risk rather than disease. Falls, being stepped on, jumping from furniture, or rough handling by children or larger dogs can cause serious injury to a dog this small, in a way that simply isn't a comparable risk for a Labrador or German Shepherd. This is worth factoring into practical daily decisions — furniture ramps or steps, supervised interactions with children and larger pets, and genuine care when carrying or handling a Chihuahua — not just health screening.

Heart Disease

Heart disease was the single most common cause of death in the VetCompass data, and Chihuahuas are genuinely predisposed to both patent ductus arteriosus (a congenital defect, often requiring surgical correction) and myxomatous mitral valve disease (a progressive, age-related valve degeneration common in small breeds generally). A vet can often detect an early heart murmur on routine examination, and regular checkups matter more for this breed than most given how prominently heart disease features in the real mortality data.

Hydrocephalus and the Molera — Separating Fact from Fear

Most Chihuahuas (roughly 80–90%) have a molera — a soft spot on top of the skull, similar to a human baby's fontanel — and this is a normal breed characteristic, not a defect in itself; it usually shrinks with age but doesn't always fully close. A large or persistent molera alone does not mean a dog has hydrocephalus (a build-up of fluid around the brain that can cause seizures, disorientation, or an unsteady "drunken" gait). Genuine hydrocephalus is a real but comparatively uncommon condition, and diagnosis depends on actual neurological symptoms and imaging, not head-shape alone. If your Chihuahua has a molera with no other symptoms, that on its own is not a reason for alarm — gentle handling of the head area is still sensible either way.

Dental Disease and Retained Baby Teeth

Periodontal disease was the single most commonly recorded condition in the VetCompass study, and this breed's small jaw genuinely predisposes it to both overcrowded adult teeth and retained deciduous (baby) teeth — which were themselves the third most common recorded condition. When a baby tooth doesn't fall out as the adult tooth erupts, the two sit side by side, trapping food and accelerating gum disease around both; extraction is the usual fix if a vet flags this. Daily brushing where possible, plus regular professional dental checks, genuinely matters more for this breed than most.

Anal Sac Impaction — A Genuine, Rarely-Discussed Predisposition

This was the fourth most commonly recorded condition in the VetCompass study, at 4.9%, yet it's genuinely rare to see it mentioned in breed guides at all. The anal sacs are two small scent glands either side of the anus that normally empty during defecation; in small breeds, these ducts are proportionally smaller and more prone to blocking, and Cornell University's veterinary college specifically notes Chihuahuas as the most commonly affected small breed for this condition. Signs include scooting, licking or biting at the area, a strong fishy odour, and visible discomfort when sitting or defecating. Left unaddressed, impaction can progress to infection or a painful abscess. Treatment is usually straightforward — manual expression by a vet or groomer — though recurrent cases may need dietary changes (more fibre) or, in persistent cases, further veterinary management.

Luxating Patella

Like many toy breeds, Chihuahuas are prone to luxating patella (a dislocating kneecap). Mild cases may cause an occasional, brief skip in the back leg that resolves on its own, while more severe, frequent dislocation can require surgical correction. It's worth mentioning any repeated skipping gait to your vet even if your dog seems otherwise unbothered by it.

Eye Conditions

The Chihuahua's characteristically large, prominent eyes make them somewhat more prone to corneal issues (including corneal ulceration and dystrophy) as well as glaucoma and cataracts. Watch for excessive tearing, cloudiness, squinting, or visible discomfort, and raise any changes with your vet promptly given how exposed this breed's eyes genuinely are.

Puppy Hypoglycaemia

As with other toy breeds, Chihuahua puppies genuinely have less metabolic reserve than larger dogs, making hypoglycaemia (low blood sugar) a real risk, particularly if a meal is missed, in cold weather, or after a period of high activity. Signs include weakness, wobbliness, shivering, or lethargy, and frequent small meals are commonly recommended for young toy-breed puppies specifically to reduce this risk. Most puppies grow out of this heightened vulnerability as they mature, but it's genuinely worth knowing about in the first few months.

Lifespan

Chihuahuas typically live 12–17 years, among the longest lifespans of any dog breed — all the more reason proactive management of their real, documented risks (dental health, heart health, and genuine physical safety given their size) matters over what's often a very long life together.

Keeping Your Chihuahua Healthy

  • Genuine physical safety measures — furniture ramps/steps, supervised handling around children and larger dogs, given traumatic injury is a real, documented risk for this breed
  • Daily dental brushing and prompt attention to any retained baby teeth flagged by your vet
  • Weight management — obesity was the second most common recorded condition
  • Watch for scooting or licking near the tail, a sign of anal sac impaction
  • Regular cardiac checkups, given heart disease was the leading cause of death in UK data
  • Frequent small meals for puppies, given genuine toy-breed hypoglycaemia risk
  • Annual vet checkups, with attention to eyes, ears, and general body condition

Supporting Your Chihuahua's Health

Given this breed's genuine predisposition to luxating patella, our Hip & Joint Chews (glucosamine, chondroitin, MSM, turmeric and green-lipped mussel) can be a useful part of a Chihuahua's routine as they age. Our Probiotic Chews may also help support digestive health, including normal stool consistency relevant to anal sac health.

More Breed Health Guides

See our full Most Popular Dog Breeds in the UK guide to see where this breed ranks nationally and browse all our UK breed health guides.

FAQ

What are the most common health problems in Chihuahuas?
A 2020 UK VetCompass study found periodontal disease (13.5%), obesity (5.9%), and retained baby teeth (5.7%) were the most commonly recorded conditions — not hydrocephalus, which most generic content leads with.

Is a molera (soft spot) always a sign of hydrocephalus in Chihuahuas?
No — roughly 80-90% of Chihuahuas have a molera as a normal breed characteristic. A large or persistent molera alone doesn't mean a dog has hydrocephalus; diagnosis depends on actual neurological symptoms.

Are Chihuahuas at higher injury risk than other breeds?
Yes, genuinely — UK data found traumatic injury was the third most common cause of death in the breed, reflecting real fragility risk from falls, being stepped on, or rough handling given their tiny size.

Are Chihuahuas prone to anal sac problems?
Yes — it was the fourth most commonly recorded condition in UK clinical data, and Chihuahuas are specifically noted as the most commonly affected small breed by veterinary sources.

What heart conditions are Chihuahuas prone to?
Patent ductus arteriosus (a congenital defect) and myxomatous mitral valve disease (a progressive, age-related condition). Heart disease was the leading cause of death in UK clinical data.

How long do Chihuahuas live?
Typically 12–17 years, among the longest lifespans of any dog breed.

Sources

This article is for general information only and isn't a substitute for veterinary advice. If your Chihuahua shows seizures, disorientation, or any symptoms described here, please speak to your vet.