Dental disease is arguably the most common and consequential health issue in Chihuahuas. Their tiny jaws create extreme overcrowding of the teeth, and retained baby teeth are the rule rather than the exception. This combination creates countless crevices where plaque, tartar, and bacteria accumulate, setting the stage for rapid progression of periodontal disease.

The consequences extend well beyond bad breath. Advanced periodontal disease in Chihuahuas can cause jaw fractures because the bone of the mandible (lower jaw) is already so thin that even modest bone loss from infection can weaken it to the breaking point. A Chihuahua chewing on a toy or receiving a dental extraction can suffer a pathological jaw fracture if the bone has been undermined by disease. This is a genuine medical emergency.

Prevention starts early. Have retained baby teeth extracted promptly. Begin daily tooth brushing as a puppy, using a soft finger brush and veterinary toothpaste. Plan for annual professional dental cleanings with full-mouth radiographs. Dental X-rays are absolutely essential in this breed because so much disease is hidden below the gumline where visual inspection cannot detect it.

Many Chihuahua owners worry about anesthesia for dental procedures, but modern veterinary anesthesia is extremely safe, even for very small dogs. The risks of untreated dental disease (chronic pain, systemic infection, jaw fracture) far outweigh the low risks of anesthesia in the hands of a skilled veterinary team. Anesthesia-free dental cleanings are not an acceptable substitute, as they cannot address disease below the gumline and do not allow for radiographs or extractions.

At home, choose appropriately sized dental chews and toys. Avoid hard objects like bones, antlers, and ice cubes, which can crack the delicate teeth. Dental diets formulated for small breeds may provide some additional benefit alongside regular brushing.

Mitral valve disease (MVD) is the most common heart condition in Chihuahuas and in small breeds generally. The mitral valve, which separates the left atrium from the left ventricle, gradually degenerates over time. As the valve deteriorates, it fails to close completely, allowing blood to leak backward (regurgitate) with each heartbeat. This creates a heart murmur that a veterinarian can detect with a stethoscope.

Many Chihuahuas develop a heart murmur in middle to older age. The presence of a murmur does not necessarily mean the dog is in heart failure. Some dogs live for years with a murmur and never develop clinical signs. Others progress through stages of compensated heart disease before eventually developing congestive heart failure.

The key is monitoring. Once a murmur is detected, periodic evaluation with chest radiographs and echocardiography allows your veterinarian to track the progression and determine when intervention is needed. Recent research has demonstrated that starting the medication pimobendan at the preclinical stage (before signs of heart failure develop) can significantly delay the onset of heart failure in dogs with advanced mitral valve disease.

Signs of congestive heart failure include coughing (especially at night or when resting), increased breathing rate, labored or open-mouth breathing, exercise intolerance, restlessness at night, decreased appetite, and fainting. If you notice any of these signs, prompt veterinary evaluation is important.

Treatment for congestive heart failure typically involves a combination of medications: pimobendan to strengthen heart contractions, furosemide (a diuretic) to remove fluid from the lungs, and an ACE inhibitor to reduce cardiac workload. With appropriate medication, many dogs with heart failure maintain good quality of life for months to years.

At home, you can monitor your Chihuahua's sleeping respiratory rate, which is a sensitive early indicator of fluid accumulation. Count the number of breaths per minute while the dog is sleeping peacefully. A consistent resting respiratory rate above 30 breaths per minute warrants a veterinary call.

Hydrocephalus, an accumulation of cerebrospinal fluid within the brain's ventricles, is more common in Chihuahuas than in most other breeds. Mild hydrocephalus is actually quite common and may cause no symptoms at all. A soft spot (open fontanelle) on the top of the skull, similar to a human infant's, is a normal anatomical variation in many Chihuahuas and does not by itself indicate problematic hydrocephalus.

However, significant hydrocephalus can cause neurological symptoms including a dome-shaped head with eyes that appear to gaze downward ("setting sun" appearance), seizures, abnormal behavior, difficulty with house-training, circling, head pressing, and vision problems. Puppies with severe hydrocephalus may be noticeably smaller and less developmentally advanced than their littermates.

Mild hydrocephalus that causes no symptoms generally requires no treatment beyond monitoring. Symptomatic hydrocephalus may be managed with medications that reduce cerebrospinal fluid production (such as omeprazole or corticosteroids) or, in severe cases, surgical placement of a ventriculoperitoneal shunt to drain excess fluid.

Atlantoaxial instability is another neurological condition seen in Chihuahuas and other toy breeds. The joint between the first and second cervical vertebrae (the atlas and axis) is abnormally loose, which can allow the axis to compress the spinal cord. Signs range from mild neck pain and reluctance to lift the head to severe neurological deficits including weakness or paralysis of all four legs. Surgical stabilization is the definitive treatment for dogs with significant symptoms.

Epilepsy (idiopathic seizures) is also seen in the breed. Any Chihuahua experiencing seizures should receive a thorough neurological workup, including bloodwork to rule out metabolic causes (hypoglycemia, liver disease) and ideally advanced imaging (MRI) to evaluate brain structure. Many epileptic Chihuahuas are well-controlled with anti-seizure medications.

Patellar luxation is extremely prevalent in Chihuahuas. The breed's tiny, delicate leg structure provides a relatively shallow groove for the kneecap, and the kneecap frequently slips medially (toward the inside of the leg). You may notice your Chihuahua suddenly hold up a hind leg for a step or two, then shake it out and walk normally. Low-grade luxation often does not require intervention, but dogs with recurrent or high-grade luxation benefit from surgical correction to prevent progressive cartilage damage and arthritis.

Legg-Calve-Perthes disease can affect young Chihuahuas, typically between four and twelve months of age. The blood supply to the femoral head deteriorates, causing bone death and collapse. Progressive hind-leg lameness is the primary sign. Surgical removal of the damaged femoral head produces excellent results in toy breeds, and most dogs return to full activity.

Fractures are a genuine concern in Chihuahuas. Falls from furniture, being accidentally stepped on, or jumping from heights can break their thin, delicate bones. Take precautions: use pet stairs or ramps to help them access furniture, supervise interactions with children and larger dogs, and be mindful of where your Chihuahua is before sitting down or walking through a room.

Cold sensitivity is significant. Chihuahuas have a high surface-area-to-volume ratio and minimal body fat, making them lose body heat rapidly. Provide a warm sweater or coat in cool weather, warm bedding, and a climate-controlled indoor environment. Prolonged exposure to cold temperatures can lead to hypothermia in these tiny dogs.

Hypoglycemia remains a risk throughout life in very small Chihuahuas (under three pounds), not just during puppyhood. Feed small, frequent meals and monitor for signs of low blood sugar: trembling, weakness, disorientation, and unresponsiveness. Keep a sugar source like honey or corn syrup on hand for emergencies, and seek veterinary care if episodes are recurrent.

Despite their small size, Chihuahuas thrive with regular exercise and mental stimulation. Short walks, indoor play, and puzzle toys keep their minds active and bodies fit. Obesity in a Chihuahua places disproportionate stress on their joints and heart, so maintain a lean body condition throughout life.