This breed requires expert veterinary attention in areas such as birthing and dental care. Chihuahuas are also prone to some genetic anomalies, often neurological ones, such as epilepsy and seizure disorders.
Chihuahuas, and other toy breeds, are prone to the sometimes painful disease hydrocephalus. It is often diagnosed by the puppy having an abnormally large head, or hydrocephalus, during the first several months of life, but other symptoms are more noticeable since "a large head" is such a broad description. Chihuahua puppies exhibiting hydrocephalus usually have patchy skull plates rather than a solid bone and typically are lethargic and do not grow at the same pace as their siblings. A true case of hydrocephalus can be diagnosed by a veterinarian, though the prognosis is grim.
Chihuahuas have moleras, or a soft spot in their skulls, and they are the only breed of dog to be born with an incomplete skull. The molera fills in with age, but great care needs to be taken during the first six months until the skull is fully formed. Some moleras do not close completely and will require extra care to prevent injury. Many veterinarians are not familiar with Chihuahuas as a breed and mistakenly confuse a molera with hydrocephalus.
Chihuahuas can also be at risk for hypoglycemia, or low blood sugar, which is especially dangerous for puppies. Left unattended, hypoglycemia can lead to coma and death but can be avoided with frequent feedings, such as every three hours for very small or young puppies. Chihuahua owners should have a simple sugar supplement on hand to use in emergencies, such as, Nutri-Cal, Karo syrup or honey. These supplements can be rubbed on the gums and roof of the mouth to rapidly raise the blood sugar level. Signs of hypoglycemia include lethargy, sleepiness, low energy, uncoordinated walking, unfocused eyes and spasms of the neck muscles or head pulling back or to the side.
Chihuahuas are prone to eye infections or eye injury due to their large, round, protruding eyes and their relatively low ground clearance. Care should be taken to prevent visitors or children from poking the eyes. The eyes also water frequently to remove dust or allergens that may get into the eye. Daily wiping will keep the eyes clean and prevent tear staining.
Collapsed trachea (reverse sneezing) is a health concern that is characteristic of the chihuahua breed.
Chihuahuas have a tendency to tremble but it is not a health issue. Instead, it occurs mainly when the dog is stressed, excited or cold. Cold can also present a problem for these small animals. They often enjoy wearing coats or sweaters when outside and enjoy digging and snuggling in blankets when sleeping.
Although figures often vary, as with any breed, the average lifespan range for a healthy Chihuahua is between 10 and 17 years.
Chihuahuas are sometimes picky eaters and care must be taken to provide them with adequate nutrition. Sometimes wet or fresh food can have the most appealing smell to these constant eaters. Chihuahuas are prone to hypoglycemia and could be at a critical state if allowed to go too long without a meal. At the same time, care must be exercised not to overfeed them.
Chihuahuas have a notorious problem with dental issues. Dental care is a must for these little creatures. Human food should be avoided. Due to their small size, even tiny high fat or sugary treats can result in an overweight Chihuahua. Overweight Chihuahuas are susceptible to increased rates of joint injuries, tracheal collapse, chronic bronchitis, and shortened life span.
Chihuahuas are also known for a genetic condition called 'luxating Patella,' a genetic condition that can occur in all dogs. In some dogs, the ridges forming the patellar groove are not shaped correctly and a shallow groove is created. In a dog with shallow grooves, the patella will luxate or slip out of place, sideways. It causes the leg to 'lock up' and will force the chihuahua to hold its foot off the ground. When the patella luxates from the groove of the femur, it usually cannot return to its normal position until the quadriceps muscle relaxes and increases in length, explaining why the affected dog may be forced to hold his leg up for a few minutes or so after the initial displacement. While the muscles are contracted and the patella is luxated from its correct position, the joint is held in the flexed or bent position. The knee cap sliding across the femur can cause some pain due to the bony ridges of the femur. Once out of position, the animal feels no discomfort and continues with activity.
Chihuahuas are also prone to some heart-related disorders, such as heart murmurs and pulmonic stenosis, a condition in which the blood outflow from the heart's right ventricle is obstructed at the pulmonic valve.
Chihuahuas, along with other miniature dogs such as Chinese Cresteds, are prone to physical deformities, especially in old age; several chihuahuas and cross-bred chihuahua/Chinese crested mixes have rated highly in the World's Ugliest Dog Contest, including a purebred chihuahua named Princess Abby (winner of the 2010 contest) and a crossbreed named Yoda (the 2011 winner).