While Chihuahuas have fewer genetic defects than many breeds, there are no perfect breeds. The following sections show you some idiosyncrasies - a few serious but most not - that are sometimes seen in Chihuahuas and other Toy breeds.
 
     Subluxation of the patella
 
     Subluxation of the patella is a relatively common problem in small breeds and some large ones as well. In simple terms, Subluxation of the patella is like a slipped stifles or loose kneecap. When it occurs, the kneecap (pertaining to the rear legs,) slips out of its groove. Depending on the severity of the problem, this can happen rarely or often. If your dog is one of the unlucky few whose kneecaps slip often, surgery may be the solution. A dog with a mild case can live a normal life, kind of like a person who has a trick knee.
 
     Hypoglycemia
 
     Hypoglycemia means low blood sugar and is a common problem in young Toy breed puppies, although most of them grow out of it before they are old enough to leave the breeder. But for a few, it's a danger throughout their lives.
 
     Symptoms of low blood sugar are a staggering gait, glassy eyes, and sometimes either limpness or rigidity. If the dog doesn't receive immediate help, he can suffer Seizures , unconsciousness, and finally, death. Treatment involves putting some sugar in your dog's mouth, calling your veterinarian, and heading for the clinic. Once you know your dog has a tendency toward hypoglycemia, you can prevent further attacks by changing his feeding schedule to small amounts several times a day and avoiding sugary treats (check the ingredients before buying dog treats). Too much sugar in his food can put your dog on a roller coaster ride of sugar highs and lows rather than keeping his blood sugar nice and level.
 
     If you get your Chi used to taking delicious liquid from an eyedropper, administering liquid medication becomes a cinch. Occasionally melt a teaspoon of vanilla ice cream, put it in an eyedropper and give it to her just as if it was medicine.
 
     Collapsing Trachea
 
     Collapsing trachea is a problem for Toy dogs of many breeds. The symptoms include coughing, shortness of breath, and exhaustion. Although it appears more often in dogs older than 5 years, an occasional puppy has it from birth. To understand the condition, think of the trachea as a straw made of cartilage that carries air from the neck to the chest. When the cartilage collapses, breathing becomes difficult, kind of like sipping soda through a flattened straw.
 
     Your vet can treat the condition with medication, but if you smoke, your Chi's prognosis may be poor. Secondhand smoke is a proven contributing factor to the problem . . . and smoke tends to settle low, where a little dog's nose is.
 
     Heart murmur
 
     Heart murmurs are relatively uncommon in Chihuahuas and even those that have one, usually have the functional type. As in people, that means they can be as active and athletic as they want and live long, normal lives.
 
     Molera
 
     The Chihuahua's molera (a.k.a. fontanel) is considered a breed characteristic, not a defect. Most Chihuahuas have a molera - a soft spot on the top of their head similar to a human baby's soft spot. Unlike babies, most Chihuahuas don't completely outgrow it. It usually shrinks as the dog matures, ending up nickel or dime sized. A Chihuahua's molera won't be a problem as long as you are gentle when petting or handling his head.
 
     In rare cases, the molera remains quite large which can be a sign of a serious problem called hydrocephalus (see next section.) Hydrocephalus has several other signs besides a larger-than-usual molera.
 
     Hydrocephalus
 
     A dog with hydrocephalus (a.k.a. water on the brain) may have an unusually large head for his size. This is caused by swelling. Other signs, of this most often fatal condition, are frequent falling, seizures, a lot of white showing in the eyes, an unsteady gait, and east-west eyes (the opposite of crossed eyes). A dog with hydrocephalus is in pain. They usually won't live long so; euthanasia is the humane solution. I struggle with this cruel fact of life, never giving up without a fight. As a proud Chihuahua Lover / Owner / Breeder who has had a baby Chihuahua who suffered mild Hydrocephalus in addition to, what I am sure was, a Liver Shunt, I can tell you, this is a heart breaking experience.
 
     Liver Shunt
 
     Liver shunts happen when Mother Nature doesn't happen right. The easiest way to explain it is this: When the babies are in the womb, the mother's heart is the one pushing nutrients, blood, and oxygen down the umbilical cords, and even throughout the babies' bodies. In turn, the wastes produced by the babies' bodies are returned to the mother to be filtered out by her organs such as, the liver or kidneys.
 
     At the time of birth, this connection with the mother's heart is disconnected. For the very first time, the baby hearts begin gently pumping the blood in the reverse direction from when the mother's heart was doing all the work. This process of reversing the direction of flow is truly one of the great miracles of life. It causes the valves of heart, lungs, and bloodstream to redirect through the vital organs of the baby. "Open flaps" are closed for accelerated healing of the separation caused by birth.
 
     When the valves, veins, or arteries are not lined up right or the tissue is too weak to support the new direction of the flow, the connection to the liver is weak or even totally by-passed. The result; toxins and wastes are not filtered out of the bloodstream. Poison builds up throughout the puppy, eventually, ending with death. Some dogs have benefited from new types of surgery being performed by highly skilled animal surgeons.
 
     The other kind of liver shunt I am familiar with is called, Hepatic microvascular dysplasia (HMD or MVD). This is where there are multiple (possibly hundreds,) of liver shunts rendering the liver equally as dysfunctional as the other kind of liver shunt. There is symptomatic treatment for this kind but, surgery is not an option. Longevity is not good for this disease.
 
     Special note: I read a study somewhere on the internet, Yorkshire Terriers (Yorkies) are thirty-six times more likely to have some sort of a Liver Shunt than all other breeds of dogs combined. I believe this warrants further investigation. I like Yorkies but, if I were going to buy one, I would have its bile acids screened before I set myself up for heartbreak. If you have a toy dog with a Liver Shunt or other Congenital Defect, I know of a few private research and support groups available online. Contact me with the details of your story and I will try to arrange a private invitation for you to enter the group.
 
     Going under anesthesia
 
     The possibility your dog may need anesthesia is the main reason you need to choose a veterinarian who is accomplished in treating Toy breeds of dogs. Anesthesia-related deaths are rare. When it does happen it is usually the result of an allergic reaction. It is my opinion, the use of anesthesia is potentially dangerous. Your vet should use anesthesia only when necessary (before surgery, for example.)
 
     Make sure to clean your dog's teeth properly so cleaning them under anesthesia isn't necessary. When your dog has to go under anesthesia (during spaying or neutering, for example), it's a good time to ask your veterinarian if any necessary dental work (such as pulling impacted baby teeth) can be done at the same time. Be sure your vet uses one of the modern gas anesthetics. They are much safer than the old fashioned intravenous products.
 
     Watch those eyes
 
     It's certainly not a condition, but because Chihuahuas have big eyes and live close to the floor, they are more prone to eye injuries than a lot of other breeds. Put several drops of saline solution in your dog's eye if the injury seems minor. That's often all it takes to flush out a foreign object that was accidentally kicked up by someone's shoe. If that doesn't relieve the problem, or if the injury appears more serious, take your dog to the vet.