While Chihuahuas have fewer genetic defects than many breeds (maybe because so many breeders try hard to eliminate problems), no breed is perfect. 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
In dog lingo, subluxation of the patella is called slipped stifles or loose kneecaps. When it occurs, the kneecap (we're talking about the rear legs) slips out of its groove — sometimes often and sometimes rarely — depending on the severity of the problem. 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 with a trick knee. Subluxation of the patella is a relatively common problem in small breeds and some large ones as well.
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 Pepe 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 and not a defect. Most Chihuahuas (80 percent to 90 percent) have a molera — a soft spot on the top of their head similar to a human baby's soft spot. But unlike babies, most Chihuahuas don't outgrow it. Although it usually shrinks as the dog matures and ends up between nickel- and dime-sized, Pepe's molera won't be a problem as long as you're gentle when petting or handling his head.
In rare cases, the molera remains quite large and can be a sign of a serious problem called hydrocephalus (see the next section). But don't borrow trouble. 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 caused by swelling. Other signs of this 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 and won't live long, so euthanasia is the humane solution. (Euthanasia is the medical term for a humane, vet-assisted death.)
Going under anesthesia
The possibility that your dog may someday need anesthesia is one main reason why you need to choose a veterinarian who is accomplished in treating Toy dogs. Although anesthesia-related deaths are rare, and usually the result of an allergic reaction, its use is potentially dangerous. Your vet uses anesthesia only when necessary (before surgery, for example).
Be sure you know how to clean Pepe's teeth properly so that cleaning them under anesthesia isn't necessary. When your dog has to go under anesthesia (during spaying or neutering, for example), 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 Pepe to the vet.