We used DNA from 380 Chihuahuas to date when merle came into the breed. The answer: around 1910, not a recent cross.

One great male can shape a whole breed. We DNA tested Chihuahua males and found 83% share one male line from the 1920s. Here is how popular sires shrink a breed and spread disease, and what breeders can do.

Chihuahuas have two coats: smooth and long. SIPGS data on FGF5, why most smooths carry long coat, and why double coat and triple coat are myths.

Umbilical hernias in Chihuahua puppies: under 1 cm, many close by 3 to 4 months. Causes, gentle rubbing, emergency signs, and when to repair.

Low blood sugar in Chihuahua puppies: the numbers, the signs, first aid with corn syrup and warmth, and how to prevent it.

Explore the GH1 mutation in Chihuahuas, its connection to small size, and why breeders and owners shouldn’t be alarmed by Embark testing res

How big will a Chihuahua puppy get? Why weight charts fail, what 238 Embark results show, and why real adult weights plus DNA are the answer.

Blue and lavender are pigment changes, not coat colors. Learn how the MLPH dilute gene works in Chihuahuas, what happens when you breed d1 to d3, and how to spot CDA early.

Chocolate is a pigment, not a coat color, and not a dilute of black. Learn how the brown gene works in Chihuahuas, how to spot a hidden chocolate, and how to read a B locus test.

Natural bobtail Chihuahuas were accepted for 68 years. It is not the T gene and not lethal. SIPGS DNA on where the bobtail may come from.