This refers to the dog's thyroid gland not properly producing hormone levels. The skin will not change color at the onset of this; however if left untreated the skin may indeed turn black. There will other symptoms as well, including a thinning of the coat, dry skin, weight gain and change in appetite.
While rare, there are countless other causes including Bowen Disease, infection, cancer, parasites and yeast infections.
How to Know if Black Skin is Normal or Not
In just about every case, if a darkening of the skin is the ONLY change and there are no raised areas, itching, fur loss
, discomfort or other signs, the blackening of the belly and other areas such as the legs will be due to the sun.
If you notice ANY other sign - as odd or as unusual as it may seem - it is highly recommended to bring your Chihuahua to the veterinarian for an evaluation. A checkup will be needed because some of the medical conditions can be quite serious.
Change in Nose Color
What color is a Chihuahua's nose? You're not alone if you wonder about this. While a deep, dark black nose is common, a Chihuahua may also have a tan nose (this is referred to as self-colored in tan or fawn coated dogs), blue (the nose will be deep navy and any Chihuahua with a blue nose will officially have a blue coat
, no matter the actual color of the fur), brown (called chocolate with chocolate coated dogs) and possibly pink - while rare, a pink nose is permissible in show.
With this in mind, there are cases of a Chihuahua's nose changing color. This will usually not be a full changeover, but rather the development of different hues on the leather. There may be a lighter pigmentation that comes in or the gradual darkening.
Why does a Chihuahua's nose change color?
There are 3 potential reasons for this:
A puppy may be born with one color on his nose and as he matures, the nose may change in color. A pink nosed Chihuahua may end up being an adult with a black nose, brown may change to black, etc. Some puppies
are born with small pink areas that will slowly turn to the main color as they mature.
For some, there will be an inherent change that leaves the nose with two colors. This is referred to as a Dudley or Butterfly nose. The difference between a Dudley nose and a Butterfly nose is where the loss of pigmentation occurs; though many people use these terms interchangeably.
With a Butterfly nose, there will be randomly located and differently sized lighter colors. Merle dogs may be more prone to this, such as a blue merle Chihuahua.
Dudley denotes to a lighter color in the middle that may or may not spread outward.
2) Change of the Season.
Opposite to how the belly may change color (black in the summer and back to pink in the winter
) a Chihuahua's nose may fade in color during cold, winter months. Black may become brown. Chocolate or tan may even turn pink. When the color change is due to a change in the season, some call this snow or winter nose; though it should not turn white.
Two possible reasons for this reaction is a response of the tyrosinase enzyme which is responsible for producing nose pigmentation and shorter days of less sunshine.
3) Medical Issues.
While very rare, Lupus Erythematosus and cancer are possible causes. With Lupus Erythematosus, there will be other issues such as scaling, crusting and swelling.