Why Did My Dogs' Fur Change Color? 10 Possible Causes
If your dog's fur changed color, you may be wondering why this has happened, and whether your dog's coat color will go back to normal.
First of all, some reassurance is needed: it's not uncommon for dog fur to change color over time.
Many dog owners report that their dogs' fur changed color after a surgery or injury causing a dog's fur to turn darker. But why does this happen?
To get to the bottom of the problem it helps taking a closer look into what gives a dog's fur its color and what can situations can cause changes.
Any changes in a dog's fur color are worth investigating as sometimes they can be a sign of something not being quite right.
So let's discover some causes of coat color changes in dogs.
What Gives Dogs Their Fur Color?
What ultimately gives your dog his fur color is a matter of the the amount of pigment found in the hair shafts, particularly your dog's guard hairs.
Interestingly, the color of your dog's fur ultimately depends on two main types of pigments, namely eumelanin and pheomelanin.
Eumelanin-Black Fur in Dogs
Eumelanin is responsible for black color. When we see black areas on a dog we are therefore looking at the result of cells producing eumelanin (such cells are known as melanocytes).
However, there can also be variations in eumelanin as as a result of genes. The black color can therefore be diluted into blue (grey) or isabella (lilac). As a result of genes, black may also be softened into liver (chocolate).
One big advantage of unaltered eumelanin is that it acts as an antioxidant, lowering the harm exerted by exposure to the sun.
This is the main reason why many breed standards put a strong emphasize on a dog's nose being black with other colors often penalized.
Pheomelanin-Red/Yellow Fur in Dogs
Pheomelanin, on the other hand, by default results in a reddish-yellow coat color. Pheomelanin therefore is responsible for the "red" coat seen in Irish setters.
However, just as in eumelanin, genes may alter its concentration and lead to softer shades such as tans, creams, yellows, golds and oranges.
Pheomelanin though can also be darkened resulting in a dark, rich mahogany color.
One main disadvantage of pheomelanin is that, unlike eumelanin, pheomelanin produces free radicals when exposed to the sun.
In dogs, therefore, coat color for a great extent depends on the variations of concentrations of eumelanin and pheomelanin.
In most cases though, dogs have both eumelanin and pheomelanin in their coats.
The amount and distribution of these pigments in a dog's hair shafts can vary depending on genetics and environmental factors.
The Role of Genetics
Genetics play a significant role in determining a dog's fur color.
Many breeds have specific genes that determine their coat color and patterns, which can be passed down from one generation to the next.
For example, the gene responsible for the black coat color in Labrador Retrievers is different from the gene that produces the black coat color in Doberman Pinschers.
The Role of the Environment
Environmental factors can often affect a dog's coat color. These are variables that your dog is exposed to in his environment which can cause coat color changes.
If your dog's fur changed color after exposure to some variable in his environment, then environmental factors are often to blame.
Why Did My Dogs' Fur Change Color?
In summary, a dog's fur color change is determined by the presence and amount of pigments in the hair shafts, which can be influenced by genetics and environmental factors.
Let's take now a look now at some of the most common factors that may cause a dog's fur to change color.
1. The Process of Maturing
If you have a puppy who is changing coat color as he's turning 8 or maybe 12 months old, chances are, his coat color changes are due to maturing.
This can vary a bit among breed. For instance, poodles are often born one color and tend to lighten or get some 'frosting' as they mature.
Airedale terriers sometimes have grey mixed with the black on the saddle portion of their coats and this can cause some gray color to mix in.
A Labrador puppy may have a lot of black on the top of the head that may turn to brown once around the age of 1 year old.
Puppies go through a temporary shed, leading them to losing their puppy coat. Occasionally, darker skin color may also arise around the beginning of hormonal changes (female dog going in heat).
The most important thing is that the color change isn't associated with any signs of skin problems such as the presence of lesions, hair loss or frequent itching, explains veterinarian Dr. John.
Did you know? Dogs boasting an agouti coat color are known for changing a lot as they mature. The agouti coat is made of hairs that display alternating bands of colors. It is the color of the coat of wolves, elkhounds and wild mice, squirrels and rabbits. For this reason the agouti coat color is often referred to as the "wild coloring."
2. The Aging Process
Humans are not the only ones to age, turns out, dogs age too, and when they do, their fur undergoes changes just as it happens in humans.
Dogs may not get white hair to the extent of humans, but it's normal to see some graying of the muzzle as dogs reach their senior years.
As a dog matures, it's therefore quite common for his darkly pigmented coat to attain a lighter color, especially by the muzzle area.
This loss of pigmentation in the dog's coat occurs because pigment takes quite a good amount of energy to make, and as dogs age, the body focuses on tending towards other more important needs.
As long as there is no irritation, redness or undesirable smells, there should be nothing to worry about.
3. The Impact of Sunlight
Just as people's' hairs tend to lighten during the summer months, Rover's hairs may bleach slightly too, explains veterinarian Dr. Christian.
This happens as a result of ultraviolet (UV) rays. UV rays basically breaks down the pigments found in the dog's hair shafts.
More precisely, UV rays oxidize the eumelanin and pheomelanin pigments found in the dog's coat making them unstable and breaking them down into smaller molecules.
This process is known as photodegradation, and typically results in a lighter or faded color of the dog's fur.
The extent to which the coat color changes will vary on several factors such as the intensity and duration of the sun exposure, along with the dog's genetics, with some dog breeds more susceptible to the effects of the sun.
4. The Effect of Shaving
Shaving a dog's coat may also cause the hair to become softer and prone to color changes. Generally lighter hues are seen after repeated haircuts.
The fact that clipping affects texture, and color of a dog's new coat coming through, has triggered some groomers to start adding a disclaimer to inform their clients of the possible coat color changes associated with shaving a dog's hair.
Why does the coat color change? More than changing, what's likely happening is that, when you shave a dog's coat too short, it can remove the top coat exposing the dog's undercoat, which may be a different color than the top coat.
This can give the appearance of a coat color change.
5. A History of Trauma
Damage to dog's hair follicles as a result of a previous injury may also cause coat color changes in dogs, explains veterinarian Dr. Loretta.
In the areas of previous trauma such as a surgical incision site, a clipper burn or even a hot spot, the hair may therefore grow darker in color.
This occurs because cells containing melanin, rush to the trauma site as part of the inflammatory process, which turns the skin and hair a darker color, explains Sandy Blackburn in the book: "The Everything Dog Grooming Book."
This darkening of a dog's skin and fur is known as "post-inflammatory hyperpigmentation."
Color changes resulting from an injury may be temporary or permanent, depending on the extent of the injury and the individual dog's genetics.
6. Thyroid Hormones Out of Whack
Changes in a dog's coat color and texture can sometimes be an indication of hormonal problems.
Hypothyroidism, a medical condition where the dog's thyroid levels are low, causes several coat changes and a change in pigmentation may be one of them.
This happens because thyroid hormones play a role in regulating the dog's metabolism and can affect the distribution of melanin in the fur.
Along with a pigmentation changes, hypothyroidism can cause hair loss, brittle hair, secondary skin infections and other symptoms such as lethargy, obesity and a slower heart rate. It's not a bad idea to have the vet run a comprehensive blood panel to exclude this condition.
7. The Impact of Estrogen
Another hormone that has been reported to cause fur color changes in dogs is estrogen.
Estrogen is produced by a female dog's ovaries and is responsible for regulating their reproductive cycle.
Since estrogen can also stimulate the production of melanin in the hair follicles, leading to a darkening of the fur, it is possible to see a darkening of a dog's fur during pregnancy or when in heat, which are times when estrogen levels are elevated.
Conversely, when a dog's estrogen levels tends to decrease, a lightening effect on the coat may be seen such as during the postpartum period or after a spay surgery.
Of course, not all female dogs are susceptible to fur color changes in response to estrogen fluctuations, but it can be seen in some.
8. A Matter of Stains
Sometimes dog owners report that the fur on their dog's face is of a different color. This is mostly seen in dogs with candid white coats that attain pink, red or brown colors around the eyes and mouth area.
In this case, the colors are really stains that come from the dog's saliva and tears.
The cause of these stains on a dog's fur are natural chemicals called porphyrins which are found in a dog's tears and saliva, explains veterinarian Dr. Dave.
Considering that dogs tend to lick several areas of their bodies, it's not surprising for other parts of the body such as feet, legs and sides to assume a brownish tint from the residue of saliva.
While the issue may be strictly cosmetic, a veterinarian should be consulted as the staining can be caused at times by underlying medical problems such as blocked tear ducts, in the case of tear stains, or periodontal disease, in the case of mouth stains.
Allergies or skin problems should also be ruled out as these can trigger excessive licking that results in brownish stains on other parts of the dog's body.
Did you know? If your dog is wearing a collar with tags, sometimes the metal in the tags may cause a color change in the dog's fur from the oxidizing effect of the metal.
This dog's fur color change around the eye area is due to porphyrins found in a dog's tears.
9. Loss of Pigmentation
"My dog's coat color has changed drastically and some areas on the face have turned white, what can this be?" Such drastic coat changes may be triggered by a medical condition known as vitiligo.
In this case, the loss of pigment mostly affects the dog's nose, lips, and face and it can be temporary or even permanent.
What happens is that, melanocytes, the cells responsible for giving pigment to the dog's coat die or no longer function, explains veterinarian Dr. Gabby.
This condition can be caused by an autoimmune disease, genetic factors or a virus, but sometimes its exact causes remain unknown.
Rottweiler dog with vitiligo (notice the white hair areas under eyes) Source: Wikimedia CC BY-SA 3.0
Did you know? White isn't really considered a coat color as white hair isn't caused by pigment but rather a lack of pigment.
10. Canine Flank Alopecia
If your dog's fur is changing color and getting lighter on the flank and shoulder area, you may be dealing with a case of canine flank alopecia.
This condition is known for causing areas of hair loss in the dog's flank area with darkened skin (hyperpigmentation). The hair may regrow eventually, but the hair may be different in color and patchy.
Predisposed dogs are boxers, Airedale terriers, bulldogs and schnauzers between 3 and 6 years of age.
The condition is also know as "seasonal alopecia" due to the fact that it's associated with shorter durations of sunlight between November and April causing changes in the dog's melatonin and prolactin secretion, explains board-certified veterinary dermatologist Dr. Alexander Werner Resnick
Seasonal canine flank alopecia in a Boxer.
Now That You Know...
As seen there are many possible reasons why dogs' fur change color.
If you are in doubt or if your dog is showing signs of of problems such as excessive itching, hair loss or presence of lesions, consult with your vet.
A referral to a board-certified veterinary dermatologist may turn insightful for complex cases.
This article was published Dec 25, 2015 at 6:44 AM
Disclaimer: this article is not meant to be used as a substitute for professional veterinary advice or behavioral advice. If your dog is acting sick or aggressive please consult with a qualified professional for proper diagnosis and treatment.
