Most people who own a dog, particularly one with white fur, will be familiar with the issue of fur staining. Patches of fur in certain areas of the body turning red or brown over time.
Thankfully, this discolouration itself doesn't cause your dog any harm - it's merely a cosmetic issue. However, it can be a symptom of an underlying health problem.
The chemistry of it all
At the chemical level, red fur staining is caused by a compound called porphyrin. Porphyrins are iron containing molecules produced when the body breaks down red blood cells. They are removed from the body primarily through faeces. However, porphyrin can also be excreted through tears, saliva, and urine.
On the other hand, brown fur staining is primarily caused by an infection with the yeast Malassezia. This is the yeast that's responsible for causing skin and ear infections in dogs.
This means that red staining and brown staining are two different problems - porphyrins cause red fur staining, while yeast infections cause brown fur staining.
However, there are commonalities between the two in terms of underlying health conditions that can cause the staining to manifest / come about.
Causes of fur staining
Medical conditions
Eye staining
Medical issues that can lead to staining around the eyes include eye irritation, blocked tear ducts, eye infections (bacterial, viral or fungal) and trauma to the eye (e.g. a scratch or cut). Poor grooming, resulting in hair around the eye can also stimulate excess production of tears, and can give yeast infections an environment in which to thrive and grow.
Anatomical or conformational abnormalities that can lead to stained eye fur include overactive tear ducts, narrow tear ducts, narrow eyes, shallow eye sockets, extra skin folds, abnormally placed eyelashes and rolling of the eyelids.
Mouth staining
Medical issues such as gum disease, excess saliva production and dental problems including abscesses can result in dogs producing large amounts of saliva. In a lot of cases, the excess saliva is produced as a way to try and get rid of excess bacteria that is present as a result of dental / periodontal problems.
These issues can also result in your dog having difficultly chewing their food, which in turn can cause excess saliva to produced, be unevenly distributed around the mouth and to trickle down the sides of the mouth.
Allergies
As with people, dogs have allergies to things like pollen, certain foods, certain plants etc. And as with people, dog's will do everything they can to relieve the irritation and discomfort caused by these allergies.
By enlarge, the way dogs do this is to lick the affected area. This means they are depositing a lot of saliva on different areas of fur around their body. Saliva which if not cleaned up and left to accumulate can result in staining (typically red staining).
Licking to relieve allergy symptoms also makes the fur quite damp, and scratching to relieve it can result in damage to the skin. Both of these can lead to areas of fur that act as a rich, fertile breeding ground for yeast infections that can result in brown fur staining.
Allergens can also cause irritation and inflammation to the eyes which results in production of more tears and so can lead to staining around the eye area.
Breed
Any dog can experience fur staining, but as with most things, some dogs are more prone to it than others. Breeds of dog that are more susceptible to experiencing fur staining tend to be dogs who have poor drainage, short noses and who have shallow eye sockets etc. These include Poodles, Maltese, Boxers, Bichons and Bulldogs.
How to treat fur staining
Unfortunately, in a lot of instances, fur staining can't be treated simply. And in the case of anatomical / conformational abnormalities, they sometimes can't be treated at all.
Sometimes, antibiotics can reduce the production of porphyrins, which can reduce red fur staining. Similarly, there are some natural products and supplements that have been said to reduce red fur staining. However there is no evidence supporting this and care should be taken before using these - and any other - supplements. Brown fur staining can be treated by treating the underlying yeast infection. In all instances, you should speak to your veterinarian about the best way to treat and manage fur staining in your dog. He or she will be able to provide you with the best advice on how to treat the problem and prevent it becoming worse.
Kristina is certified in Advanced Canine Nutrition.
She provides consultations on general canine nutrition and home prepared diets working closely with a wide variety of vets. Kristina also write articles on canine nutrition and care for many publications. You can visit her at: Elmoskitchen.com
She recently finished her first booklet; "How to Choose the Best Commercial Dog Food". This guide explains the latest facts and findings on a variety of ingredients and pet food marketing, as well as debunking some popular myths.