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Dog Skin Disorders: Causes, Symptoms, Types, and Breeds Prone to Them

The West Highland is a breed that's prone to skin problems.

The West Highland is a breed that's prone to skin problems.

Does Your Dog Have Skin Problems?

While we are blessed with the pets in our lives, we also encounter problems with our pets that can be sad and/or frustrating. I refer, of course, to allergies and other skin disorders. Our dogs sometimes scratch and shed, and they get ugly scars or hairless patches on their skin.

Lately, my West Highland white terrier Cloudy has had huge fallouts of hair around her leg area. Terriers, especially the West Highland terrier, are among the breeds of dogs that have high instances of skin problems. Currently, she is due for a vet’s appointment to have her urine assessed so that we can determine if it is a reaction to a food allergy or if there is another cause.

In the Article

Below I've listed the diseases, symptoms, and causes of some of the most common skin disorders in dogs. Hopefully, my research will help you understand the skin diseases a little better. It is important to note that this is only an introduction, so please consult your veterinarian for a proper diagnosis if your dog is showing any of the symptoms listed below.

The Chow Chow is another breed that's prone to skin disorders.

The Chow Chow is another breed that's prone to skin disorders.

Causes of Skin Disorders in Dogs

Other than allergies, skin problems in dogs can be attributed to a number of causes. Skin problems may result from any of the following.

1. Parasites and Fungal Growth

Parasites are an ornery contributor to skin diseases in dogs. An example of this is ringworm, a contagious fungal infection that may cause inflammation, scaly patches, and hair loss. It requires immediate treatment to prevent other dogs and people from becoming infected.

Parasitic diseases like sarcoptic mange, an infection caused by the Sarcoptes scabiei mite, will produce an allergic response and lead to extreme itching.

Stick tight fleas

Stick tight fleas

2. Fleas

When these nasty cretins bite, itchiness will follow. The saliva that fleas leave behind may also cause an allergic response. Aside from fleas, dogs may also have allergic reactions to the products used to get rid of them.

3. Seasonal Allergies

Your pet may develop a skin disorder as a result of a reaction to grasses that grow in the spring or summertime. They can also be allergic to pollen, weeds, dust, mites, mold, or grasses.

4. Food

Feeding your pet the wrong food may also cause skin irritation as they may have allergic reactions to corn, soy, or wheat. Their immune systems may even reject colorings and fillers, just as ours do.

5. Skin Infections

Dogs can have both primary and secondary skin disorders. For example, they can develop bacterial or yeast infections as a result of a disorder that may already be present.

6. Grooming Products

Shampoos and grooming products may irritate your dog’s skin. Although it is tempting to wash our dogs with shampoo that we use, this can cause negative reactions. Be sure to use products only meant for dogs.

7. Stress or Boredom

Dogs may start licking their skin when bored or stressed. This is due to the fact that they do not have anything to do to stimulate their minds.

8. Metabolic Problems

Metabolic problems can cause coat dilution or discoloration. They may also lead to changes in coat consistency, thickness, and distribution as well.

9. Seasonal Changes

Skin may become flaky or dry during the winter.

Scabs on a dog

Scabs on a dog

Symptoms of Skin Disorders in Canines

Now that we know some of the most common causes for skin disorders in dogs, let's learn about their symptoms.

1. Scratching, Licking, or Chewing

A dog usually licks or chews to ease the itch on the portion of skin that is irritated. He/she may also constantly scratch the affected areas as well.

2. Scabs

The appearance of scabs may signal the presence of mange or irregularities in your dog's immune system. Mange is generally treatable but is not curable.

3. Inflammation

If your pet’s skin appears red or inflamed, it could be a sign of a problem related to the skin.

4. Hair Loss

Hair loss may occur if your pet has an allergy, especially around the leg or the underbelly areas.

My dog Cloudy experienced hair loss around her underbelly and legs. Temporarily, I use Nova Soothing Balm to relieve the itchiness, and it has helped the hair grow again.

5. Rashes

Just like humans, dogs also develop rashes on the skin when they experience disorders.

6. Appearance of Blood or Pus

Dogs can develop abscesses, which is painful, warm, reddened skin with pockets of pus beneath. Puppies also experience diseases like folliculitis (a hair pore infection). Blood or pus may also be a sign of impetigo (hairless skin around the abdomen or groin). These symptoms may also be caused by acne. Yes, dogs get pimples too! Interdigital cysts between the paws, mycetoma, or swelling at the site of a puncture wound may also bring about these symptoms.

A dog with pus in a facial area because of an auto immune skin disorder.

A dog with pus in a facial area because of an auto immune skin disorder.

7. Swellings Lumps or Skin Discoloration

Some puppies experience facial disorders like "puppy strangles" (a painful swelling of the face) followed by the development of painful pustules. Lumps may also set into the skin or and the skin itself may be discolored.

When dogs experience irritation in the facial area, they might rub their face against furniture or carpeting to relieve the itchiness.

Types of Dog Skin Disorders (With Photos)

Hormonal Skin Diseases

These are skin disorders in dogs that arise because of an imbalance in hormone levels.

Black Skin Disease or Alopecia

This is not really a disease, but a loose term referring to hair loss that is hormonally influenced, progressive, and non-inflammatory. It causes hyper-pigmentation or black spots on a dog’s skin, hence the term "black skin disease."

Its exact causes are not widely known, but obesity, hormonal imbalance, and genetics are all suggested to be contributors to the disease. It does not affect a dog’s health and is only a cosmetic issue.

What Should We Do?

Too little is known about the disease to suggest prevention. However, weight management may reduce some of the symptoms, as would neutering, which will reduce any hormonal imbalance. It may also help with hair loss and pigmentation changes.

Autoimmune Diseases

Changes or damage to a dog’s immune system may cause pemphigus, a group of autoimmune diseases that result in the ulceration or crusting of the skin. Fluid in sacs or pustules may also develop. Some of these autoimmune diseases include:

  • Foliaceus: Symptoms may include scales, crust, pustules, redness, and itchiness. It mostly affects the head area but may appear on other parts of the body as well, including the gums and lips. The dog may also experience swollen lymph nodes, swelling, depression fever, and lameness. Bacterial infection may set in as a result of ulcerated skin, and itch that occurs from this may be painful.
  • Erythematosus: This disease shares the same symptoms as foliaceus except that skin lesions are confined to the face, head, and footpads. The lips may also lose their color.
  • Vetegans: These are pustule groups that form larger patches of lesions which ooze pus. This disease usually affects the mouth area. Besides painful pustules, the dog will show few signs of general ill health.
  • Vulgaris: This is one of the most serious forms of autoimmune diseases. With vulgaris, ulcers set into the skin. The dog may also have deep blisters and crusted skin as well. The disease affects the gums, but may spread to other parts of the body, including the underarm and groin. The dog will have an onset of fever or depression and experience anorexia if the mouth ulcers are terminal.

What Should We Do?

If severely affected, you must seek a veterinarian. Usually steroids are suggested to bring the condition under control. Some steroids, like cortisol, may cause weight gain so the dog will usually have to switch to a low-fat diet.



Ringworm is a highly contagious skin disease that is either transmitted through spores or by coming into contact with the infected hair on dogs and cats. It usually invades hair follicles and mainly affects puppies and young adult dogs. Areas affected include the face, ears, paws, and tail.

The name comes about because of its appearance. Ringworm is characterized by hair loss and is accompanied by scaly skin and a red ring-like appearance. By itself, it is not an itchy skin condition, but the itch arises when bacterial infection sets in. Because it appears very much like other skin diseases, an accurate and thorough diagnosis from your veterinarian is necessary.

What Should We Do?

Vets will usually recommend using anti-fungal agents containing miconazole to combat the growth and progression of the fungus. The treatment and healing process usually takes about 4 to 6 weeks, during which the dog should wear an Elizabethan collar (cone) to prevent scratching.

Mange: Skin Disorder Caused by Parasites

The term “mangy mutt” usually refers to a dog that is somewhat dirty and has unfortunate encounters with this disease, which is caused by several species of tiny mites. If allowed to proliferate, these mites cause infections.

Sarcoptic Mange

This type of mange is easily transferable between dogs. Also known as
"canine scabies," this type of mange is cause by a light-colored, oval-shaped mite that is microscopic. It tends to cause severe itching in dogs.

What Should We Do?

This type of mange is best cured with medicated dips, shampoos, and other prescription therapies. If administered regularly, the disease takes 4 to 6 weeks to resolve.

Demodectic Mange

All puppies raised by infected mothers will have this type of mange passed from mother to pup when she cuddles it. Localized mange is usually confined to certain areas, but generalized mange can spread throughout the entire body. This disease results in hair loss and bald patches.

What Should We Do?

90% of cases, especially localized mange, usually resolve themselves.

Note: Please do not use old-time remedies like rubbing motor oil on a dog’s skin to ease the mange. This method will never touch the mites because they live beneath the skin. In fact, motor oil may increase skin damage.

Which Breeds Are Most Prone to Skin Diseases?

Generally, “blue” dogs, a term used to refer to dilute-colored or light-colored dogs, are the most prone to skin infections and hair loss. This is caused by a recessive genotype. These breeds include West Highland terriers, Yorkshire terriers, German shepherds, retrievers, and chow chows.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

© 2012 Michelle Liew


Hi my dog keeps getting like hard black material only on his face currently under his mouth. Any idea what causes this. It hurt to pull it. on April 15, 2020:

Hi my dog keep getting scaly black hard things only on his face currently up under his mouth like hard crust it hurts him when I try to pick it off but it hurt. I take him to the vet they have to put them to sleep to shave it off but then it comes right back any idea what this is

Brenda on November 17, 2019:

My dog has little tiny (same size everywhere) scabs/scales about the size of pencil erasers that just pull off. No sign of irritation under the scab/scale. Hair comes with each scab. Dog does NOT itch. Doesn't even care that I scratch them off when petting him. But it is new and he is 5. Where the little scabs/scales are, his hair is turning grey. His stomach and under areas have little or no hair and has been that way since we got him around possibly age 2 (he is about 5 or 6) (mention it to the vet and they never seemed to care). He is a medium size mutt. Sits off to the side like a pity, but has a face or a regular dog. He goes outside to play ball or to do his necessities, but not much traveling outside the lawn. We live in NE PA and no environmental changes have taken place. He is on thyroid medication, but has been LONG before this issue. He had medication in one ear for bacteria and one ear for yeast. He has severe teeth/gum issues, but just recently started brushing his teeth with Petrodex Enzymatic Toothpaste. (maybe that is it?) It seems to be helping his halitosis/gingivitis and tooth decay. I don't knpw what else to tell you. He suffered from a brain issue for about 3 days where he was almost put down, but the steroids seemed to do the trick and was back to his old "self" in days. He's had to take this twice in the last few months. I can't remember why the other time, maybe the teeth? i can't seem to find any image that matches our issues. Help?

Natalie on September 12, 2018:

My dog got black dark patch under arm pits and on belly feel sweaty is there something i can do to get rid of it as he does get sore thank you.

Westie mom on June 17, 2018:

My 1 year old Westie female has skin discoloration on her back and a big patch near her tail

Dottie Gray on January 16, 2018:

Rusty Smart Shame, was my entire litter and without adequate heating and after obtaining only noodle sop and vanilla pudding they both died in Feb.!

Richard morton on November 03, 2017:

I have a Scipper key and a English massive. Both are loosing hair on there back close to the tail and the skin is turning black. Also they have puss in there eyes and are very itchy. My blonde shepard appears to have a yeast infection. No black skin on her but red skin and loosing patches of hair. We had a male rabbit for years who recently pass. He sprayed the dogs daily but has been gone about two months. HELP!!!!!

Mitchell Lopez on June 09, 2017:

"17th World Dermatology Congress” welcomes all the speakers, delegates(both from academy and business) sponsor’s and other research expertise which is going to be a part in Dubai, UAE held during September 25-26, 2017 . This conference will help to exchange and share your views and experience on the Dermatology . Dermatology has evolved into one of the most dynamic specialties in medicine. Dermatology is also dedicated to correct the appearance disorders. Indeed, the skin, the largest organ of the human body, is often a place of disease. Skin exposure to environment influences and its importance to the good-looking and well-being requires extra care that can be provided by Dermatology. This conference provides beautiful platform for business networking and luxurious stay at the most beautiful city Dubai which includes the prominent attractions Burj al arab, Burj-Khalifa, Burj-Khalifa-Lake, Deira-Clocktower, Mall-Of-The-Emirates, Palm-Jumeirah-At-Night, wild-wadi, Bastakia.

Michelle Liew (author) from Singapore on July 16, 2014:

Sounds like cherry eye or another bring it to the vet. Stop the dog from rubbing it's eyes by putting an Elizabethan collar on.

wanda barrios on July 15, 2014:

my small five yr old chiguagua has a lump under his eye full of blood n yucky stuff it rupture today wat can i do ??

Michelle Liew (author) from Singapore on May 30, 2014:

I understand. A skin disorder is so difficult to cope with! Thanks for sharing.

BODYLEVIVE from Alabama, USA on May 29, 2014:

We've had a dog with a serious case of Demodectic Mange. He was hospitalized but never regained all of his hair back. It was a hurting thing for us and we couldn't do anything for him. We had to make a pen off the ground so he did lay in the dirt. The vet gave us medicine that we had to bathe him in twice a week. We did all that was asked but we soon had to give him up.

Michelle Liew (author) from Singapore on April 15, 2014:

Thanks, Devika.

Elliott Raggio from Hove on April 11, 2014:

i've got a canine and this hub proves to be really really helpful..thanks a lot..i'm sure gonna share it with my friends

Devika Primić from Dubrovnik, Croatia on March 18, 2014:

Very interesting about dogs and skin disorders. An informative and useful hub.

Marcie63 on February 16, 2014:

Addi have a Tea Cup Chihuahua that has redness on her paws, around her mouth, around her eyes(sometimes) and on her chest with a large patch on her back. She is not scratching more then normal. There is no open sores, no puss. She is shedding but it does not seem to be more then normal. She is 5 years old current on everything, vet said she thought it was an allergy to something and to give her Childrens Benadryl, which I have from time to time it helps a little but not much. We have changed her food from wet/dry mix to straight dry and have even changed the band. She is a bit over weight at 5 1/2 lbs. It look better some days then back to bright red the next with no chane in anything. I am at a loss as yo what it coul be! But it does seem to be getting worse. Help please, she is my baby and I feel so bad because I cannot help her.

Michelle Liew (author) from Singapore on December 31, 2013:

Sounds like abscess. Do have a check with the vet to confirm!

Bridget on December 29, 2013:

Our Golden Retriever is experiencing nodules on the skin, one a time, along her back. They begin small, then grow in size to a full dime size and full of green puss, then leach and heal but leave black round spots until they're gone. Do you have any idea what this could be?

Michelle Liew (author) from Singapore on November 16, 2013:

It is probably an allergic reaction...or she probably requires supplements to stop hair loss. An infection is possible too. Get them to probe a little further.

elissa on November 15, 2013:

I'm wondering if maybe she can have an infection. Or what to ask my vet to look for because seems to me I've went to three vets and they are idiots

elissa on November 15, 2013:

My dog doesn't have redness or any patches of hair loss. But recentlyhad fleas but is treated monthly and i don't know if its due to winter but she is a chow and is losing fur on her belly and by her on her inner and back of legs. I'm bring her to the vet often shese on an itch relief med but doesn't help much

Pete on October 23, 2013:

I came back to say that everything seems to be ok now. I read more information about the meaning of those fatty acids and now changed dogs diet totally to bit more better and I could cut down the added oils. Funny thing is that my dogs ate and pooped way better when I added the krill oil for dogs.

Michelle Liew (author) from Singapore on September 22, 2013:

Pete, I think the cheapest way I can think of is to change the dog's living circumstances. If you can find ways for it to avoid the allergies, it will be the best course, because any treatments are usually quite expensive.

Pete on September 17, 2013:

I started feeding krill oil to my dogs for flaky skin as recommended here It seems to work but I am wondering if there is cheaper way? there are some recommended amazon products on their site but I am interested other opinions too.

Michelle Liew (author) from Singapore on June 05, 2013:

Thanks, Lady Deonne! I hope that the vet can help with the problem! Thanks for sharing!

Deonne Anderson from Florence, SC on June 03, 2013:

Very well researched and presented subject. Your pictures speak volumes about how allergies and other skin problems can affect our beloved dogs.

My Red Nosed Pit has been having problems with her breathing. She has an appointment with the vet for this Wednesday. Her brother also has seasonal allergies.

Michelle Liew (author) from Singapore on June 01, 2013:

If only they could indeed, Thelma! Thanks for sharing!

Thelma Alberts from Germany on May 31, 2013:

Poor dogs! If they only can tell us what bothers them. Thanks for this well researched, useful and informative hub. Thanks for sharing.

Nithya Venkat from Dubai on May 26, 2013:

Great hub, useful and so much detailed information about skin disorders affecting dogs. Poor dogs, they can't even tell us what is troubling them.

Michelle Liew (author) from Singapore on March 30, 2013:

Thanks, Francene! Nice to see you here too!

Francene Stanley on March 30, 2013:

Wow! That's some list for the poor doggy palls. I hope the information is useful to some owner/friends.

Michelle Liew (author) from Singapore on November 30, 2012:

Hi Mike, indeed they are. But if treated on time, they don't suffer too much, don't worry! Thanks for sharing!

Mike Robbers from London on November 30, 2012:

Poor dogs,, Those pictures are so sad :( .. it so much painful seeing animals suffering..

Thanks Michelle for giving us so much in this hub, you did an excellent research.. voted and shared!

Michelle Liew (author) from Singapore on November 29, 2012:

Hi Dana! Oh dear....glad that he's doing ok now....hope the remedies don't have to be long term, though!! Thanks for coming by!

Dana Strang from Ohio on November 29, 2012:

This is fantstic. So much great info... I had a coworker that had a bulldog who was sooooo itchy. Turns out it was food allergies. His allergy tests also showed he was allergic to HUMANS! How crazy. A dog allergic to people. Poor thing. He is doing well now.

Michelle Liew (author) from Singapore on October 22, 2012:

Thanks, Lipnancy. It's indeed painful to see an animal suffer! Thanks for coming by!

Better Yourself from North Carolina on October 22, 2012:

Interesting hub! Thankfully I haven't had a dog with a skin disorder and I didn't know there were so many. Thanks for sharing - always good to know what to look for.

Nancy Yager from Hamburg, New York on October 22, 2012:

Oh those pictures are so sad to look at. Great hub.

Michelle Liew (author) from Singapore on October 20, 2012:

Thanks for the compliment, toknowinfo!

Michelle Liew (author) from Singapore on October 20, 2012:

Butler could be allergic to something there, Meldz, so best to be careful! Thanks so much for coming by!

toknowinfo on October 20, 2012:

Thanks for putting this excellent hub together. It is very well written and explained and very full of useful info.

ignugent17 on October 20, 2012:

Very useful Michelle. I feel pity to those dogs who are affected by different skin diseases. Thanks for sharing this information.

The skin of Butler turns red when he goes to the pond.

Voted up and more. :-)

Michelle Liew (author) from Singapore on October 19, 2012:

My blessings to Missy, Keith. Glad this was useful.

Michelle Liew (author) from Singapore on October 19, 2012:

Spaniels do qualify, Lord, and they have their share of skin problems. Thanks for the compliment!! Still much for me to learn about animal care. I hope this is helpful!!

KDuBarry03 on October 19, 2012:

We're taking our dog, Missy, to the vet asap because she's showing some of the very same symptoms you have stated. Thank you for another informative hub, Michelle!

Joseph De Cross from New York on October 19, 2012:

Well done Michelle. There is so much put in this hub, that a vet student would love to have it for reference. Seems that you know more than the average writer about puppies and puppy love. I had a Cocker Spaniel and she didn't have much issues. I'm not sure if she qualify for a blue dog, but she was light colored. Thanks for giving us so much in a hub.

Michelle Liew (author) from Singapore on October 19, 2012:

Thanks, Healthy life, and I wish the best of happy health to your schnauzer! Glad you find this useful too!

healthylife2 on October 19, 2012:

Very well researched hub on skin disorders for dogs. My miniature schnauzer is my first dog so it's good to know what to watch out for. Some itching is normal but it's good to know to watch for excessive itching and hair loss and all the other skin conditions. Voted up and shared!

Michelle Liew (author) from Singapore on October 18, 2012:

Fleas are terrible, Mary. When they manage to bite us somehow it's really itchy, so we can guess how it is for the dog. Thanks for sharing!!

Michelle Liew (author) from Singapore on October 18, 2012:

Thanks, Richard!! Actually, I think more things affect them than they do us. Thanks for coming by!

Mary Hyatt from Florida on October 18, 2012:

Baby, my Miniature Schnauzer, is terribly allergic to flea bites! I have to use a product to keep the fleas off her. She will scratch until she has a "hot spot", then I have to put the lampshade collar on her so she can't scratch more.

You did a lot of research on this Hub. I voted it UP, and will share.

Rich from Kentucky on October 17, 2012:

Michelle - Very informative. So many things can affect the pets we love. It's a matter of constant awareness to catch them as quickly as possible. Great Job and presentation! Up & Useful & Interesting!

Michelle Liew (author) from Singapore on October 17, 2012:

Thanks, Denise! Could be mange....that often causes a bit of hair fallout. It's sad what they go through not that we suffer less when we are sick...for them, they've fewer ways of communicating their problems and helping their owners understand them. So I guess we've to be observant!! Thanks for coming by!

Denise Handlon from Michigan on October 17, 2012:

Interesting information, Midget. I've been noticing a lack of fur on my dog's 'elbow' area of one leg. Thanks for sharing this. Some of these skin disorders are so sad on these poor dogs. Great photos to help with the info. Rated Up/U/I

Michelle Liew (author) from Singapore on October 17, 2012:

Thanks, Farmer Rachel. Yes, it's hard to see a nice dog suffering from any of these problems. I hope that it will help owners and dogs with skin trouble! Thanks for coming by!

Rachel Koski Nielsen from Pennsylvania to Minnesota on October 17, 2012:

Very informative hub. Some of those pictures are sad and disturbing, but then again who wants to see a dog that is sick or suffering? You 0bviously did a lot of research and put a lot of time into this hub - great job!

Michelle Liew (author) from Singapore on October 17, 2012:

Glad that the dogs are ok, Bill. And fortunately, you have a great vet. They really itch when they have skin disorder, so it's good to watch for it. Thanks for coming by!

Bill Holland from Olympia, WA on October 17, 2012:

Those were some ugly pictures! Ewww....those poor dogs. We have three dogs, and they have had their rashes, but never anything like those pictures. Crossing my fingers! Anyway, we have always had our treated by the vet and it has gone away quickly. Yuck! Glad I already ate breakfast! :) Good job; sharing!

Michelle Liew (author) from Singapore on October 17, 2012:

Thanks, Diana. Those who suffer from these are indeed pitiful because they cannot say anything about their pain. And it's quite extreme. Thanks for the compliment! Researching dogs and finding out everything I can about them is something I truly love doing. Thanks for dropping in!

Dianna Mendez on October 17, 2012:

Poor doggies. I am wincing after looking at some of their photos. As a teacher, I saw a few cases of ringworm on kids who had pets in the home. You have really done an excellent job in researching this topoic and I am sure it will help many pet owners in discovering the relief for the dog's ailments.

Michelle Liew (author) from Singapore on October 17, 2012:

Thanks, Janine! Glad that you find it useful. Well, they do have a bit of mange by nature, and will experience some skin trouble...but I guess less was known about them then! Thanks for stopping by!

Michelle Liew (author) from Singapore on October 17, 2012:

Mary, thanks for coming by! Glad that you've found this useful. Sorry that Min Pin has allergies...but take heart that they're usually curable unless they get a form closer to Vulgaris. Yup, always something new to discover about dogs! WIll share more soon. Thanks for coming by!

Janine Huldie from New York, New York on October 17, 2012:

Michelle, you have done your homework here and this is a well researched and laid out article on skin disorders in dogs. As you know growing up we did have a West Highland Terrier, but to be honest I truly don't remember him having any real skin conditions, but that was indeed a long time ago, so it is possible that I just don't remember anymore. Thanks for sharing this here and have voted up and shared all over too!!

Mary Craig from New York on October 17, 2012:

You've done a very comprehensive job here Michelle. While we love our dogs there are so many things we don't know about them. I've had dogs all my life and now my Min Pin has allergies. Never heard of it before but between him and now your hub I can see it is more common than I imagined. Always something with our beloved four legged friends.

Voted this hub up, very useful, awesome, and interesting.

Michelle Liew (author) from Singapore on October 17, 2012:

What are the symptoms, causes and types of skin diseases in dogs? Which breeds usually experience them?