Baldness in Dogs (Alopecia)

Bald SetterI’ve been seeing a number of bald dogs in the consulting room recently, and it made me wonder how common a problem it is – and how many conditions there are that can lead to a dog losing his hair!

Baldness (or alopecia, to give it its technical name) isn’t generally a disease in its own right – it is almost invariably a symptom of an underlying disease condition. So, when I’m faced with a poor, balding dog in the consult room, my first task is to try and define what the underlying cause is. With a symptom with so many possible causes, what we do to narrow down the possibilities is to work out a differential list – a list of all the possible conditions that can cause baldness – and then eliminate them until we come to the actual cause in this specific case.

So, in no particular order, here are the more common causes of hair loss in dogs, along with their other major signs or symptoms:

Firstly, those disorders that give a symmetrical pattern of hair loss (i.e. the same pattern of hair loss on both sides of the body):

Hypothyroidism

Hair loss is symmetrical along the trunk and may also involve the tail, armpits and the belly. The skin isn’t inflammed or itchy, but there may be a darkening of colour and dandruff or greasy skin. Caused by production of too little thyroid hormone, other common symptoms include lethargy, weight gain, and sometimes muscular weakness. To diagnose hypothyroidism, your vet will take a blood sample; treatment is simple, with daily tablets containing replacement thyroid hormone.

Cushing’s Disease

Once again, hair loss is symmetrical, and there may be hard lumps in or under the skin (calcinosis cutis). Cushing’s is caused by too much cortisol (an important natural steroid hormone) being produced by the body. Other symptoms include increased hunger, thirst and urination, development of a pot-belly, muscle weakness, skin thinning and “spots” or “blackheads” developing. To diagnose it, your vet may have to do a series of blood tests to see how your dog’s body responds to injections of steroids or other hormones. Tablets to treat Cushing’s usually act to reduce production of steroids, although some destroy the adrenal glands that make the excess hormones.

Iatrogenic Cushing’s Disease

This is a form of Cushing’s disease caused by long term use of steroid medications (e.g. Prednisolone for severe allergies). The only treatment is to VERY GRADUALLY reduce the steroid dose – but this needs to be done carefully, following advice from your vet, because if you reduce it too far, too fast, it can result in severe withdrawal effects, or even death, due to a lack of cortisol in the body.

Sex hormone disorders

Excess production of sex hormones (e.g. due to a testicular tumour) or insufficient sex hormones (usually after neutering) can, in rare cases, cause symmetrical hair loss.

And now, those diseases where there are patches of hair loss in various sites across the body:

Flea Allergic Dermatitis

This is probably the commonest cause of all! Dogs with a flea allergy scratch and scratch, and wear the hair away. FAD is usually straightforward to diagnose (very itchy dog plus fleas is something of a giveaway), although in extreme cases, a single flea bite can set it off, which is harder to detect. Prevention is simple – avoid and kill fleas – although it can be hard in severe cases to keep the flea population low enough, and anti- allergy medication may be required.

Sarcoptic Mange

Mange mites burrow into the skin, creating a very itchy patch covered in little bumps. The dog scratches away at it, wearing the hair away, creatng a bald patch. The most common site is on the ear; fortunately, there are some spot-on treatments available from your vet that will kill the mites and stop the itching.

Demodectic Mange

This is a different variety of mite, and unlike the sarcoptic mite, it doesn’t itch at all. Most dogs have a few, and they don’t cause any problems, living harmlessly deep inside the hair follicles. However, sometimes they can start to multiply, and the sheer numbers start to result in hair loss. Typically, it is a patchy disease, with hair loss in distinct regions that get bigger over time. Sometimes there is a bit of scale forming, but the mites themselves do not cause itching, although secondary bacterial infection may occur, which can. To diagnose Demodex mites, your vet will have to take a deep skin scrape, usually with a scalpel blade, and then look at it under the microscope. If Demodex mites are found, treatment may involve spot-ons like Promeris Duo, or bathing with Aludex for several months – sadly, it can take a lot of work to get it under control.

Primary Pyoderma

Bacterial skin infections are common in dogs, and can result in hair loss. The skin is usually reddened and inflamed, and there may be pussy “spots”. Often the area is itchy and sore, but occasionally there are cases where the skin looks almost normal, but hairless. The vet can diagnose it by taking scrapes and smears from the skin, then looking at them under the microscope. Treatment nay involve antibiotic creams, washes, and sometimes tablets to kill the bacteria.
Sometimes a yeast infection can cause the same symptoms; treatment then is usually with anti-fungal washes.

Ringworm

(Or dermatophytosis) is often diagnosed in practice, generally by using a Woods Lamp, which makes the fungus glow. Its appearance can vary widely, but most looking involves patches of hair loss, sometimes with scales, sometimes itchy (but not always). It’s particularly a problem in dogs that are ill with something else, and have reduced immunity. To get a definite diagnosis, hair plucks have to be sent to a lab and cultures, but that can take weeks so vets will often start treatment while waiting for confirmation to come back. Treatment usually involves washes, shampoos and occasionally tablets to kill the fungus, but it can take a long time to completely clear a bad infection.

Allergic Reactions

(e.g. to a spot-on medicine, or a new floor cleaner, sometimes even to food!). Usually, there is reddening and inflammation of the skin, and itching, before the hair comes out, but occasionally hair loss is noticed first.

There are other causes (e.g. genetic disorders, immune diseases like pemphigus) but they are generally far less common. It’s important to remember the old adage that “common things are common” before jumping to cocclusions.

Baldness and hair loss in dogs can be a marker for a serious underlying condition – it’s almost never due to simple old age! – but most of these conditions are either curable, or at least manageable.

And the dogs I saw this week? Well, one was a nice simple skin infection (although it didn’t look like it to begin with, the tests were clear and she responded really well to antibiotics). The other one had been on steroids for several years, and the effect over that time had given him Iatrogenic Cushing’s. His owners are working to reduce the dose (very, very gradually, as his body has become dependant on the tablets now), and to keep him warm, they’ve bought him a coat to wear when he goes out in the cold for a walk!

If you are worried about bald patches on your dog, talk to your vet or check any other symptoms using our interactive Dog Symptom Guide to help decide how urgent the problem may be.

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22 thoughts on “Baldness in Dogs (Alopecia)

  1. Yes, you’re right – sebaceous adenitis can occur in many breeds, although with the exception of Standard Poodles, Akitas, Samoyeds and Vizslas, its not considered common.
    SA is an immune-mediated disorder (where the immune system attacks the sebaceous glands in the skin); there are a wide range of these diseases, but as they aren’t the commonest causes of alopecia, I’ve skipped over them here – however, I’ll be talking more about these in a later blog.
    Interestingly, despite a lot of research, the exact genetic cause is still to be determined, although many researchers think it is likely to be polygenic (i.e. there are several genes involved).

    David Harris BVSc MRCVS

  2. Yes, you’re right – sebaceous adenitis can occur in many breeds, although with the exception of Standard Poodles, Akitas, Samoyeds and Vizslas, its not considered common.
    SA is an immune-mediated disorder (where the immune system attacks the sebaceous glands in the skin); there are a wide range of these diseases, but as they aren’t the commonest causes of alopecia, I’ve skipped over them here – however, I’ll be talking more about these in a later blog.
    Interestingly, despite a lot of research, the exact genetic cause is still to be determined, although many researchers think it is likely to be polygenic (i.e. there are several genes involved).

    David Harris BVSc MRCVS

  3. my dog suffering from chronic skin problem, from that lots of issues arise like hair fall, itching. I used different different product but still has the same problem, could you please tell me about Dermapaw? Is it really works? Please reply me.

    1. Hi, it is a product that might help – like many skin products what works for one animal may not for another. It might be worth speaking to your vet for their advice as well, as they know you dog and the condition.

  4. my dog suffering from chronic skin problem, from that lots of issues arise like hair fall, itching. I used different different product but still has the same problem, could you please tell me about Dermapaw? Is it really works? Please reply me.

    1. Hi, it is a product that might help – like many skin products what works for one animal may not for another. It might be worth speaking to your vet for their advice as well, as they know you dog and the condition.

  5. Hello,
    My year-old rescued dachshund is experiencing hair loss and pretty severe dandruff on her ears (mostly on the folds, but partly on the outer flap as well).Does dandruff usually occur with conditions like pinnal alopecia and canine pattern baldness? I’d appreciate your insight.
    Thanks!

    1. Hello Anne, thank you for your message. There can be dandruff around the ears, but its also usually on other parts of the body too. If your dog seems to be scratching at thet area, it is best to get them checked, as sometimes it can even be another underlying problem such as earmites causing the issue. We’d advise a trip to the vets for a proper check. Dave RVN Vet Help Direct admin.

  6. Hello,
    My year-old rescued dachshund is experiencing hair loss and pretty severe dandruff on her ears (mostly on the folds, but partly on the outer flap as well).Does dandruff usually occur with conditions like pinnal alopecia and canine pattern baldness? I’d appreciate your insight.
    Thanks!

    1. Hello Anne, thank you for your message. There can be dandruff around the ears, but its also usually on other parts of the body too. If your dog seems to be scratching at thet area, it is best to get them checked, as sometimes it can even be another underlying problem such as earmites causing the issue. We’d advise a trip to the vets for a proper check. Dave RVN Vet Help Direct admin.

  7. My 12 year old chihuahua Leesa has lost most of her hair. It is definitely symmetrical hair loss. The hair she does have is very thin and brittle. She gets lots of these warty looking things that never really go away, but do get smaller over time. Also her skin is just covered with thousands of tiny blackheads. If I gently scrub with a washcloth, you can see them come away on the cloth. She does not scratch or itch.She has been tested for thyroid disease, and she does not have it. I bathe her once a week with Pyoben shampoo, and i just started a new spray for her skin called Miconahex+ Triz. Any suggestions?

  8. My 12 year old chihuahua Leesa has lost most of her hair. It is definitely symmetrical hair loss. The hair she does have is very thin and brittle. She gets lots of these warty looking things that never really go away, but do get smaller over time. Also her skin is just covered with thousands of tiny blackheads. If I gently scrub with a washcloth, you can see them come away on the cloth. She does not scratch or itch.She has been tested for thyroid disease, and she does not have it. I bathe her once a week with Pyoben shampoo, and i just started a new spray for her skin called Miconahex+ Triz. Any suggestions?

  9. My one year old apricot miniature Poodle has lost his hair along the truck on both side 3 months ago. He does not scratch or itch. The bald spots start small and become quite large and also the skin of the bald spots are darken in colour. Beside the look, he is happy dog and eating and sleeping well. After a month, his hair started to grow back slowly but in darker colour. Now he is losing hair again on both sides. what should I do? I took him to the vet but he think my dog is too young to have Hypothyroidism. Any suggestion?
    Thanks!

    1. Hi Peggy. I’m glad to hear that other than his alopecia, he’s happy in himself! I’d pop him back to your vet for another check-up; they may want to run some tests to rule some conditions out, as there are a few causes of alopecia. It would also be worth from your point of view keeping a diary of anything that may be happening when his hair loss starts – what has he eaten, is there anything that’s changed in his routine, is he relaxed and happy or is anything causing him stress, has he come into contact with anything? All of this may help your vet to pinpoint what could be causing his hair loss.

  10. Hi,
    We are at a total loss with my 15yr old Pomeranian cross. I’m a VN and our 3 vets have no clue what’s going on.
    He used to have the most gorgeous hair but after being clipped it never grew to it’s full potential.
    Over the past year it has thinned out incredibly causing to almost be bald!
    No know skins issues, blood work, urine is beautiful!
    He gains growth when he loses the top layer of skin e.g he has a sore on his back! (Not skin disease related) and the hair has just shit through beautifully.
    What can be the cause of this?
    No symptoms, not itchy, no redness, etc.
    only blackheads and darkening of the bald areas.

    If you guys have any insight it would be wonderful!

    1. Hi Emily. Your boy sounds like a very unusual case, especially if he’s baffled three of your vets too! We would always suspect parasites/endocrine disorders/hormone imbalance or allergies, but it sounds as though these have been ruled out. There is also a condition called post-clipping alopecia, and although the reason for regrowth isn’t known, it’s been suggested it could be due to vasoconstriction of blood vessels in the skin surface. It’s more common in dogs with dense coats. Dogs in these cases do regrow hair, but it can take 12-24 months, and the coat may never quite be the same as it originally was. If you do find the exact cause of his alopecia though, please do let us know!

  11. I have a patterdale terrier puppy and she has recently gotten some bald patches on her front leg. She has worming and flea treatment regularly. I’ve been told I bath her too often, could that be the cause?

    1. Sometimes it can be a cause Jade, or it could be something like allergies/other external parasites/overgrooming etc. I’d recommend having a chat to your vet who will be aware of her clinical history and would be happy to advise you as to what the cause could be/any necessary check-ups she may need.

  12. Is treatment advised if the symmetrical hair loss is due to a hormone imbalance due to castration? Or will time be the best healer? My 20 month old (nervous) bc has been neutered 3 months ago. His fur became drier or coarse and then started breaking and/or thinning at the upper legs. This led to patches of very thin fur both sides of his body and has now also started on his flanks, again symmetrical. There is no sign of redness, lumps, puss or anything else and although he has always had the occasional scratch he doesn’t seem itchy. His scratching usually seems more stress related than anything else and doesn’t happen very often.

    1. I’m really sorry to hear that – it’s not common, but there is a known syndrome, sometimes called Alopecia X, that can cause coat alterations similar to the ones you describe. In some dogs, it is triggered by neutering, in others, the symptoms may even be resolved by castration. It’s known as Sex Hormone Dematosis, Castration Responsive Dermatosis and Testosterone Deficiency Dermatotis, as well as a wide range of other names, including Pseudo-Cushings Syndrome and Growth Hormone Deficiency; however, it’s probably actually a number of different disorders with similar clinical signs.
      As a result, there’s no universally accepted treatment regime, although some researchers report positive results from a range of different hormonal treatments – although, of course, such treatments invariably have potential side effects. It is possible that it will settle down after a moult, but it definitely isn’t certain. This is such a complex area I think that you would be best to seek advice from your vet, and if necessary, a dermatology or endocrinology referral to an advanced practitioner or specialist. David Harris MRCVS

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