What can be the cause for patchy re growth/bald patches ?

picture showing patchy regrowth on a spaniel

I think that most groomers have encountered dogs with bald spots or patchy hair loss in their salons.
We sometimes also get accused by the client of causing it with our grooming techniques, and the question pops up on a regular basis in grooming groups on Facebook.
I will try to address the most common issues that we see in this blog post- how they look, the cause of them, and what we can advise the owners.
Remember that we are not vets – so we don’t diagnose. But we can tell the owners what it  “looks like” and also adapt our grooming routine based on what we find.
This is not a scientific write-up as that would be too long -this is just a brief overview of the topic.

You will notice that many of them look the same. This is because the symptom of the problem, in most cases, is that the hair follicles are affected and either go into arrest or are deformed. But the reason for the problem can be different things.

Patchy regrowth after a clip off on a spaniel type of coat.  

picture showing patchy regrowth on a spaniel
Patchy re growth on a spaniel

You clip the dog for years without a problem and then one day the clients turn up with the dog for an appointment and the hair on the loin/croup area hasn’t grown back. It is as short as on the day when the dog went home.

This is NOT caused by the clipping in itself or the fact that you reverse clipped ( it happens when you clip with the grain as well )  This is down to the hair follicles in that area being stuck in the resting phase and not shedding and then moving on to the growth phase. That paused cycle will be visible when the coat is clipped.

The cause for this is 9 times out of 10 a medical issue.  It can either be a thyroid problem- the thyroid hormone is part of the signals that trigger a move to the growth phase /creation of new hair.
If the dog lacks enough of that hormone no signal will be sent to the hair follicles to start the process of creating new hair/ actively growing hairs.
A thyroid problem can sometimes be visible as a general bad regrowth of hairs or sometimes as this patchy regrowth.

Treatment with steroids can also cause this as they suppress the signals and the dog ends up stuck in one phase and not moving forward to the next.

The reason why other medical problems can cause it is that the body will reduce the nutrition to the coat if it’s needed elsewhere in the body to fight an illness.

The coat and skin need around 30 % of the nutritional intake -but as it is the less important organ of the body it gets whatever is left once the others have had what they need. And if the dog is sick – the body will redirect all nutrition to that area to help fight the illness and the coat growth is shut down to save energy/reduce the use of nutrition.  Old age also slows down coat growth. 

We can also see this if the dog has been treated with a Fentanyl patch. A Fentanyl patch is a sort of pain reliever that you apply to the dog’s croup area. It works like a nicotine patch. You must shave the area for the substance in the patch to be able to be released onto the dog’s skin.
A side effect is that Fentanyl has shown to affect the hair follicles and they seem to go in to arrest. There have also been reports of change of color on the hair in the treated area.

Cavailer clipped with a 7F with the grain. This picture is taken 8 weeks after the last groom and as you can see that no hair has grown back on the body. It emerged shortly after this picture was taken that she had a liver tumor.
Photo :Shauna Kerin

The guard hairs grow in a mosaic pattern.  If you were to pull them all out they would first come back over the shoulders and on the croup. The next step will be on the neck, back, and loin area. And then the new hairs gradually start to show up on the sides of the body -slowly spreading down on the sides.

This is why they can get this defined empty “ square” over the croup/loin. If the hair follicles were in the resting phase when we clipped the dog and the dog has a medical problem – the hairs won’t be shed and no new hairs will start to grow. The hairs we cut off are just left in limbo. 

How can we prevent this from happening?
We as groomers can’t prevent the dog’s health/age issues – but one thing that we can do in order to reduce the “damage” is to wash and dry and de-shed the dog before we clip it.  Make it into a habit of carding your short clipped spaniel type of coats after the clip off as well.
By doing that we remove all old hairs and signal to the body that it’s time to create a new hair as the hair follicle is empty. By reducing the number of hairs in each hair follicle we also allow for more nutrition to the hairs that are left. 

What advice can I give the owner?
Tell them to make an appointment with the vet to check the thyroid function and also to do a general check-up.
They can also stimulate blood circulation in the area by brushing the dog with a bristle brush – the increased blood flow helps to transport more nutrition to the hair follicles in the area. And it aids in removing old hairs.
Advise them to look into the dog’s nutritional intake – as I said before – the skin/coat is the largest organ of the body and demands 30% of the nutritional intake in order for optimal function. But it only gets the leftovers – so we need to make sure there’s enough left over to cover the need.
So changing to a high-quality food or adding an extra high-quality protein to the current food can help improve the growth once the initial problem is addressed.

The difference when you switch to high-quality food.
You can see the patchy regrowth in the right picture – the picture to the left is 3 months later.
It will take time to see a complete difference as we can only affect the hair that is created after the change of food. So we need to give it time to emerge above the skin in order for us to notice the difference.
Photo :Barbara Kavanagh

Patchy regrowth/coat funk on a so-called “ double-coated breed “ 

Patchy regrowth on a collie that’s been clipped with a 5F with the grain or a 3F in reverse for several years. He gets done 2-3 times per year and most of the time it is patchy -but once every 2nd year it grows back fine.

Dogs have 2 main types of hairs that create the coat – undercoat /wool and guard hairs. They share the same hair follicle – but have two separate growth cycles. The cycles are run by several factors like hormones, temperature, daylight, nutrition, stress, and genetics

There is 4 stages in the growth cycle:

Anagen or Growth Phase

The anagen phase is the first phase of new hair growth. Dogs that do not tend to shed heavily have a longer anagen phase. Dogs that continuously shed have shorter anagen phases. The amount of time the hair follicle stays in the anagen phase is genetically predetermined.  Poodles for example spend almost 98% in the anagen state – their coat grows more or less constantly. Other breeds with short hair spend only a short time in this phase.

Catagen or Regressing Phase

The catagen phase is the transition phase. This phase begins when the cell creation signals to stop. Hair stops growing during this phase and the outer root sheath attaches to the hair.

Telogen or Rest Phase

Telogen is the resting period. This period varies depending on the type of coat the dog has – in most breeds this is the longest period in the cycle. Breeds with a “Nordic” type of coat – as Huskies, Elkhounds can spend several years in this phase. This is nature’s way of using the nutrition/energy in a good way – in a cold climate, you need the energy to keep yourself warm – not to grow a coat.

Exogen or Shedding Phase

The final phase, exogen, is the shedding phase. This phase occurs when the hair falls out and the follicle moves back into the anagen phase. The length of this phase depends on the season.

A new phase has lately been introduced when we talk about coat growth phases – ‘‘kenogen’’: It applies to hair follicles that have passed the telogen stage, lost their hair fiber (exogen), and remain empty for a certain time before a new anagen phase is starting.

The hair follicles are all in different stages all over the dog – some are resting – some are preparing to shed –some shed and some are creating new hair. There is a practical reason for that – creating new hairs demands a lot of nutrition so if all hairs fell out at the same time there would be a huge amount of nutrition needed to create a full coat again – and it’s going to be tough to fill that demand.
But if some hairs are resting while others are created the nutritional demand will be much lower.

We would also lose the purpose of the guard hairs if they all fell out at the same time – that would leave the dog without a “weather shield “ and exposing the wool to the elements.

As I mentioned above – some breeds guard hairs can be in the resting phase for 4-5 years – while the undercoat usually has a 6-month cycle on most breeds  –they shed and grow new undercoat twice a year as the undercoat is there to keep them warm in the winter and gone in the summer to keep them cool.

During spring they shed the thick winter wool and set thinner summertime wool and then in the autumn is time to shed the summer wool and set thicker winter wool again.

The shedding of the wool is much more synchronized and usually happens all over at the same time – at least it feels like that when it happens ….

When we clip a so-called double-coated breed there is a high risk that the guard hairs won’t grow back for a long time and the dog will look really stupid during that time. It all depends on where in the growth cycle the hair is when we clip the dog.  It can grow back just fine but in the worst-case scenario it can be at its start of the resting phase and it will be 2-3 years before all hairs are out in normal length. Or the dog is elderly and the body decides that the nutrition is needed for more important things than hair….

A lot of elderly dogs also suffer from medical problems and that will also affect the growth as the body needs the nutrition to battle the sickness – not to create hair. And it’s sometimes an underlying medical problem that suddenly gets visual when you clip the hair.

A 14-year-old Tibetan spaniel has been clipped with a 7F twice a year for many years and always grown back fine. But at 14 years of age, it didn’t come back after the last groom. The hair growth has slowed down with age and we can see that the hair follicles on the back and sides haven’t moved to the growth phase this time.
Photo : Valerie Power

There are also medical conditions that can cause the hair follicles to go into a permanent resting state. You won’t see it until you clip the dog as the hair isn’t growing – but it’s not the actual clipping that caused it – it just made it visible.

So there is a risk that the hair never grows back again….The body can also decide to put the hair follicles in a permanent resting phase when we clip them short. This is most common in the ” nordic type” of breeds – but it sometimes occurs in other breeds as well.
The cause of this is still not known – one of the theories is that the cooling of the skin when the hair is gone gives a signal to the body to reduce the blood flow to the skin to keep the core heat and that affects the hair follicles growth cycle. Another theory is that hormones disrupt the growth cycle. 

What can we do to prevent this?
Always wash and de-shed the dog before clipping it in order to remove as much of the hairs that are ready to come out as possible. That will signal to the hair follicle to create new hairs. You will also have fewer hairs competing about nutrition.
Do another round of carding once you have clipped the dog.

Don’t clip the dog too short – try to leave at least 1 cm so the skin doesn’t feel the chill that can trigger a shut down of follicular activity. That will also protect the skin and reduce the risk of thickening of the skin that can affect the hair follicles.

What advice can we give to the owner?

Always warn them about the risk if they ask for a “Boo clip” on a pom or shaving their collie for the summer. Just so that they are aware and can’t blame you for it.

If the problem occurs – tell the owner to brush the dog on a regular basis to remove the “dead” undercoat and to feed high-quality food to allow for more nutrition to the coat. Brushing also increases the blood flow to the hair follicles.

What can I do in the shop if the problem occurs?
Bring the dog in on a regular basis for a wash and de-shedding session. Don’t use any aggressive coat rakes as they tend to cut some of the hairs –
The undercoat is usually like Brillo as it changes in texture due to suddenly being the main protection for the body.
Use a light silicone-based conditioner to soften it to prevent matting.

Clipped pomeranian – you can see the area on the croup and flank where the guard hairs are missing. This is the exact pattern for the mosaic pattern I talked about. If we left the coat untouched for another year -the coat would in 9 times out of 10 come back in those areas as well.
Photo :Lisa Curran


Alopecia means hair loss and it can be caused by a wide range of factors as genetic, hormonal, and medical. Sometimes we don’t even know why it appears.

The most common we hear about is Alopecia X . . This name was coined a few years ago to refer to the following disease(s): pseudo-Cushing, adult-onset growth hormone deficiency, hyposomatotropism of the adult dog, growth hormone-responsive alopecia, castration responsive dermatosis, gonadal sex hormone alopecia, sex hormone/growth hormone dermatosis, hypogonadism in intact males, biopsy responsive alopecia, post-clipping alopecia (of plush-coated breeds), adrenal sex hormone imbalance, adrenal hyperplasia syndrome, Lysodren responsive dermatosis, follicular dysplasia of Nordic breeds, Siberian husky follicular dysplasia, follicular growth dysfunction of the plush-coated breeds and black skin disease of Pomeranians.

The diversity in names is mostly based on a description of the symptom and based on the differences in endocrine evaluation results and/or clinical responses to various treatments.

So as you can see – it can be a wide range of diagnoses for the same visual symptom.
This is why it is important that a dog that starts to show signs of alopecia gets checked by a vet and not just get put into the bracket ” ooh you clipped him so you destroyed the coat ”
You as a groomer can’t promise to get the coat back with shampoo treatments if it is an underlying medical condition.

The typical Alopecia X patient is a Spitz or Nordic breed such as an American Eskimo, Chow Chow, Pomeranian, Alaskan Malamute, Elkhound, or similar. Poodles have also been over-represented. Hair loss begins in early adulthood, usually by age of three years.
They first lose the long guard hairs, leaving a fuzzy, puppy-like coat but eventually, that goes, too. The bald skin becomes hyperpigmented but is not itchy, and the skin does not usually get infected.

There is no set cure for this condition as there can be different causes for it – hormonal, genetic, endocrinal, and in some cases, there are no clinical findings at all.
Some dogs respond well to neutering. But the problem tends to come back a couple of years later. In other cases, vets have had success with melatonin treatment – but again – the problem tends to come back again.

This condition in itself is not caused by clipping – but can be visible due to clipping. Clipping of so-called double-coated breeds can cause a similar problem – but rarely the complete hair loss that we see with Alopecia X. Clipping causes more of a patchy regrowth – but not a naked dog.

White toypoodle with Alopecia X.
photo: Sofia Nandrup

Colour dilution alopecia – appears in any dog that has a blue/steel grey color. The cause is unknown. The hair breaks and no new hair growth appears. The skin can be thickened and scaly. It usually appears when the dog is from 6 months to 2 years of age.
What can we do in the salon? : Avoid heavy scrubbing as that will increase the breakage of the hair. Shampoos like benzoyl peroxide remove scales, and hydrating sprays or rinses improve the skin appearance.

Seasonal flank alopecia in a labradoodle. She has a similar patch on the other side

Seasonal alopecia/flank alopecia/
Canine flank alopecia is a localized, often cyclic, disease of the hair follicles resulting in hair loss over the flanks of affected dogs. It is also known by the names cyclic flank alopecia, recurrent flank alopecia, and seasonal flank alopecia, but these terms are not always accurate as the condition can appear at various times of the year, vary in duration, be continuous or be sporadic in nature.

Science doesn’t know the full cause of this condition. One theory is that it is linked to daylight as it seems to follow daylight cycles and that melatonin has seemed to help in some cases.

It usually appears when the dog is 3-6 years of age. It can affect all breeds but Airedale, British Bulldogs, Boxer, Schnauzer are common breeds that get affected.

This is mainly a cosmetic condition.

What can we do in the salon?
The skin in affected areas can be thickened and a bit scaly, so use a remoisturizing conditioner to soften the skin.

“Curly coated breed alopecia “is not the scientific name – but it explains what breeds are involved –   It is caused by hair follicles that are misfunctioning due to structural abnormality.  It is a genetic disease  that affects   Portuguese water dog, Spanish water dog, Lagotto Romagnolo, Irish water spaniel, curly coated retriever
its believed to be linked to the curly coat gene.
They get progressive hair loss around the eyes, flank, and saddle. This starts around 2-4 years of age.

What can we do in the salon?
As this is down to a structural problem inside the hair follicle it’s not much we as groomers can do.
We have to be careful during the groom as the hairs break easily and they won’t grow back. So make sure you treat the coat with a conditioner to keep the hairs soft. Don’t do any excessive brushing/scrubbing.

Symmetrical hair loss due to medical conditions :
Cushing’s syndrome and Thyroid problems: Dull, dry, brittle, easily removed hair coat – fails to regrow after clipping. It usually starts occurring in a symmetrical pattern – at the back of the back legs, sides of the neck, and on the sides of the chest. It then gradually involves the whole body – but the head and legs stay hairy. So, a similar pattern to Alopecia X.
You will also see an increased pigmentation of the skin and the skin usually looks dry and a bit scaly. The dog will also start to get a more pronounced belly.
Cushing’s is a condition where the body produces too much cortisol ( that is a natural steroid) and what we see is the same side effects as a high dose of steroids for a long time would give the dog.

What to advise the owner: Tell them to see the vet for further investigation. There are medications that can ease the problems.

What can we do in the salon? : We can choose products that rehydrate the skin and makes the coat softer to prevent breakage.

Hormonal changes :
Hormonal changes due to tumors or hormonal imbalance can cause alopecia. How it manifests itself can be different depending on the cause of the problem.
We can see a gradual loss of guard hairs in areas where there is friction, symmetrical hair loss on the sides of the chest or the back of the back legs, or in the front.
There is usually no itching or skin problem visible.

What can we do in the salon? It is not much we can do – use a moisturizing conditioner to reduce the hair breakage.

Spanish water dog with progressing hair loss in patches on the body.
The coat on the neck has started to thin out and she has lost some hair on her face as well.
Photo: Jane Ashbrook

Pinnal Alopecia – a fancy name for a condition that mostly affects Dachshunds – but it is also seen in Whippets, Boston terrier, chihuahua, Italian greyhounds, miniature poodles, and Portuguese water spaniel
They get a progressive hair loss on the ears – it starts at the edges and they then gradually lose all hair on their ears and they become completely naked.
It usually starts when the dog is around 12 months of age- but can occur later in life. The cause is unknown.
It usually doesn’t affect the dog – it’s normally no itching or skin irritation. But they can sometimes develop irritation at the edges of the ear due to inflammation in the blood vessels. The skin becomes crusty and can bleed.
The owner needs to protect the skin from cold/strong sun and seek veterinary advice if the dog develops skin damage on the edges.

Smooth haired dachhund with completely naked ears .
photo: William O’brien

A big Thank You to my groomer friends that have allowed me to use their pictures !

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