Why is My dog SO Itchy? The Big 5 Causes!

If your dog is scratching so much that it’s keeping you both up all night, you need to find a solution right now. Before you can fix the problem and banish the itch however, you need to know what’s causing your dog to scratch in the first place. Here are the 5 main causes!


Causes of Itching in Dogs

  1. Parasites

  2. Infection

  3. Allergies

  4. Skin problems

  5. Anal gland disease

Skin infection

So let's jump into the five main causes of itchiness in dogs. And the first one is going to be infections, These can be a bacterial infection, a fungal infection, or a yeast infection.

One really important consideration if your dog has a skin infection causing them to scratch, is that more often than not there is a separate underlying cause that allowed the infection to take hold in the first place. This could very well be some of the other causes of itchiness that I'm going to be talking about.

So it's important that if you think your dog has got an infection, they get a proper diagnosis. Otherwise, it will likely come back or it will be a recurrent problem further down the line.

Now like I say, these can be bacterial infections causing things like hot spots which result in patches of really wet, moist, inflamed, and painful skin. You can also get little pustules, red inflamed skin, a lot of scale and crusting, or even large ulcers forming on the skin.

You can also get ear infections as well, with the ear canal being affected by many of the same causes of itchiness and scratching as the rest of the skin.

Not every infection cause is a result of a long term skin condition. It might just be that there's an infected cut or an insect bite that's become a little bit nasty and causing that itchiness.

Anal gland impaction

Now the next problem and number two on the list of the main causes of itching in dogs is going to be anal gland disease.

The anal glands are two sacks either side of a dog’s back passage. If they become really full and enlarged then that can become quite irritating and uncomfortable for a dog. Some dogs will scoot their bottom along the ground to try and relieve that irritation. Others though will chew and nibble and lick and scratch, much like an itchy dog would.

Anal gland impaction definitely can look a dog is just generally itchy, when they're actually more uncomfortable than anything. The big give-away is that the itchiness will more be focused around their backside, their thighs, around their tail base, and the very kind of back part of their spine.

Because they’ll be chewing and nibbling at their skin a lot, they can also make their skin quite sore and damaged which may also result in a nasty skin infection just because of the damage that they're doing to themselves.


My third cause of itchiness in dogs is going to be parasites. And this is perhaps the most common cause of itching (depending on your local climate and parasite population of course).


Out of all the parasites, fleas are the most likely reason your dog is scratching.

They are common throughout the year. It's not just an issue in the warmer months, although they are more prevalent then and their numbers are higher, but as our houses are getting better insulated and are heated more effectively, fleas are able to survive and thrive at any time of year. Even in really cold climates.

Because of this, we should certainly be thinking about flea prevention as a year-round necessity.

Fleas are that common that if your dog has started itching and they haven't had a recent flea treatment, then it’s the first thing to try and do to stop your dog scratching. Even if you can’t see any evidence of fleas being present.

It's a frustrating trip to the vet if they do nothing more than find evidence of fleas on your dog and dispense a treatment. You could probably put that consultation money to better use!


As well as fleas, Dogs also get mites, with the big one here being Sarcoptes scabiei resulting in sarcoptic mange. This mite is intensely itchy, and infected dogs can have a lot of skin damage as a result of the scratching, as well as being completely miserable. that a dog's doing because it's really that bad. But there are a number of other Mites as well.


There are other mites, and then lice are the final main parasite responsible for an itchy dog. These are not common, at least in the parts of the world I’ve practiced, but are certainly something to consider if you see little creepy crawlies in your pets fur and down by their skin. Whereas mites live in the skin, lice live on the outside of the body.

Skin problems

At number four we've got actual skin conditions themselves. This category is a catch-all for everything not really covered by the other causes of itching and scratching.

It could be dry skin or the opposite,  greasy skin causing itchiness. There could be something like an underlying hormonal abnormality that's causing problems within the skin.

It could also be a problem with the diet. For example, a diet that's not got enough essential fatty acids in it, causing the skin to be dry and of poor general quality.

Very often there will be other signs and symptoms of the underlying disease, at other times they are diagnosed through a process of elimination and treatment trials.

Allergic skin disease

I’ve saved the best for last. The biggest cause of recurrent itchiness in dogs has got to be allergic skin disease. If your dog has a long history of scratching themselves, especially when other treatment haven’t worked, chances are they’re suffering from a skin allergy of some kind.

Flea allergic dermatitis

There are a number of different types of allergies that our dogs can suffer from. Flea allergic dermatitis is the first, and this is actually an allergy to flea saliva. As a result, even when there's only one or two fleas present, something that would cause a non-allergic dog little bother, an allergic dog will develop a really intense itch. In some cases, a single bite can cause a dog to scratch themselves to pieces.


Atopy is another cause of allergies. This is an allergy to environmental pollens or other substances within a dog’s environment. I liken it to hayfever in humans. Much like we develop hayfever that causes us to sniff and sneeze and be all snotty, atopy is a similar reaction except the result is really itchy skin.

Food allergy

The final big allergic skin disease is a food allergy. This may not be as common as you might think or you might have heard, but it is something that we see on a not too irregular basis. By far and away the most common cause of food allergies is to the protein part of a diet. With chicken and beef being the most common. Grains get a pretty bad rap these days as a cause of allergies, and while they can cause itchy skin, they are certainly not the most common group.

If you think your dog is suffering from a skin allergy, be sure to head over to my post all about treating skin allergies.

Less frequent allergies include a group known as contact allergies. This is where something comes into direct contact with the skin and an allergic reaction develops. An allergy to insect bites can also cause itchiness as well as an inflamed hive-like reaction, where you get little swollen bumps or just general swelling of the skin surrounding the bites.

Successful Treatment

Those are the five main causes of itchiness in dogs: infection, anal gland problems, parasites, skin conditions, and allergic skin disease.

It's important to get a proper diagnosis because a lot of these conditions will need ongoing management to try and prevent them from becoming a real problem in the future, or to prevent them from getting worse and to keep them under control.

If your dog is really itchy, your dog is up-to-date with their flea treatment, and you've got no idea how to stop them scratching, don’t waste time and money on internet miracle cures, a trip to your vet is going to be the best course of action.