What this means
Itching is the skin's response to inflammation, and the cause usually falls into one of three groups: parasites, infection, or an allergic reaction. Those groups overlap — allergic skin picks up infection more readily, and a dog that scratches damages its own skin and deepens the inflammation. That is why the picture later on is more tangled than it was at the start.
It helps a great deal to notice where your dog scratches. Ears, armpits, groin, belly and paws are one typical combination; the back near the base of the tail is another; the head and neck another again. It is also worth remembering whether the itch is there all year or only in certain months, and whether anything changed at home, on the walking route or in the food.
A frequent question is what to make of a dog that scratches with no fleas to be found. Not seeing fleas does not mean there were none: some dogs react to only a couple of bites, and flea dirt is sometimes easier to spot than the fleas themselves. On the other hand, itching without fleas is an entirely ordinary picture, and the search then moves to allergies, skin infections and other parasites too small to see.
Possible causes
These are things that can cause this sign. It is not a diagnosis, and they are not equally likely for your dog.
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Fleas and other external parasites
Even a few bites can be enough to set off strong itching. The pattern is scratching along the back near the base of the tail, with black specks visible in the coat.
About the condition: Fleas -
Mites too small to see
Some skin mites cannot be seen with the naked eye. They cause a stubborn itch with redness and flaking, and ordinary flea products make no difference to it.
About the condition: Demodectic mange -
Environmental allergy
Pollen, house dust mites or moulds cause itching felt most in the paws, ears, armpits and belly. It can be seasonal or run all year round.
About the condition: Allergies (food, skin and environmental) -
A reaction to something in the food
Some dogs react to a particular ingredient. The itch then carries on year-round, and softer stools often appear alongside it.
About the condition: Allergies (food, skin and environmental) -
Skin infection
Bacteria or yeast multiply on already damaged skin. The skin reddens, starts to smell, develops crusts or scale, and the itching gets worse.
About the condition: Skin infections -
Dry and irritated skin
Dry air, washing too often or the wrong product strips the skin's protective layer. The skin flakes and the dog scratches without much redness to show for it.
What else to watch for
These observations help your vet build the picture faster. Note down what you saw and when.
- Which areas your dog scratches or licks the most
- Whether the skin is red, flaking, or has bald patches
- Whether there are fleas or black specks in the coat
- Whether the itch is seasonal or year-round
- Whether the skin has started to smell
- Whether your dog is also shaking the head or pawing at the ears
When to book a routine visit
Book a visit if your dog scratches daily for more than a week, if the skin is red, flaking or smelly, if bald patches appear, or if the itch returns every season. Tell your vet which parasite products you have used and when.
Related conditions
Conditions whose entries mention this sign. The list is somewhere to read on, not a way to reach a diagnosis.
- Allergies (food, skin and environmental) Skin and coat An allergy is an overreaction of the immune system to substances that are essentially harmless, such as pollen, house dust mites, moulds, flea saliva or an ingredient in food. In dogs it shows up mainly in the skin and ears, and constant itching wears a dog down and can open the way to skin infections. More than one trigger can be involved at once, so finding the cause takes patience.
- Atopic dermatitis Skin and coat Atopic dermatitis is a long-term allergic skin disease driven by an inherited tendency: the skin overreacts to environmental allergens such as pollen, house dust mites or moulds. These dogs have a weaker skin barrier, so allergens get in more easily, and scratching irritates the skin even further. Signs can begin in young dogs and, depending on the allergen, may flare up at certain times of year.
- Skin infections Skin and coat Skin infections are caused by bacteria or yeast that start to multiply when the skin's defences are weakened, for example by an allergy, parasites, moisture trapped in skin folds or constant scratching. An infection can stay on the surface or reach the deeper layers of the skin, causing pain and intense itching. What caused the infection and what keeps it going is for a vet to work out.
- Demodectic mange Skin and coat Demodectic mange is a skin disease caused by microscopic Demodex mites that live in the hair follicles. A small number of them live on healthy dogs too, but when the immune system fails to keep them in check, the mites multiply rapidly and damage the skin and coat. It can stay small and local or spread over the whole body, which is a sign that the dog's body is struggling to cope.
- Hot spots (acute moist dermatitis) Skin and coat A hot spot, or acute moist dermatitis, is a patch of skin that suddenly turns moist, red and painful, which the dog makes worse by licking or scratching it. It can spread within hours, and it can be set off by something else, such as itching from parasites or an allergy. A vet should look at the patch and decide what to do.
- Sensitive skin Skin and coat Sensitive skin gets irritated easily: it turns red, itches or flakes, and skin folds that trap moisture can become inflamed. The irritation can come from a food or environmental allergy, parasites, unsuitable grooming products or other causes, and constant itching takes a real toll on a dog's comfort. What exactly is bothering a particular dog's skin is for a vet to work out.
- Skin problems Skin and coat This is an umbrella term for a range of skin disorders, from allergies and parasites to infections, hormonal diseases or growths in the skin. The skin also reflects a dog's overall health, so changes in it sometimes point to a problem elsewhere in the body, and constant itching or soreness takes a real toll on a dog's comfort. What lies behind particular changes is for a vet to work out.
- Fleas Parasites Fleas are small, jumping parasites that feed on a dog's blood and cause itching. Some of them live on the dog, while the eggs, larvae and pupae live in the home: in the dog's bed, carpets and soft furnishings. That is why fleas can keep coming back even when none are left to see on the dog; your vet can advise on protecting your dog and your home.
Body systems: Skin and coat Parasites