Why Does My Dog Scratch So Much?

It's completely normal for a dog to scratch several times a day, but when they scratch too insistently, it can cause wounds or alopecia (hair loss). In these cases, it's necessary to find the cause of the problem and take action.

There are many factors that can cause itching in their skin, from parasites, fungi, insect bites, or allergies. We should carefully examine their skin for signs like erythema (redness), dermatitis, pustules, ulcers, and so on. Let's take a detailed look at all the possible causes and their treatment.

What should I do if my dog scratches a lot?

As mentioned, to rule out wounds, parasites, or other issues, we should examine their skin, parting their fur with our hands or a brush, and checking the whole body.

These are the symptoms to look for:

• Small bites or rashes (little bumps).
• Redness of the skin (erythema).
• Bad smell.
• External parasites (fleas, lice, or ticks).
• Flaky skin or excess dandruff.

If we notice any of these symptoms, we should see our vet so they can run the appropriate tests and apply the right treatment. We should never apply home remedies or self-medicate our dog.

What can cause itching in a dog?

As mentioned, excessive scratching in a dog can be due to itching triggered by various causes, including:

1. Food or seasonal allergy.
2. Heavy flea infestation, or dermatitis caused by flea bite allergy (FAD).
3. Mange (mite infestation).
4. Dermatophytosis or Malassezia.
5. Seborrhea.
6. Insect or tick bites.
7. Atopic dermatitis.

As you can see, there are many factors that can cause itching in our dog's skin, making them scratch a lot and making their condition even worse. Either way, we should see a vet for an exam and to help determine the cause so the right treatment can be applied. Let's look at each of these in more detail. Remember there can be several causes at once, not just one, so pay close attention when examining your dog.

Allergies

Allergies in dogs can have different origins, whether food-related or environmental (seasonal). They usually cause skin irritation with intense itching, and even dermatitis or skin inflammation, either localized or widespread. Although it can occur anywhere on the body, it especially affects the paws, abdomen, muzzle, and ears. If scratching and irritation are more intense in these areas, it's likely an allergy.

Flea bites

Fleas are very small and fast, so we may not be able to spot them with the naked eye even after a thorough check of our dog. To feed, they bite our dog and suck their blood, which in heavy infestations can cause a lot of itching.

What's more, some dogs have an allergy to flea bites, resulting in a condition called "flea allergy dermatitis" (FAD), with intense itching and inflammation. Fleas can affect any part of the body, though they tend to settle especially on the back, tail, chest, and areas near the ears.

Mite infestations (mange)

Mites are external parasites that affect the skin, causing a disease known as mange. They multiply quickly, so within a matter of days they can cause extreme, widespread itching in our dog.

The two mite species that most commonly affect dogs are Demodex canis, which causes demodectic mange, and Sarcoptes scabiei, which causes sarcoptic mange. The first is normally found on a dog's skin, doesn't usually cause much itching, and generally appears as a secondary problem linked to weakened immunity from some other cause. The second is more serious, causing intense itching and more serious lesions; it's also zoonotic, meaning it can spread to humans.

It's essential for our vet to take samples and identify the mite species causing the problem and give effective treatment to resolve our dog's itching and prevent it from spreading to other dogs.

Fungi and bacteria

Bacteria can cause an infection on our dog's skin, causing a lot of itching. A common cause of dermatitis in dogs is infection with Staphylococcus aureus, a bacterium normally found on the skin that, in situations of weakened immunity, can cause dermatitis, especially affecting the hair follicle and causing bacterial folliculitis.

Fungal infection is also a common cause of itching in dogs, causing diseases such as dermatophytosis and Malassezia. These infections are usually linked to an unpleasant, characteristic smell.

While bacteria can affect any part of the skin, fungi tend to mainly affect the paws and ears, sometimes the areas near the eyes and even the armpits, causing constant, intense itching.

Seborrhea

Seborrhea is a condition caused by excess oil buildup in the skin, which causes flaking, cracked skin, dandruff, and generally excess grime in the ears too. It can be caused by a poor diet, stress, using a shampoo not suited for dogs, or some skin disease. It causes a lot of itching in our dog's skin, making them scratch intensely.

Insect and tick bites

Bees, wasps, spiders, and many other insects can bite our dog, causing major skin irritation and, in some cases, even allergic reactions requiring urgent veterinary treatment. Ticks also feed on our dog's blood, inserting their mouthparts under the skin. This causes very bothersome itching that will make our dog scratch a lot.

What's more, ticks act as vectors for bacteria and viruses, and can transmit various diseases to our dog, such as ehrlichiosis or babesiosis. The one upside to ticks is that they're usually easy to spot due to their size once engorged with blood. Removing them is fairly simple, as long as we make sure to also remove their mouthparts.

Atopic dermatitis

Other times, the itching isn't due to any of the causes above, but rather atopic dermatitis, more common in breeds with skin folds, such as the Bulldog, Shar Pei, Dogo, or Pug. This disease is caused by a hypersensitivity reaction — that is, an exaggerated immune system response from contact with various allergens (such as pollen or mites).

It's a chronic disease that can appear at any point in the animal's life and usually has a genetic component among its causes. To treat it, options include immunotherapy, giving specific vaccines against the antigens causing this reaction, or a diet rich in omega fatty acids.