My dog won't stop scratching, what could it be?

If your dog is constantly scratching, biting their paws, or rubbing their face on the ground, it's natural to be concerned. Persistent itching, technically called pruritus, is one of the most frequent reasons for veterinary consultations in dogs. Fortunately, in most cases, there's a solution – but it's important to understand the cause before acting.

In this article, we explain the most common reasons why a dog won't stop scratching and what you can do to help your companion.

What are the most common causes of itching in dogs?

Itching is not a disease in itself – it's a sign that something is wrong. It can have several origins, from something as simple as fleas to more complex problems like food allergies.

1. External parasites - fleas, ticks, and mites

Fleas are the most frequent cause of intense itching in dogs. Even if you can't see fleas on your dog's fur, just one can trigger an allergic reaction, especially in sensitive animals. Look for small dark spots on the skin – these are flea feces, which look like black sand.

Ticks also cause local irritation. Mites, in turn, cause diseases such as sarcoptic mange (which causes extreme itching and is contagious) and demodectic mange. If your dog is scratching uncontrollably, losing fur in specific areas, or has red, crusty skin, consult a veterinarian.

2. Food allergies

Food allergies are more common than many owners imagine. Dogs can develop an allergy to an ingredient they've always eaten without problems – usually proteins like chicken, beef, wheat, or eggs.

Signs of food allergy usually include chronic itching (especially on the paws, belly, ears, and face), recurrent ear infections, digestive problems, and red skin. Unlike environmental allergies, food allergies occur year-round and do not improve with the seasons.

The only way to confirm a food allergy is through an elimination diet, prescribed by the veterinarian, which consists of feeding the dog food with proteins and carbohydrates they have never consumed before. There are specific hypoallergenic foods for this type of problem; see the best options in this article. 

3. Environmental allergies (atopy)

Dogs can be allergic to pollen, fungi, dust mites, grasses, and other environmental particles – just like humans. This condition is called canine atopy and is one of the most frequent causes of chronic pruritus.

Unlike food allergies, atopy tends to be seasonal at first (worsening in spring and summer), although it can become permanent over time. The signs are similar: itching on the face, paws, and belly, inflamed ears, and red skin.

4. Contact dermatitis

Some dogs react to products they come into direct contact with – laundry detergents, floor cleaners, inappropriate shampoos, or even grass treated with pesticides. Itching and redness appear in the areas that have been in contact with the irritant, such as the belly, paws, and muzzle.

5. Dry skin or nutritional imbalances

A diet poor in essential fats (such as omega-3 and omega-6 fatty acids) can result in dry skin, dull coat, and itching. In these cases, the itching is not intense, but the dog scratches regularly, especially after bathing.

A quality, balanced diet appropriate for the dog's size and life stage makes a huge difference in skin and coat health.

6. Bacterial or fungal infections

When the skin's protective barrier is compromised – whether by allergies, parasites, or repeated trauma from scratching – bacteria and fungi take the opportunity to settle in. Pyoderma (bacterial infections) and Malassezia infections (a fungus) are frequent complications of untreated pruritus.

The skin becomes smelly, scaly, crusty, or with moist areas. These secondary infections require veterinary treatment, usually with antibiotics or antifungals.

7. Ear infections

If your dog won't stop shaking their head, repeatedly scratching their ears, or tilting their head to one side, they may have an ear infection. Ear inflammations are very common in dogs and can be caused by allergies, mites, bacteria, or fungi. The inside of the ear may be red, smelly, or have dark discharge.

What to do when your dog won't stop scratching

The first step is always to consult a veterinarian. Persistent scratching should never be ignored, because the longer the dog scratches, the more the skin is damaged and the easier it is for infections to enter.

Meanwhile, you can take some preventive measures:

• Keep external deworming up to date with products appropriate for your dog's weight and size, all year round.
• Avoid overly frequent baths, which can remove the skin's natural oils. Always use shampoos formulated for dogs.
• Review their diet. A food with quality ingredients, rich in essential fatty acids, and without unnecessary ingredients significantly contributes to skin health.
• Do not change their food abruptly. Transition gradually over 7 to 10 days to avoid digestive problems and skin reactions.
• Clean your dog's paws after walks, especially during peak pollen season.

FAQs - Frequently Asked Questions

My dog scratches but has no fleas. What could it be? The absence of visible fleas does not rule out a flea bite allergy (FBA), as just one bite can trigger the reaction. Other possible causes without visible parasites include food allergies, atopy, dry skin, or fungal infections. A veterinarian can help identify the cause through a physical examination and, if necessary, specific tests.

Can changing their food resolve the itching? If the cause is a food allergy, yes – a change to a hypoallergenic diet or one with different ingredients can make a big difference. However, the transition should be made gradually and, ideally, under veterinary recommendation, to ensure the new food is appropriate for your dog's problem.

How long should I do the elimination diet to find out if it's a food allergy? Elimination diets should be maintained for at least 8 to 12 weeks to observe a clear improvement. During this period, the dog cannot eat anything outside the prescribed diet – no treats, no table scraps.

My dog scratches more in the summer. Is it an environmental allergy? Most likely yes. Canine atopy tends to worsen in seasons with higher concentrations of pollen and fungi, such as spring and summer. The veterinarian can confirm through allergy tests and, if necessary, initiate desensitization treatment or supportive medication.

Can dry skin cause itching in dogs? Yes. A lack of essential fatty acids in the diet is a frequent cause of dry skin and moderate itching. Foods rich in omega-3 (such as those containing salmon or fish oil) help keep the skin hydrated and the skin barrier protected.

Is ear itching the same problem as body itching? Not necessarily, but they can be related. Recurrent ear infections are often a sign of food or environmental allergies. If your dog has recurrent ear infections and also scratches their body, it is very likely that there is an underlying systemic cause like an allergy.