Common Causes of Itching in Dogs & How to Find Relief

Have you ever been kept up all night by the sound of your dog constantly licking and chewing on themself? If so, you can relate to the frustration this causes for many pet owners, in addition to the significant discomfort that excessive itching can cause for your dog.  

In this article, we will discuss what itching can look like, common and uncommon causes of itching, and how to provide much-needed itch relief for your dog.

What itching can look like in your dog

To know when to seek veterinary treatment for your itchy dog, you first need to be able to recognize the various manifestations of pruritus (itching). You may notice the following signs:

• Dogs can have generalized itching all over the body, or more specific areas that are itchy.
• Itching can manifest as scratching (side of body, head, neck), chewing (limbs and paws), and licking (limbs and paws).
• Itchy ears will often cause dogs to shake their heads frequently, or they may whine in pain when they scratch their ears.
• Excessive scratching may be more evident at night, and your dog may be disrupting your sleep.
• Depending on the cause of the itching, hair loss may be present.
• If your dog has a skin infection, their skin may be red and swollen, have bumps such as pustules (pimples), scabs, or other lesions, exude a colored discharge, feel either greasy or very dry, or have a bad odor.

What are the most common causes of itching in dogs?

Itching is a symptom, not a specific disease. There are numerous possible underlying causes of itching in dogs, which can make diagnosis and treatment equally frustrating for the dog, the dog owner, and the veterinarian. The following are some of the most common causes of itching in dogs:

Ectoparasites

Several types of skin parasites, or ectoparasites, can cause your dog to itch. Fleas, mites, and lice are three common ectoparasites that can invade the skin and hair of dogs and cause moderate to severe itching. While fleas and lice are visible to the naked eye, mites (including Demodex and Sarcoptes) can only be identified under a microscope.

Fleas and flea bite allergy: These small parasites feed on a dog’s blood and may cause itching, hair loss, and secondary skin infections. Some dogs can also develop an allergy or “hypersensitivity” to flea bites (specifically, flea saliva), known as flea allergy dermatitis. While most dogs will exhibit some degree of scratching as a result of fleas, these dogs have a more significant reaction leading to intense itching.  

Mange mites: The two most common types of skin mites in dogs are Demodex and Sarcoptes, which are sometimes referred to as Demodectic Mange (“red mange”) or Sarcoptic Mange (“scabies”). Demodex are mites that live inside or near the hair follicle, while Sarcoptes are a burrowing mite that go deeper into the skin. Both can cause itching, however, intense itching is more commonly seen with Sarcoptic Mange. Dogs naturally have small numbers of Demodex on the skin, but infection and clinical signs arise when the infestation becomes too great, usually in animals that are young or immunocompromised.  

Lice: The final type of ectoparasite that can cause itching in dogs is lice. Luckily, lice are host-specific, meaning lice on your dog cannot be passed to other species or people living in the home. Unlike fleas, lice do not survive off of their host for more than a few days, making treatment of the dog and environment relatively straightforward. Lice are visible to the naked eye, can often be seen moving, and are pale in color. While lice can lead to itching and scratching in your dog, they do not tend to cause significant damage to the skin or other issues.

Allergies

Allergies are a common cause of dog itching when no fleas or other ectoparasites have been identified. Allergies in dogs are often divided into two categories – food allergies and environmental allergies (also known as atopy or atopic dermatitis).

Food allergies can lead to itching when a dog is allergic to something in their diet, usually a protein source. Environmental allergies are caused by something in the environment, such as pollen. It is not uncommon for dogs to be allergic to more than one thing.

They can lead to scratching, redness, and recurrent skin and ear infections as a result of an immune-mediated and inflammatory response to an allergen. Food allergies may also cause gastrointestinal issues in some cases, while environmental allergies may have a seasonal component.  For more information on dog allergies and treatment options, visit our page “Dog Allergies: All You Need to Know From Symptoms to Treatment”.

Infections: Bacteria vs. Yeast

Infections caused by bacteria or yeast are another common cause of scratching. While small amounts of bacteria and yeast are naturally present on the skin of dogs, an overproduction of either can lead to infection. Skin infections can cause pain, discomfort, and itching in dogs. Malassezia, a type of “budding yeast”, is a common culprit for ear infections. Skin infections, whether caused by bacteria or yeast, will often be associated with redness, swelling, skin lesions such as pustules and scabs, colored discharge, and a foul odor.

Several factors may lead to a skin infection. Trauma or injury to the skin (including burns, bites, self-trauma from scratching, etc.) is a common way for an infection to arise. Dogs with immune-mediated diseases or those with impaired immune systems may be more prone to skin infections. Breed dispositions, anatomy, and genetics may also play a role. Finally, underlying allergies and chronic itching often lead to chronic and recurrent secondary skin infections.

Ringworm (Dermatophytosis)

Ringworm (also known as Dermatophytosis) is caused by a group of fungi known as dermatophytes and is not a worm at all! This type of infection is much more common in cats but is another potential cause of scratching in dogs. In dogs, ringworm can cause itchy lesions with circular areas of hair loss, where the underlying skin may be red or have small scabs.

Hormonal (Endocrine) Skin Diseases

Underlying medical conditions such as hypothyroidism (an auto-immune disease that causes decreased thyroid hormone production) and hyperadrenocorticism (i.e. Cushing’s Disease; a disease of excess steroid production by the adrenal glands) are not primary causes of itching in dogs; however, these conditions result in increased susceptibility to developing skin infections that then cause your dog to scratch.

Breed Predisposition

Some breeds of dogs may be more prone to causes of itching and require extra care and consideration to maintain healthy skin. Cocker Spaniels, Golden Retrievers, and English Bulldogs are a few examples that are known to be more susceptible to ear and skin infections. Regularly cleaning the ears and skin folds in these breeds can help prevent infections that may lead to scratching and discomfort. Pitbulls have been anecdotally linked to having a higher chance of developing food and environmental allergies, though the underlying reason for this is not well understood.

Less common causes of itching

A few less common causes of itching can include neurogenic (nerve-related) causes or certain types of cancers (neoplasia). Discuss these possibilities with your veterinarian when more common causes of itching have been ruled out.

Diagnosis of the underlying cause of itching in dogs

Because there are many causes of itching in dogs, and many of those causes result in lesions (abnormal areas of tissue) that appear very similar, diagnosing the underlying cause may require multiple diagnostic tests.

First and foremost, however, your veterinarian will obtain a thorough medical history and perform a physical exam on your dog. This can provide invaluable clues as to the cause of itching and can also aid in excluding some causes of itch. A detailed patient history includes answers to questions such as the age of onset, areas of the skin that are affected, living environment, what time of year the condition is worse (i.e. seasonality), past and current diets, current medications, coexisting medical conditions, the severity of the itching (pruritus scale), and prior diagnostics, treatments, and responses to those treatments.

Following a detailed medical history and exam, your veterinarian may perform one or more of these diagnostic tests:

• Cytology (sample of skin or ears) is viewed under a microscope to determine the presence of yeast or bacteria.
• Skin scrapings (superficial or deep) are also viewed under a microscope to demonstrate the presence of mange mites such as Demodex or Sarcoptes.
• Flea combing and tape impressions are helpful in the diagnosis of parasites such as fleas and lice.
• Aggressive flea control should be implemented in all itchy dogs even if fleas are not identified. In flea-allergic dogs, even the bite of a single flea can cause a significant reaction. 
• Wood’s lamp examination (certain strains of ringworm will fluoresce an apple green color when viewed with this ultraviolet light), trichogram (examination of plucked hairs under the microscope to look for fungal spores and hyphae), and fungal cultures may be warranted if dermatophytosis (ringworm) is suspected.
• Culture and sensitivity testing should be considered in the case of repeat or non-responsive bacterial skin infections to determine the causative bacteria and the antibiotics that will be most effective.
• An elimination diet trial is required to diagnose a food allergy. This involves feeding a prescription hydrolyzed, limited ingredient, or novel protein diet for a minimum of two to three months. 
• Allergy testing utilizing skin or blood tests may be recommended if an owner wishes to identify allergens or is interested in pursuing allergen-specific immunotherapy. Allergy tests using hair samples or saliva have not yet been shown to be accurate or helpful.
• Bloodwork may be recommended to check for underlying conditions such as hypothyroidism and hyperadrenocorticism that could contribute to itching in your dog. 
• Skin biopsy is indicated for those patients with minimal response to treatment or non-typical lesions, as may often be the case with some types of skin cancers.
• Referral to a veterinary dermatologist is always an option, especially for more complex cases.

How to prevent and treat itching

While some causes of itching in dogs, such as fleas, are fairly straightforward and can be “cured” using regular flea prevention, other causes such as allergies may require long-term management and regular checkups with your veterinarian. The following methods are often employed to prevent pruritus and provide anti-itch solutions for dogs:

1) Supplements:  Omega-3 Fatty Acids (such as those found in fish oil) and probiotics have been shown to promote healthy skin, reduce inflammation, and prevent skin infections, especially when used in conjunction with other treatments.

2) Diet:  Avoid common protein allergens such as chicken and beef or consider feeding a prescription hypoallergenic (hydrolyzed protein, limited ingredient, or novel protein) diet. A homemade diet can also be utilized but should be formulated under the direction of a veterinary nutritionist.

3) Flea prevention: If you have an itchy dog, be sure to use a veterinary-prescribed flea prevention on all pets in your household year-round. 

4) Prescription medications from your veterinarian will be dependent on the diagnosis but may include antibiotics, antifungals, steroids, immune suppressants (such as Apoquel®), allergen-specific immunotherapy (also known as allergy shots), or biologics (such as Cytopoint®).

5)  Over-the-counter options such as Benadryl (antihistamine) may help to relieve mild allergy symptoms, but should only be administered under the direction of a veterinarian.

6) Topical remedies might be recommended by your veterinarian to treat more localized areas of infection and reduce itching and inflammation of the skin. This may include anti-itch sprays, ointments, or medicated shampoos. Many of these can be obtained over-the-counter or through your veterinarian.

7) Alternative therapies such as acupuncture and phytotherapy (the use of plants and herbs) have been used to treat itchy skin and allergies in dogs.

8) Lifestyle changes such as avoiding allergens, wiping off your dog’s paws after coming in from outdoors, and regular grooming and ear cleaning can also help prevent itching due to some environmental allergies.

Final thoughts on itching in dogs

While excessive itching and scratching can be incredibly frustrating as an owner and cause significant discomfort for your dog, there are many options available to help prevent and treat the common causes discussed above. Remember, obtaining a proper diagnosis of the underlying cause is very important when it comes to getting itch relief for your pet, especially if the problem is severe and does not seem to be resolving.

FAQs

What do I do if I suspect my dog may have lice or fleas?

Certain ectoparasites, such as fleas (and flea dirt) and lice are visible to the naked eye. If you see or suspect any of these, you should see your veterinarian to obtain a prescription preventive and also discuss the best ways to clean and disinfect your home. There are several options for preventives including topical, chewable tablets that are given monthly or every 3 months, and even medicated collars. Year-round prevention is recommended. Be sure to discuss the different options with your veterinarian to determine the most appropriate preventive for your pet.

My dog is itching. What can I do at home to try and help?

If your dog is itching but no fleas or lice have been identified as the cause, supplementation may be an appropriate first step to try and mitigate itching in your dog. If you notice your dog has dandruff or dry skin, Omega-3 Fatty Acids are a great way to support the skin’s natural barrier and oils. Probiotics have also been shown to increase healthy bacteria on the skin and reduce infections. Both of these are extremely safe to give and do not require a prescription. Bathing with an anti-itch or aloe-oatmeal shampoo can reduce mild to moderate itching. As tempting as it may be, avoid over-bathing your dog – this can strip away their natural oils and make the problem worse. If your dog’s itching is severe or they have signs of a skin infection, you will need to see your veterinarian for treatment. 

Can diet help my dog’s itching?

If an underlying food allergy is suspected, try a change in diet, or diet trial.  Several diets are available on the market to target skin issues in dogs, including prescription hypoallergenic diets (hydrolyzed protein, limited ingredient, or novel protein diets) which should be fed for a minimum of 3 months (without any additional treats or food sources) to definitively rule out a food allergy. As chicken and beef tend to be the two most common protein sources linked to food allergies in dogs, transitioning to a diet with an alternate protein source such as duck, turkey, lamb or salmon is a good place to start. Always double-check the ingredients of the dog food since chicken and beef by-products may be hiding within the ingredient list. If you choose to make a homemade diet for your dog, only do so under the direction of a veterinary nutritionist as balancing homemade diets is extremely important, and poorly balanced diets can lead to more serious problems. Any diet change should be done slowly, over at least 7 days, as an abrupt diet change could lead to gastrointestinal upset (vomiting and diarrhea) in your dog.

Can I use Benadryl for itch relief or to treat allergies in my dog?

Benadryl (diphenhydramine) can be helpful for minor allergic reactions (such as minor hives or a mild reaction to a bee sting) or occasional upper respiratory allergies such as sneezing and weepy eyes. Benadryl is not usually an appropriate long-term solution for itching in dogs and is unlikely to be effective against chronic causes of itching or severe allergies. Side effects may include moderate sedation.  

How often can I give my dog Benadryl for itching?

Benadryl can be given every 8 to 12 hours (by mouth) to reduce itching associated with mild allergic reactions or allergies. The actual dose is based on your dog’s weight, so remember to always consult your veterinarian before giving.

When should I take my dog to the vet if I am worried about his/her itching?

If your dog has excessive itching (for example, the itching is keeping you and your dog awake at night), it has not resolved on its own over a few days, or you see evidence of a skin infection (lesions, redness, welts, bumps, discharge, or odor), it is time to have them examined by a veterinarian. Head shaking, smelly ears, or excessive scratching of the ears can indicate an ear infection which should also be assessed by a veterinarian.

Sources:

https://pubmed.ncbi.nlm.nih.gov/35883379/

https://pubmed.ncbi.nlm.nih.gov/29067183/

https://pubmed.ncbi.nlm.nih.gov/15206474/

Small Animal Dermatology, Kinga Gortel DVM, MS, Dipl. ACVD, VSAC 463: Western College of Veterinary Medicine, November 2014

Small Animal Medical Differential Diagnosis, Mark S. Thompson, DVM, Dipl. ABVP, Second Edition, 2007

The Small Animal Veterinary Nerdbook, Sophia Yin, DVM, MSc, Third Edition, 2010

CYTOPOINT® − Mode of Action (The Itch Cycle) | Zoetis UK

https://veterinarypartner.vin.com/default.aspx?pid=19239&id=4952556

Diagnostic Approach to the Pruritic Dog