Itching and Scratching (Pruritus) in Dogs

Summary

Itchy skin, or pruritus, is a common symptom of multiple conditions. Scratching, rubbing, licking, and chewing are the most common signs shown by itchy dogs.

Occasional scratching is a normal behavior for dogs. Sustained or repeated scratching, pawing at the face or ears, dragging or rubbing parts of the body against surfaces, or biting/chewing/“worrying” at an area with teeth is more likely to indicate a problem and cause injury.  Pruritus is a symptom of conditions which range from mild or superficial (e.g. a small healing wound) to serious (e.g. deep pyoderma).  Seek veterinary care if a dog is scratching continuously or repeatedly, or shows signs of hair loss or injury. 

Sudden itching can indicate the onset of symptoms of anaphylaxis, which is an EMERGENCY. Other symptoms like difficulty breathing and collapse are expected if a dog is experiencing this rapidly-escalating type of shock. 

Pruritus can be caused by conditions such as parasite infestation, allergic reaction, or bacterial or fungal infection. Diagnosis involves physical examination of the skin, and typically begins with skin scraping analysis, skin cytology, and fungal culture. Allergy testing, dietary trials, and biopsies may be necessary in more complicated cases. Treatment depends on the underlying condition.

Guidelines

Pruritus as a single symptom doesn’t indicate an emergency, but when it’s severe it can be hard for both the dog and the people in the house with the dog. Severely itchy dogs are uncomfortable and benefit from veterinary care as quickly as possible. 

Pruritus is a common symptom of a variety of disorders and/or exposure to parasites, allergens or irritants. Itching may be a secondary symptom of infection.

Veterinary care is warranted for severely itchy dogs who scratch a lot, especially if they also shows signs of: 

• Bleeding, wounds or scabs • Inflamed and/or thickened skin • Crusty, draining sores • A foul smell to the skin

• Excessively flaky or greasy skin • Hair loss • Hives or swelling

Possible Causes

Pruritus is a symptom of many skin conditions and disorders. The most common cause of pruritus in dogs is flea allergy dermatitis, or FAD. Lack of visible flea infestation does not rule out FAD.

A variety of skin disorders can become itchy, especially when secondary bacterial or fungal infections set in.  Autoimmune disorders, like pemphigus foliaceus, can result in damaged skin which is vulnerable to infection.

Less common causes of pruritus include:

• Rash (contact dermatitis): can be caused by contact with some types of plants or from topical medications, soaps, or other irritants

• Some types of cancer

Risk Factors

Pruritus may be a localized (e.g insect bites) or a full-body sensation (e.g. allergic reaction due to food).

A dog may be able to relieve more minor itches by scratching or rubbing, but continuous scratching and self-injury indicate a more serious problem. 

Other common conditions that cause pruritus include:

• Non-flea parasites, e.g. mites (sarcoptic mange, and demodectic mange) and lice

• Allergic reactions, including atopy and food allergy

• Bacterial or fungal infection of the skin and/or ears

Rarely, a dog may have a neurological disorder such as sensory neuropathy, cauda equina syndrome, or syringomyelia/Chiari-like malformation. Neurological dysfunction causes itching sensations or scratching action not due to problems with the skin itself.

Testing and Diagnosis

Many skin disorders appear alike upon physical examination and are difficult to differentiate. Diagnosis requires tests or trials to eliminate potential causes and find treatments which relieve the dog’s discomfort.

Diagnostic tools include:

• Examination for fleas or visible parasites • Skin scraping and cytology • Fungal culture

• Allergy tests • Elimination dietary trials • Medication trial • Skin biopsy

Treatment varies depending on the diagnosed or suspected causes. These may include:

• External parasite control • Medications • Limited ingredient or hydrolyzed diets • Bathing, medicated shampoo

Similar symptoms

Similar symptoms to pruritus include normal scratching or grooming, normal shedding, scrapes or other injuries, boredom, anxiety.

Associated Symptoms

Pruritus in dogs is often observed along with

• Inflammation of skin • Flaky/scaly, crusty skin • Oily skin (seborrhea) • Skin wounds, self-injury • Hair loss (alopecia) • Head shaking