Canine Demodicosis

In some cases, managing this condition can be challenging and requires long-term monitoring.

Overview

Demodex canis is a mite that resides in the hair follicles and sebaceous glands within the skin. They are transmitted directly from the dam to puppies at birth. This condition predominantly affects dogs with a compromised immune system and can be quite challenging to treat. Prognosis and treatment depend on the form of the disease.

Localised	Involves a few localised areas, typically on the face or forelimbs Tends to affect dogs less than 1 year old Approximately 90% resolve on their own within 6-8 weeks
Generalised	Involves multiple areas or the entire body
Juvenile-onset	Develops before the dog reaches 1 year of age Can present as either the localised or generalised form
Adult-onset	Develops in dogs aged 4 years or older Often coexists with other underlying diseases such as diabetes, Cushing's disease, cancer, corticosteroid use, hypothyroidism, heartworm disease, or internal parasites

Purebred dogs appear to be predisposed to juvenile-onset and generalised demodicosis; therefore, they are often recommended to be neutered and not used for breeding.

Signs

Common signs of demodicosis include:

Hair loss (often in circular patterns)
Skin odour
Itchiness
Infection
Ulceration
Pustules
Hyperpigmentation

This diagram illustrates the most common distribution of skin lesions in a dog with a Demodex infestation.

Demodex Distribution in Dogs

Diagnosis

Diagnosis is made through:

Clinical signs
Skin scrapings
Hair shaft examination
Skin biopsy

Management

Management of canine demodicosis requires treating any underlying diseases or skin infections with antibiotics or medicated shampoos.

Your pet may be prescribed one of the following miticide treatments:

ADVOCATE® (imidacloprid/moxidectin)	For the treatment and control of generalised demodicosis	Applied to the skin between the shoulder blades once a month
BRAVECTO® (fluralaner)	For the treatment and control of demodicosis	Administered as a chewable tablet every 3 months
NEXGARD® (afoxolaner)	Treats and controls Demodex mites	Administered as a chewable tablet every month
SIMPARICA® (sarolaner)	Treats and controls Demodex mites	Administered as a chewable tablet every month

It is important to note that once treatment begins, patients must be checked every 4-6 weeks to monitor progress and obtain skin scrapings. It is not uncommon for treatment to take 6-12 months before two consecutive negative skin scrapings are obtained. Relapses can occur, so skin scrapings at annual revisits may be required.

Even if your pet appears to be doing well after 2 months of treatment, mites may still be present, and a relapse is likely if treatment and monitoring are not adhered to.

What to Expect with Surgery (if applicable)

In cases where surgical intervention is required (e.g., for severe skin infections or secondary complications), the following should be noted:

Pre-Surgery: Your pet will undergo a thorough examination and may require blood tests to ensure they are fit for anaesthesia.
During Surgery: The procedure will be performed under general anaesthesia, and your pet will be closely monitored throughout.
Post-Surgery: Expect some swelling and discomfort at the surgical site. Pain relief will be provided, and you may need to restrict your pet's activity for a period of time.
Recovery Time: Most pets will require 10-14 days for initial recovery, but full healing may take longer depending on the extent of the surgery.
Prognosis: The prognosis will depend on the underlying condition being treated and your pet's overall health. Follow-up appointments will be necessary to monitor healing.

Home Care

At home, you can help manage your pet's condition by:

Administering medications as prescribed, ensuring you follow the dosage instructions carefully.
Monitoring your pet for any changes in behaviour, appetite, or the appearance of the skin.
Keeping your pet's environment clean and free from irritants.
Regularly bathing your pet with medicated shampoos as directed by your veterinarian.

Prognosis

The successful cure rate for juvenile-onset generalised demodicosis is 70-80%. Dogs with adult-onset generalised demodicosis have a lower cure rate.

Treatment failure may occur due to:

Poor compliance with medications or skin scraping regime
Poor storage of medications
Resistance in rare cases

When to See the Vet

Contact your veterinarian if you observe any of the following:

Increased hair loss or worsening of skin lesions
Persistent itching or discomfort
Signs of infection (e.g., redness, swelling, discharge)
Changes in appetite or behaviour

References

Fourie JJ et al (2015) Efficacy of orally administered fluralaner (Bravecto™) or topically applied imidacloprid/moxidectin (Advocate®) against generalised demodicosis in dogs. Parasitic Vectors Mar 28;8:187. doi: 10.1186/s13071-015-0775-8.

Hutt JH, Prior IC, Shipstone MA (2015) Treatment of canine generalised demodicosis using weekly injections of doramectin: 232 cases in the USA (2002-2012). Vet Dermatol. 2015 Jul 20. doi: 10.1111/vde.12223. [Epub ahead of print]

Mueller, R. S et al (2012), Treatment of demodicosis in dogs: 2011 clinical practice guidelines. Veterinary Dermatology. doi: 10.1111/j.1365-3164.2011.01026.x