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Demodicidosis in Dogs:Causes, Treatment, and Related Symptoms

Dog Medicine
Demodicosis is a cutaneous parasitic disease of dogs caused by Demodex Canis of the family Demodex and genus Demodex. This disease is also known as canine trichomoniasis or canine lipidosis. It is a common and stubborn skin disease. Demodex Canis is usually found in the eyes, ears, lips and hairless parts of the inner forelegs of the dog, and mostly in the hair follicles. In severe cases, Demodex Canis can be found in the lymph nodes and other tissues of the dog, and even in the ear canal and toes (fingers) of the dog.

Causes of Demodicidosis in Dogs

Demodicosis, also known as cysticercosis Canis or lipolyacariasis Canis, is a skin disease caused by Demodex Canis parasitic on the hair follicles or sebaceous glands of dogs. Very few demodex mites are considered normal in dogs. Demodicosis, with clinical symptoms, occurs when mites proliferate excessively. Dogs with juvenile generalized demodex infection generally have a genetic predisposition. Adult demodicosis is often associated with an underlying medical condition (e.g., Cushing's disease, hypothyroidism), immunosuppressive drugs, or immunosuppression due to cancer (immunosuppression).

Demodicidosis symptoms

Affected dogs can show different symptoms at different times:

Early stage

In the early stage of demodex infection, the affected part of the skin becomes red, thick and wrinkled, the secretion of sebaceous glands is enhanced, and covered with silvery white viscous furfury-like scales. Pruritus is rare, and a few may present with blackheads, papules, and small red protrusions.

Late stage

Depilation lesions in systemic demodicosis are widely distributed and can be present throughout the body. Blackheads, papules, and red protuberances and bleeding from the lesion were present. Crusts often present secondary infections on the surface that develop into folliculitis, pyoderma, etc., which also lead to itchy skin. The skin becomes pale blue or copper, and emits an unpleasant odor.

Diagnostic Criteria for Demodicidosis in Dogs

A preliminary diagnosis can be made based on clinical symptoms. Laboratory diagnosis is required, which mainly includes the following three methods:

(1) The sebum of the lesion was scraped with the blunt end of the surgical blade, placed on a clean slide, fixed with glycerin, and observed under a light microscope at low magnification.

(2) The skin at the hairless junction of the lesion was squeezed with both thumb nails, and the content of the hair follicle was extruded. Then the sebaceous content was scraped with the blunt end of the surgical blade, and the sebaceous content was placed on the slide, fixed with glycerin, and observed under a light microscope at low magnification.

(3) The adhesive tape was cut into a size of 2.5cm×2.0cm and pasted on the lesions after being shaved. After 1 minute, the adhesive tape was removed and affixed to the slide.

The third method of cellophane tape is recommended because it has the characteristics of light injury to animals, little stress, simple operation and high detection rate, and should be used as the main clinical diagnosis method of canine demodex.

Demodicidosis treatment

(1) The common treatment for systemic demodex mites in dogs is oral ivermectin. Not recommended for Collies. However, other dog breeds can be used.

Oral ivermectin :0.4-0.6mg/kg/ day, preferably with food. If a concentration of 1% of ivermectin could be determined, the algorithm for oral dosing could be more straightforward: 0.04-0.06ml/kg orally daily. For dogs receiving ivermectin for the first time, to prevent side effects, it should be gradually increased to the recommended dose over 7 days, for example: day 1:1/7 of the recommended dose (approximately 0.005-0.008ml/kg); Day 2:2/7(0.01-0.016mg/kg); Days 3 to 7 and so on. The owner was careful to observe the response of the animals during the first week of medication at home. Ivermectin was discontinued if abnormalities occurred. "Possible side effects: anorexia, depression, vomiting, mydriasis, tremor, ataxia, salivation, coma, seizures, and death." If the method of gradually increasing the dose is chosen, once the side effects are found, most dogs can recover by withdrawal of the drug or supportive therapy. The first week of observation was followed by 3 weeks at the recommended rate of 0.04 to 0.06ml/kg/ day.

(2) For severe pustules, the pustules can be opened and cleaned with 3% hydrogen peroxide solution and then applied with 2% iodine tincture.

(3) Systemic infection can be treated with antibiotics.

Methods of prevention and control Demodicidosis in Dogs

(1) Pay attention to the hygiene of the kennel, keep the bedding dry, and regularly disinfect (the pollutants of demodex such as the dog cage and bedding can be disinfected at 50 ° C for 30 min or 60 ° C for 10 min).

(2) Pay attention to the balanced nutrition of dog food and enhance the body's resistance.

(3) In order to prevent vertical transmission, the infected dogs should not be used for breeding.

(4) Do not let healthy dogs contact with sick dogs to prevent direct contact transmission.