Canine demodicosis
Canine demodicosis is also known as folliculosis or fat mange. It is a common and stubborn skin disease caused by Demodex canis parasitizing on sebaceous glands or hair follicles. Mostly occurs in puppies aged 5 to 10 months.
Pathogen and life history of canine demodicosis
Demodex canis is translucent and milky white, and the body is long and narrow like a worm, with a body length of 0.25~0.3 mm, about 0.04 mm wide, and can be divided into three parts: front, middle and back. The mouthparts are in the shape of a horseshoe in the front; there are 4 pairs of very short feet in the middle, and each foot is composed of 5 segments; the rear is slender, and the surface is densely covered with horizontal stripes.
The entire developmental process of Demodex canis is carried out on the dog body. Including egg, larva, nymph, adult 4 stages, nymph has 3 stages. Demodex canis mostly parasitizes on the upper part of the hair follicles of the diseased skin, and then turns to the bottom, and rarely parasitizes in the sebaceous glands. In addition to parasitic inside and outside the hair follicles, they can also live in the tissues and lymph nodes of dogs, and some of them reproduce in them.
Key points for diagnosis of canine demodicosis
(1) The clinical symptoms can be divided into two types: Squamous type: mostly occurs in and around the eyelids, corners of the mouth , forehead, nose and lower neck, elbows, between toes, etc. The affected area is depilated, accompanied by mild flushing of the skin and the occurrence of silvery white sticky dander. The skin appears slightly rough and cracked, or has small nodules. Later, the skin was blue-grey-white or copper-colored, and the affected area was almost non-itchy. Some remained unchanged for a long time, and some turned into pus scars.
Pustular scar type: mainly occurs in the neck, chest, medial thigh and other parts, and spreads to the whole body in the later stage. Large areas of hair loss on the body surface, large areas of erythema, hypertrophy of the skin, often forming wrinkles. There are diffuse pus rashes from millet to wheat grain dogs, the pus scars are blue-red, pus is discharged when squeezed, and contain a large number of Demodex mites and eggs, and the pus scars rupture and form ulcers, scabs, and have an unpleasant smell the stench.
There is almost no itching in the abscess type. If there is severe itching, it may be a mixed infection. Eventually die of exhaustion, poisoning or sepsis.
(2) Laboratory examination: Cut nodules or pus scars on the skin, take their contents for smear microscopy, and confirm the diagnosis if the parasites are found.
Prevention and control measures for canine demodicosis
Isolate and treat sick dogs, and disinfect the contaminated places and utensils with acaricide. Select following medicine to treat for use: dimethyl ether, application concentration is 250ppm, body surface is bathed and washed. Ivermectin 200 μg/kg body weight, subcutaneous injection; ivermectin is a broad-spectrum anthelmintic against nematodes and spider-loving insects, so it should be used with caution in dogs suspected of suffering from heartworm disease at the same time, so as not to kill the heartworm. Heart meridian worms cause blockage and accidents. 14% tincture of iodine, apply to the affected part. In addition to topical application of insecticides to severely ill dogs, antibiotics should also be applied systemically to prevent secondary infection.
