Dog Mites
Mange Mite Infestation

These dog mites are skin parasites of warm-blooded vertebrates and include 3 genera, of which the following two affect dogs:

• Sarcoptes
• Notoedres

Sarcoptes scabiei or the sarcoptic mange mite is a small and roughly circular mite.  They have large numbers of triangular scales and spines on their backs and two pairs of legs are situated around the mouth parts, whereas a further 2 pairs of legs are situated around the anus.  Some legs have suckers on long unjointed pedicles.

The life cycle of the sarcoptic mange mite is completed in 10 to 14 days.  Copulation of adult mites occurs in a moulting pocket on the surface of the skin.  Thereafter the newly fertilized females burrows into the horny layer of the skin while laying large eggs singly in the tunnel behind her, at a rate of about 2 a day for about 2 months.  The eggs hatch after 2 days and the larvae either leave the burrow or remain in it and moult into nymphs.  The nymphs wander about the skin but may stay in a moulting pocket until they are mature.  Mites prefer the less hairy regions of the body and are therefore common on the stomach, hock, root of the tail, head and muzzle of dogs.

The sarcoptic mange mite causes a nonseasonal, intensely pruritic (itching), transmissible infestation of the skin of dogs, and these mites are transferable to other species, including man.  The mites result in alopecia (loss of hair) and the early skin lesions are characterized by pruritic, reddish papulocrustous eruptions (the lesions look and feel like small scabs).  These lesions initially involve the less hairy areas as described above.  The itching thought to be more severe in warm environments and is cause by allergic substances that are secreted by the mites.  In long term cases, hyperpigmentation (darkened spots on the skin due to an increase in melanin, the brown pigment that is produced by certain cells in the skin called melanocytes) of the skin develops and the lesions may spread over the body, but the back is usually spared.  Some dogs however never have the classical lesions of scabies and although the scratch intensely, they have few if any real lesions apart from mild erythema (redness of the skin and excoriations (abrasions).  Secondary weight loss may occur.

Reactions in man occur within 24 hours after brief direct exposure to the sarcoptic mite and are characterised by pruritic papules (small, solid, usually inflammatory elevations of the skin that do not contain pus) on the trunk and arms.

A diagnosis is made by means of deep skin scraping until blood is drawn.  Scabies mites can however be difficult to demonstrate, especially under the following conditions:

• When the patient is intensely pruritic
• When the patient had the disease for a long time
• When the patient has received multiple baths or dips

All affected and all in-contact dogs must be treated with a scabicide.  As per traditional therapy, dogs should first be bathed with an antiseborrheic shampoo to remove the crusts, prior to applying a topical scabicide every 7 days for at least 5 weeks.  Alternative treatment includes the off-label use of macrocyclic lactones.  If the animal is severely pruritic, cortisone treatment may be helpful.  In kennel situations, the bedding should be disposed of, and the environment thoroughly cleaned and treated with a parasiticidal spray.

Notoedres cati or the cat scabies mite mainly occur on cats, but may sometimes also occur on dogs, man and rabbits.

Hair follicle mites infest man and other mammals.  They are elongated mites that live in dermal glands and hair follicles.

The demodectic mange mite is a tiny, cigar-shaped mite with short stumpy legs that is a normal inhabitant of the skin of the dog.  They live permanently in the hair follicles and skin glands of the dog.  Small numbers of demodectic mange are therefore present in healthy dogs.  Demodectic mange present in larger than normal numbers, result in an inflammatory parasitic disease in dogs.

For additional information on Dog health conditions

other conditions which are transmissible to humans: Zoonotic Diseases

Itchy Dog - Scratch my back - I'll scratch yours

Dogs and Fleas

Ticks

Go from Dog Mites to Veterinary Articles

Veterinary articles supplied by Dr S Strydom and published with kind permission of DIA Publishing - publishers of KUSA Dogs in Africa Magazine

Dr Sunelle Strydom qualified as a veterinarian in 2004 at the Faculty of Veterinary Science, University of Pretoria.  She has a passion for writing and the sharing of knowledge to promote animal health and welfare.  She has written several articles for KUSA Dogs in Africa as well as for Vra vir Faffa on the Landbouweekblad website at www.landbou.com