Sarcoptic mange of the dog

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Severe sarcoptic mange in a domestic dog

The sarcoptic mange the dog is a highly infectious parasitic skin disease characterized by the mange mite Sarcoptes scabiei var canis. Is caused. It is characterized by reddened papules and , in severe cases, by crusty skin changes. It is combated with acaricides that kill mites . The disease is also contagious for humans, however, as a false host, the mites do not multiply in humans, so that the disease heals within two weeks without constant re-infection, even without treatment.

Occurrence and development of the disease

Dog's burial mite ( Sarcoptes scabiei var.canis )

The dog sarcoptes mite ( Sarcoptes scabiei var. Canis , occasionally also regarded as a separate species Sarcoptes canis ) belonging to the grave mites is a parasite with a relatively high host specificity that occurs mainly in dogs. Occasionally it can also occur in the red fox , rabbits , hares , guinea pigs , pigs and domestic cats . Even in humans it can cause a short-term illness with itching and small papules , but it usually heals spontaneously after a few days ("pseudo- scabies "). In addition to Sarcoptes scabiei var. Canis , Sarcoptes scabiei var. Vulpes , the causative agent of the fox mange, can also be the cause of Sarcoptes mange in dogs.

The entire development cycle of the mite takes place on or in the dog's skin. The males live on the surface of the skin or in shallow tunnels. This is where copulation takes place, after which they die. Female grave mites burrow into the stratum spinosum or granulosum of the epidermis with their mouthparts ( chelicerae ) and feed on keratin and tissue fluid. During their lifetime they lay eggs in the drill holes they have created. The development cycle of the grave mite takes about three weeks and shows three stages of development.

The larvae hatch from the eggs after 3 to 5 days . They only carry three pairs of legs and live mainly in the drill holes. The larvae molt into their own skin niches nymphs , which morphologically resemble the adult females, but are much smaller and not yet sexually differentiated. These molt into adult grave mites.

The transmission takes place regardless of the season, mostly through direct contact with infected animals. The sarcoptic mange is highly contagious. However, transmission from the environment is also possible. Under favorable conditions (10–15 ° C), the grave mite can survive in skin remnants for up to three weeks, and three to six days at room temperature. In particular, it can also be found in brushes or cracks.

Clinical picture

Severe sarcoptic mange in a feral street dog

The sarcoptic mange shows itself initially in the form of reddened small papules, possibly also pustules . They occur mainly on the outside and edges of the auricles , around the eyes, as well as on the elbows , ankles and abdomen. In the further course there is severe reddening of the skin ( erythema ) and, as a result of the severe itching , self-inflicted skin injuries from excessive scratching, sometimes biting into the itchy areas of the skin, as well as hair loss (alopecia), flaking, crusts and excessive keratinization ( hyperkeratosis ). Often the outer sides of the limbs and the edges of the auricle are affected. Secondarily, pyoderma caused by bacteria often occurs.

It is believed that the clinical picture is less due to the harmful effects of the mites and more to allergic reactions .

A special form is the "Norwegian mange". High-grade cornification and crusts dominate here, while the itching can only be mild. This form occurs primarily in animals with impaired immune systems, with Cushing's syndrome or after treatment with glucocorticoids .

Diagnosis

The pinna pedal reflex is almost always positive in sarcoptic mange. It has a sensitivity of 82% and a specificity of 94%. The diagnosis is confirmed by a superficial scraping of skin , whereby the detection of a mite, a nymph, eggs or mite excrement is considered conclusive. Alternatively, Sarcoptes-specific antibodies can be detected two to four weeks after infection by a blood test . The sensitivity of the detection via skin scrapings is only 20%, while via antibody detection ( ELISA ) sensitivities and specificities of over 90% are possible. False positive results mainly occur in atopic people through cross-reactions with house dust mites , false negative results because antibodies only appear after two to five weeks.

Food allergies and atopic dermatitis must be distinguished . Other differential diagnoses, which are usually associated with less pronounced itching, are malassezia dermatitis , pyoderma , contact dermatitis, cheyletiellosis and demodicosis .

Combat

To combat this, washing treatments with amitraz , the injection of ivermectin (cave MDR1 defect ) or spot-ons with fipronil , selamectin , moxidectin , pyriprole or flumethrin are suitable . Only selamectin (trade name Stronghold ) and moxidectin (trade name Advocate ) are approved in Germany for the treatment of sarcoptic mange in dogs . In a new study, Fluralaner also proved to be highly effective, which can be administered in tablet form or as a spot-on. All dogs that have had contact with the affected animal must also be treated. At the start of treatment, a glucocorticoid may be given for several days to relieve itching.

It is advisable to remove thick crusts mechanically, as these are populated with many mites. Care items and berths must also be cleaned and treated with miticidal agents, as the mites can survive there for up to three weeks.

Individual evidence

  1. ↑ a b Georg von Samson-Himmelstjerna, Horst Zahner, Johannes Eckert, Peter Deplazes: Textbook of Parasitology for Veterinary Medicine. 2012, ISBN 3830412053 , p. 426.
  2. ↑ a b c d e f Kerstin Wildermuth: The canine Sarcoptesräude: diagnostic and therapeutic possibilities. In: Kleintierpraxis 59 (2014), pp. 680–688.
  3. ↑ a b c d e f g Katrin Timm and Claudia S. Nett-Mettler: Pruritus in dogs (part 2) - Infectious and neoplastic causes. In: Kleintierpraxis , Volume 60, 2016, Issue 6, pp. 311–332.
  4. ^ DB Pence and E. Ueckermann: Sarcoptic mange in wildlife Rev. sci. tech. Off. int. Epiz., 2002, 21 (2), pages 385-398.
  5. ↑ Nordkurier: Old plague, new victims: wolves
  6. ↑ a b Thomas Schnieder: Veterinary Parasitology. Georg Thieme Verlag, 2006, ISBN 3830442025 , p. 542.
  7. ^ C. Romero et al .: Efficacy of fluralaner in 17 dogs with sarcoptic mange. In: Vet. Dermatol. Volume 27, Issue 5, 2016, pp. 353-e88.

literature

  • Chiara Noli, Fabia Scarampella: Practical Dermatology in Dogs and Cats. Clinic, diagnosis, therapy. 2nd unchanged edition. Schlütersche Verlagsanstalt, Hanover 2005, ISBN 3-87706-713-1 .