Sarcoptes spp

From Dog
Sarcoptes scabiei var canis[1]
Generalized sarcoptic mange. [1]

Sacroptes spp are a parasitic mite of most mammals, and commonly infests the skin of dogs worldwide[2].

Sarcoptes is a ubiquitous parasite[3] which resides on both the skin surface and within the epidermis.

The role of transmission to humans is debatable, since S. scabiei var hominis is genetically distinct from those on dogs in sympatric populations, suggesting zoonotic infections may be an accidental parasitism[4][5].

Species which are pathogenic to dogs include:

  • Sarcoptes scabiei var canis

Females burrow tunnels in the superficial layers of the skin, where she lays eggs over a one month period. Larvae emerge from the eggs and molt through protonymph and tritonymph stages to become adults, where they re-emerge onto the skin to mate. The life cycle is approximately 2 - 4 weeks. Adults feed on serum and epidermal debris while mating and are transmitted to other dogs during this period of superficial parasitism.

As with Demodex canis, secondary infections with Malassezia spp and Staphylococcus pseudintermedius (and in severe infestations S. aureus) are common during burrowing activity. Immunosuppression and hypersensitivity to exoantigens[6] appear to be a factor in the extent of clinical symptoms[7]. Death due to secondary bacterial sepsis is not uncommon in refractory or neglected cases[8].

Transmission occurs by direct contact but also by infestation from the environment. The disease predominantly affects young dogs, of all breeds and both sexes, implicating age-related immunity[9].

Clinical signs are usually referable to the burrowing activity of mites, with pruritus, erythema, papules, lichenification, scales, crusts, alopecia, seborrhea and secondary dermatitis common[10]. Lesions predominate on the lateral ear margins, but other areas of the body may be affected, including the ventral abdomen, chest, elbows and legs. Generalised sarcoptic mange often involves peripheral lymphadenopathy, weight loss and unthriftiness.

Diagnosis is based on clinical signs, microscopic evidence of parasite from skin scrapings and response to therapy[11].

Treatment is primarily aimed at parenteral acaricidal therapy using milbemycin oxime, selamectin, imidacloprid[12], moxidectin and ivermectin.

In refractory cases, or suspicion of resistance, fipronil has shown promise at eradicating the parasite[13][14].

Response to therapy is usually good in most cases, but the use of broad-spectrum antimicrobials such as amoxycillin/clavulanate or enrofloxacin should be considered in generalized sarcoptic mange cases.

References

  1. 1.0 1.1 Bayer Animal Health
  2. Jamshidi S et al (2012) A survey of ectoparasite infestation in dogs in Tehran, Iran. Rev Bras Parasitol Vet 21(3):326-329
  3. Chee JH et al (2008) A survey of ectoparasite infestations in stray dogs of Gwang-ju City, Republic of Korea. Korean J Parasitol 46(1):23-27
  4. Walton SF et al (2004) Genetic epidemiology of Sarcoptes scabiei (Acari: Sarcoptidae) in northern Australia. Int J Parasitol 34(7):839-849
  5. Moriello KA (2003) Zoonotic skin diseases of dogs and cats. Anim Health Res Rev 4(2):157-168
  6. Arlian LG et al (1996) The development of protective immunity in canine scabies. Vet Parasitol 62:133-142
  7. Singh SK et al (2011) Determination of oxidative status and apoptosis in peripheral blood of dogs with sarcoptic mange. Vet Parasitol 178(3-4):330-338
  8. Nakagawa TL et al (2009) A pathological study of sepsis associated with sarcoptic mange in raccoon dogs (Nyctereutes procyonoides) in Japan. J Comp Pathol 141(2-3):177-181
  9. Feather L et al (2010) A retrospective investigation into risk factors of sarcoptic mange in dogs. Parasitol Res 107(2):279-283
  10. Morris DO, Dunstan RW (1996) A histomorphological study of sarcoptic acariasis in the dog: 19 cases. J Amer Anim Hosp Assn 32:119-124
  11. Kimberly S et al (2001) Evaluation of an enzyme-linked immunosorbent assay (ELISA) for the serological diagnosis of sarcoptic mange in dogs. Vet Dermatol 12:315-320
  12. Fourie LJ et al (2006) The efficacy of an imidacloprid/moxidectin combination against naturally acquired Sarcoptes scabiei infestations on dogs. Aust Vet J 84(1-2):17-21
  13. Terada Y et al (2010) Sarcoptes scabiei var. canis refractory to ivermectin treatment in two dogs. Vet Dermatol 21(6):608-612
  14. Curtis CF (2004) Current trends in the treatment of Sarcoptes, Cheyletiella and Otodectes mite infestations in dogs and cats. Vet Dermatol 15:108-114