Otodectes spp

From Dog
Otodectes cyanotis eggs under light microscopy[1]
Otodectes cyanotis adult[2]

Otodectes spp are a common nuisance mite parasite of dogs and cats worldwide[3].

The mite normally resides in the environment, under leaf litter and moist vegetation and infests dogs during foraging activity or close contact with infected dogs or cats.

They reside on the epidermal surface of auditory canal without burrowing into the tissue and feeding on tissue fluids and debris. In most of the cases they induce hypersensitivity reactions in the host[4].

The life cycle of the mite lasts three weeks but it can survive for several weeks off the host[5]. Female lays eggs and sticks them to the epithermal surface. Thereafter, eggs will hatch to six-legged larvae and molt into eight-legged protonymphs and deutonymphs within two months[6]. Although this is primarily an external parasite of dogs and cats, foxes and other wild animals are thought to be reservoir hosts[7].

Mite infestation can occur at any age but are more common in younger dogs. The cat is a common cause of transmission in adult dogs

Species which are pathogenic to dogs include:

  • Otodectes cyanotis

Clinical signs include head shaking, continual ear scratching, ear droop and secondary otitis externa. There is usually an accumulation of thick, dark brown to black crusty exudates and cerumen in auditory canal. However, some dogs may have asymptomatic infection. Pruritus is variable and is mainly caused by hypersensitivity to the mite saliva[8]. Secondary Staphylococcus pseudintermedius and Pseudomonas spp infections are common.

Development of aural hematoma are a common sequel in older dogs due to constant ear shaking. Rare cases of generalized ototdectic mange have been reported in dogs[9].

Diagnosis is based on microscopic identification of the parasite within ear debris[10].

Treatment is usually effective with parenteral or topical imidacloprid[11], ivermectin[12], moxidectin, selamectin[13] or fipronil.

Curiously, application of non-acaricidal otitic preparations have shown an equal efficacy against this parasite[14].

References

  1. Vet Online
  2. Dog Grooming
  3. Kristensen S (1978) Otodectes cynotis infestation. Arch Dermatol 114(9):1402
  4. Maazi N et al (2010) Ear mite infestation in four imported dogs from Thailand; a case report. Iran J Arthropod Borne Dis 4(2):68-71
  5. Otranto D et al (2004) Otodectes cynotis (Acari: Psoroptidae): examination of survival off-the-host under natural and laboratory conditions. Exp Appl Acarol 32(3):171-179
  6. Harvey RG et al (2001) Ear diseases of the dog and cat. Manson Publishing Ltd; London
  7. Lohse J et al (2002) Validity of species status of the parasitic mite Otodectes cynotis. Med Vet Entomol 16(2):133-138
  8. Maazi N et al (2010) Ear mite infestation in four imported dogs from Thailand; a case report. Iran J Arthropod Borne Dis 4(2):68-71
  9. Kraft W et al (1988) Otodectes cynotis infestation of dogs and cats: biology of the agent, epidemiology, pathogenesis and diagnosis and case description of generalized mange in dogs. Tierarztl Prax 16(4):409-415
  10. Xhaxhiu D et al (2009) Ectoparasites of dogs and cats in Albania. Parasitol Res 105(6):1577-1587
  11. Krieger K et al (2005) Efficacy and safety of imidacloprid 10% plus moxidectin 2.5% spot-on in the treatment of sarcoptic mange and otoacariosis in dogs: results af a European field study. Parasitol Res 97(1):S81-S88
  12. Yazwinski TA et al (1981) Efficacy of ivermectin against Sarcoptes scabiei and Otodectes cynotis infestations of dogs. Vet Med Small Anim Clin 76(12):1749-1751
  13. Six RH et al (2000) Efficacy and safety of selamectin against Sarcoptes scabiei on dogs and Otodectes cynotis on dogs and cats presented as veterinary patients. Vet Parasitol 91(3-4):291-309
  14. Engelen MA & Anthonissens E (2000) Efficacy of non-acaricidal containing otic preparations in the treatment of otoacariasis in dogs and cats. Vet Rec 147(20):567-569