Canis ISSN: 2398-2942

Otodectes cynotis

Synonym(s): O. cynotis, ear mites

Contributor(s): Rosanna Marsella

Introduction

Classification

Taxonomy

  • Family: Psoroptidae.
  • Genus: Otodectes.

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Clinical Effects

Epidemiology

Habitat

  • Deep in the ear canal of dogs, cats, foxes, other Canidae and Felidae, and ferrets.
  • May spread to the pinna, neck, head, rump, paws, tail tip.

Lifecycle

  • O. cynotis lifecycle Lifecycle Otodectes cynotis - diagram :
    • Adult male Otodectes cynotis adult male and female Otodectes cynotis female.
    • Egg Otodectes cynotis egg in feces of dog.
    • Larva Otodectes cynotis larva hatched from egg.
    • Nymph.

Transmission

  • Permanent parasite of the ear, therefore transmission by close, direct contact, particularly mother to young while suckling, but also in kennels, etc.
  • O. cynotis seems not to be host-specific so transmission occurs between different host species, especially the cat and dog.
  • O. cynotis can be maintained in vitro on ear debris and survives in the environment, but the importance in transmission of environmental contamination with mites remains unsubstantiated.

Pathological effects

  • Infection induces a pruritic, hypersensitivity reaction.
  • This has been studied only in cats and consisted of an immediate (Type I) and Arthus (Type III) hypersensitivity reaction.
  • Marked infiltration of wall of ear canal with plasma cells and lymphocytes.
  • Severe pruritus, head shaking and scratching.
  • Excess cerumen production exuding as a dark brown colored, waxy discharge that can crust. Mites live beneath the crust next to the skin.
  • May lead to purulent otitis with invasion of neutrophils and a brown, purulent, fetid discharge.

Other Host Effects

  • Surface parasites feeding on epidermal debris and excess cerumen.

Control

Control via animal

  • Treatment of dog and all in-contact animals.
  • Remove wax and cleanse ear canal.
  • Most acaricidal ear drops or ointments have little or no residual activity so many treatments are given daily, and treatment should be repeated at least once at 10-14 days to kill mites hatched from eggs present at the time of treatment.

Control via chemotherapies

Either
  • a) Amethocaine hydrochloride/neomycin sulfate/thiabendazole (ear drops).
  • b) Diethanolamine fusidate/framycetin/nystatin/prednisolone (ear drops).
  • c) Piperonyl butoxide/pyrethrins (ear drops).
  • d) Amethocaine hydrochloride/neomycin sulfate/permethrin (ear drops).
  • e) Chlorbutol/phenoxyethanol (Otodex ear drops).
  • f) Thiabendazone/dexamethasone/neomycin sulfate.
Or Effective acaracides:
  • a) Amitraz Amitraz (0.025% in mineral oil), by topical application and used at least twice, is effective (unlicensed use in dogs).
  • b) Ivermectin Ivermectin (200-400 ug/kg) by injection used at least twice, is effective in kennel situations (not licensed for use in dogs).
    Toxic in Collies and Collie crosses.
  • Fipronil Fipronil (topical application in ears once) - unlicensed use in dogs.
  • Selamectin Selamectin , 1x month, is an effective treatment for ear mites - unlicensed use in dogs.

Control via environment

  • The relevant importance of mites in the environment is unknown. Repeated treatment of the dog at about 10-day intervals should eliminate any reinfestation from the environment.
  • In persistent cases, remove and boil bedding and clean or treat the area where the dog sleeps with acaricide.

Other countermeasures

  • In persistent cases it may be useful to treat the whole body with amitraz bath or lime sulfur dip.

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from VetMedResource and PubMed.
  • Chickering W R (1988) Cytologic evaluation of otic exudates. Vet Clin North Am Small Anim Pract 18(4), 773-782.
  • Pott J M et al (1979) The efficacy of a topical ear preparation against Otodectes cynotis infection in dogs and cats. Vet Rec 104(25), 579.

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