Mites: Treatment Plan

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Sarcoptes scabiei

Selamectin, 6–12 mg/kg q30d (label dose11) or q2wk (greater efficacy)

  • Labeled for treatment and control of S scabiei.

A moxidectin/imidocloprid combination, flumethrin/imidacloprid collars, and spray-on fipronil are approved for the treatment of sarcoptic mange caused by S scabiei. Other off-label treatments include amitraz, lime sulfur dips, milbemycin oxime, moxidectin, and doramectin. However, nonapproved treatments are rarely necessary.

Demodex spp

Localized lesions

  • Amitraz, used spot-on
    • Young dogs with localized lesions will usually recover spontaneously at maturity.12 Consider the above only if treatment is necessary.

Generalized form

  • Amitraz (dogs)
    • Adverse effects can occur, and dipping is labor-intensive.
  • Ivermectin, q24h at high doses
    • Exercise caution in dogs susceptible to the MDR-1 gene mutation.
      • Test patients at risk for this gene mutation before treatment.
      • Use caution in dogs receiving spinosad-containing medications, as neurologic side effects have been observed in dogs receiving this combination.13
  • Milbemycin oxime, q24h
    • Beneficial for dogs that cannot tolerate other treatments.
  • Injectable doramectin, q1wk
    • Use caution in MDR-1 susceptible dogs.
  • Moxidectin, label dose
    • Used more frequently in an extralabel fashion.  

Treatment is imperative; every attempt should be made to determine and treat the underlying condition. Ovariohysterectomy should be performed on female patients, as demodicosis will recur with estrus. Any secondary pyoderma must be treated with antibiotic therapy; bathing with benzoyl peroxide shampoos is advantageous.

Otodectes cynotis

  • Topical milbemycin oxime and ivermectin, single dose applied directly to the affected ear canal(s)
  • Systemic miticides (eg, selamectin, moxidectin/imidocloprid), label dose q1mo
    • Effective in treating current infestations and possible re-exposure.

The first treatment goal is thorough cleaning of the affected ear canals. Topical medications will be more efficacious when allowed to reach the infection site.

Pneumonyssoides caninum

There is no approved treatment for nasal mites, but ivermectin, milbemycin oxime, and selamectin have been used.14,15 Ivermectin should be avoided in breeds with MDR-1 sensitivity.

Cheyletiella spp

These mites are susceptible to all the avermectins mentioned. The key is treating not only all affected household pets with an appropriate avermectin, but also treating the environment with pyrethrins. All clothing and bedding should be washed thoroughly, the household vacuumed, and all in-contact hosts treated.  

Physical Examination

The veterinarian should determine:

  • If lesions are generalized or localized, and to what area and extent
  • If the lesion is pruritic or nonpruritic
  • Presence of secondary conditions
  • Presence of otitis externa and character of the debris
  • Presence of sneezing and visibility of mites on the external nares.

Key diagnostics include:

  • Skin scraping of affected areas to rule in/out Sarcoptes scabiei, Demodex spp, Notoedres cati, and Cheyletiella spp  
  • Otic cytology to reveal possible Otodectes cynotisor or identify secondary bacterial and/or yeast infection
  • Skin surface cytology to identify Cheyletiella spp and secondary bacterial and/or yeast infection
  • Rhinoscopy to diagnose nasal mites.  

Editor's note: Dr. Chris Adolph is affiliated with Zoetis Animal Health.

References Show
References
References: 
  1. The ACVD task force on canine atopic dermatitis (I):  incidence and prevalence. Hillier A, Griffin CE. Vet Immunol Immunopathol 81:147-151, 2001.
  2. Prevalence of canine otitis externa in Jammu. Kumar S, Hussain K, Sharma R, et al. J Anim Res 4:121-129, 2014.
  3. Prevalence of respiratory signs and identification of risk factors for respiratory morbibity in Swedish Yorkshire terriers. Madsen MF, Granström S, Toft N, Houe H, et al. Vet Rec 170:565, 2012.
  4. Mites (Acari). Mullen G, O’Connor B. In Mullen GR, Durden LA (eds): Medical and Veterinary Entomology, 2nd ed—Oxford: Elsevier, 2009, pp 433-492.  
  5. Arthropods. Bowman DD. In Bowman DD.  Georgi’s Parasitology for Veterinarians, 9th ed—St. Louis: WB Saunders, 2009, pp 4-82.  
  6. Life-threatening dermatosis in dogs. Lewis D. Comp Cont Educ Pract 20:271-283, 1998.
  7. Demodicosis-A frequent problem in dogs. Mueller RS. World Small Animal Veterinary Association World Congress Proceedings, 2008.  
  8. The efficacy of Selamectin in the treatment of naturally acquired aural infestations of Otodectes cynotis on dogs and cats. Shanks DJ, McTier TL, Rowan TG, et al. Vet Parasitol 91:283-290, 2000.
  9. Respiratory Parasites. Ballwebber L. Western Veterinary Conference Proceedings, 2004.
  10. Sneezing and Snorting-What should I do? McKiernan L. World Small Animal Veterinary Association World Congress, 2001.  
  11. Current trends in the treatment of SarcoptesCheyletiella and Otodectes mite infestations in dogs and cats. Curtis C. Vet Dermatol 15:108-114, 2004.  
  12. An update on therapeutic management of canine demodicosis. Singh SK, Kumar M, Jadhav RK, Saxena SK. Veterinary World 4:41-44, 2011.  
  13. Pharmacokinetic interactions of the antiparasitic agents ivermectin and spinosad in dogs. Dunn ST, Hedges L, Sampson KE, et al. Drug Metab Dispos 39:789-795, 2011.
  14. Efficacy of selamectin in the treatment of nasal mite (Pneumonyssoides caninum) infection in dogs. Gunnarsson L, Zakrisson G, Christensson D, Uggla A.  JAAHA 40:400-404, 2004.
  15. Treatment of canine nasal mite infection. Rehbinder C, Karlsson T. Svensk Veterinartidning 55:19-22, 2003.

Suggested Reading

AAHA’s Complete Guide for the Veterinary Client Service Representative. Renfrew J. AAHA Press, 2013.

AAHA Canine Life Stage Guidelines. Bartges J, Boynton B, et al. American Animal Hospital Association, 2012.

External Parasites. American Veterinary Medical Association; https://ebusiness.avma.org/files/productdownloads/external_parasites_brochure.pdf

The Art of Veterinary Practice Management. Opperman M—Lenexa, Kansas: Veterinary Medicine Publishing Group, 1999.

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