Overview of Mites

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Almost all domestic mammals can be infested by S scabiei.

Skin, otic, and respiratory conditions commonly affect dogs and cats; the prevalence for each is estimated at 15%1, 21%2, and 23%3 respectively. A multitude of etiologies exist (eg, allergic, infectious, parasitic). Because more than one etiology is commonly present in a patient, a thorough diagnostic protocol should be followed to allow detection of parasitic organisms and secondary bacterial or fungal infections. The following are common mites that lead to these conditions in small animals.

Related Article: Clinical Protocol for Ticks 

Sarcoptes scabiei (Sarcoptic Mange Mite)

With the exception of cats and guinea pigs, almost all domestic mammals can be infested by S scabiei.4 Cats may be infested by Notoedres cati, a mange mite very similar to Sarcoptes. Lesions appear first on thin-haired parts of the body (eg, ear margins, elbows, hocks, inguinal and axillary regions).5 A hallmark of sarcoptic mange is intense pruritus; infested animals will self-traumatize  attempting to relieve the itching, which may lead to secondary infections, hair loss, thickened skin, and eventually lichenification. If a dog scratches with a hindlimb when the ear margin is rubbed or scratched, S scabiei should be suspected.1 Transmission of S Scabiei is by direct contact and is extremely zoonotic.  

Demodex spp (Demodectic Mange Mite)

These mites are considered normal fauna of the host hair follicles and sebaceous glands. They are routinely detected in younger patients with localized alopecia and will usually resolve once the patient is mature. However, in genetically predisposed or immunocompromised patients, Demodex spp may become debilitating and even life-threating.6 Clinical signs occur in these immunodeficient or genetically predisposed patients.7 Pustular demodicosis, characterized by moist, purulent dermatitis with an unpleasant, rancid odor, may develop. The prognosis is poor without proper treatment.  

Otodectes cynotis (Ear Mite)

Ear mites are common in dogs, cats, and ferrets worldwide. All developmental stages of Otodectes live deep in the external ear canal.4,8 Transmission occurs through direct contact with an infected animal; younger patients tend to be more affected. Unlike Sarcoptes and Demodex, ear mites live as surface parasites only, piercing the skin to feed on blood, lymph, and serum. Clinical signs range from asymptomatic to severe otitis externa; debris is typically dark brown to black and thick. Secondary bacterial infection, yeast infection, and aural hematomas may develop as a result of excessive head shaking.

Pneumonyssoides caninum (Nasal Mite)

These mites are commonly referred to as nasal mites because of the infestation site (ie, the nasal sinuses of dogs). Details of the life cycle are not completely understood; however, adults with 4 pairs of legs and larvae with 3 pairs have been identified.9 Clinical signs include hyperemia of the nasal mucosa, nasal secretions, tearing of the eyes, chronic sneezing, facial pruritus, and epistaxis.10

Cheyletiella spp (Fur Mite)

Like ear mites, these mites are nonburrowing and pierce the skin to feed on blood, lymph, and serum.4 Although most infested patients are asymptomatic, clinical signs can include mild alopecia, pruritus, and skin scaling that resembles eczema. Fur mites can survive several days off the host, so infested bedding and household furniture may be a source of infection.


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 Sarcoptes, Cheyletiella 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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