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680.e2 Nasal Mites

Nasal Mites
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• No nasal or facial asymmetry
BASIC INFORMATION
All dogs in household/kennel should be treated,
• Mites are rarely found on the external nares is relatively effective with many acaricidal drugs.
Definition and are difficult to visualize due to small size not just the affected dog.
Infection with Pneumoysoides caninum, a (1.5 mm).
hematophagous mite of the caudal nasal cavity Acute General Treatment
and frontal sinus Etiology and Pathophysiology • Ivermectin (oral) 200-300 mcg/kg PO weekly
The life cycle of P. caninum is incompletely for 3 weeks
Synonyms understood. Mites live in the nasal passages • Ivermectin (injectable) 200-400 mcg/kg SQ
Pneumonyssus caninum, nasal acariasis and paranasal sinus. There is no nymphal stage q 2 weeks for 3 treatments
in the life cycle. The female is ovoviviparous, • Selamectin (Revolution) 6-24 mg/kg applied
Epidemiology and mature females contain eggs. It is probable topically q 2 weeks for 3 treatments
SPECIES, AGE, SEX that females give birth to larvae. • Milbemycin (Sentinel, Trifexis) 0.5-1 mg/
Older (>3 years), large-breed dogs appeared kg PO q 7 days for 2-3 doses
predisposed in a single study DIAGNOSIS ○ This is considered safe for dogs with
sensitivities to macrocyclic lactones.
GENETICS, BREED PREDISPOSITION Diagnostic Overview
No known genetic or breed predisposition Diagnosis requires direct visualization of the Drug Interactions
mite or positive response to therapy. ELISA Macrocyclic lactones should not be used in
RISK FACTORS assays have been developed in a laboratory dogs with the MDR1/ABCB1-Δ mutation
• Exposure to other dogs setting but are not available for clinical patients. (p. 638).
• A single study suggested increased risk among
working dogs. Differential Diagnosis PROGNOSIS & OUTCOME
• Dogs receiving heartworm prophylaxis are • Rhinitis (lymphoplasmacytic, fungal, second-
very unlikely to become infested. ary bacterial, parasitic, fungal) Prognosis is excellent.
• Oronasal neoplasia
CONTAGION AND ZOONOSIS • Dental disease (oronasal fistula) PEARLS & CONSIDERATIONS
Infection occurs after direct transfer of larva • Nasal foreign body
from one dog to another. Foxes may act as • Coagulopathy (with epistaxis) Comments
reservoir hosts. Disease has been reported only • Eucoleus boehmi (nasal capillarid) • Nasal mites should be considered as a dif-
in dogs and foxes. • Other causes of nasal discharge (p. 678) ferential in dogs with signs of nonspecific
nasal disease and a normal physical exam
GEOGRAPHY AND SEASONALITY Initial Database other than nasal discharge.
Distribution appears to be worldwide, with • If mite infestation is suspected, it is • P. caninum may be a primary or secondary
cases reported in the United States, Canada, reasonable to begin with a trial treatment pathogen.
Australia, South Africa, Japan, and Europe. before pursuing more invasive or expensive • Common use of heartworm prophylaxis
diagnostic tests for nasal discharge. seems to have reduced the number of dogs
ASSOCIATED DISORDERS • CBC: often unremarkable; a transient, mild demonstrating signs of infestation compared
• In a single study P. caninum was implicated eosinophilia has been reported in some dogs. with decades past.
in development of gastric dilation/volvulus
(GDV), presumptively due to aerophagia. Advanced or Confirmatory Testing Prevention
• Impaired scenting ability has been reported • Rhinoscopy/choanal exam (p. 1159): may Regular use of heartworm prophylaxis contain-
in working dogs. allow visualization of the mites by magnifica- ing ivermectin, selamectin, or milbemycin can
• Implicated in lymphoplasmacytic rhinitis tion of the endoscope. prevent infection.
○ Mites typically scurry away in response
Clinical Presentation to the light from the endoscope. Technician Tips
HISTORY, CHIEF COMPLAINT ○ Instilling cool water into the nasal passages Testing for the ABCB1 mutation can be per-
Dogs often present with vague upper respira- seems to slow the mites’ ability to run, formed by cheek swab and is recommended for
tory signs. Sneezing and reverse sneezing are aiding visualization. all at-risk dogs before treating with macrocyclic
common complaints. Less commonly, nasal/ • Nasal flushing (anterograde or retrograde): lactones.
ocular discharge, excessive lacrimation, restless- may allow collection of mites in the fluid
ness, coughing, epistaxis, facial pruritus, and • Imaging (radiographs/CT) is unremarkable SUGGESTED READING
orbital cellulitis are reported. but can help rule out several differential Gunnarsson L, et al: Efficacy of selamectin in the
diagnoses. treatment of nasal mite (Pneumonyssoides caninum)
PHYSICAL EXAM FINDINGS infection in dogs. J Am Anim Hosp Assoc 40:5,
• Often, exam is entirely normal. TREATMENT 2004
• Nasal discharge (often serous) AUTHOR & EDITOR: Megan Grobman, DVM, MS,
• ± Ocular discharge Treatment Overview DACVIM
• ± Epistaxis No drugs are currently approved for the
• Normal nasal airflow treatment of P. caninum. However, treatment

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