NAVLENervous·⏱ 25 min read·📅 Mar 28, 2026·by NAVLE Exam Prep Team·👁 0
Avian Air Sac Mites Study Guide
Overview and Clinical Importance
Air sac mites are obligate endoparasitic hematophagous arthropods that infest the respiratory tract of birds, causing respiratory acariasis or sternostomatosis. These tiny arachnids colonize the trachea, syrinx, lungs, and air sacs, where they feed on blood and tissue. Air sac mite infestations are particularly devastating in Gouldian finches and canaries, representing a leading cause of morbidity and mortality.
Species
Primary Hosts
Location
Significance
Sternostoma tracheacolum
Gouldian finches, canaries, budgerigars
Trachea, syrinx, lungs, air sacs
Most pathogenic; #1 killer of Gouldians
Cytodites nudus
Chickens, turkeys, pheasants, pigeons
Air sacs, pneumatic bones, lungs
Pneumonia, peritonitis; white spots
Ptilonyssus spp.
House sparrows, wild passerines
Nasal passages
Usually subclinical in wild birds
Etiology and Classification
Air sac mites belong to family Rhinonyssidae, order Mesostigmata. Key species:
Mite Morphology
Size: Males 0.4 mm; females 0.5-0.7 mm long; 0.2-0.3 mm wide
Color: Clear to dark red depending on blood meal status
Legs: Four pairs (arachnid characteristic)
Feeding apparatus: Chelate-dentate chelicerae for blood feeding
Fomites: Contaminated perches, water containers, nest materials
Direct contact: Close proximity between infected and naive birds
NAVLE TipThe 6-day life cycle explains why treatment must be repeated at 10-14 day intervals. Initial treatment kills adults and nymphs but NOT eggs. The repeat dose catches newly hatched mites before they can reproduce.
High Susceptibility
Moderate Susceptibility
Low/Resistant
Gouldian finches, Canaries, Australian finches, Cordon bleu, Parrot finches
Budgerigars, Zebra finches, Other small finches, Pictorella manikins
Excessive salivation (ptyalism), copious saliva in oropharynx, excessive swallowing motions
Severe Infestation
Pneumonia, airsacculitis, airway obstruction, coelomitis, death (especially in fledglings)
Clinical Signs
High-YieldGouldians and canaries that just do not look right should always be suspected of air sac mite infection. Decreased breeding performance and unexplained fledgling deaths are common presentations.
Method
Technique
Sensitivity
Transillumination
Darkened room, pinpoint light through moistened neck skin. Mites appear as tiny black specks moving in trachea.
Variable; best for heavy infections
Tracheal Endoscopy
Direct visualization of mites in trachea/syrinx. Requires specialized equipment.
High when performed
Treatment Response
Improvement following ivermectin/moxidectin therapy supports diagnosis.
Retrospective
Necropsy
Definitive. Examine trachea, syrinx, lungs, air sacs. May find greater than 100 mites in trachea.
Gold standard
Diagnosis
Pathological Findings
Gross: Mites in respiratory tract, thickened air sacs with fluid, mucopurulent exudate, congested/hemorrhagic lungs
Histopathology: Bronchopneumonia, airsacculitis with lymphocyte infiltration, epithelial loss in trachea, macrophage infiltration at attachment sites
Drug
Dose
Route
Protocol
Ivermectin
0.2-0.4 mg/kg
PO, IM, or topical
Repeat in 10-14 days; 2-3 treatments
Moxidectin (SCATT)
0.2 mg/kg or 1 drop/30g
PO, topical, or SC
Repeat in 14-21 days; 2-3 treatments
Carbaryl 5%
Mix into nest substrate
Environmental
Adjunct to systemic treatment
Treatment
Treat quickly with minimal handling. Macrocyclic lactones (ivermectin, moxidectin) are drugs of choice. Treat entire flock when one bird diagnosed.
Important Treatment Considerations
IM ivermectin can be fatal in small birds - use oral or topical for finches
Paradoxical worsening: Heavy mite die-off can temporarily worsen respiratory signs
Dilution for small birds: 1:4 dilution of 1% ivermectin recommended
SCATT (moxidectin): Not recommended for birds younger than 6 months
Secondary infections: Consider amoxicillin for 2 days post-treatment
Exam Focus: Drugs kill active mites but NOT eggs. With 6-day life cycle, second treatment (10-14 days) catches newly hatched mites before reproduction. Canaries may need 3-6 treatments.
Strategy
Implementation
Quarantine
Isolate new birds 30-45 days; treat prophylactically before introducing
Environmental
Discard wooden nest boxes; clean water containers daily; use acaricidal sprays
Prophylaxis
Treat flocks 2-4 times yearly; monthly during hot months for high-risk flocks
Wild Bird Exposure
Minimize exposure to wild birds (house sparrows, wild Gouldians are reservoirs)
Foster Parenting
Use Bengalese finches as foster parents - naturally resistant
Prevention and Control
High-YieldMites can survive up to 10 months off-host in the environment. Environmental cleaning is critical.
Differential Diagnosis
Aspergillosis: Fungal respiratory infection
Chlamydiosis: Bacterial; respiratory and systemic signs
Knemidocoptes: External mite; different presentation
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Test yourself before moving on. Click an answer to reveal the explanation.
Question 1
A 2-year-old male Gouldian finch presents with decreased singing, clicking sounds when breathing, weight loss, and fluffed appearance. On exam, you note tail bobbing and high-pitched wheezing. Transillumination of the trachea reveals tiny dark specks moving within. What is the most appropriate treatment protocol?
Explanation
Ivermectin 0.2 mg/kg PO repeated in 10-14 days is correct because this Gouldian finch has classic air sac mite infestation: susceptible species, respiratory signs, and positive transillumination. Ivermectin is drug of choice. Treatment MUST be repeated because ivermectin kills adults and nymphs but NOT eggs.
Option A (Doxycycline) is for chlamydiosis (bacterial). Positive transillumination confirms parasitic etiology.
Option B (Single dose) will kill current mites but NOT eliminate infection. Eggs will hatch and perpetuate infestation.
Option D (Itraconazole) is antifungal for aspergillosis, not effective against parasites.
Option E (Metronidazole) is for protozoa (trichomoniasis), not mites.
Board Tip: 6-day life cycle: eggs laid day 0 hatch by day 6. Treat day 0, retreat day 10-14. Always treat the entire flock when one bird is diagnosed.
Question 2
Regarding Air sac mites in Avian species, which of the following statements is most accurate?
Explanation
The correct answer reflects a key high-yield fact about Air sac mites: Gouldians and canaries that just do not look right should always be suspected of air sac mite infection. Decreased breeding performance and unexplained fledgling deaths are common presentations.
Question 3
Regarding Air sac mites in Avian species, which of the following statements is most accurate?
Explanation
The correct answer reflects a key high-yield fact about Air sac mites: Mites can survive up to 10 months off-host in the environment. Environmental cleaning is critical.