Mange is a skin disease caused by microscopic mites that burrow into or live on the skin surface. Two very different diseases share this name: demodectic mange (Demodex mites — usually not contagious, related to immune function) and sarcoptic mange (Sarcoptes mites — highly contagious, intensely itchy). Distinguishing between them determines treatment approach and prognosis.
Demodectic Mange (Demodex canis)
What It Is
Demodex mites are NORMAL skin residents — every dog has them, inherited from their mother during nursing. Disease occurs only when the immune system fails to keep mite populations in check, allowing overgrowth.
Forms
| Form | Age | Appearance | Prognosis |
|---|---|---|---|
| Localized (juvenile) | 3-12 months | 1-5 small hairless patches, usually on face/legs. Mild or no itch. | 90% resolve spontaneously as immune system matures |
| Generalized (juvenile) | 3-18 months | Widespread hair loss, secondary infections, thickened skin | Requires treatment; most resolve but may take months |
| Adult-onset | Over 4 years | Generalized hair loss in previously healthy adult | Investigate for underlying immunosuppression (Cushing's, cancer, immune-suppressive drugs) |
Treatment
- Isoxazoline class (first-line): Fluralaner (Bravecto), afoxolaner (NexGard), sarolaner (Simparica). Oral, well-tolerated, effective. 2-3 monthly treatments typically curative.
- Ivermectin (traditional): Daily oral dosing. Effective but more side effects and contraindicated in MDR1-mutant breeds (Collies, Australian Shepherds).
- Treat secondary infections: Antibiotics + medicated bathing for bacterial pyoderma that accompanies generalized demodicosis.
Sarcoptic Mange (Scabies)
What It Is
Sarcoptes scabiei mites burrow into the skin, laying eggs in tunnels. Intensely contagious between dogs and zoonotic (can temporarily infect humans — causes red itchy bumps that self-resolve when the dog is treated).
Symptoms
- INTENSE itching — the most intensely pruritic condition in dermatology
- Crusty ear margins (highly suggestive — "ear margin reflex" where rubbing the ear makes the dog scratch)
- Elbows, hocks, chest, belly — areas with less hair
- Hair loss from self-trauma
- Thick crusts and scales
Diagnosis Challenge
Skin scrapings find mites in only 20-50% of cases (mites are sparse). Often diagnosed based on clinical presentation + response to treatment (therapeutic trial).
Treatment
- Isoxazoline class: Same as demodex treatment — highly effective
- Selamectin (Revolution): Topical, monthly, effective
- Treat ALL dogs in household (even if not showing symptoms)
- Environmental decontamination: Wash bedding in hot water; mites survive off-host for only 2-3 days
Key Differences
| Feature | Demodectic | Sarcoptic |
|---|---|---|
| Contagious? | No (immune-mediated overgrowth) | Highly contagious (dogs + humans) |
| Itching? | Mild to none (unless secondary infection) | Extreme — frantic scratching |
| Pattern | Hair loss, often starts on face | Ear margins, elbows, belly — crusty |
| Age | Usually young or immunocompromised | Any age |
Frequently Asked Questions
Can I catch mange from my dog?
Sarcoptic: temporarily yes. The mites can burrow into human skin causing red itchy bumps, but they cannot complete their lifecycle on humans and the infestation self-resolves once the dog is treated. Demodectic: no — Demodex canis is species-specific.
