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Vetdle Archive

Archive Case #30: Canine Demodicosis

Dog veterinary case - Easy - April 2, 2026

Clinical Clues

  1. A young dog is presented for patchy hair loss affecting the face and forelimbs.
  2. The owner reports the areas are not especially itchy, but they have gradually expanded.
  3. On examination there is alopecia, scaling, and mild follicular plugging.
  4. Skin scrapings reveal large numbers of cigar-shaped mites.
  5. Secondary bacterial skin infection is beginning to develop in some lesions.
  6. Overgrowth of a normal follicular mite can cause juvenile-onset alopecia and comedones in dogs.

Diagnosis

Canine Demodicosis

This case is most consistent with Canine Demodicosis because the dog has juvenile-onset alopecia with scaling and mites identified on skin scraping. The most important clues are the low-pruritus follicular pattern and the presence of Demodex mites, which distinguish it from allergic skin disease.

Learning review

Review the case evidence

Use the paired clues to explain how the evidence in this dog case supports the provided diagnosis, Canine Demodicosis, then compare your reasoning with the case explanation.

Evidence checkpoints

Clues 1-2

  1. Clue 1: A young dog is presented for patchy hair loss affecting the face and forelimbs.
  2. Clue 2: The owner reports the areas are not especially itchy, but they have gradually expanded.

Clues 3-4

  1. Clue 3: On examination there is alopecia, scaling, and mild follicular plugging.
  2. Clue 4: Skin scrapings reveal large numbers of cigar-shaped mites.

Clues 5-6

  1. Clue 5: Secondary bacterial skin infection is beginning to develop in some lesions.
  2. Clue 6: Overgrowth of a normal follicular mite can cause juvenile-onset alopecia and comedones in dogs.

Self-review prompts

  1. After clues 1-2, what evidence from this dog case shaped your initial interpretation?
  2. When you compare clues 3-4 with clues 1-2, what changed in your reasoning about Canine Demodicosis?
  3. How do clues 5-6 align with the case explanation for Canine Demodicosis?

Educational Use

Vetdle archive cases are educational veterinary games for diagnostic reasoning practice. They do not provide veterinary advice, diagnosis, treatment, or professional medical guidance.