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Vetdle Archive

Archive Case #229: Canine Sebaceous Adenitis

Dog veterinary case - Easy - October 18, 2026

Clinical Clues

  1. A dog has developed a dry, dull coat and spreading scale over several months.
  2. The owner reports gradual hair thinning along the trunk with little scratching.
  3. Examination finds adherent follicular casts around groups of hairs and patchy alopecia.
  4. Skin cytology and deep scrapings do not find a bacterial overgrowth or demodectic mites sufficient to explain the pattern.
  5. Biopsies from affected and nearby skin show inflammation directed at sebaceous glands and loss of those glands.
  6. The gland-centred biopsy pattern with follicular casting supports canine sebaceous adenitis.

Diagnosis

Canine Sebaceous Adenitis

Follicular casts, dry scaling and gland-centred inflammatory destruction on biopsy support sebaceous adenitis. Demodicosis and pyoderma can also cause scale or alopecia, so the negative competing-cause checks and histology are important; low itch alone is not diagnostic. Remember: Follicular casts suggest sebaceous adenitis, but skin biopsy and checks for demodicosis or infection prevent overcalling a distinctive-looking coat change.

Learning review

Review the case evidence

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

Evidence checkpoints

Clues 1-2

  1. Clue 1: A dog has developed a dry, dull coat and spreading scale over several months.
  2. Clue 2: The owner reports gradual hair thinning along the trunk with little scratching.

Clues 3-4

  1. Clue 3: Examination finds adherent follicular casts around groups of hairs and patchy alopecia.
  2. Clue 4: Skin cytology and deep scrapings do not find a bacterial overgrowth or demodectic mites sufficient to explain the pattern.

Clues 5-6

  1. Clue 5: Biopsies from affected and nearby skin show inflammation directed at sebaceous glands and loss of those glands.
  2. Clue 6: The gland-centred biopsy pattern with follicular casting supports canine sebaceous adenitis.

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 Sebaceous Adenitis?
  3. How do clues 5-6 align with the case explanation for Canine Sebaceous Adenitis?

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.