Diagnosis


A tentative diagnosis of Clavarial Hyperosteosis can be based on:

  1. The occurrence of the above clinical signs in lion cubs and young adults from captivity
  2. Normal CBC and blood chemistry
  3. Negative titers for infectious diseases

Definitive diagnosis

Computed Tomographic (CT) scan or MRI performed under general anesthesia, detecting excessive bone formation around the caudal fossa.

Bone abnormality indicating Clavarial Hyperosteoses include:

  • narrowing of the foramen magnum to less 15 mm
  • thickened and/or malformed occipital bone, occipital protuberance and basioccipital part of the occipital bone
  • thickening of the tentorium cerebelli
  • reduced volume of the caudal fossa
  • lateral ventricle enlargement
  • In MR images, herniation of the cerebellum resulting in compression and angulation of the medulla oblongata may be present

Evaluation of Vitamin A status

Reference value of vitamin A concentration is available in the literature, but is based on a single presumably healthy individual from the wild. (4,500 IU/g wet liver [8]) although measuring the vitamin A concentrations in the liver of the affected lions is recommended, definitive conclusions regarding the vitamin status cannot be made until the actual reference values from several healthy lions are established.

Liver biopsy method

True-cut liver biopsy can be performed by ultrasound guided percutaneous 14-gauge needle biopsies, using a biopsy gun, obtained through a single 1–2-cm skin incision made immediately caudal to the last rib halfway between the spine and the ventral midline [3].

Based on our recent unpublished data, Vitamin A is stored in equal amounts throughout the liver lobes of the lion hence a biopsy sample obtained from the right lateral lobe which is easy to perform using the describe approach is proved to be representative of the overall vitamin A concentration.

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Merav Shamir
Rona Nadler

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