JPC SYSTEMIC PATHOLOGY
Musculoskeletal System
March 2019
M-M08

Signalment (JPC Accession #1983084):  Double-crested cormorant (Phalacrocorax auritus)

HISTORY:  This bird had marked beak and limb deformities.  The skeleton was soft and pliable with bowing deformities and folding fractures in many of the long bones.  The beak and bones could easily be cut with a scalpel.  Periosteal regions and marrow cavities of the long bones often contained excessive fibrous connective tissue.

HISTOPATHOLOGIC DESCRIPTION:  Long bone:  The physeal cartilage is markedly thickened, up to 10 times normal, and there is retention of the zone of hypertrophy as thick tongues of cartilage extend into the diaphysis and fill the medullary cavity.  Bony trabeculae are sparse and thin (osteopenia).  Cartilage and bone trabeculae are surrounded by eosinophilic osteoid seams up to 40 um wide and lined by plump osteoblasts that often pile up to several cell layers thick.  Medullary spaces contain a small amount of bone marrow, plump fibroblasts and collagen (medullary fibrosis)).  Multifocally, bone is lined by few multinucleated osteoclasts which lie in Howship’s lacunae.  Cortical bone is markedly thinned, discontinuous, and essentially parallel from the metaphysis to the cut border (loss of the cutback zone).  Diffusely, the periosteum is markedly thickened up to 500um by fibrous connective tissue.

MORPHOLOGIC DIAGNOSIS:  Long bone:  Failure of endochondral ossification with persistent metaphyseal and diaphyseal tongues of hypertrophied chondrocytes, and medullary and periosteal fibrosis (rickets), double-crested cormorant (Phalacrocorax auritus), avian.

ETIOLOGIC DIAGNOSIS:  Nutritional osteodystrophy

CAUSE:  Vitamin D or phosphorus deficiency

CONDITION:  Rickets

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Craig LE, Dittmer KE, Thompson KG. Bones and joints. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed. St. Louis: Elsevier; 2016:60-63, 68-74.
  2. Hardcastle MR, Dittmer KE. Fibroblast growth factor 23: A new dimension to diseases of calcium-phosphorus metabolism. Vet Pathol. 2015;52(5):770-784.
  3. Olson EJ, Carlson CJ. Bones, joints, tendons, and ligaments. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:981-982.
  4. Olson EJ, Shaw GC, Hutchinson EK, et al. Bone disease in the common marmoset: Radiographic and histological findings. Vet Pathol. 2015;52(5):883-893.
  5. Pritzker KPH, Kessler MJ. Arthritis, muscle, adipose tissue, and bone diseases of non-human primates. In: Abee CR, Mansfield K, Tardif S, Morris T, eds. Nonhuman Primates in Biomedical Research: Diseases. Vol 2. 2nd ed. Waltham, MA: Elsevier; 2012:661-663.


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