JPC SYSTEMIC PATHOLOGY
Musculoskeletal System
March 2019
M-M10

Signalment (JPC #2506867 - slide A):  An adult male Dromedary camel (Camelus dromedarius)

HISTORY:  This camel was one of a group of camels grazed on irrigated pastures of the Werribee Open Range Zoo (Australia).  It developed chronic progressive multiple limb lameness and stiffness that was unresponsive to treatment.  No other clinical signs were noted.

HISTOPATHOLOGIC DESCRIPTION:  Bone, maxilla and nasal turbinates:  Diffusely, the medullary cavity is expanded up to 5 times normal, the trabeculae are thin and widely separated and the cortices are thin or lost.  There is separation and partial to complete replacement of normal cortical and trabecular bone and hematopoietic elements by numerous loosely arranged fibroblasts and thin, haphazard collagen bundles (fibrosis) admixed with numerous, irregular, thin spicules of woven bone.  Spicules of woven bone are lined by variable numbers of osteoblasts (new bone formation) and spicules of lamellar bone are lined by fewer osteoblasts and variable numbers of osteoclasts, often within Howship's lacunae (bone resorption).  Multifocally, there are variable numbers of osteoclasts also within the fibrous connective tissue.  Multifocally, in less affected turbinates are low numbers of submucosal lymphocytes and plasma cells.

MORPHOLOGIC DIAGNOSIS: 

  1. Bone, maxilla and nasal turbinates:  Fibrous osteodystrophy, diffuse, severe, Dromedary camel (Camelus dromedarius), camelid.
  2. Nasal turbinate: Rhinitis, subacute, multifocal, minimal. 

CAUSE:  Low dietary calcium and/or high dietary phosphorus

CONDITION:  Nutritional secondary hyperparathyroidism with fibrous osteodystrophy

SYNONYMS:  Osteodystrophia fibrosa, osteitis fibrosa, osteitis fibrosa cystica, rubber jaw, renal rickets

Signalment (JPC #1947452 - slide B):  An 11-week-old female Alaskan malamute dog

HISTORY:  Gross pathology of dog included small firm kidneys, multiple rib fractures, soft bones, swelling and distortion of the facial bones and mandible, enlarged parathyroid glands and anemia.

Laboratory Results:

Glucose                     116 mg/dl (76-119)              RBC     2,070,000 (4.95-7.87)

Sodium                      148 mmol/l (142-152)          Hct     19.25% (35-57)

Chloride                     104 mmol/l (110-124)          Hb             5.7 gm/dl (11.9-18.9)

Calcium                     8.8 mg/dl (9.1-11.7)             MCV    92.99 fl (66-77)

Protein                       5.4 g/dl (5.4-7.5)                MCH    27.53 pg (21.0-26.2)

Albumin                     2.6 g/dl (2.3-3.1)                 MCHC  29.61 gm/dl (32.0-36.3)

AST                            42 IU/L (13-15)                   Retic    6%

ALT                             26 IU/L (10-109)                WBC     11,292/mm (5,0-14,100)

LDH                            70 IU/L (0-236)                   Neuts    68% (7678) (2,9-12,000)

Phosphorous                9.3 mg/dl (2.9-5.3)             Eos     2% (226) (0-130)

Potassium                    6.2 mmol/l (3.9-5.1)           Lymph   26% (2936) (400-2,900)

BUN                           150 mg/dl (8-28)                 Mono  4% (452) (100-1,400)

Creatinine                   5.1 mg/dl (.5-1.7)

Cholesterol                 296 mg/dl (135-278)

Alk Phos                     276 IU/L (1-114)

Clinical Pathology Summary:  Macrocytic, hypochromic anemia (with adequate regenerative response after corrected reticulocyte percentage calculation and reticulocyte index calculation) and a mild eosinophilia.  Hyperphosphatemia, azotemia, elevated alkaline phosphatase, hypocalcemia, hypercholesterolemia, and mild hyperkalemia

HISTOPATHOLOGIC DESCRIPTION:  Bone, maxilla and turbinates with tooth:  Diffusely there is expansion, separation and partial to complete replacement of the normal compact and trabecular bone and hematopoietic elements by variably dense fibrous connective tissue (fibrosis) and randomly arranged thin trabeculae of woven bone.  The fibrous connective tissue is densely cellular with many large fibroblasts  Trabeculae of woven bone are frequently scalloped and thinned and lined by numerous osteoblasts (new bone formation), while trabeculae of lamellar bone are lined by variable numbers of osteoclasts within Howship’s lacunae (resorption), which are also free within the fibrous stroma.  There are occasional microfractures of woven bone spicules surrounded by hemorrhage with few hemosiderin-laden macrophages.  Multifocally the nasal respiratory mucosa is infiltrated by low to moderate numbers of neutrophils, and within the lumen, there is a focal accumulation of abundant degenerate neutrophils admixed with eosinophilic cellular debris.   

MORPHOLOGIC DIAGNOSIS: 

  1. Bone, maxilla and turbinates:  Osteodystrophy, fibrous, diffuse, severe, Alaskan malamute, canine.
  2. Turbinates, mucosa: Rhinitis, suppurative, acute, multifocal, moderate.

CAUSE:  Hyperparathyroidism secondary to renal failure

CONDITION:  Renal secondary hyperparathyroidism with fibrous osteodystrophy

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

Lesions (early):

Chronic Lesions (disease progression)

ADDITIONAL DIAGNOSTIC TESTS:

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, MO: Elsevier; 2016: 74-80.
  2. Ferguson DC, Hoenig M. Endocrine system. In: Latimer KS, Mahaffey EA, Prasse KW, eds. Duncan & Prasse's Veterinary Laboratory Medicine, Clinical Pathology. 5th ed. Ames, IA: Wiley-Blackwell; 2011: 295-297.
  3. Finch NC, Geddes RF, Syme HM. Fibroblast Growth Factor 23 (FGF-23) Concentrations in cats with early nonazotemic chronic kidney disease (CKD) and in healthy geriatric cats. J Vet Intern Med. 2013; 27(2)227-33.
  4. Finch NC, Syme HM, Elliott J. Parathyroid hormone concentration in geriatric cats with various degrees of renal function. J Am Vet Med Assoc. 2012;241(10)1326-35
  5. Geddes RF, Finch NC, Elliott J, Syme HM. Fibroblast Growth Factor 23 in feline chronic kidney disease. J Vet Intern Med. 2013: 27(2)234-41.
  6. Olson EJ, Carlson CS. Bones, joints, tendons, and ligaments. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:981-983.
  7. Olson EJ, Shaw GC, Hutchinson EK, Schultz-Darken N, et al. Bone disease in the common marmoset: radiographic and histologic findings. Vet Pathol. 2015; 52(5)883-93.
  8. Rosol, TJ, Gröne A. Endocrine glands. In: Maxie, MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 3. 6th St. Louis, MO. Elsevier, 2016:292-301.
  9. Taylor MB, Geiger DA, Saker KE, Larson MM. Diffuse osteopenia and myelopathy in a puppy fed a diet composed of an organic premix and raw ground beef. J Am Vet Med Assoc. 2009; 234(8):1041-1048.
  10. Woodard JC. Skeletal System. In: Cann C, ed. Veterinary Pathology. 6th ed. Baltimore, MD: Williams and Wilkins; 1997: 917-924.


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