JPC SYSTEMIC PATHOLOGY
MUSCULOSKELETAL SYSTEM
April 2019
M-T01 (NP)

Signalment (JPC #2018940):  A broiler breeder chicken

HISTORY:  This chicken received a new feed 2 weeks prior to showing weakness and reluctance to move.

HISTOPATHOLOGIC DESCRIPTION:  Skeletal muscle:  Approximately 80% of the myofibers have undergone one or more of the following changes: have hypereosinophilic, fragmented sarcoplasm with disorganized or hyalinized myofibrils (which is often invaded by heterophils and macrophages) with nuclear pyknosis and rare contraction bands (necrosis); have swollen, vacuolated sarcoplasm with loss of cross striations and faded, occasionally internalized nuclei (degeneration); have a proliferation of satellite cells, slightly basophilic sarcoplasm and internalization and rowing of nuclei (regeneration); or are lost and replaced with necrotic debris and deeply basophilic granular or fragmented material (mineral).  Multifocally expanding the endomysium and perimysium and surrounding necrotic myofibers are low to moderate numbers of macrophages and heterophils admixed with eosinophilic cellular and karyorrhectic debris and fibroblasts with associated collagen (fibrosis). 

MORPHOLOGIC DIAGNOSIS:  Skeletal muscle, myocytes:  Degeneration, necrosis, loss and regeneration, multifocal to coalescing, moderate, with heterophilic and histiocytic inflammation and fibrosis, chicken, avian.

ETIOLOGIC DIAGNOSIS:  Ionophore myodegeneration and necrosis

CAUSE:  Ionophore (monensin) toxicosis

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ULTRASTRUCTURAL FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS for myopathy in birds:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Bautista AC, Tahara J, Mete A, Gaskill CL, Bryant UK, Puschner B. Diagnostic value of tissue monensin concentrations in horses following toxicosis. J Vet Diagn Invest. 2014; 26(3):423-427.
  2. Cheville NF. Ultrastructural Pathology: The Comparative Cellular Basis of Disease. 2nd ed. Ames, IA: Blackwell Publishing; 2009:84-85, 648-649.
  3. Constable PD, Hinchcliff KW, Done SH, Grunberg W. Veterinary Medicine: A Textbook of the Diseases of Cattle, Horses, Sheep, Pigs and Goats. 11th ed. St. Louis, MO: Elsevier; 2017:701-703.
  4. Fulton RM. Other toxins and poisons. In: Saif YM, Fadly AM, Glisson JR, McDougald LR, Nolan LK, Swayne DE, et al. Diseases of Poultry. 12th ed. Ames, IA: Blackwell Publishing; 2008:1231, 1233-1235.
  5. Miller LM, Gal A. Cardiovascular system and lymphatic vessels. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 6th ed. St Louis, MO: Elsevier; 2017:593.
  6. Hovda LR. Disorders caused by toxicants. In: Smith BP, ed. Large Animal Internal Medicine. 5th ed. St. Louis, MO: Mosby Elsevier; 2015:1609-1610.
  7. Valentine BA. Skeletal muscle. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 6th ed. St Louis, MO: Elsevier; 2017:925, 935-936, 943.
  8. Cooper BJ, Valentine BA. Muscle and Tendon. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed. Philadelphia, PA: Elsevier; 2016:219.

 


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