Dr. Matt Sturos - Tremors, Down Pigs And Muscle Necrosis. An Unusual Clinical Disease, Diagnostic Cases of Muscle Disease in Swine

Tremors, Down Pigs And Muscle Necrosis. An Unusual Clinical Disease, Diagnostic Cases of Muscle Disease in Swine - Dr. Matt Sturos, from the 2015 Allen D. Leman Swine Conference, September 19-22, 2015, St. Paul, Minnesota, USA.

More presentations at http://www.swinecast.com/2015-leman-swine-conference-material

1. Ionophore diagnostics Matt Sturos, DVM University of Minnesota-Veterinary Diagnostic Laboratory

2. Outline Diagnosis Gross findings Histological findings Diagnostic samples Testing

3. Diagnosis Clinical signs in groups of pigs Gross and/or histological findings Ionophore in feed At toxic levels At an otherwise safe levels with concurrent potentiators Exclusion of differential diagnoses

4. Expected gross findings Acute – Often mild or absent Pale pink to white areas of necrosis in skeletal muscle Red-brown urine due to myoglobinuria +/- hemorrhage in skeletal or cardiac muscle

5. Gross findings Chronic – Often no residual gross lesions Firm , fibrotic, hard cutting muscles White , gritty foci of mineralization within skeletal muscles

6. Histopathology Acute Skeletal muscle necrosis +/- Myocardial necrosis +/- Pigmentary tubular nephrosis

7. Histopathology Sub-acute and Chronic Macrophage infiltrate to remove necrotic tissue Regenerative myofibers +/- Fibrosis, mineralization

8. Diagnostic samples to collect Feed/medication history Multiple feed samples from feeders in affected pens/barns Fresh and formalin-fixed tissues +/- Blood

9. Feed/medication history New feed? Source of feed? Company owned mill Does mill use ionophores (narasin is swine labeled)? Purchased feed Does mill provide feed to ruminants or poultry? Is feed supposed to contain ionophores? Introduction of new medications? Tiamulin

10. Feed samples Multiple representative feed samples Distribution in feed most likely not homogeneous Transition between bins may result in two formulations present within a barn Quantitative ionophore testing Need to demonstrate toxic level Mineral/vitamin analysis Rule out nutritional diseases

11. Ionophore testing Liquid chromatography AOAC-approved method Qualitative identification of multiple compounds Retention time Parent ion identification (LC/MS) Daughter ion identification (LC/MS/MS) Quantitative identification Requires standard curve Not all labs will offer

12. Fresh samples Liver – GC/MS screening for other toxic organic compounds Mineral/vitamin analysis Limbs/joint swabs – Rule out infectious arthritis Rib – Rule out metabolic bone diseases Bone ash, bone density, mineral composition Lung – Rule out other causes of respiratory distress Culture, PCR Brain/spinal cord or head/section of spine – Rule out meningitis/ encephalomyeltis

13. Fresh samples Blood – PCV and bilirubin – rule out hemoglobinuria Serum chemistry: Creatine ( phospho )kinase = CK or CPK Aspartate transferase = AST Electrolytes: Potassium

14. Fixed tissues Skeletal muscle – muscle groups are not equal Diaphragm Proximal esophagus Major muscle groups Shoulder Ham Flank Loin

15. Diaphragm Esophagus Inner Outer Semimembranosus – Ham Longissiumus – Loin

16. Fixed tissues Cardiac muscle – Atria – A ffected more frequently than ventricle Left > right Ventricles Rarely affected Rule out nutritional myopathy

17. Fixed tissue Major organs – rule out differentials Lung Liver Kidney Brain/head Spinal cord/section of spine

18. Rule out differentials Clinical Lame or painful pigs Infectious arthritis Metabolic bone disease Pigs unable to rise Selenium toxicosis Meningitis or encephalomyelitis Respiratory distress Pneumonia Heart disease Not eating/refusing feed Sick pig Feed contamination

19. Rule out differentials Gross/histopathology Skeletal muscle and/or cardiac necrosis and hemorrhage Vitamin E/Selenium deficiency Porcine stress syndrome Gossypol toxicity Red/brown urine and pigmentary nephrosis Hemoglobinuria due to hemolysis

20. Review Diagnosis Lesions Sample collection Testing Differential diagnoses

21. Acknowledgements Dr. Stephanie Rossow Dr. Steve Ensley

22. Questions?