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vet general medicine.pptx

  1. Chapter 1 Veterinary General Medicine
  2. INTRODUCTION General systemic states • DEFINITION: Systemic alterations that are contributed from many diseases • Examples are toxemia, fever, septicemia and hyperthermia.
  3. Con… 1.1. Toxemia: refers to the presence of toxins in the blood It is a generalized/systemic disease state caused by the presence of toxins derived from bacteria or injured body cells/tissues. • This state doesn’t not include the diseases caused by plants or insects or ingested organic or inorganic poisons
  4. Classification of toxins • 1. Antigenic toxins • 2. Metabolic toxins. • 1. Antigenic toxins: toxins produced mainly by bacteria and to less extent by helminthes parasites • Act as antigens and stimulate the development of antibodies.  Antigenic toxins are divided into:-  Exotoxin  Endotoxin  Enterotoxins
  5. Con… • 1. Exotoxins: toxins (proteins) produced inside certain species of pathogenic bacteria • These are gram-positive bacteria (cell wall-40 layers of peptidoglycan) • They produce it during their multiplication (growth and metabolism). • The exotoxins are secreted or released in to the surrounding media following lysis. • They are heat labile toxins.
  6. Con… • The important bacterial exotoxins are those produced by Clostridium spp., and for which commercial antitoxins are available. • Toxemia due to the exotoxins of Clostridium species can be:  Ingested as preformed in botulism (ex., botulin toxin of Cl. Botulinum)  Produced by heavy growth in the bowel e.g., enterotoxaemia, E.coli or enterotoxaemic clostridia (C1. perfringens (A–E)).  Grow in tissues and produce toxin as in blackleg and black disease
  7. Con… 2. Enterotoxins:  Those are exotoxins and exert their effect principally on the mucosa of the intestine causing disturbances of fluids and electrolyte balance.  Example: enterotoxin released by enterotoxigenic E.coli, which causes a hypersecretory diarrhea in neonatal farm animals
  8. Con… 3. Endotoxins: • It is produced from lipopolysaccharide structural components of cell wall of Gram Negative Bacteria (40% of cell wall is LPS). • Heat stable • Get in to the medium and into the systemic circulation only when the bacterial walls break down and liberate them, i.e., released during lysis of the cell (needs cell lysis or death of bacteria) • The presence of endotoxins in the blood is known as endotoxemia and is very common form of toxemia in farm animals
  9. Con… • In ruminants, causes are: E.coli, Salmonella spp., Pasteurella spp., and Haemophilus. • Most of them are normal floras of the intestinal tract. • Endotoxemia is characterized clinically by abnormalities of all major body systems. • These abnormalities include:  Marked alterations in cardiopulmonary function  Abnormalities in blood cellular elements (leukons and thrompocytes), often leading to coagulopathies
  10. Con…  Change in vascular integrity  Decreased organ blood flow and metabolism leading to heart and renal failure  Major changes in gastrointestinal function, especially motility  Decreased perfusion of peripheral tissues leading to shock.  The need for intensive and complex therapy  A high case fatality rate.
  11. Con… • The most causes of endotoxemia in horse are associated with disease of the gastrointestinal tract including colitis, intestinal strangulation and obstruction or ileus. • Complications associated with foaling and grain overload are also common causes. • N.B. the endotoxins are not ordinarily absorbed through the intestinal mucosa unless it is injured as in enteritis or acute intestinal obstruction
  12. Con… • If small amount of it is absorbed in to circulation, it is detoxified by the liver but if hepatic efficiency is reduced or the amounts of toxins are large, a state of endotoxemia is produced. • Endotoxins may be absorbed in large amount from sites other than intestine including the mammary gland, peritoneum, abscess and other septic foci or from large areas of injured or traumatized tissues. • The best known endotoxins are those of E.coli and Salmonella spp.
  13. Con… • Varying degree of severity of toxemia occur in disease such as mastitis, peritonitis, pneumonia and pleuritis, pericarditis, septic metritis, septicemia of neonates, myositis, meningoencephalitis and some enteritides.
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  15. Con… 2. Metabolic toxins • These are toxins produced by body metabolism • Toxin will be accumulated and developed in to toxemia if only if there:  incomplete elimination or higher production-due abnormal metabolism or  when the normal mechanisms of detoxifications are disrupted, mainly in hepatic dysfunction, the toxins accumulate beyond the critical point and resulted in a state of toxemia.
  16. Con… • Obstruction of lower alimentary tract • Example are:  Phenols  Cresols  Amines  Ketone and lactic acidemia
  17. Con… Reason for accumulation  Incomplete elimination  Higher production-due to abnormal metabolic process in the cell  Obstruction of lower alimentary tract • Significance: play important role in pathogenecity but they don’t stimulate immunity
  18. Con...  The most common metabolic toxemias in animals are:  Ketonaemia  Lactic-acidaemia  Ketonaemia/ Pregnancy toxemia is caused by disproportionate fat metabolism characterized by hyperketonemia, ketonuria, ketolactin and hypoglycemia mostly in large and small ruminants and pigs.  In sheep and goats the disease is known as pregnancy disease, lambing sickness and twin-lamb/kid disease.
  19. Con… • The principal cause of pregnancy toxemia is low blood sugar (glucose). • Lactic-acidaemia: is a metabolic toxemia caused by acute ruminal impaction of rumen by easily digestible carbohydrate rich animal feeds. • Also known as Lactic acidosis/metabolic acidosis Carbohydrate engorgement
  20. Toxomeia-diagnosisosis Theoretically the diagnosis of toxemia should depend on the isolation of the toxin causing toxemia. But practically diagnosis is based on observation of the common clinical signs for early treatment.
  21. Treatment of endotoxemia  The principles of treatment of toxemia should be directed towards  Removal of the foci of infection  Administration of antimicrobial agents  Aggressive fluid and electrolyte therapy to combat the relative hypo-volemia, hypoglycemia and electrolyte and acid-base disturbance
  22. Con…  Using of anti-inflammatory pre-parates like that of glucocorticoides (e.g., prednisolone, methylprednisolone and Dexamethasone)  Treatment of toxemia should be directed towards removal of the toxin and provision of specific antitoxins.