Manifestation of Clinical Diseases PDF

PRINCIPLES OF DIAGNOSIS 2 Types of Fever: Manifestation of Clinical 1) Septic Fever – Infection with bacteria, viruses, protozoa...

PRINCIPLES OF DIAGNOSIS 2 Types of Fever: Manifestation of Clinical 1) Septic Fever – Infection with bacteria, viruses, protozoa Diseases or fungi A disease can be defined as the “inability to perform physiologic Examples: functions at normal levels even though nutrition and other ▪ Localized infection such as abscess, cellulitis, environmental requirements are provided at adequate levels.” empyema During a disease process, systemic alterations are common to many ▪ Intermittently systemic, as in bacteremia, diseases. endocarditis ▪ Consistently systemic, as in septicemia GENERAL SYSTEMIC STATES 2) Aseptic Fever – Fever associated with aseptic wounds, Infection can manifest locally or systemic. The presumably due to disintegration of leukocytes or to the manifestation of a disease may develop gradually over a period of absorption of avascular or traumatized tissue days to months or years after the animal becomes infected. It may also manifest in multiple organ system; however, these 3) Chemical Fever – Fever caused by the intake of a sterile manifestations may resolve when a successful treatment is given to substance, ex., injection of foreign protein, administration treat the underlying infection. of dinitrophenols 4) Surgical Fever – Fever due to breakdown of tissue and HYPOTHERMIA blood Lower than normal body temperature. - Fever from tissue necrosis (ex. breakdown of muscle Major cause of neonatal mortality and morbidity in farm after injection of necrotizing material), severe hemolytic animals. crisis (hemoglobinemia), extensive infarction Causes: Excessive heat loss – ex. Exposure to cold air - Extensive necrosis in rapidly growing neoplasms such as temperature. multicentric lymphosarcoma in cattle o Insufficient heat production - Immune reaction such as anaphylaxis and angioneurotic o Insufficient body reserves of energy and edema insufficient feed intake o Also occurs secondary to several diseases in which there is a decreased ability of the animal to Forms of Fever: shiver or a decrease skeletal muscle contraction associated with decreased cardiac output, 1) Transient – Touches normal during the day decreased peripheral perfusion and shock. Combination of excessive heat loss and insufficient heat 2) Sustained/Continuous – There is little change in the production elevated temperature during a 24-hour period, it does not fluctuate more than 1°C during the 24-hour period but at HYPERTHERMIA (Heat Stroke or Heat Exhaustion) no time touches normal Increase of core body temperature. Causes: 3) Remittent – Elevated body temperature showing o Exposure to high environmental temperature fluctuation each day, but never falling to normal o Prolonged, severe muscular exertion Other Causes: 4) Intermittent Fever – An attack of fever, with recurring o Neurogenic hyperthermia – Damage to paroxysms of elevated temperature separated by intervals hypothalamus during which the temperature is normal. Fever that is o Dehydration – Due to insufficient tissue fluids to present only for several hours in a day accommodate heat loss by evaporation o Excessive muscular activity 5) Atypical – When temperature variations are irregular o Miscellaneous poisoning including levamisole and dinitrophenols SEPTICEMIA AND VIREMIA o Malignant hyperthermia (ex. malignant porcine hyperthermia, quarter horses) SEPTICEMIA o Hyperkalemic periodic paresis in horse Acute invasion of the systemic circulation by pathogenic o Fescue toxicity in ruminants and horses bacteria accompanied by septic shock with possible o Cattle with hereditary bovine syndactyly bacterial localization in various body systems or organs. o Administration of tranquilizers in sheep during A common cause of morbidity or mortality in newborn farm hot weather animals with insufficient intake of colostrum in the first 24 o Iodine poisoning hours after birth. FEVER (Pyrexia) Increase of body temperature above the normal value and BACTEREMIA is independent of the effects of ambient condition on body Bacteria are present in the bloodstream for a brief temperature. period and do not produce clinical signs. A combination of hyperthermia and infection or It is not accompanied by sepsis or septic shock. inflammation that results from an increased set point for temperature regulation. VIREMIA Mediated through the action of: Invasion of systemic circulation by pathogenic viruses with ▪ Endogenous pyrogens produced by granulocytes, localization in various body tissues and in which the monocytes and macrophages lesions produced are characteristic of the specific virus. Interleukin-1 produced by monocytes and macrophages, most important and best-known endogenous pyrogens TOXEMIA AND ENDOTOXEMIA ▪ Introduction of an exogenous pyrogens into the body ▪ Bacteria, viruses, bacterial endotoxins, Ag-Ab complexes, TOXEMIA hemoglobinemia in a hemolytic crisis and many inorganic A clinical systemic state caused by widespread activation substances of host defense mechanisms to the presence of toxins derived from bacteria or injury to tissue cells. How does interleukin stimulate fever? Diagnosis can only be made if toxins are demonstrable in the blood stream. Interleukin-1 stimulates T-lymphocyte proliferation in the presence of antigen, enhancing immune response. IL-1 induces an 2 Classification of Toxins: abrupt increase in the synthesis of prostaglandin (PgE2) in the hypothalamus. Increased prostaglandin level in the hypothalamus 1. Antigenic Toxins raises the thermostatic set point and induce the mechanisms of heat conversion (vasoconstriction) and heat production (shivering) until Produced by bacteria, and helminth parasites but to a the blood and core temperature are elevated to match the lesser degree Toxins act as antigen and stimulate hypothalamic set point. production of antibodies.  Exotoxins ALLERGY AND ANAPHYLAXIS Produced by bacteria then diffuse into the surrounding medium Allergy With specific pharmacologic effect and in the antibodies, Altered bodily reactivity (such as hypersensitivity) to an they stimulate antigen in response to a first exposure. These responses are defensive and beneficial in animals ✓ Enterotoxins but, occasionally, it can be detrimental to the host. o These are exotoxins that mainly affects the intestinal mucosa causing fluid and electrolyte Anaphylaxis disturbance When the antigen-antibody reaction is sudden and Example: Toxins released by enterotoxigenic E. clinically severe and if sufficiently severe it may result in coli causing hypersecretory diarrhea in neonatal anaphylactic shock. farm animals. Examples of circumstances where anaphylactic reactions can occur: Endotoxins o Repeated IV injections of biological preparations Lipopolysaccharides found in the outer wall of the bacteria such as glandular extracts and are released into the immediate surroundings when o Repeated blood transfusions from the same the bacteria ruptures or disintegrates donor Endotoxin gains access to the blood when there is a o Repeated injections of vaccines, e.g. against severe localized infection FMD and rabies Endotoxins of several species of gram-negative bacteria Rarely after first injection of a conventional drug such as are a major cause of morbidity and mortality in farm penicillin animals EDEMA 2. Metabolic Toxins Excessive accumulation of fluid in the interstitial space of Toxins accumulate as a result of incomplete elimination of tissue caused by a disturbance in the mechanism of fluid toxic materials normally produced by body metabolism, or interchange between capillaries, the interstitial space and by abnormal metabolism. the lymphatic vessels. 4 Causes: Signs of Acute Toxemia: o Increased hydrostatic pressure in capillaries and Depression veins due to chronic (congestive) heart failure of Anorexia obstruction to venous return Muscular weakness o Decreased plasma oncotic pressure Signs of chronic toxemia: Lethargy ▪ Decreased total protein concentration in Separation from the group plasma, and particularly decreased plasma Inappetence albumin concentration Failure to grow or produce o Increased capillary permeability Emaciation o Obstruction to lymphatic flow Clinical Signs of Toxic or Septic Shock Due Toxin Formation or DISTURBANCE OF FREE WATER, ELECTROLYTE AND Liberation into the Circulation: ACID-BASE BALANCE DEHYDRATION Severe peripheral vasodilation Abnormal depletion of body fluids. Pallor of mucosa Major Cause: Inadequate water intake and excessive fluid loss Hypothermia Tachycardia ACUTE OVERHYDRATION (WATER INTOXICATION) Pulse of small amplitude Caused by rapid ingestion of large quantities of water by Muscle weakness thirsty animals. Clinical Signs of Severe Endotoxemia: ELECTROLYTE IMBALANCES Depression Hyperthermia followed by hypothermia Due to a net loss of electrolytes associated with diseases of the alimentary tract Tachycardia followed by decreased cardiac output Electrolytes of Major Concern: Sodium, Chloride, Decreased systemic blood pressure Potassium, Calcium and Phosphorus Cool skin and extremities o Hyponatremia – Most common caused is Diarrhea increased loss of sodium through the intestinal Congested mucosa with increased CRT tract in enteropathies Muscular weakness leading to recumbency o Hypochloremia – Occurs as a result of an increase in the net loss of the electrolyte in the SHOCK (Hypovolemic, Hemorrhagic, Maldistributive and intestinal tract in acute intestinal obstruction, Obstructive Shock) dilatation and impaction and volvulus of the abomasum and enteritis SHOCK o Hypokalemia – A result of dietary intake, Due to reduction in venous return secondary to increased renal excretion, abomasal stasis, hypovolemia, hemorrhage, maldistribution of blood or intestinal obstruction and enteritis and, repeated obstruction to venous return. administration of corticosteroids with mineralocorticoid activity Hypovolemic Shock o Hypocalcemia Occurs when there is reduction in circulating blood volume o Hypophosphatemia caused by loss of blood, plasma or free water o Hypomagnesemia Hemorrhagic Shock ACID-BASE IMBALANCE Occurs when there is reduction in circulating blood volume caused by rapid loss of blood Acidosis Refers to an excess of acid in the blood. Maldistributive Shock Causes: Occurs when there is reduction in circulating blood volume o Increased acid production within the body caused by increased capillary permeability, pooling of o Consumption of substances that are metabolized to blood in capacitance vessels (such as the veins in the acids splanchnic circulation) or pooling of plasma in a large third o Decreased acid excretion space such as abdominal or thoracic cavity o Increased excretion of base Obstructive shock Alkalosis Occurs when there is reduction in venous return caused Occurs when blood pH rises above normal by mechanical obstruction such as pericardial tamponade Can be due to decreased acid or increased base or pulmonary artery thrombosis o Electrolyte disturbances caused by, for example during prolonged vomiting or severe dehydration  o Administration or consumption of base o Hyperventilation PAIN A distressing sensation arising from stimulation of specific end-organs in particular part of the body and perceived in the thalamus and cerebral cortex. The 3 Types of Pain are: Cutaneous (or Superficial), Visceral and Somatic or Musculoskeletal) STRESS A systemic state that develops due to long-term exposure to environmental factors that stimulate homeostatic, physiological and behavioral responses in excess of normal (stressors) Stress may: o Lead to development of psychosomatic disease o Increased susceptibility to infection o Represents an unacceptable level of consideration for the welfare of animals o Reduce efficiency of production LOCALIZED INFECTION 1. Abscess Localized collection of pus that generally develops in response to infection or presence of foreign materials under the skin 2. Disturbance of appetite, food intake and nutritional status Anophagia or aphagia, pica or allotriophagia, starvation, inanition (malnutrition) 3. Weight loss or failure to gain weight 4. Sudden or unexpected death