Exam 4: Dr. Mackin Fever Flashcards
At what temperature is an animal considered to have a fever?
Greater than 103 degrees
What is fever also known as?
Pyrexia
What are the 2 reasons to have high body temperature?
Hyperthermia and fever
What is hyperthermia?
When a hot animal wants to be cooler
What is fever?
When a hot animal wants to be warmer
What is the difference between fever and hyperthermia?
Thermoregulatory set point
What happens to the thermoregulatory set point with true fever?
It is reset to higher level in animals
What do pyrogens do?
Give you pyrexia
What are the endogenous pyrogens?
Organisms
Antigens
Foreign substances
Drugs
What are the exogenous pyrogens?
Cytokines IL-1, IL-6, TNF-α
What are endogenous pyrogens?
The universal endpoint to cause a fever
What do the cytokines that are released during a fever do?
Reset thermoregulatory set point via local prostaglandins
What are the steps to a fever?
IL-1 secreted by phagocytes travels in blood to hypothalamus
Hypothalamus secreted prostaglandin, which resets hypothalamic thermostat
Nerve impulses cause shivering, higher metabolic rate, inhibition of sweating, and vasoconstriction
These increases body temperature to the point set by the hypothalamic thermostat
What do the endogenous pyrogens do?
Non-specific response to many infections, inflammatory, and neoplastic diseases
Mediators of systemic inflammatory response
What is the demeanor of an animal with hyperthermia?
Excited
Agitated
Distressed
What is the behavior of an animal with hyperthermia?
Panting
Vasodilation
Sweating
Cold-seeking
What is the body temperature of an animal with hyperthermia?
Up to 110 degrees F or greater
What is the demeanor of an animal with fever?
Lethargic
Depressed
Anorectic
What is the behavior of an animal with fever?
Shivering/huddling
Vasoconstriction
Piloerection
Heat-seeking
What is the body temperature of an animal with fever?
Rarely more than 106 to 107 degrees F
What are the causes of fever?
Infectious Inflammatory Immunologic Neoplastic Drug-associated
What is the most common cause of fever?
Bacterial infection
Why do we have fever?
May be a protective mechanism
What does having a fever do?
Enhances host immunity
Inhibits bacterial growth by reducing serum iron concentration
Contributes to neoplastic cell death
Encourages rest in affected animal
What happens with enhanced host immunity?
Increased leukocyte mobility
Enhanced phagocytosis
Increased proliferation of T cells
What is inflammation?
Complex reaction in vascularized connective tisse
What does inflammation lead to?
Accumulation of fluid and white blood cells in extravascular tissues
How is inflammation a protective mechanism?
It removes the cause of cell injury (organism/toxin)
Consequences of cell injury (dead cells/debris)
What are the potentially harmful consequences of inflammation?
Hypersensitivity Chronic inflammatory disease Immune-mediated disease Scar tissue/fibrosis Systemic inflammatory response
What is the entire inflammatory process mediated by?
Chemicals derived from plasma and cells (inflammatory mediators)
What are the 5 cardinal signs of inflammation?
Redness (rubor) Swelling (tumor) Heat (calor) Pain (dolor) Loss of function (functio laesa)
What are inflammatory mediators?
Vasoactive amines (histamine and serotonin)
Plasma proteases Arachidonic acid metabolites (prostaglandins and leukotrienes)
Platelet activation factor
Nitric oxide
Oxygen-derived free radicals
Cytokines (IL-1, IL-6, TNF-α)
What is the source of cytokines as a mediator?
Lymphocytes, macrophages, and EC
What is the systemic inflammatory response mediated by?
Cytokines IL-1, IL-6 TNF-α
What makes up systemic inflammatory response?
Fever Anorexia/cachexia Lethargy/malaise Acute phase proteins Neutrophilia Anemia of chronic disease Glucocorticoid release
What are the predictable lab results in a patient with fever?
Inflammatory or stress leukogram
Anemia or chronic disease
Mild hypoalbuminemia
Mild to marked hyperglobulinemia
Why is physical cooling bad?
Contraindicated
Stressed and distresses patient
What should be used instead of physical cooling?
NSAIDs
How do NSAIDs work?
Turn off the prostaglandins in the hypothamus which helps reset the thermoregulatory set point
