PATOLOGÍA Unidad 3

• The circulatory system adjusts blood flow to tissue needs, closely linked to O2 concentration
• It regulates extracellular and blood fluid volume with the kidneys and lymphatic system.
• Blood carries oxygen from the lungs, absorbed intestinal substances, enzymes, and hormones.
• Pathologic conditions affecting circulation include renal, hepatic, pulmonary issues, and acid-base/electrolyte imbalances.

Hiperemia

• Involves arterial blood flow.
• It's an active and acute process of short duration.

Physiological Causes of Hyperemia

• Increased metabolic needs in active tissues like muscles during exercise, stomach/intestine during digestion, mammary glands during lactation, and the uterus during menstruation.
• Stimulation of nerve centers regulating blood pressure can cause skin flushing due to emotional reasons.
• It exclusively happens in living organisms.

Pathological causes of Hyperemia

• Acute infectious diseases
• Irritant substances on the skin.

Congestion

• It is an excess of blood that cannot exit the venous circulation.

Local Congestion

• Can be caused by tight bandaging on a limb or volvulus.
• It's classified as acute, like a tight bandage, or chronic, like a tumor compressing a vein.
• A common sign is "Godet's sign," where the finger leaves a mark upon palpation, indicating edema.

General Congestion

• This affects the venous system broadly, stemming from heart failure or pulmonary issues.

Heart Failure

• Can be caused by valvular lesions, myocardial pathologies, pressure on the heart, or congenital heart defects.
• The tricuspid valve is more frequently affected than the semilunar valve.
  • Insufficiency occurs when valves don't fully close, causing blood backflow.
  • Stenosis happens when valves don't fully open, restricting blood flow during systole.

Heart Failure Causes

• Bacteria
• Valvular endocardiosis in older dogs
• Uremia
• Ascites, liquid accumulation in the abdomen, can cause swelling with Godet's sign upon palpation.

Stasis Liver

• Chronic passive congestion leads to excessive blood accumulation.
• Blood refluxes due to insufficiency or stenosis, returning via the vena cava and congesting/enlarging the liver, resulting in a "nutmeg" appearance.
• Improper valve function can prevent lung blood removal resulting in
• The lung's failure to collapse upon opening the thoracic cavity.
• This can lead to hydropericardium and hydrothorax.

Myocardial Pathological Processes

• Leishmaniasis
• Trypanosomiasis
• Toxoplasmosis
• Parvovirus
• These could also cause fever and hyaline or Zenker degeneration and calcium deficiencies

Heart Lesions

• Traumatic reticulum pericarditis in cattle.
• Tumors like aortic body tumors, lymphosarcomas, and hemangiomas.
• Abscesses
• Granulomas

Congenital Heart Defects

• Persistent ductus arteriosus connects the aorta and pulmonary artery.
• Septal defects cause left-to-right blood flow.
• Lipoma is a fat mass.
• A premature animal put in water will sink if it didn't breathe and float if it did breathe.

Lung Lesions Causing General Congestion

• Parenchymal lesions caused by infectious agents like pneumonia
• Vascular disorders, Altitude sickness.

Bronchopneumonia

• Meconium aspiration during birth can cause lung issues or intoxication in newborns.
• Suppurative bronchopneumonia shows cranioventral distribution with firm texture and aerogenous entry, involving bacteria and mycoplasmas.
• Fibrinous bronchopneumonia has cranioventral distribution, hard texture, fibrin in the pleura, aerogenous entry, and involves bacteria with toxins.

Vascular Disorders

• Altitude sickness occurs at high altitudes above sea level.

Congestive Heart Failure

• This causes fluid to exit the blood and accumulate in body cavities and interstitial spaces, favoring gravity.
• It can cause both inflammatory (exudate) and non-inflammatory (transudate) edema.
• Positive Godet's Sign

Exudates Vs. Trasudates

• Exudates have a density > 1.017, high albumin concentration, protein >3%, abundant leukocytes/fibrin, and fibrin clots.
• Transudates’ density is < 1.017, lower albumin concentration, protein <3%, traces of leukocytes, and no fibrin.
• Hydrostatic pressure is the force exerted by a liquid against a surface.
• Colloid osmotic pressure is generated by plasma proteins in the vascular space.

Causes of Edema

• Increased hydrostatic pressure due to congestion.
• Decreased colloid osmotic pressure due to hypoproteinemia.
• Lymphatic circulation obstruction from tumors, abscesses, or granulomas.
• Sodium and water retention from renal conditions.
• Increased capillary permeability from anorexia, shock, anaphylaxis, trauma, or inflammation.

Types of Edema

• General: Anasarca
• Thorax: Hydrothorax
• Pericardium: Hydropericardium
• Cephalic: Hydrocephalus
• Testicle: Hydrocele
• Peritoneum: Ascites
• Eye: Glaucoma

Hemorrhage

• It describes the escape of blood from blood vessels of and may result from:
• Diathesis diseases which characterized by multiple bleeding.

Hemorrhage Types

• Hemothorax: thoracic cavity.
• Hemoperitoneum: peritoneal cavity.
• Hemopericardium: pericardial sac.
• Hemoptysis: expulsion of blood from the lungs through the mouth.
• Hematemesis: vomiting of blood.
• Epistaxis: nasal expulsion of blood.
• Melena: rectal expulsion of blood.
• Hematuria: blood in urine.
• Hemosalpinx: fallopian tubes.
• Hematocele: vaginal tunic of testicle.
• Purpura: multiple hemorrhages on serous/mucous surfaces and skin.
• Cows with lung hemorrhage exhibit neck hyperextension, indicating severe lung bleeding.

Magnitude Types of Hemorrhage

• Petechiae
• Ecchymosis
• Suffusion
• Hematoma

Pathogenesis Types of Hemorrhage

• Hemorrhage due to rexis.
• Hemorrhage due to diapedesis.

Causes of Hemorrhage

• Hypoxia
• Trauma-induced rexis
• Vascular wall lesions
• Toxins
• Coagulation disorders
• Allergies

Hypoxia

• A common cause of diapedesis-related hemorrhage (petechiae) due to congestion

Traumatic Rupture

• This causes rexis of large vessels or viscera.
• Losing 25-30% of total blood volume can induce hypovolemic shock.

Vascular Wall Lesions

• Rupture and rexis
• Aneurysms
• Atheromas
• Parasites
• Neoplasms

Toxins

• These injure vascular endothelium, causing diapedesis-based hemorrhaging from:
• Pasteurella sp.
• Escherichia coli.
• Petechial fever in horses.
• Streptococci.
• Black leg disease.
• Bacillus anthracis.
• Hemomelasma.
• Clostridium perfringes.
• Swine cholera.
• Plant toxins from beetroots

Coagulation Disorders

• Can be brought on by hepatic (prothrombin deficiencies) conditions, hypocalcemia, fibrinogen deficiency, vitamin C/K deficiencies, beet consumption, hemophilia or epistaxis.

Allergies

• These immune processes may be caused by:
• Equine purpura from streptococcus/ equine herpesvirus, bovine mastitis, metritis, umbilical infections, erysipelas in pigs and distemper in dogs.
• The previously listed are cause of vascular permeability

Ecchymosis

• The appearance of skin bruises or hematomas that are violet, blue, or yellow.

Thrombosis

• The presence of blood clots in circulating blood leads to adherence to vascular endothelium from:

• Direct endothelial or endocardial injury from parasites.

• Hypoxia, DIC

• Altered blood composition may cause hypercoagulability

Thrombi Classification

• Arterial thrombi appear as red masses.
• Venous thrombi, white.
• Capillary thrombi, laminated.
• One form of thrombi termination is by liquefaction

Embolism

• An embolus is a free-flowing, organic or inorganic particle in the blood, comprising of fibrin, parasites, bacteria, lipids, air and foreign bodies
• They are found in arteries and veins.
• An embolus causes thrombosis when it blocks blood flow resulting in endothelial injury.

Shock

• This is a pathological state of insufficient capillary perfusion that leads to cellular dysfunction causes:
• Hypovolemia
• Cardiogenic issues
• Septic conditions
• Neurogenic conditions
• Anaphylactic reactions

Cardiogenic Shock

• It is the inability of the heart to pump enough.

Endotoxic Shock

• It is characterized by the release of bacterial toxin

Neurogenic Shock

• This is caused by trauma or fear due to a sudden stimuli or analgesic

Anaphylactic Shock

• This is caused by antibody/antigen interaction