5 – Vascular System Flashcards
Vascular lesions can cause:
- Edema, congestion
- Hemorrhages
- Thrombosis
- Ischemia
- Infarction in affected tissues and organs
Degenerative disease of arteries
- Arteriosclerosis
- Artherosclerosis (predispose to arterial rupture)
- Arterial hypertrophy
- Aneurysms (predispose to arterial rupture)
- Arterial medial calcification
Arteriosclerosis and atherosclerosis
- DISTINCT degenerative diseases that are manifested by
o Hardening of arterial wall
o Loss of elasticity
o Reduced vascular lumen
Arteriosclerosis
- ‘hardening’ of an artery
- Loss of arterial elasticity, hardening and luminal narrowing
- Mainly found in elastic arteries (ex. arterial branching sties)
- *raised corrugated whit plaques, may have calcium deposits
- Usually an incidental finding
Plaques in arteriosclerosis
- Fibrous tissue and smooth muscle proliferation
- Sometimes mineralization
Atherosclerosis
- Major cause of mortality in humans
- *Excessive circulating cholesterol is deposited in arterial walls
- Rare in domestic animals
Major risk factors of atherosclerosis in humans
- Familial hypercholesterolemia
- High blood pressure
- Poor diet habit
- Sedentary life-cycle
- Cigarette smoke
Lesions that form with atherosclerosis
- Atheromas
Atheromas
- Cholesterol plaques in intima and media of arteries
- Particularly common in the coronary arteries (heart attacks) and cerebral arteries (stroke)
- Reduce lumen and cause blockage
- Can lead to thrombosis
Atherosclerosis steps
- Early cholesterol deposits in intima
- Accumulation of cholesterol and lipid-laden macrophages in arterial wall
- Large lipid plaques occlude the arterial lumen and cause ischemia
Atherosclerosis is most commonly reported in
- Hypothyroid dogs with hypercholesterolemia or diabetes mellitus
- Pigs
- Psittacine birds and pigeons feed a high lipid diet
Atherosclerosis grossly
- Prominent thick arteries
- Yellow plaques
Atherosclerosis microscopically
- Plaques containing foamy, lipid-laden macrophages
- Cholesterol clefts
- Fibroblasts
- Smooth muscle proliferation
Arterial hypertrophy
- Occurs in muscular arteries
- Hypertrophy and hyperplasia
- *hypertension=common cause
- Ex. high altitude (Brisket disease)
Hypertrophy and hyperplasia in arterial hypertrophy results in
- Loss of elasticity
- Narrowing of arterial lumen
- Increased resistance
Muscular hypertrophy is frequently seen in the LUNG of cats
- Past: associated with Aelurostrongylus abstrusus
- Now: Dirofilaria immitis (hypertrophy and proliferation/inflammation)
Aneurysm
- Localized weakening and dilation of blood vessels
o Elastic arteries (less extent in veins) - Prone to rupture
2 main anatomic types of aneurysm
- Saccular (or fusiform) aneurysm
- Dissecting aneurysm (arterial dissection)
Saccular (or fusiform) aneurysm
- Spherical or ovoid dilation of blood vessel resembling a ballon filled with blood
Dissecting aneurysm (arterial dissection)
- Tear of intima allowing blood to enter into potential space between intima and media
o Progressively dissecting the wall of the vessel - Ex. hematoma separating the tunic intima from tunica media
Aneurysm prone to rupture and cause
- Hemothroax
- Hemoabdomen
- Hemopericardium
- Brain hemorrhage
Common cause of aneurysm in domestic animals:
- Strongylus vulgaris in horses
- Spirocerca lupi in dogs
- Copper deficiency in mares and pigs
- Trauma
- Atherosclerosis and hypertension (humans)
- Genetic diseases
Fusiform aneurysm in dog
- Died due to massive hemothorax caused by rupture of an aortic aneurysm
- Caused due to larval migration of Spirocerca lupi=PARASITIC AORTITIS
- Mature S. lupi parasitize the esophagus
Common causes of arterial calcification
- Hypervitaminosis D (or ingestion of toxic plants containing Vitamin D analogs)=metastatic calcification
- Chronic granulomatous diseases (ex. Johnes, TB)
- Age-related arteriosclerosis
- Aortic lesions associated with migrating larvae of Spirocerca lupi in dogs
Aortic calcification grossly (ex. cow with Johne’s disease)
- Confluent, raised, rectangular plaques on intima surface
Fibrinoid necrosis
- Only detected histologically
- Non-specific term of vascular change in small arteries and arterioles
- *microscopic disposition of acidophilic proteinaceous material (fibrin) in vascular walls
What conditions is fibrinoid necrosis associated with?
- Viral infections
- Toxic conditions
- Bacterial toxins
- Nutritional deficiencies
- Purpura hemorrhagica
- Immune mediate vasculitis
Fibrinoid necrosis: viral infections
- Classical swine fever
- Porcine circovirus
Fibrinoid necrosis: toxic condition
- Uremia
- Mercury poisoning
Fibrinoid necrosis: bacterial toxins
- Enterotoxemia
- Edema disease of swine (E. coli)
Fibrinoid necrosis: nutritional deficiencies
- Mulberry heart disease
Fibrinoid necrosis: purpura hemorrhagica
- In horses following infections with Streptococcus equi
Fibrinoid necrosis: immune mediated vasculitis
- lupus
Vasculitis
- Generic term
- Describes inflammation of small arteries AND veins
- Only detected by histopathology (but effect is grossly visible)
What is seen grossly because of vasculitis?
- Hemorrhages
- Edema
- Small infarcts
Common causes of vasculitis
- Systemic infections (viruses, bacteria, fungi)
- Hypersensitivities where Ag-Ab complexes attached to walls of blood vessels
- Adverse drug reactions
Malignant catarrhal fever (bovine)
- Vasculitis with fibrinoid necrosis
- *systemic vasculitis
What are some sequels to vasculitis
- Palpebral and mesocolon edema
- ITEM in cattle
- Mycotic vasculitis with infarction and hemorrhages in omasum
Kidney of an FIP cat
- Renal vasculitis=white linear lesions
Mesenteric artery parasitic arteritis (in horses)
- Migration of Strongylus vulgaris
o Predispose to fibrosis of blood vessel and aneurysm (may produce areas of infarction=colic in horses)
Dirofilaria immitis (nematode parasite)
- Pulmonary artery and R ventricle
- *cause endoarteritis
- Pulmonary hypertension associated with hypertrophy of intimal surface
- *predispose to thrombosis
Phlebitis
- Inflammation of veins
o Often become thrombosed=thrombophlebitis
What are the most common forms of thrombophlebitis in vet practice
- Vena cava thrombosis in cattle
- Omphalophlebitis
- Iatrogenic phlebitis
- Some parasites (Schistosoma sp)
Omphalophlebitis: thrombophlebitis
- Umbilical veins, (particularly farm animals) become infected and inflamed after birth
- Filled with purulent exudate
Vena cava thrombosis in cattle: thrombophlebitis
- Typically secondary to hepatic abscess eroding into wall of vena cava
Iatrogenic phlebitis: thrombophlebitis
- In all species caused by improper venipuncture
Vena cava thrombophlebitis (cow)
- Hepatic abscess eroding into vena cava and causing thrombosis (scar)
- Pieces of infected thrombus often detach and released into circulation causing embolic pneumonia
- *sudden death due to ruptured pulmonary aneurysm
Lymphangiectasia
- Dilated with chyle
Rupture of lymphatics
- Thoracic duct or cisterna chyli leak fluid
- Ex. chylous ascites
- Ex. chylothorax (milky fluid=chyle)
Johnes disease: lymphangitis in cattle
- Mycobacterium avium subsp.
- Paratuberculosis cattle
Glanders: lymphangitis in horses
- Burkholderia mallei
Ulcerative lymphangitis in horses and cattle
- Corynebacterium pseudotuberculosis
Epizootic lymphangitis: horses
- Histoplasma farciminosum
Sporotrichosis: lymphangitis in various species
- Sporothrix schenckii
Primary tumours of the cardiovascular system
- Hemangioma and hemangiosarcoma
- Rhabomyoma and rhadomyosarcoma
- Myxoma and myxosarcoma
- Heart base tumors
Heart base tumors examples
- Aortic body chemodectoma
- Ectopic thyroid carcinoma
Secondary tumor in the cardiovascular system (metastatic)
- Lymphoma
Hemangiosarcoma: dogs
- Primarily spleen and heart (R. atrium)
- Important canine malignancy
Hemangiosarcoma can cause
- Cardiomegaly
- Hemopericardium
- Cardiac tamponade
Neoplastic cells from hemangiosarcoma’s form
- Channels filled with blood = dark red colour
Hemangiosarcoma readily metastasizes to
- Lungs
- Other organs (brain, kidneys, liver, etc)
Chemodectoma
- Arises from chemoreceptors normally present in the aorta
- Non-functional but can cause heart failure
o Due to compression of the R atrium, vena cavae or great arteries - *BASE of the heart
Myxoma/myxosarcoma
- Neoplastic cells embedded in a mucinous matrix
Lymphoma may result from
- Bovine leukemia virus (BLV) infections
- *other tumours in the body: enzootic lymphoma (after 3 years)
