Cardiovascular Pathology

Atrophy or Hypertrophy

• Fatty Degeneration
• Lipofuscinosis
• Vacuolar Degeneration

Apoptosis - little to zero inflamm/fibrosis

Necrosis - typically inflames and becomes fibrotic because myocardial cells cannot regenerate(*can regenerate in amphibian, fish, some birds, lab strain mice, and neonates)

• 1. Cardiac Dilation
• 2. Myocardial Hypertrophy
• 3. Increase HR
• 4. Increase peripheral resistance
• 5. Increase Blood Volume
• 6. Redistribute Blood Flow

• Gradual loss of Cardiac Pumping Efficiency
• -Increase workload (pressure/volume
• - pulmonary/renal/vasc dz)
• -Myocardial damage (heart dz)

Result:Decrease Blood Flow to peripheral tissues (forward failure)Accumulation of Blood behind the failing chamber (backward failure)

Left - Pulmonary Edema manifesting as cough

• Right - Hepatic Congestion
• Horses/Rums = Ventral SubQ Edema
• Dogs = AscitesCats = Hydrothorax

• Primary - idiopathic and irreversible
• Secondary (more common) - Compensatory to increase workload; Reversible

• 1. Initiation
• 2. Stable hyperfnxn
• 3. Deterioration of fnxn assoc w/ degeneration of hypertrophied myocytes

• Concentric
• small ventricular chambers w/thick walls and papillary mmdue to increased PRESSURE load (valvular stenosis, hypertension)
• Eccentric
• enlarged chambers with walls of normal to decreased thicknessdue to increased BLOOD VOLUME (mitral insuff., ventricular septal defect)

• Left
• due to Left outflow problems OR systemic hypertension
• Right
• due to Right outflow problems OR pulmonary hypertension OR severe pulmonary dz-Heartworm, Pulmonic stenosis, High Altitude Dz in cattle, Chronic alveolar emphysema (heaves

Both - Chronic Renal Failure / Idiopathic

• Cats - Hypertension
• Dogs - Hyperadrenocorticism

• 1. Hypertrophic
• 2. Dilated (congestive)
• 3. Feline - Left Ventricular Endocardial Fibrosis (a restrictive cardiomyopathy)
• 4. Other Restrictive Cardiomyopathies
• 5. Arrythmogenic Right Ventricular Cardiomyopathy

1. Hypertrophy of L-Vent, InVent Septum, L-Vent cavity is small, L-Atr is dilated*Male Cats 1-3yrs oldsome cats have posterior paresis due to concurrent 'saddle embolus'

• 2. Cardiac dilation, contractile dysfunctionHeart is Rounded due to biventricular dilation*Cats and Dogs
• Cat - Taurine def. and 1-3yr old Males
• Dog - Large breed Males (Dobes, Dalmations, Boxers, Juvenile Portuguese Water Dogs)

3. Cats - extensive endocardial fibrosis of L-Vent impairing filling; a sequela of endomyocarditis

• 4. Heart w/ inadequate compliance and diastolic ventricular volumeExcessive L-vent Moderator Bands, Fibrosis in Rats, Fibroelastosis in Burmese Cats
• 5. Replacement of R-Vent myocardium with Adipose and Fibrosis
• *Boxers - sudden death

• 1. Hereditary (X-linked musc.dystrophy - goldies and other dogs)
• 2. Nutritional Def (Taurine in cats)
• 3. Toxic (doxorubicin)
• 4. Endocrine (thyrotoxic cardiomyopathy in Cats)
• 5. Neoplastic infiltration (lymphoma)

• Pale Yellow - Gray +/- gritty mineralized regions.
• Acute - hypereosinophilic swollen myocardia - Mphage and Neutro infiltrate
• Healing - fibroblasts and fibrosis

• Depends on Extent of Damage:
• Death of acute cardiac failure
• Early death from arrythmiaDevelop 2o Chronic Congestive heart failure...or just fibrosis in animals that die of something else entirely

• 1. Nutritional Def(Vit E Def - White m Dz in rums; Mulberry Hrt Dz in pigs)
• 2. Toxins(Ionophores - monensin - coccidiostat for birds and growth for cattles, cardiotoxic to horse and pig)
• 3. CNS lesions and trauma(Heart-Brain Syndrome - catecholamines, likewise pheochromocytoma, iatrogenic)
• 4. Gossypol in Pigs
• 5. Doxorubicin in Dogs
• 6. Poisonous Plants (foxglove, oleander)

• 2o to some necroses (vit E def)
• also Vit D tox -> spontaneous myocardial calcification in older rats and guinea pigs

• 1. Bacteria
• 2. Protozoa
• 3. Parasites
• 4. Viruses (*CPV-2 - pups under 10wks - no intestinal lesions, but intranuclear bodies in cardiomyocytes)

• 1. Bacterial (rarely parasitic/fungal)
• 2. Friable, irregular, yellow-gray raised 'vegetative' lesions.Abundant fibrin, necrotic leukocytes, granulation tissue, and bacteria
• 3. Valves - may extend to Mural region.1o M>A>T>P **Cattle T is most common above M4. Bacterial Emboli
• 5. Only detected late in Dz - Fever, Murmurs, Death from valvular dysfnxn OR bacteremia.

• 1. Sustained/Recurrent Bacteremia(Cattle - A.pyogenes, Dog/Pig - Strep)
• 2. Tendency for lesion to occur at Lines of Apposition of Valve surfaces exposed to the Fwd Flow(minor damage allows adherence of bacteria)

Dogs older than 5yrsIdiopathic degen of valve collagenM>>T>>>>>>Semilunars

Smooth glistening nodules and thicker valve marginsProliferation of loose fibroblastic tissue, No Inflamm.

• Valvular Insufficiency --> Congestive Heart Failure
• thickening > incompetent valves > improper closure > L-Atr regurg > jet lesions of L-AtrRupture of Chordae TendinaeL-Atr Thrombi (to Thromboemboli)Rarely - L-Atr rupture > tamponade
• All leading to Congestive Heart Failure (not enough blood pumped for body's demands)

• Vit D intoxication
• Calcinogenic plants (Cestrum, Trisetum) have Vit D analogs
• Johne's
• Dogs with Uremia 2o to Renal F --> Ulcerative Endocarditis

Jet Lesions (atria, intima of large vessels)Restrictive Cardiomyopathies

Traumatic, Spontaneous, or Assoc w/Chronic Valvular Degen or Endocarditis

Causes valve insuff and heart failure

Blood or Lymph filled cysts on margins of AV valves (common in Cattle)

Incidental Finding

Frequently involved by Direct Extension from myocardial, pleural, pulmonary, or systemic dz

• 1. Hydropericardium
• 2. Hemopericardium
• 3. Miscellaneous
• 4. Pericarditis
• A. Acute Fibrinous, B. Suppurative, C. Chronic

• Clear-Yellow, watery, serous fluid
• occurs w/generalized edema (hrt fail, renal fail, vascular injury, etc..)
• acute can cause tamponade

• Blood in pericardium
• usually results in Rapid Death

caused by Hemangiosarcoma, Heart Base Tumor, Atrial RuptureHorse - intrapericardial aortic ruptureLarge Dogs - idiopathic, slow onset

• Serous Atrophy of Fat
• Urate Deposits (gout in birds/snakes)

Hematogenous spread of infxn (Pasturella, Strep, Salmonella)

Yellow fibrin deposits on pericardiaFibrin w/neutrophils and vessel congestion

• Pyogenic Bacteria
• Thick, malodorous exudate in pericardium(Hardware Dz)
• Congestive Failure and Septicemia

chronic inflamm of pericardia resulting in Fibroblast prolif w/collagen depot and fibrous adhesions bw visceral/parietal pericardium

• 1. PDA (aorta to pulmonary a.)
• 2. Atrial Septal Defect (foramen ovale or a true defect) (L to R atrium)
• 3. Ventricular Septal Defect (L to R Ventricle, overload on R ventricle)

• 1. Pulmonic stenosis (esp Dogs - concentric hypertrophy of R-vent)
• 2. Subvalvular aortic stenosis (concentric hypertrophy of L-vent, possibly aortic dilation)
• 3. Mitral and Tricuspid Dysplasia (esp cats, esp mitral)

• 1. Persistent R.Aortic Arch - forms a vascular ring around esophagus and trachea, causing Proximal Megaesophagus
• 2. Transposition of aorta and pulmonary artery

• Heart is outside of the thoracic cavity.
• Most frequent in Cattle

Peritoneal-pericardial diaphragmatic hernia

• 1. Pulmonic Stenosis
• 2. Ventricular Septal Defect
• 3. Dextroposition of Aorta
• 4. R-Vent Hypertrophy (secondary)

Pulmonic Stenosis -> increase R pressure -> R-vent Hypertrophy -> Blood shunting R to L through Ventricular Septal Defect -> venous blood enters systemic circulation (due to great dextropositioning) -> Cyanosis

• 1. inflammation of a.a.
• 2. inflammation of many a.a.
• 3. inflammation of v.v.
• 4. inflammation of vessels (a.a. and v.v.)

• A. Inflammatory cells
• B. in/around blood vessel wall
• C. concomitant vessel wall damage
• D. fibrin depot, collagen degen, necrosis of endothelia and smooth m.
• E. Thrombosis

• 1. Virus
• 2. Bacteria
• 3. Rickettsia
• 4. Fungi
• 5. Immune Mediated
• 6. Parasites
• A. S. vulgaris (cr. mes. artery -> thromboembolism of intestinal aa. -> colic)
• B. D. immitis (more to come)

• 1. Pulmonary a, "R-vent, R-atr"
• 2. Proliferative Endarteritis (irregular fibromuscular proliferation of the intima - Gross as Rough, Granular/Shaggy intimal surface)
• 3. Thromboemboli, R-vent Hypertrophy (possibly R-failure)
• 4. Cough, exercise intolerance
• 5. Caval Syndrome (shock, intravascular hemolysis, hepatic/renal failure)

• 1. Arteriosclerosis
• 2. Atherosclerosis
• 3. Arterial medial calcifcation

intimal fibrosis of large elastic arteries

-loss of elasticity and luminal narrowing = "hardening of the arteries"(rarely clinically significant)

• a subset of arteriosclerosis*Important in Humans... infrequent in animals
• -lipid, fibrous, and Ca deposits in vessel walls = luminal narrowing
• Arteries are thick, firm, and yellow-white. See Lipid Globules in cytoplasm of smooth m. and Mphages (Foamy cells)

Pig, Rabbit, Chicken -- with high cholesterol diet

Dogs with Hypothyroidism and Diabetes Mellitus (w/assoc hypercholesterolemia)

• often occurs w/concurrent Endocardial Mineralization
• caused by Calcinogenic Plant Tox, Renal inusuff, Johne's, etc...

Arteries appear as Solid, Dense, Pipelike structures w/raised White Intimal Plaques

Inflammation of Umbilical Vein

(bacterial -- can lead to septicemia, polyarthritis, hepatic abscesses, umbilical abscesses)

Localized abnormal dilation or outpouching of a thin/weak portion of a vessel

Often in large arteries - rupture is fatal

Causes - Cu def, S.lupi or S.vulgaris damage in dog, horse.

• Malig neo of Enothelial Cells (fusiform neoplastic endo. cells)
• Dogs - R-atr/aur (liver, spleen, heart, subcutis, adipose around urinary bladder)
• Red/Black - rupture lead to fatal hemopericardium, tamponade, and hemoabdomen

White soft nodules or diffusely spread

Cattle Hearts predominantly, but any animal w/multiorgan lymphoma may have it at the heart

usually Aortic Body (chemodectoma) in Brachycephalic dogs (Boxer, Boston)

May compress great vessels and atria

Pigs and Guinea Pigs

actually a malformation, not a true neoplasm --- a Hamartoma of myocytes

rare

Involve cardiac nerves in Cattle

Benign neoplasm of endothelia, well circumscribed

in dermis and subcutis of dogs

Redundant proliferation of vessels ranging from large arteries to small capillary buds

Dog/Cat subcutis (rarely other sites)

originates from the Pericytes which surround the vessels

Subcutis and Dermis in Dogs - rarely metastasize

Ventral Abdomen - dermis and subcutis of Cats

Tissue is edematous and bruised.

• 1. Hemangiosarcoma
• 2. Lymphoma
• 3. Heart Base Tumor
• 4. Congenital Rhabdomyomatosis
• 5. Rhabdomyo(sarco)ma
• 6. Schwannoma (neurofibroma)
• 7. Hemangioma8. Vascular Hamartoma
• 9. Hemangioperictyoma
• 10. Feline Ventral Abdominal Angiosarcoma