Test 2: lab 3

Question 1

Heart from a 10-year-old golden retriever dog that presented for acute lethargy and collapse. On physical examination, the dog had pale mucous membranes and muffled heart sounds.

Description:
Morphologic diagnosis:

Answer 1

SALTD
DSSCLL
An approximately 3 cm x 2 cm X 1 cm region of the right auricle is effaced by an infiltrative, firm, dark red mass.

Right atrial hemangiosarcoma

Question 2

Right atrial hemangiosarcoma

What are potential sequelae if this mass ruptures?

Answer 2

Rupture of right atrial hemangiosarcoma → bleeding into the pericardial cavity (hemopericardium) → rapidly increased pressure within pericardial cavity → compression of the heart with decreased cardiac filling (cardiac tamponade) → cardiogenic shock (can be fatal)

Question 3

What are other common sites for hemangiosarcoma
in dogs

Answer 3

Spleen, liver, and skin are other common sites. German Shepherds, Golden Retrievers, Portuguese Water Dogs and Labrador Retrievers are over-represented.

Question 4

Name some other neoplasms primary to the heart (or heart base)?

Answer 4

Chemodectoma (aortic body/carotid body tumors), lymphosarcoma, rhabdomyosarcoma.

Question 5

cat heart
This heart weighs 24 grams. Normal weight of a feline heart is approximately 14-18 grams.

Description:
Morphologic diagnosis:

Answer 5

The heart is severely enlarged with diffuse thickening of the left ventricular wall.

Severe cardiomegaly with diffuse left ventricular hypertrophy

Question 6

Name the most likely type of cardiomyopathy IF this were a PRIMARY disease of the cat heart:

Answer 6

Hypertrophic cardiomyopathy (HCM)

Question 7

What is the typical age and sex of cats with HCM and which breeds are predisposed

Answer 7

HCM is the most common primary myocardial disease in cats. The typical patient is a young adult to middle-aged male. Maine coon, and ragdoll, Persian, Bengal breeds are over-represented.

Question 8

Name the most likely disease if cardiomegaly is SECONDARY disease of the heart. What other organ would you expect to have pathologic changes?

Answer 8

Thyrotoxic cardiomegaly secondary to feline hyperthyroidism. An associated lesion would be adenomatous hyperplasia of one or both thyroid glands.

Question 9

DOG HEART

Description:

Name the type of cardiomyopathy this represents:

Answer 9

The left ventricle is severely dilated, and the ventricular wall is thin.

Dilated cardiomyopathy (DCM)

Question 10

What are potential causes of the dilated cardiomyopathy in a dog?

Answer 10

DCM can be primary (heritable) in several breeds of dog, including Doberman pinschers, Boxers and Great Danes. This particular case came from a dog who was fed a grain-free diet; some formulations of grain-free diets particularly including various types of peas, lentils, or potatoes have been linked to the development of DCM in dogs. Studies on this are still ongoing.

Question 11

A variant of this type of cardiomyopathy is found in boxers and English bulldogs. What is the name of that specific cardiomyopathy, and what are the gross changes to the heart with that disease?

Answer 11

Arrhythmogenic right ventricular cardiomyopathy. The typical gross changes include replacement of the myocytes of the right ventricle by adipose or fibroadipose tissue. The right ventricle is dilated in about 1/3 of Boxers with this disease. Patients may die suddenly of an arrhythmia.

Question 12

Dog with a history of exercise intolerance, cough, and heart murmur.

Description (hint: there are two lesions to describe):

Morphologic diagnoses:

Answer 12

The margins of the mitral valve leaflets are multifocally thickened and distorted by several 1-3 mm diameter, smooth, firm, glistening, pale tan nodules. Within the left atrium superior to the mitral valve, two approximately 1.5 cm linear regions of the endocardium and subendocardial tissue are roughened, irregularly raised, and white.

1. Severe multifocal chronic mitral valvular endocardiosis.
2. Moderate multifocal chronic subendocardial fibrosis (jet lesions).

Question 13

What is the relationship between valves and jet lesions?

Answer 13

Valvular endocardiosis → improper closure of valve leaflets → abnormal jets of blood regurgitating into the atrium → chronic mechanical irritation of the atrial surface → focal fibrosis and inflammation of the atrial endocardium and subendocardial tissue (jet lesion)

Question 14

What do the nodules on the valve leaflets consist of?

chronic mitral valvular endocardiosis

Answer 14

The nodules are myxomatous degenerative lesions consisting of proliferations of loose, fibroblastic tissue with deposition of mucopolysaccharides. Inflammation is NOT a feature.

Question 15

pig

Description:
Morphologic diagnosis:

Answer 15

The valve leaflets are severely thickened and effaced by multiple coalescing 0.2-1.8 cm diameter, friable, tan to red, rough masses.

Severe multifocal to coalescing subacute vegetative endocarditis

Question 16

What do the proliferations on the valve leaflets with vegetative endocarditis
consist of?

Answer 16

The proliferative lesions on the valve consist of abundant fibrin, bacteria, and neutrophils, with granulation tissue and fibrosis developing with chronicity.

Question 17

Pathogenesis of vegetative endocarditis

Answer 17

Persistent bacteremia (many potential causes) → adhesion of the bacteria to the valve at the site of minor endocardial damage (usually at the lines of valve apposition) → proliferation of bacteria with further endothelial damage and inflammation → growth of septic thrombus on valve (vegetative valvular endocarditis)

Question 18

What lesions might you see in other organs with vegetative endocarditis

Answer 18

As pieces of the thrombi break off, they can form thromboemboli and potentially carry bacteria (septic thromboemboli). From the left side of the heart, the thromboemboli can lead to infarcts and localized inflammation in the kidneys, brain, and other organs. From the right side of the heart, the thromboemboli can lodge in the pulmonary arteries of the lungs. The mitral (left AV) valve is the most common site of vegetative valvular endocarditis in most species, so renal infarcts are a common associated finding.

Question 19

sheep

Description
Morphologic diagnosis:

Answer 19

Approximately 60% of the epicardial (visceral pericardial) surface is covered by strands and mats of pale tan to yellow material (fibrin).

Severe diffuse acute fibrinous pericarditis

Question 20

Possible routes of infection and possible etiologic agents that causes acute fibrinous pericarditis

Answer 20

Routes of infection include hematogenous spread of bacteria, direct penetration into the pericardial sac, or local extension from the myocardium or other adjacent structures. Common bacterial agents include Haemophilus parasuis, Pasteurella, E. coli, Streptococcus, or Salmonella.

Question 21

If the disease progresses to a chronic stage, how will heart function be affected?

Answer 21

With time, the fibrin may be replaced by collagenous tissue (fibrosis). If severe enough, the fibrosis can constrict the heart and cause a decrease in cardiac filling/output, resulting in congestive heart failure.

Question 22

Similar but more suppurative lesions can be seen in cows with traumatic reticulopericarditis (hardware disease). Outline the pathogenesis of traumatic reticulopericarditis:

Answer 22

Cow ingests a metallic foreign body → foreign body penetrates wall of reticulum → perforation of diaphragm and pericardium → inoculation of pericardium and pericardial cavity with bacteria from the reticulum → fibrinosuppurative pericarditis

Question 23

Description
Name the condition:

Answer 23

A short, narrow band of fibrous tissue passes between the pulmonary artery and the aorta, which in this animal is descending to the right rather than the left. As the ligamentum crosses over the esophagus, it compresses it. The esophagus proximal to the partial obstruction is dilated.

Persistent right aortic arch

Question 24

What is the name of the band of tissue crossing and compressing the esophagus?

What clinical effects could this condition cause?

Answer 24

Ligamentum arteriosum, the remnant of the ductus arteriosus which was patent in the fetus.

Megaesophagus can lead to regurgitation and aspiration pneumonia.

Question 25

Tissue from an 8-year-old mixed breed dog that presented to the veterinarian for coughing, lethargy and dyspnea.

Description:
Name the condition and etiologic agent

Answer 25

The right ventricle and pulmonary artery are filled with numerous 15-30 cm long, slender, pale tan nematodes. The lungs are diffusely firm and red-brown with several discrete dark red foci ranging from pinpoint to 8 cm in diameter. The pleural surface contains multiple irregular, coalescing, pale tan plaques.

Heartworm disease, caused by Dirofilaria immitis

Question 26

What changes have been reported in the lungs of dogs with severe heartworm disease

Answer 26

Diffuse hemosiderosis, multifocal, sometimes extensive, hemorrhage and multifocal areas of fibrosis that involve the pleura. Lesions can be generalized but are often most severe in the right caudal lobe.

Question 27

Heartworm disease causes thrombosis in the pulmonary arterial system. Why does one not usually see infarcts in the lung?

Answer 27

Infarction is rare because of collateral blood supply from the bronchial arterial system and from anastomoses between the bronchial arterial system and esophageal branches of the left gastric artery.

Question 28

Both sets of lungs are considered normal. One is a fresh specimen for reference while comparing to other sets of lungs in this lab. The other, while still considered normal, has an incidental (not clinically significant) finding commonly seen in the lungs of older dogs.

Description of the lungs with the common incidental finding

Morphologic diagnosis

Answer 28

Throughout the lung parenchyma, there are numerous 1-2 mm diameter, hard, white spicules.

Multifocal heterotopic bone

Question 29

Sections of the nasal passages and sinuses of two pigs are presented here. One is normal, one is affected.

Description of the affected
Name the disease:

Answer 29

The nasal turbinates are bilaterally atrophied with significant loss of tissue and no longer appear as tightly packed scrolls that fill the nasal cavity.

Atrophic rhinitis

Question 30

Pathogenesis of atrophic rhinitis

Answer 30

Colonization by cytotoxin-producing strains of Pasteurella multocida → bacterial toxins inhibit osteoblastic activity and promote osteoclastic resorption → atrophy, deformation, and loss of nasal conchae
Note: in cases of atrophic rhinitis, the Pasteurella multocida infection typically occurs following Bordetella bronchiseptica infection of the nasal cavity

Question 31

CAT NASAL SINUS

Description

What are some differential diagnoses for primary neoplasms of the nasal sinus?

Answer 31

The right nasal sinus is effaced by a firm, pale tan, multilobulated mass with regional destruction and loss of the nasal turbinates.

Squamous cell carcinoma, nasal carcinoma/adenocarcinoma, lymphosarcoma, and primary tumors of the mesenchymal tissues

Question 32

What clinical signs would you expect from this patient?

Answer 32

Epistaxis (blood from the nares), neurologic signs if the neoplasm extends through the cribriform plate

Question 33

What are some infectious causes of rhinitis/sinusitis in cats?

Answer 33

Infectious causes of rhinitis include feline herpesvirus 1, feline calicivirus, Mycoplasma felis, and other infections such as Cryptococcus neoformans.

Question 34

This specimen is from a pot-belly pig 1 ½ years old
Describe the lungs
Morphologic diagnosis:

Answer 34

Both lungs are diffusely firm and non-collapsed, with generalized red discoloration more severe caudodorsally. Additionally there are irregular deep red-brown patches visible from the pleural surface scattered throughout all lobes of both lungs.

Severe diffuse acute to subacute bilateral interstitial pneumonia

Question 35

What are the usual differences in the gross appearance of an interstitial pneumonia and a bronchopneumonia:

Answer 35

Bronchopneumonias will have a cranioventral distribution of discoloration and consolidation. The etiologic agent arrives via the airways (inhalation). Interstitial pneumonias characteristically result in lungs that are diffusely firm or rubbery, generally fail to collapse when removed from the chest and may have impressions from being pressed against the ribs. They may alternatively have scattered firm foci randomly distributed throughout all lobes. The etiologic agent typically arrives hematogenously, but inhalation of toxic gases can also cause an interstitial pattern of inflammation.

Question 36

Possible etiologies of bilateral interstitial pneumonia

Answer 36

Among the most likely would be porcine circovirus, porcine respiratory coronavirus, and porcine reproductive and respiratory syndrome virus (PRRS).

Respiratory diseases are responsible for major financial losses in the swine industry. This pig tested negative for PCV-2, PRRSV, SIV, and Mycoplasma hyopneumonia. Organisms compatible with Pneumocystis were seen in tissue sections of the lungs.

Pneumocystis has been recognized as an ubiquitous commensal fungus in immunocompetent hosts and a major opportunistic pathogen responsible for severe pneumonias in immunocompromised humans. In pigs its epidemiology and association with pulmonary diseases have been rarely reported. It is probable that this animal was in some way immunocompromised, likely due to a viral infection.