104 terms

Systemic Pathology: Neoplasia and Pleural Dz

What are examples of primary benign neoplasias of the lung that are epithelial origin?
Primary benign: rare

- Papillary adenoma

- Bronchiolar‐alveolar adenoma
Image 1A
Primary Adenocarcinoma
Image 1B
Primary adenocarcinoma

- flower appearance
What are examples of malignant primary lung neoplasia that are epithelial in origin?
Bronchiolar‐alveolar carcinoma: esp. dogs

Adenocarcinoma: esp. cats

Squamous cell carcinoma: rare in lung

Anaplastic carcinoma

Carcinoid (neuroendocrine)

Retroviral pulmonary carcinoma (sheep)
What is Jaagsiekte sheep retrovirus?
Exists in most sheep raising parts of the world

A significant problem in south Africa

Disputed breed differences in susceptibility

A retrovirus has been identified
Describe the lesions it produces?
Infectious multicentric pulmonary tumors of sheep

Image 2b
Jaagsiekte retrovirus

also flower appearance
What are examples of benign primary neoplasia that are mesenchymal in origin?
- hemangioma → pretty rare, potential because of BV in lungs
What are examples of malignant neoplasia's of the lungs that are mesenchymal in origin?
Osteosarcoma, chondrosarcoma - both rare


Malignant histiocytosis (canine) → Bernese Mtn Dog

Lymphomatoid granulomatosis

Granular cell tumor (equine) → common in horses

Mesothelioma → pleural kind
What is the most common primary lung tumor in horses?
Granular Cell tumor
What cells/tissues do granular cell tumors originate from?
- Neuroectodermal or neuroendocrine
What do granular cell tumors look like grossly?
- Bulge into bronchial lumen and obstruct airways

- half of lung blocked off → becomes atelectic
Describe the histology of granular cell tumors?
Round cells with eosinophilic cytoplasm
and PAS‐positive granules
What are examples of metastatic tumors?

Uterine carcinoma cow

Malignant melanoma

Sarcoma‐ dogs and cats → HSA, OSA, mast cell tumor

Carcinoma → urinary bladder, thyroid gland, pancreas, intestine
multi focal
dark brown to black
What is pneumothorax?
- air/gas in the thorax
What does pneumothorax result in?
- atelectasis because negative thoracic
pressure cannot be maintained

- something cause negative pressure to change
What should you listen to during the opening of a thorax during a necropsy?
- listen for entry of air → normal
What are causes of pneumothorax?
Trauma‐ bite wound, projectile, hit‐by‐car ****

Rupture of emphysematous bullae

Rupture of abscess or granuloma that
communicates with airway.
thymus : light pink in cranial cavity

lungs: atelectic, doesn't look real
Describe the mediastinum in the:

1. horse

2. Cattle

3. Dog/Cat
1. Communication between the two pleural cavities

2. No communication between the two pleural cavities → only 1/2 will be affected

3. The partition is very delicate but complete
What is hydrothorax?
- noninflammatory pleural effusion

- clear to yellow (amber) fluid (transudate)
What might cause a hydrothorax?
- increased venous pressure

- lymphatic obstruction

- hypoproteinemia
What animal do we see hydrothorax commonly in?
cats with CHF

When do we see hydrothorax in dogs?

can be just around the heart or in chest
What might be seen microscopically with chronic hydrothorax?
- can cause reactive hyperplasia of
mesothelial cells

- fibrotic pleura
What is chylothorax?
- noninflammatory pleural effusion

- accumulation of lymph fluid and chyle
In what Clinical Dz's is chylothorax seen?
- Feline cardiomyopathy

- right‐sided heart failure

- Obstruction of thoracic duct by thoracic masses → prevent release of lymph into vena cava
What are examples of possible thoracic masses?


What might you be looking for in a cytology of the pleural effusions?
look for bacteria
What is a hemothorax?
blood in the thorax
What are possible causes of a hemothorax? 6
1. Blood loss into thorax

2. Rupture of blood vessels‐ trauma

3. Inherited coagulopathy

4. Anticoagulant rodenticide → brodifacoum, diphacinone

5. Rupture of lung neoplasm → hemangiosarcoma

6. Aortic ruptures in horse
rodenticide toxicity
What is pleuritis?
- inflammation of the pleura
What is the most common cause of pleuritis?
- infectious agents (usually bacteria)

- most often reach pleura from
blood or from lesions of bronchopneumonia, aspiration pneumonia or lung abscesses
What is a pyothorax?

White to red exudate
What are causes of pyothorax in dogs? cats?
Dog‐ grass awns

Cat‐ bite wound, FIP
- unilateral pyothorax

- see one side atelectasis

- pyothorax/pleuritis, unilateral

- against wall, see reactive mesothelial cells and fibrin
What are causes of bacterial pleuritis?
What kind of infections usually cause bacterial pleuritis?

What condition does it usually occur with?
1. usually mixed

2. primary pneumonia
- pus
- granular nodules
What are sulfur granules?
- granular nodules, crumbly yellow
- if see these think actinomyces
Bacterial Pleuritis
Bacterial pleuritis
Fibrinous Pleuritis
- fibrin peeling off
- bacterial pneumonia
Chronic (fibrous) pleuritis
- more fibrous appearance

- fibrin becomes organized
When do you see a chronic fibrous pleuritis?
with recurrent problems
primarily feedlot cattle
What is mesothelioma? ****

What structures does it arise from? 2
- neoplasia of the pleura

- from pleura and pericardium
Where do pleural mesothelioma spread from?

What do they cause in the thorax?
- spreads along pleura

- thoracic effiusion
Describe grossly mesothelioma?
- Velvety plaques or occasionally nodules on the pleural surface
What is a cause of mesothelioma in ppl?
- plaques along pleura, diaphragm

- will often extend to wall thru extension not metastasis
How do neoplasms metastisize to the pleura?
- Transpleural dissemination of carcinomas and sarcomas

- from the lung, chest wall and mediastinum
Metastatic Neoplasms
Metastatic Neoplasms
What is herpesvirus?

Where do they primarily cause disease in most animals?

Where does the virus hide out?
DNA virusesIntranuclear inclusion bodies

At least one for every species

Many of which are primarily respiratory pathogens


like to hide in nerves and come out when stressed → trigeminal
What is the fline respiratory complex?
Feline herpesvirus‐1

Feline calicivirus

Bordetella bronchiseptica

Chlamydophila felis

Secondary bacterial infections
When is herpes seen in cats?
- crowded living conditions
Describe the pathogenesis of feline resp. complex?
Mostly URT → moves to LRT

- viral infection of cells
→ epithelial necrosis/disruption
→ erosion/ulceration
→ acute inflammation
→ mixed secondary bacterial infection
→ severe infection can extend to LRT
Feline Herpes Virus
- lots of ulceration = nasal planum

- exudate from around eyes

- often have FeLeuk and FIP
Feline Calicivirus

What is a key characteristic of this in cats?
- ulceration on tongue
What is Cryptococcus neoformans?
- Most common systemic fungal infection in cats

- less common in dogs

- from spores in dirt - unusual to get from necropsy
What immune condition are cats in that often have crypto
immunosuppressed → FeLV or FIV or both
Describe the most common signs of cryptococcus neoformans?
nasal ulceration and drainage
What clinical dz may also occur with crypto?
Granulomatous pneumonia (rare)
Where can crypto in the cribiform plate spread to?
Cryptococcus neoformans
Cryptococcus neoformans
Cryptococcus neoformans
What is Infectious tracheobronchitis? *****
- kennel cough

- Syndrome affecting dogs
What pathogens are involved in kennel cough?
1. Bordetella bronchiseptica

2. Parainfluenza type 2

3. Canine Adenovirus‐2

4. Mycoplasmas → s/t cultured

5. CAV‐1, CHV‐1 and CRCoV
What does bordetella bronchiseptica do to respiratory tract?
- Attach to the cilia and causes ciliostasis
What does CAV-2 do to the redo. tract?
Tracheal epithelial necrosis → so bord can get in and set up
What are sources of kennel cough infections?
Boarding facility
Obedience classes
Off‐lease dog parks Dog shows
Vet clinics
What can kennel cough progress to?

What bacteria may be involved?

Streptococcus Escherichia coli Pseudomonas
Kennel cough pathogenesis
What effect does CDV (distemper) have on the immune response?
- decreases it

- Down‐regulates cytokines
- Persists in tissues
What kind of pneumonia can CDV cause? ****
- PRIMARY viral pneumonia → broncho‐interstitial

- SECONDARY bacterial pneumonia

- interstitial pneumonia
What conditions can an interstitial pneumonia be accompanied with?
Necrotizing bronchiolitis

Alveolar edema

Type II pneumocyte hyperplasia

Intranuclear and intracytoplasmic eosinophilic inclusion bodies
What is Blastomycosis? **NAVLE**
Endemic to Mississippi, Missouri, Ohio river valleys

Soil saprophyte, associated with water
How do dog acquire it?
- infection via inhalation, young adult dogs
What organs or tissue become involved after inhalation>
Lung and regional lymph nodes usually involved
Where can the pathogen disseminate to?
skin, lymph nodes, eyes, CNS, bones, urogenital, joints
Describe gross lesions of blastomycois?

What must you rule out?
- Granulomatous pneumonia, usually multiple nodules

- Have to rule out neoplasia
can look miliary
does look like neoplasia, but its blasto
What are the influenze A virus hosts?
humans, swine, horses, birds

HA: 1‐16
NA: 1‐9

H1N1, H1N2, H3N2
What are INflu. B hosts?
humans, swine evidence of Ab but not isolated
What in influenza C hosts?
INfluenza A
- Equine: H3N8 (H7N7 not seen in several years)

- Canine: H3N8 related to equine
Influenza A external and internal proteins?
2009 influenze triple resortment virus mixed with eurasion
What are CS of Influenza in swine?



Nasal discharge


Poor weight gain

Labored breathing to "thumping"
What ages are affect by influenze?
When do lung lesions resolve?

What is the prognosis of influenza in pigs?
- in 14 -21 days

- self limiting in uncomplicated cases
When did pigs experimentally inoculated begin to show CS?

When did these CS end?

What did CS coincide with?
- Starts: 1‐3 days after infection

- Ends: 4‐8 days after infection

- virus shedding → nasal secretions
What can reduce virus shedding?
48‐72 hours with protective antibodies


Previous exposure
- can look like mycoplasma,

CrVentral consolidation of the lung
3-4 DPI with Influenza in pig
basal cells trying to stretch out and cover exposed basement membrane
7-10 DPI with influenza in pig