resp notes more cow diseases Flashcards
viral pneumonia mostly affects who?
young calves, uncommon in adults
common causes of viral pneumonia in cattle?
which can cause primary pneumonia?
- Bovine respiratory syncytial virus
- Bovine herpesvirus-1
- Bovine coronavirus
- Bovine parainfluenza virus
Bovine respiratory syncytial virus
- causes what disease?
- lesions?
- primary viral pneumonia
- can also predispose to bacterial pneumonia
<><><><> - cranioventral lobular pattern of atelectasis with rubbery texture, but not as firm or consolidated as is typical of bronchopneumonia
- Dorsocaudal lobes are often emphysematous and rubbery
viral pneumonia diagnosis
- dead
- live
Dead:
- bronchiolar necrosis and alveolar hyaline membranes or type II pneumocyte proliferation
- syncytia in bronchioles indicate BRSV
- PCR
- IMHC
<><><><>
Live:
- nasal swabs using PCR, antigen-detection assays, or virus isolation
> only positive for first 1-4 days of clinical signs
- serology
Bovine herpesvirus-1 (BHV-1)
- causes what disease?
- signs?
- causes of death?
- lesions?
- infectious bovine rhinotracheitis (IBR)
- also: systemic disease in neonates, or encephalitis, or abortion
<><><><> - fever, depression, dyspnea, nasal erosions
<><><><> - Most deaths from IBR result from secondary bacterial bronchopneumonia
<><><><> - erosions of nasal, laryngeal and tracheal mucosa
> white mat of fibrin and necrotic tissue
3-Methylindole toxicity
- what is this?
- who gets it?
- signs
- pathogenesis
- histo lesions
- acute bovine pulmonary edema and emphysema, “fog fever”
- adult cattle given sudden access to lush pastures
<><><><> - acute onset of severe dyspnea, and death if forced to exercise
<><><><> - Lush pastures contain tryptophan, which is metabolized by rumen microbes to 3-methylindole
- toxin is absorbed from the rumen, and delivered by the blood to the lung
- Club cells and type II pneumocytes convert 3-MI to a reactive intermediate in the process of detoxification
- oxidative injury to alveolar and bronchiolar epithelium > interstitial lung disease
<><><><> - alveolar edema and hyaline membranes
interstitial pneumonia of feedlot cattle
- what is this?
- signs
- lesions
- cause?
- acute onset of severe dyspnea and lesions of diffuse interstitial pneumonia
- Lesions present throughout the lung, more evident in caudal lobes
> may be diffuse or checkerboard pattern where some lobules are affected more than others - cause unclear… feed??
dictyocaulus viviparus
- prevalence? why its important?
- pathogen characteristics, location
- rare in ontario, but important because multiple animals are usually affected, and disease control is very different than for other respiratory pathogens
<><><><> - Adults worms are grossly visible
- thread-like, white nematodes
- in bronchi within caudal lobes
There are three distinct manifestations of lungworm in cattle:
- Acute diffuse interstitial pneumonia in naive calves exposed to pastures that are contaminated with many larvae.
- so acute that there are no adults in the bronchi or larvae in feces
- diagnosis: histologic detection of larvae in formalin-fixed sections of lung
<><><><> - Chronic patent infections causing acute or chronic respiratory disease
- adults in bronchi, and larvae in feces
- This is the most common disease manifestation
- diagnosis is usually made by detecting larvae in feces of live animals (Baermann test) or by seeing worms in the caudal bronchi of animals that have died
<><><><> - “Reinfection syndrome”:
- sensitized adult animals that are re-infected with large numbers of larvae may develop acute interstitial pneumonia, but the partial immune response doesn’t allow patency
- no adults in the bronchi, and no larvae in feces
- least common disease manifestation
- diagnosis: histologic detection of larvae in the multifocal nodular lung lesions.
Ascaris suum in cattle
- who gets it
- lesions, histology
- calves raised in barns that formerly housed swine
- diffuse interstitial pneumonia
- histology: numerous eosinophils and rare larvae
pathogenesis of liver abscess formation in cattle and subsequent lung lesions
- manifestations?
- Feedlot cattle on high-energy rations may develop chemical rumenitis, leading to showering of liver with Fusobacterium necrophorum, or other rumen bacteria
- These cause liver abscesses, which may eventually erode a branch of the hepatic vein or caudal vena cava, and septic emboli move to the lung
<><><><>
3 manifestations: - embolic pneumonia > chronic seeding
- acute diffuse interstitial pneumonia > sudden showering
- Massive embolism > may obstruct pulmonary arterial flow > RHF, sudden death
- Caval syndrome > when a thrombus obstructs the caudal vena cava
Histophilus somni fibrinous pleuritis
- pathogenesis
- PM dx for lungs
- compare to what?
- bacteremia, with localization of the blood-borne bacteria on serosal surfaces:
- pleura, pericardium, joints, and sometimes peritoneum
<><><><> - induces inflammation with abundant fibrin
- one or more of these body cavities are filled with fibrin and clear fluid
<><><><> - serofibrinous pleuritis without involvement of the underlying lung
<><><><> - different from fibrinous pleuritis secondary to extension from cranioventral bronchopneumonia ie. bronchopneumonia with secondary pleuritis > This could be caused by H. somni, M. haemolytica or other bacteria
Mycobacterium bovis
- disease caused
- human risk? significance?
- bovine tuberculosis
- zoonotic > contaminated, non- pasteurized milk
- immediately notifiable (reportable) disease
<><><><>
Mycobacterium bovis
- immune response
- signs, transmission
- lesions
- Bacilli are phagocytosed by macrophages
- complex cell wall lipids prevent killing by non-activated macrophages
- cell-mediated immune response enables T lymphocytes to activate macrophages to kill the pathogen
<><><><> - Most chronically infected animals do not show clinical signs, even though they can intermittently shed bacteria in sputum
<><><><> - caseating tubercles in retropharyngeal and tracheobronchial lymph nodes and in lung
> tubercles consist of a focal area of caseous necrosis, often with mineralization, and usually with a fibrous capsule - Lesions may erode through the pleura and cause multiple tiny nodules on pleural surfaces, or erode blood vessels to cause disseminated small granulomas (miliary tuberculosis) or larger granulomas in multiple organs
Mycobacterium bovis
- diagnosis
- tresting by CFIA
- intradermal skin testing of affected and in-contact animals
- testing of lung and lymph nodes of euthanized animals using special mycobacterial culture as well as acid-fast stains of histologic sections
