L27: Pt. 2 Flashcards
Parainfluenza virus type 3
- viral respiratory disease of cattle
- RNA virus
- affects cattle, sheep, goats
- short incubation period
- ubiquitous but mild
- destroys cilia on tracheal mucociliary escalator**
- dx: PCR, serology, viral isolation
- prevent with MLV or killed vaccine
Bovine Viral Diarrhea Virus***
- Pestivirus
- causes destruction of ACQUIRED immunity (T cells, Peyer’s patches)**
- get from contact with PI calf
- infection subclinical or mild (similar to IBR)
- can get oral/tracheal ulcers***
- Prevent: MLV and killed vaccines
Bovine coronavirus
Causes calf diarrhea, and Winter Dysentery in adult cattle
RESPIRATORY bovine coronavirus is a different strain and causes mild to moderately severe respiratory signs:
- emerging dz
- in dairy and feedlot calves
- no vaccine
Lower Resp Tract Diseases: 3 categories
1) Bronchopneumonia
- Enzootic calf pneumonia
- Shipping fever complex
- Sporadic occurrence in dairy cows
2) Metastatic pneumonia
- Vena caval thrombosis
3) Interstitial pneumonia
- ARDS
- Hypersensitivity pneumonitis
- Chronic interstitial pneumonia
- Parasitic pneumonia
Risk factors of enzootic calf pneumonia
- FPT**
- poor ventilation, overcrowding, poor sanitation, noxious gases, temp/humidity, commingling from different sources
- nutritional deficiences (ie. Zn, selenium, Cu)
3 most important bacteria that cause Enzootic Calf Pneumonia***
1) Pasteurella multocida
2)
Vaccination for BRSV
- core
- MLV and killed vax available
- MLV (with BHV1) given at feedlot entry
- evidence of pneumonia prevention with use of vaccine on feedlots
CS of enzootic calf pneumonia
Fever Cough Nasal d/c Ill thrift Resp. Distress Otitis media Large airway sounds
Dx of calf pneumonia
CS Hematology Nasal swab PCR for viral/mycoplasma TTW Rads or US Necropsy: sharp demarcations on lungs \+/- paired serum samples for viruses
Tx of enzootic calf pneumonia
- Abx
- NSAIDs
- nursing care
- prognosis usually good (80-90% recovery)
Prevention of enzootic calf pneumonia
- no shared airspace w/ older animals
- lower humidity, temps
- ammonia
most common cause of morbidity/mortality in feedlot cattle
Shipping Fever Complex
Preconditioning includes:
Vaccines:
- MLV BHV1, BRSV, BVD, PIV-3
- Lepto
- Clostridial
- Mannheimia bacterin-toxoid
Dewormer
Ear tags, branding, castration, dehorning, implants
Metaphylaxis
Vit. A/D
CS of Shipping Fever Complex
(Peaks at 7-14 days after arrival)
- dec. feed intake
- isolation
- inc. RR
- ocular/nasal d/c
- moist cough
- fever
- dyspnea, death
Etiologic agents of Shipping Fever Complex
Viral:
-IBR, BRSV, BVDV, PI-3, Coronavirus
Bacterial:
- mannheimia
- pasteurella
- histophilus
- mycoplasma
- trueperella
- fusobacterium, etc.
Mannheimia haemolytica Properties
- GN aerobic bacteria
- A2 serotype normally in nasopharynx
- A1 serotype occurs after stress
Mannheimia haemolytica pathogenesis***
- LPS initiates inflammatory cascade and increases expression of binding sites of leukotoxin
- Leukotoxin causes cytolysis of platelets, lymphocytes, macs, and neuts***
- results in fibrinopurulent/fibrinonecrotic bronchopneumonia** (UNIQUE TO MANNHEIMIA)
Most common isolate from pneumonic lungs at necropsy of feedlot cattle**
Mannheimia haemolytica
-NOT commonly assoc. with enzootic calf pneumonia
Pasteurella multocida
- part of shipping fever complex
- GN aerobic
- produces LPS
- also assoc. with enzootic calf pneumonia
- causes purulent bronchopneumonia w/ cranioventral consolidation and purulent exudate
Histophilus somni
- part of shipping fever complex
- GN aerobic bacteria
- normal in resp. And genital mucosa
Histophilus MOA and necropsy
Lipooligosaccharide –> formation of vasculitis and thrombi –> infarct, lung hemorrhage, thromboembolic meningoencephalitis, arthritis, abortion, otitis, endometritis, myocarditis, mastitis, laryngitis, etc.
-can affect many organs
Necropsy: cranioventral plum consolidation, infarcts/hemorrhage, fibrinous pleuritis + pleural effusion from bacteremic spread
Mycoplasma
- part of shipping fever complex
- causes chronic, nonresponsive pneumonia
- CS: fever, tachypnea, inappetance, resp. Distress, otitis, arthritis, tenosynovitis
Mycoplasma MOA/necropsy
Attaches to ciliated epithelial cells, toxin increases vascular permeability –> direct impairment of neuts, mucociliary escalator
Necropsy: cranioventral lung consolidated, dark red, firm with white to yellow nodules
Tertiary invaders in shipping fever complex
Trueperella (GP aerobic) –> foul smelling abscesses
Fusobacterium (GP anaerobic) –> opportunistic from eructated ruminal gas
