Equine respiratory 1 Flashcards
Oxygen toxicity is more likely to be seen in neonatal foals mechanically ventilated with increased levels of 02 (Fi02>50%) for several days. Which statements is correct
a) It’s frequently followed within a few days by opportunistic bacterial pneumonia
b) Can produce interstitial pneumonia and alveolar type II cell proliferation
c) Can result in lysis of the macrophage, chronic alveolitis, and fibrosis
d) Can result in bronchopneumonia and alveolar type I cell proliferation
b) Can produce interstitial pneumonia and alveolar type II cell proliferation
Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) comprise a syndrome of severe pulmonary dysfunction and respiratory failure that affects foals. Which of the following statements is correct?
a) The fraction Pa02/Fi02 is >300mm Hg in cases of ALI (which is the less severe form) and >200mm Hg for ARDS.
b) It is related to pulmonary surfactant deficiency in neonatal foals
c) The pathophysiology includes dysregulation of pulmonary inflammation and coagulation
d) It is not related to an infectious etiology
c) The pathophysiology includes dysregulation of pulmonary inflammation and coagulation
ALI or ARDS arises as a complication after major infectious or noninfectious bodily injury. When this occurs, a protective response starts that involves controlled activation of the inflammatory and coagulation system. In ALIARDS an imbalance of pro inflammatory and anti-inflammatory factors produce an uncontrolled pulmonary inflammatory response and pro coagulation environment in alveoli and the pulmonary microcirculation.
Negative prognostic indicator in R. equi pneumonia
- Intra-abdominal abscess
- Osteomyelitis
Most important immune cell for R. equi
T lymphocytes?
Diagnosis of Chronic carrier state for S. equi
Guttural pouch fluid/swab PCR
Fungi that most commonly causes pneumonia in horses
Coccidiomicosis
Horse with a nasal granuloma (mass), histopathology revealed large amounts of eosinophils around the lesions
Condidiobolus coronatus
What is the best immune response against R. equi:
IFN-y
Elimination of EIV Australia
canary pox 14 days
Drug of choice of Pneumocystis carinii
TMS
Immune response in R. equi pneumonia
IFN-g –> macrophages
Which is the desired immunological response in cases of R. equi pneumonia?
Type 1 response:
This is characterized by the production of antigen-specific Th1 lymphocytes, which allow for clearance of intracellular R. equi via the production of IFN-g and the activation of macrophages, and by antigen specific cytotoxic T lymphocytes which recognize and kill R. equi infected cells.
Which immunological response is detrimental for foals infected with R. equi?
Th 2 response:
Predicted to develop potentially life-threatening pulmonary lesions
Gene associated with virulence in R. equi, and where is it located?
Vap A gene, located in the pathogenicity island (PAI)
These genes are necessary for the correct functioning of the main virulence factor of R. equi, so the bacteria can replicate and survive in the macrophages. Y’all know what I’m talking about?
VirR and Orf
Each of them encondes a regulatory protein
Receptor used by macrophages to engulf opsonized R. equi
Complement receptor 3 = CR3 or Mac-1
Which receptor does R. equi use for entry in the macrophage
Mannose receptor in the macrophage that recognized lipoarabinomannan (LAM) in the bacterium
Which cell is required for complete pulmonary clearance of R. equi
T lymphocytes (> CD4+)
Why are adult horses more resistent to R. equi pneumonia?
Developement of R. equi-specific CTLs
Why are foals more susceptible to R. equi pneumonia?
- Deficient in CTL
- Ag presenting cells have decrease CD1, MHC II expression
- IFN-g deficiency and Th2 bias
Which infectious agents can cause lung infections in utero?
- EVA
- EHV-1, 4
Diagnosis of P. carinii pneumonia
- Trophozoites in histology
- Interstitial, miliary pattern
How long is the nasal shedding in strangles
2-3 weeks
Which test is more sensitive than culture for diagnosis of strangles?
PCR → SeM protein, the gene for the antiphagocytic M protein
- Guttural pouch sampling is the most reliable
- > Se than culture, always use in combination
What is the detection rate? ~90%
Interpretation of a SeM ELISA for strangles where the titer is ≥ 1:3200
High antibody → predispose to develop purpura when vaccinated
- Do NOT vaccinate
T/F
For EIV, serum antibody concentrations correlates with protection
True
Which lineage of EIV is currently circulating?
H3N8
Vaccine recommendation for EIV by OIE
Florida clades 1 and 2
What is the purpose of the lymphocyte-associated viremia of EHV-1?
- Virus reaches other tissues, targets the endothelial cells and causes vasculitis
- Viremia can persist for 21 days! FFS!
Most important cell for immunity against EHV-1?
- CTLs –> MHC class I restricted
- Mediated by CD8+
How does EHV-1 evade the immune system?
- Downregulationof MHC-1
- Alteration of NK cells
- Modulation of cytokine response
Measures to prevent EAV
- Vaccinate colts in the first year and annually thereafter
- Vaccinate mares that will be bred
- Manage carrier stallions separate, or castrate
- MLV
Which animals are at higher risk for infection with equine adenovirus
- Arabian foals with SCID
- Immunocompromised animals
Which diagnosis with high Se and Sp can be used for Conidiobolomycosis?
Serum antibodies
What is necessary in a cytology to diagnose a fungal pneumonia?
Large number of fungi in degenerated neutrophils in a speedily processed sample
What is your interpretation of high titers for aspergillosis?
Is common from environmental exposure
- Definitive diagnosis is by culture*, IHC, IF
Why antifungals like azoles or amphotericin B are not effective against pneumocystosis?
Pneumocystis carinii lacks ergosterol! FML!
If you want to diagnose pneumocystosis, what sample would you submit?
BAL for cytology
- Can NOT be cultured
Would you use bronchodilators to treat a case of ALI/ARDS?
No! It can worsen the V/Q mismatch
Use low tidal volumes
What is the reason for vaccine failure in EIV?
Antigenic drift
Best measure for eradication of EAV from herd ©
- Manage carrier stallions
- Vaccinate mares that are bred to the carrier stallion
Advantages of ultrasouund for R. equi
Evaluation of severity of pneumonia and response to therapy
