Diseases of the Lower Respiratory Tract, Pt. 2 Flashcards
What is the etiology of exercise-induced pulmonary hemorrhage?
alveolo-capillary membrane ruptures due to increased stress on the pulmonary artery and pleural space associated with exercise
- pulmonary artery increases to 90 mmHg
- pleural space decreases to -60 mmHg
What are 3 major risk factors to developing EIPH? What are some others?
- pulmonary capillary hypertension
- rheological properties of blood (increased PCV associated with exercise)
- subatmospheric pleural space
- extra/intra-thoracic airway obstruction
- mild equine asthma
- coagulopathies
- bronchial neovascularization
- pulmonary fibrosis causing altered compliance
- locomotor forces
In what horses is EIPH most common?
horses that run at higher speeds —> more intense exercise = greater proportion developing EIPH
- less common in jumpers and barrel racers
- common in racing Thoroughbreds
What is the pathophysiology of EIPH?
- exercise causes pulmonary capillary rupture
- hemorrhage induces inflammation of fibrosis
- this leads to reduced lung compliance and increased susceptibility to capillary rupture recurring
What are the 2 most common clinical signs of EIPH?
- bilateral epistaxis
- poor performance
- may be none if it it mild enough and horse swallows blood
When should endoscopies be done to diagnose EIPH?
30-120 minutes (or as long at 7 days) after intense exercise
What diagnostic is considered more sensitive than endoscopy for diagnosing EIPH? What should be seen?
cytology of TW or BAL fluid
- RBCs and erythrophages around 1 week
- hemosiderophage around 21 days
(fluid will be red)
What can be seen on pulmonary radiographs in cases of EIPH? When is this a useful diagnostic?
dorso-caudal opacification
when evaluating other secondary issues, like pneumonia
What are the 4 major ways to treat EIPH?
- prevent stress rupture of capillaries by decreasing pressure in pulmonary capillaries and increasing alveolar inspiratory pressure
- decrease inflammation and angiogenesis
- reduce bleeding by controlling coagulopathies and platelet function
- maintain capillary integrity
What drug is most commonly used to decrease pressure in pulmonary capillaries in cases of EIPH? What are other possibilities?
Furosemide (banned in Europe)
- Enalapril
- L-NAME
- Sildenafil
- Pentoxifylline
How is URT alveolar pressure increased to treat EIPH?
flair strips are placed on the nose and used to correct dynamic collapse by widening the nostrils
In what 3 ways is LRT alveolar pressure increased to treat EIPH?
- bronchodilators
- corticosteroids
- reduce environmental dust
What 5 alternative medications may be used to treat EIPH?
- vitamin K
- vitamin C
- aminocaproic acid
- aspirin
- biflavinoid
What is the prognosis of EIPH like?
- may have an effect on racing horse careers with severe episodes associated with poor performance
- 1 episode has the ability to cause more in the future
What is the most common cause of pneumonia in adult horses?
aspiration of bacteria from nasopharynx and oral cavity
- begins at airways as bacterial bronchitis or septic IAD
- then spreads to pulmonary parenchyma and extends to the pleural space
What is the most common bacterial etiology of pneumonia in adult horses?
bet-hemolytic Streptococcus equi subsp. zooepidemicus
What are the 2 most common aerobic Gram-positive bacterial etiologies of pneumonia in adult horses?
- Staphylococcus
- Rhodococcus
What are the most common Gram-negative non-enteric/enteric etiologies of pneumonia in adult horses?
NON-ENTERIC = Pasteurella, Actinobacillus, Pseudomonas (contaminant), Bordetella bronchiseptica
ENTERIC = Klebsiella, E. coli, Enterobacter, Salmonella
What are the 3 most common anaerobe etiologies of pneumonia in adult horses? What are they associated with?
- Bacteroides
- Clostridium
- Peptostreptococcus
less favorable prognosis
In what adult horses is pneumonia most commonly seen?
- younger racehorses that were just undergoin prolonged transportation
- those just under general anesthesia or undergoing upper airway surgery
- recent viral respiratory disease
- aspiration after choke (obstructed esophagus)
What is the pathophysiology of pneumonia in adult horses?
weakened immune defenses and massive numbers of bacteria allows for the colonization of lung by opportunistic bacteria