Equine bacterial respiratory disease Flashcards
Which bacteria causes strangles?
Streptococcus equi equi
Streptococcus is a bacterial respiratory disease mainly affecting which 2 areas?
Upper respiratory tract
Lymph nodes of head
What are the clinical signs of Streptococcus equi equi?
Pyrexia (fever), dull, inappetent Inflammatory changes on blood sample Nasal discharge Lethargy Abscessation
In a severe case of strangles what can occur?
Dyspnoea (laboured breathing)
- pharyngeal compression
- tracheotomy required
What is bastard strangles?
Complication
- Transient bacteremia
- Abscesses can form in other tissues and lymph nodes
- Disseminated abscesses difficult to treat (spread throughout body)
What are the characteristic features of Streptococcus equi var. equi bacteria?
Gram positive Cocci Pairs/chains Facultative anaerobe Hyaluronic acid capsule Lactose fermentation negative
On the Streptococcus equi var. equi structure, what is the target for vaccines?
M-protein on the cell wall
How is Streptococcus equi var. equi spread? How well adapted to the environment is it?
- Highly contagious: spread by direct contact and fomites
- Sensitive to sunlight and heat
- Sensitive to most disinfectants
- Survives in environment for up to 4 weeks
Rate of Streptococcus equi var. equi increase with…?
- Increasing group size
- Increasing horse movement
- Increased mixing of horses
- Communal feeders and drinkers
- Younger horses
What are the two methods of confirming a horse is free from a Strangles infection?
- Guttural pouch wash - 1 negative result
2. 3 negative nasal swabs each week for 3 weeks
In an outbreak what do red, amber and green areas refer to?
Red = Confirmed cases Amber = Been in contact with confirmed cases Green = No contact with confirmed cases
In a disease outbreak when can a yeard open again?
When all horses are declared ‘free of disease’
Which bacteria causes Rattles?
Rhodococcus equi
What are the acute signs of Rhodococcus equi infection?
- Affects young foals
- Fever, anorexia, cough, nasal discharge
What are the chronic signs of Rhodococcus equi infection?
- Affects older foals
- Cough, dyspnoea, weight loss, exercise intolerance, loud crackles on auscultation
Where does Rhodococcus equi multiple to spread infection in the body?
Alveolar macrophages
Which anatomical structures are destroyed by Rhodococcus equi as abscesses form?
- Alveoli in lungs
- Peyer’s patches in gut
What are Rhodococcus equis virulence factors?
- Polysaccharide lipid rich capsule inhibits phagocytosis
- Intracellular pathogen due to inhibitory cell surface antigens
- Antigens encoded by VAP plasmid & only expressed at 34-41 degrees
How is Rhodococcus transmitted?
- Inhaled: affects cranial right lung first
- Oral route
How can Rhodococcus equi be prevented/controlled?
- Long term antimicrobials
- Avoid crowding and remove foal manure
- Reduce dust
- No vaccine
- Examine foals closely twice a week until 4 months old
- Won’t eradicate from environment
