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| | *[http://www.ivis.org/special_books/Lekeux/chanter/chapter_frm.asp?LA=1 Overview of equine respiratory disease] by N Chanter of the Animal Health Trust, taken from Equine respiratory diseases edited by P Lekeux. Chapters of this book are published by the International Veterinary Information Service (IVIS) | | *[http://www.ivis.org/special_books/Lekeux/chanter/chapter_frm.asp?LA=1 Overview of equine respiratory disease] by N Chanter of the Animal Health Trust, taken from Equine respiratory diseases edited by P Lekeux. Chapters of this book are published by the International Veterinary Information Service (IVIS) |
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| − | ===Strangles=== | + | ===[[Strangles]]=== |
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| − | *Caused by very pathogenic [[Streptococci|''Streptococcus equi subsp. equi'']]
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| − | *Haemolytic streptococci of Lancefield group C are common inhabitants of the equine nasopharynx
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| − | *''Streptococcus zooepidemicus'' and ''S. equisimilis'' are usually non-pathogenic
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| − | *Typically [[Nasal Cavity Inflammatory - Pathology#Infectious causes of rhinitis|suppurative rhinitis]], [[Nasopharynx Inflammatory - Pathology#Infectious causes of pharyngitis|pharyngitis]] and '''lymphadenitis''' of the lymph nodes of the head and neck that drain the upper respiratory tract, these lymph nodes often rupture and discharge pus 2-3 weeks after the onset of infection
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| − | *Infection with ''Streptococcus equi'' occurs after contact with contaminated feed, water bowls or an infected carrier [[Hindgut Fermenters - Horse - Anatomy & Physiology|horse]]
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| − | *Organism remains viable in environment for months
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| − | *Possibility of other sources of infection - in pharynx of in-contact dogs?, guttural pouches of persistently infected horses
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| − | *Attaches to nasopharyngeal epithelial cells, then mucosa, lymphatics and lymph nodes
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| − | *Multiplies extra-cellularly
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| − | *Gross pathology
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| − | **Initial bilateral nasal discharge, serous becoming purulent
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| − | **Catarrhal conjunctivitis may be present
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| − | *Less frequently, complications can occur as follows :
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| − | **Purulent inflammation may extent to [[Guttural Pouches Inflammatory - Pathology|guttural pouches]] or [[Lungs Inflammatory - Pathology#Infectious causes of pneumonia|lungs]], [[Paranasal Sinuses Inflammatory - Pathology#Infectious causes of sinusitis|sinusitis]]
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| − | **Bacteraemia with metastatic abscesses - most often to the mesenteric and mediastinal lymph nodes, less frequently, other organs such as [[Liver - Anatomy & Physiology|liver]], kidney and brain can be involved - '''Bastard strangles'''
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| − | **Retropharyngeal abscesses can rupture onto the skin of neck or into the [[Guttural Pouches Inflammatory - Pathology|guttural pouch]] resulting in '''guttural pouch empyema or chondroid formation''' - carrier state
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| − | **[[Muscles Degenerative - Pathology#Ischaemia|'''Purpura haemorrhagica''']]: an acute vasculitis causing urticaria and extensive oedema of ventrum, head and distal limbs
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| − | **[[Larynx Degenerative - Pathology#Laryngeal hemiplegia|Laryngeal hemiplegia]] due to enlarged retropharyngeal lymph nodes
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| − | **Compression of cranial nerves
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| − | *Interview with Professors Josh Slater and Ken Smith providing an interesting insight into the pathogenesis, prevalence and possible prevention of ''Streptococcus equi'' infections in horses - listen to [http://www.rvc.ac.uk/Review/Podcasts/RVC_Podcast_12.m4a Strangles podcast]
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| | ===''Streptococcus equi subsp. zooepidemicus''=== | | ===''Streptococcus equi subsp. zooepidemicus''=== |