Strangles Exam 2 Flashcards by Hailey Carroll

What is strangles caused by?

Streptococcus equi

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What is Strangles?

a highly contagious upper respiratory disease

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How is strangles transmitted?

by purulent discharge from direct and indirect contact

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How long can the disease be carried?

some horses continue to shed the bacteria weeks after clinical signs have disappeared

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What can happen to horses later in life that have had strangles?

complications may arise later in life

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What is the “human form” of strangles?

strep throat
-forms a lot of pus
-can lead to heart disease or scarlet fever if left untreated

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What can happen in 10% of horses with strangles?

the guttural pouch can become infected
-the horses then develop empyema of guttural pouch and can transmit the disease for years

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Where does bacteria enter?

through the mouth or nose and affects the tonsils

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Within hours of transmission where does the bacteria reach?

the mandibular and subpharyngeal lymph nodes

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When does fever occur with strangles?

3-14 days after exposure

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Clinical signs of strangles

-fever
-mucopurulent nasal discharge
-swelling and abscess formation of lymph nodes
anorexia, depression
-pharyngitis, laryngitis, rhinitis
-ocular discharge, periorbital abscesses

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What age of horse develops a milder disease?

older horses

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How long is the latent period?

4-14 days

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When does shedding of bacteria stop

3-7 weeks post acute infection

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When does nasal shedding of bacteria start?

after the latent period of 4-14 days

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How many times should horses test negative before going back out with the herd?

at least 3 times

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What can be done with the pus filled abscesses?

-it may open itself
-they can possibly be lanced
-the pus is contagious

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Where in the guttural pouch does pus collect?

on the ventral floor in cases with empyema

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Chondroids

inspissated pus that occurs in the guttural pouch as a result of chronic guttural pouch infection (empyema)
-“pus stones”

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What is a complication of strangles?

chondroids

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Initial diagnosis is made via:

PCR (most sensitive)

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Definitive diagnosis is made via:

culture of nasal swabs, nasal washes, and pus aspirated from abscesses

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What do blood tests detect?

serology to find antibodies
-can detect recent, but not necessarily current infection (antibodies don’t show up immediately during infection)

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When do serum titers peak?

at 5 weeks after exposure

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How long do serum titers remain high?

for at least 6 months

What happens after a horse has strangles?

they have a strong immunity to it for at least 2 years

Biosecurity

you must have a separate person that mucks/feeds and cares for the horses infected (if you do not have a designated person, always deal with the horse last then immediately clean yourself)

What % of horses on farms with recurring strangles are carriers of the bacteria?

4-50%

When should horses be tested?

any horse that had signs of the infection should be tested all 3 times and return negative

What type of treatment do most horses NOT require?

treatment with antibiotics

What treatment will complicated cases require?

antibiotics and other treatments like tracheostomy's

If antibiotics are used, how long is the course of treatment?

several weeks

How are mild cases treated?

by feeding soft, palatable food (like mashes)

What should be done to treat a horses showing early clinical signs during an outbreak?

antibiotics should be administered in the early acute phase with fever and depression

When will antibiotics only be useful?

before abscess formation

Can horses on antibiotics become reinfected?

yes, they don't become immune to the disease, and if they stay around other infected horses they can become reinfected

What is the course of treatment once abscesses have formed?

-enhance maturation and drainage of abscess using hot packs and ichthamol (sticky tar that warms the area to help mature the lymphnodes)

When should an abscess be lanced?

once it is mature and almost ready to supurate

What is the care of open abscesses?

daily flushing with 3-5% povidone

What do NSAIDS help do with strangles cases?

-reduces fever -help pain -help inflammatory swelling of abscess

What antibiotics can be given after the abscess has supurated?

-penicillin -cephalosporins -macrolides

Bastard strangled

metastasis may occur in other locations, carried by the blood stream or lymphatic vessels causing abscesses in lungs, liver, spleen, kidneys, and brain

What % of horses get bastard strangles?

up to 30%

What causes bastard strangles?

caused by the bacteria reaching the blood circulation - to then get carried to and cause abscesses in other organs

When does bastard strangles occur?

once a horse is already over strangles

Is bastard strangles easy to detect?

no, because most of the abscesses are internal now

Complications after strangles

-bastard strangles -pneumonia -guttural pouch empyema -endocarditis -myocarditis -septic arthritis -purpura hemorrhagica

How does pneumonia occur after strangles?

the same strep bacteria makes its way to the lungs

Endocarditis

infection of the inner heart with no cure

Myocarditis

infection of the outer chamber of the heart (muscle) with no cure

Septic arthritis

bacteria that causes infection of joints that causes arthritis

Purpura hemorrhagica

immune mediated disease, the immune system gets overzealous and starts to attack itself -causes necrotizing vasculitis

How does strangles lead to purpura hemorrhagica?

S. equi elicits a very strong immune response that goes overboard (it is no longer an infection)

What is the cause of purpura hemorrhagica?

immune complexes attack blood vessel walls (the exact reason WHY it happens is unknown)

What may predispose horses to purpura hemorrhagica?

high serum antibody titer

What is used to treat purpura hemorragica

-Dexamethasone with antibiotics (very hard to treat - very high dose of steroids is needed)

What can the treatment of purpura hemorragica lead to?

laminitis

Why do we not vaccinate horses who have had strangles for 1-2 years after?

to not induce high serum antibody titer (which could lead to purpura hemorrhagica)

What three groups should strangles outbreak herds be split into?

1. infected horses 2. horses that have been exposed to or contacted infected horses 3. clean horses with NO exposure

How often and what should be cleaned during an outbreak?

-stalls cleaned after manure removal -water and feed troughs cleaned and disinfected daily -all cleaning and disinfection daily

How long should pastures being used to house the infected horses be rested for afterwards?

4 weeks

How are strangles vaccines administered?

IM or intra-nasal

Which vaccine administration works better?

intra-nasal because it is modified live bacteria

What can be done to better determine timing for vaccination of horses recently exposed to strangles?

blood antibody tests (to avoid purpura hemorrhagica