strangles Flashcards
complications of strangles
pus collects on the ventral floor of the guttural pouch in cases of empyema with strangles, chondroids are dried pus that occurs often as a result of guttural pouch infection (empyema)
strangles diagnosis
culture of nasal swabs, nasal washes and pus aspirated from abcesses, blood test: serology to find antibodies can detect recent, but not necessarily current infection, may compare titers from sequential samples to investigate exposure and infection status (serum titer peaks at 5 weeks after exposure and remains high for at least 6 months)
diagnosis challenges
Asymptomatic carrier horses, 4-50% of horses on farms with recurring strangles are carriers of the bacteria, all horses that had signs of infection should be tested 3 times and be negative on all before being reintroduced to healthy horses, shedding can occur for weeks to months after infection in most horses (rare cases may shed for years and cause continual source of new infection)
treatment before abscess formation
*most horses do not require treatment with antibiotic, antibiotics will only be useful before abscess formation, antibiotics should be administered to new cases in the early acute phase with fever and depression, give soft and palatable food, horses that are treated with antibiotics do not develop immunity to the disease and are highly likely to be reinfected in they remain in contact with infected horses
treatment after abscess formation
enhance maturation and drainage of abscess by applying hot packs and icthamol, lance abscess once it is mature and almost ready to rupture, flush daily with 3-5% povidone, NSAIDs (banamine) reduce fever, pain and inflammatory swelling of abscess, may give antibiotics after abscess has ruptured
use of antibiotics to treat strangles
uncomplicated cases do not require antibiotics, complicated cases often require antibiotics and other treatments (penicillin usually used), if antibiotics are used treatment course is usually weeks or longer to completely clear infection
bastard strangles
horse never fully recuperates from the disease, metastasis may occur to other locations carried by blood stream or lymphatic vessels causing abscesses in other parts of the body: lung, liver, spleen, kidney, brain, can happen in up to 30% of horses
complications after the horse has had strangles
bastard strangles, pneumonia, gutteral pouch empyema, endocardosis/myocardosis (bacteria stops at the heart), septic arthritis
purpura hemorrhagica
immune mediated disease, S. equi elicits a very strong immune response, causes necrotizing vasculitis (causes death of tissue), caused by immune complexes attacking blood vessel walls, high serum antibody titer may predispose horses, treated with dexamethasone and antibiotics
prevention of strangles
most horses develop solid immunity for 2 years after they recover from strangles, vaccines (IM, intra-nasal), horses that have had strangles in previous year should not be vaccinated, quarantine is difficult because of sub-clinical carriers,
outbreak management
create groups of horses
1.infected horses 2.horses that have been exposed to or contacted infected horses 3. clean horses with no exposure-should be housed separately in an area infected horses have not been kept, handle clean horses first
outbreak management-cleanliness
people/equipment can transfer infection, water and feed troughs should be disinfected daily, stalls should be cleaned after manure removal, bleach will kill strangles bacteria but will be deactivated as soon as it touches wood, manure and waste feed should not be spread on pastures, pastures used to house infected horses should be rested 4 weeks
vaccination
IM and intra-nasal vaccines available, improper administration can result in poor protection or complications at injection site, intra-nasal vaccine provides the best local immunity, horses may be vaccinated 1-2 months after an outbreak is over, recently exposed horses may result in pupura hemorrhagica if vaccinated too early.
