Strangles Flashcards
what are clinical signs of strangles?
- pyrexia
- pharyngitis
- abscess formation in lymph nodes: usually submandibular and retropharyngeal
what lymph nodes are most commonly affected by strangles?
submandibular and retropharyngeal
when do horses get pyrexia with strangles?
3-24 days after exposure
what is the severity of strangles?
- varies: some die and some barely affected
- correlated with the dose and frequency of infectious challenge
- varies with immune status
what age of horse is more at risk for severe disease with strangles?
older horses: complications from strangles more common
how long does immunity of strangles last?
10 years: not uncommon to get 18 year old horses that had it when they were younger and now get re infected and sick
what does pharyngitis from strangles cause?
- difficulty eating and drinking/dysphagia
- abnormal head positions
what is the major severe consequence of strangles?
upper respiratory tract obstruction: lymphadenopathy causes. can lead to choke, ARDS, death
nasal shedding of s. equi begins when? how long does it last?
begins 2-3 days after onset of fever and persists for 2-3 weeks in most animals
where do lymph nodes rupture?
- thru skin to the outside
- into the resp tract: nasopharynx and GUTTURAL POUCH
what is the only way to detect subclinical infections of strangles (chondroids in guttural pouch and spread it to others)
endoscopy
does strangles have good or bad immunity?
good immunity: 75% not treated will have long term immunity
- 20-25% susceptible within several months: they fail to produce or maintain antibodies
how does strangles persist with chronic shedders?
10% of horses experience failure of the GP drainage mechanism, which leads to empyema and then chondroids. so these horses can shed for months to years and be subclinical
what is atypical strangles?
- catarrhal strangles: mild form seen in animals with limited susceptibility
- older horses with residual immunity
- foals with waning maternal ab production
- vaccinated animals
- THESE ANIMALS SHED VIRULENT S EQUI
T/F: atypical strangles animals are non infectious and we don’t need to worry about them
false- they shed virulent S. equi!!
what are common fomites for transmitting Strangles?
veterinarians and farriers!
direct transmission of Strangles
horse to horse: HAS TO BE DIRECT CONTACT with material. is nOT aerosolized. or contact with lymph node abscessation material
indirect transmission of Strangles
drinking, bedding, tools, vets, farriers, etc
T/F: Strangles is commonly transmitted via aerosols
false- it is not aerosolized.
convalescent strangles horses
outwardly healthy horses that continue to harbor the organism after full clinical recovery. consider all recovered horses potentially infectious for at least 6 weeks after their purulent dc have dried up
with a recovered horse from strangles, they should be considered infectious for at least _________ after their purulent dc has dried up
6 weeks
when culturing potential strangles cases, what are we looking for
- beta hemolytic streptococci
- unsuccessful during incubation, early clinical phases, when bacterial count is low during convalescence
when is strangles culture unsuccessful?
incubation, early clinical phases, when bacterial count is low during convalescence
PCR is more sensitive than culture, but what is the downside of it?
it doesn’t tell you if the organism is active or viable, just that there are segments there
