Streptococcus equi ss. equi Flashcards
What is the most common signalment with a horse with SEE?
young horses 1-5 y.o is most common this can, however, occur at any age
Clinical sings of SEE infection
- fever- usually persists until LN abscesses and drains
- Mucopurulent nasal discharge
- Lymphadenitis >> abscessation
- mandibular and retropharyngeal are most commonly involved
- swollen ~ 1 week after infection
- Retropharyngeal abscessation leads to drainage into the gutteral pouches
- any LN can be involved. If located along the trachea, they can lead to tracheal obstruction
- mandibular and retropharyngeal are most commonly involved
- Painful pharyngitis can have impaired swallowing and anorexia
what is bastard strangles?
This is where SEE infection becomes metastatic and occurs in any organ or LN
Hematogenous or lymphatic spread
Pathogenesis of SEE infection
enters oral or nasal cavities > attaches to crypt cells of tonsilar tissue > relocates tot he Ln’s
Once in LN: Complement-derived chemotactic factors>(PMN) recruitment to the LN causing abscessation
Nasal shedding begins several days after onset of fever and can persist for 2-3 weeks. some shed for 6+ weeks.
Immune responses are evident 2-3 weeks after infection
in reecovered animals of SEE infection, how long after infection do we anticipate immunity being present?
~5 years.
this is for animals that are NOT treated with antimicrobials
Are suckling foals susceptible to SEE infection
Generally no, clostral maternal antibody ingestion helps protect them
How is SEE transmitted?
active SEE infection with nasal discharge and draining LN’s are extremely contagious for direct and indirect transmission
1) horses incubating the organism go on to develop SEE
2) Horses that are recoverign from recent SEE infection, but are still shedding
3) Horses that have clniically recovered, but become persistent carriers (Primary route for transmission to a naive population)
Environmental persistance of SEE
There is no convincing evidence that this occurs under normal conditions.
Diagnosis of SEE infection
diagnosis is crutial to do as soon as it is suspected!!!
appropriate samples include contents of mature LN abscesses, nasopharyngeal swabe, nasopharyngeal wash and gutteral pouch lavage.
Cytologic evaluation of these samples may show inflammation and Gram+ cocci (not defionitive diagnosis)
- culture- preferred method on mature abscess aspirates
- may get strain-specific susceptibility
- PCR- more sensitive than culture- nasopharyngeal wash is more sensitive than a swab because it covers a larger surface area
- Serology May be useful to determine if previous exposure to disease. Determines need for a Vx.
What are recommendations for Vaccination vs. SEE in horses?
- Extract vaccines
- IM vaccine can elicit Ab responses in 7-10 days
- Requires 2-3 doses in naive horsesat 2 week intervals
- Can be used in prengant mares to improve colostral Ab, but there is no label claim to supprot this
- Attenuated Live intranasal vaccine
- Exposure to tonsilar tissue
- 2 doses required in naive horses at 2-3 weeks
- NOT recommended in animal less than 1 year of age - incites clinical disease
- CAUTION: when administering injectable vaccines the same day! Recommended NOT administering on the same day as injectable vaccines
what are recommendations to control SEE outbreaks?
Isolation of new horses for a minimum of 3 weeks
Controling outbreaks on SEE affected premises:
- prevent the spread of SEE to horses on other premeses and to new arrivals on the affected premesis
- Establish whether convalescign horses are infectious at least 3 weeks after clinical recovery
- Eliminate SEE infection from the gutteral pouches- specific treatment for empyema or chondroids and retest after 3 weeks
- Prevent indirect cross-infection by SEE from horses in the “dirty” area to those in the clean area of the premises by implamenting strict biosecurity practices.
What is the recommendation for treatment for horses with early clinical signs of of SEE infection?
The use of antimicrobials is highly controversial IF exposed horses are immediately started on antimicrobials prior to clinical signs, there may be a chance to eliminate infection.
Potential side effects: prolongation to ultimate abscess maturation, potential for antimicrobial-associated colitis
Treatment recommendations for horses with uncomplicated lymph node abscessation associated with SEE
Uncomplicated cases are managed with benign neglect. This practice improves lasting immunity
- surgical drainage AFTER a mature abscess develops.
- Rinse lanced abscess daily with dilute povidone-iodine until granulated.
- Judicious use of NSAID therapy may be warranted. Flunixin at 1mg/kg PO or IV q 12hr or PRN
Treatment recommendations for horses with complicated SEE infections and lymph node abscessation
Systemic antimicrobial therapy, IV fluid therapy, NSAIDS and enteral nutrition
Temporary tracheostomy should be considered in cases of dyspnea with significant airway obstruction
True/ False
Treatment of SEE infection with antimicrobials increases the risk for developing metastatic disease (Bastard strangles)
FALSE!!!!
This is an old therapy by many horse owners and veterianrians, but is not supported by any data
What are antimicrobials of choice for see treatment?
Beta lactams
Penicillin G Procaine
Potassium Penicillin
Ceftiofur (Excede)
Crystalline-free Ceftiofur
Is TMS Trimethoprim-sulfa a good antimicrobial selection for SEE infections?
no, they are of limited benefit in areas of necrotic tissue and pus accumulation (ie abscess)
Doxycycline is better than TMS
Beta lactams are the antimicrobial of choice!
Define Empyema
exudate accumulation within the Gutteral pouch
if not treated, it can form firm concretions = chondroids
How do you treat Gutteral pouch empyema and chondroids
aggressive specific medical treatment
Chondroids must be removed and the gutteral pouch flushed.
What are complications associated with Metestatic spread of SEE ifnection?
this has been reported in every organ system
- Liver, kideny, mesentery, and spleen are common abdominal locations that lead to peritonitis and cause abdominal pain (colic)
- Surgical therapy may be necessary in appropriate situations
- Neurologic signs predominate when the brain or spinal cord are involved
- Aspiration of exudate into lower airways may lead to bronchopneumonia
Mortality rates ~62% where as uncomplicated cases <2%
what is Purpura Hemorrhagica in regards to SEE
aseptic, immune-mediated, necrotizing vasculitis that occurs as a type 3 hypersensitivity in mature horses after repeat exposure to natural disease after vaccination.
CS: pitting edema, petechiae and ecchymosis
vasculitis in the target organs
what is the sequellae for Purpura hemorrhagica that causes infarction of the muscle
rhabdomyolysis/ necrotic muscle and ultimately open wounds
