Streptococcus equi ss. equi

Question 1

What is the most common signalment with a horse with SEE?

Answer 1

young horses 1-5 y.o is most common this can, however, occur at any age

Question 2

Clinical sings of SEE infection

Answer 2

• 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
• Painful pharyngitis can have impaired swallowing and anorexia

Question 3

what is bastard strangles?

Answer 3

This is where SEE infection becomes metastatic and occurs in any organ or LN

Hematogenous or lymphatic spread

Question 4

Pathogenesis of SEE infection

Answer 4

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

Question 5

in reecovered animals of SEE infection, how long after infection do we anticipate immunity being present?

Answer 5

~5 years.

this is for animals that are NOT treated with antimicrobials

Question 6

Are suckling foals susceptible to SEE infection

Answer 6

Generally no, clostral maternal antibody ingestion helps protect them

Question 7

How is SEE transmitted?

Answer 7

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)

Question 8

Environmental persistance of SEE

Answer 8

There is no convincing evidence that this occurs under normal conditions.

Question 9

Diagnosis of SEE infection

Answer 9

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.

Question 11

What are recommendations for Vaccination vs. SEE in horses?

Answer 11

• 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

Question 12

what are recommendations to control SEE outbreaks?

Answer 12

Isolation of new horses for a minimum of 3 weeks

Controling outbreaks on SEE affected premises:

1. prevent the spread of SEE to horses on other premeses and to new arrivals on the affected premesis
2. Establish whether convalescign horses are infectious at least 3 weeks after clinical recovery
3. Eliminate SEE infection from the gutteral pouches- specific treatment for empyema or chondroids and retest after 3 weeks
4. 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.

Question 13

What is the recommendation for treatment for horses with early clinical signs of of SEE infection?

Answer 13

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

Question 15

Treatment recommendations for horses with uncomplicated lymph node abscessation associated with SEE

Answer 15

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

Question 16

Treatment recommendations for horses with complicated SEE infections and lymph node abscessation

Answer 16

Systemic antimicrobial therapy, IV fluid therapy, NSAIDS and enteral nutrition

Temporary tracheostomy should be considered in cases of dyspnea with significant airway obstruction

Question 17

True/ False

Treatment of SEE infection with antimicrobials increases the risk for developing metastatic disease (Bastard strangles)

Answer 17

FALSE!!!!

This is an old therapy by many horse owners and veterianrians, but is not supported by any data

Question 18

What are antimicrobials of choice for see treatment?

Answer 18

Beta lactams

Penicillin G Procaine

Potassium Penicillin

Ceftiofur (Excede)

Crystalline-free Ceftiofur

Question 19

Is TMS Trimethoprim-sulfa a good antimicrobial selection for SEE infections?

Answer 19

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!

Question 20

Define Empyema

Answer 20

exudate accumulation within the Gutteral pouch

if not treated, it can form firm concretions = chondroids

Question 21

How do you treat Gutteral pouch empyema and chondroids

Answer 21

aggressive specific medical treatment

Chondroids must be removed and the gutteral pouch flushed.

Question 22

What are complications associated with Metestatic spread of SEE ifnection?

Answer 22

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%

Question 23

what is Purpura Hemorrhagica in regards to SEE

Answer 23

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

Question 24

what is the sequellae for Purpura hemorrhagica that causes infarction of the muscle

Answer 24

rhabdomyolysis/ necrotic muscle and ultimately open wounds

Question 25

What is the recommended course of treatment for Purpura Hemorrhagica

Answer 25

Corticosteroid treatment is the hallmark of therapy for PH and control of systemic vasculitis

• dexamethasone
• Supportive care may include leg wrapping, analgesics, fluid therapy, and nutritional support.

antimicrobial therapy may be necessary

Question 26

Strep myositis and SEE

Answer 26

Strep Myositis is an immune-mediated disorder that has been associated with SEE

• QH breed is over represented
• immune system targets skeletal muscle resulting in acute, severe progressive myositis

Owners report 100lbs lost in 24 hours

Treatment: corticosteroids are indicated