Exam #4: Equine Respiratory Pt. 2 Flashcards
(70 cards)
DDx? 7 wk old foal with throat latch area swelling, dyspnea, stridor, mucopurulent nasal discharge, fever, tachypnea (6)
> Lymphadenopathy = bacterial (Strep), viral/inflam, neoplasia
Guttural pouch disease - tympany, empyema
Allergic reaction = previously sensitized older horses
Parotid gland inflammation
Severe lymphoid hyperplasia
Cyst
Goiter or thyroid tumor
Neoplasia
Diagnostics for suspected strangles
1) CBC
2) Rads
3) U/S
4) Tracheal fluid analysis and culture
5) Aspirate swelling
6) Chem panel = creatinine, albumin, Na+, K+, Cl-, TCO2 (proxy for bicarb) = previous renal damage (using aminoglycosides), acid-base
What happens with K+ during acidic and alkalotic processes?
- Acidotic = exchange H+ for K+ intracellularly = blood becomes hyperkalemic
- Alkalotic = expect K+ to move intracellularly, look artificially hypokalemic
Which is a less contaminated tracheal fluid sample - endoscopic or percutaneous?
Percutaneous
Initial treatment for strangles suspected animals
- K penicillin (IV, needs to be dosed more frequently)
- Rifampin = concentrates in WBC’s
- Banamine
- IV fluids to correct dehydration
- Hot pack swelling
+/- Tracheostomy with severe dyspnea
PaCO2 and PaO2 that may indicate hypoxemia and the need for a tracheostomy
- PaCO2 > 50 (hypoventilation)
- PaO2 < 80
Etiologic agent for “strangles” - who does it commonly affect?
> Strep equi var. equi
- Gram + B-hemolytic Strep
+ URT inflammation, LN abscessation, “bastard” or metastatic strangles
*Primarily affects foals and young horses
- Most horses develop immunity (4-5+ years)
Transmission, incubation period, and pathogenesis of “strangles”
- Direct contact with infected or subclinical shedders
- Indirect contact with contaminated (nasal discharge, pus from LN’s) fomites
- Incubation period = 3-14 days = disease can develop QUICKLY
- Ingested/inhaled and organism adheres to buccal/nasal mucosa
- Translocates below mucosa to local lymphatics, attracts neutrophils, disseminates
Which provides better immunity - natural strangles infection or Strep vax?
Natural infection = generates mucosal cell-mediated and humoral immunity
Main pathogenic factor (what vax and diagnostic testing targets) for strangles
SeM protein = anti-phagocytic
Diagnosis of strangles
- History
+ Clinical signs - Culture of exudate from LN, nasopharyngeal swab, guttural pouch
- Screening tests = PCR on nasopharyngeal swab/wash or exudate, serology (ELISA for SeM protein)
- Don’t detect current or viable infections
What should you not do if your strangles serology/titers show up as > 1:3200
DO NOT VACCINATE for strangles - may induce immune mediated vasculitis (purpura hemorrhagica)
What can serology of strangles do for you?
> ELISA for SeM protein
- Tells you about recent, but not current infections
- May determine the need for vax (< 1:3200)
- May ID animals at risk for purpura hemorrhagica (5-digit titers)
- HIGH titers may give evidence of bastard/metastatic abscessation
Which strangle-horse situations do and don’t we treat with antimicrobials?
> DON’T TREAT? Let natural disease progress
- Early clinical signs, no abscesses
- No sign the animal is compromised or has a complicated infection
> TREAT?
- Any horse with signs of compromise - fever, ongoing throat latch or LN enlarging, anorexia, dyspnea
+/- Horses exposed to strangles to prevent “seeding” of lymph nodes
- Purpura hemorrhagic + corticosteroids
- Bastard strangles
How do we treat uncomplicated strangles cases?
- Open, drain, and flush
- Keep environment clean to avoid contamination
- Hot packing to enhance maturation and drainage of abscess
How do we treat purpura hemorrhagica?
High levels of antimicrobials + corticosteroids (decrease immune mediated vasculitis with Ag+Ab)
Prevention of strangles
- Isolate all new arrivals for 3 weeks
- Immediately isolate any infected horses = shedding occurs for 2- weeks post recovery
- Decontaminate infected fomites
- Rest pastures and paddocks for 3 weeks
- Divide horses into 3 groups if outbreak occurs: direct/indirect contact, presumed infected, not infected
- Screen horses with nasopharyngeal swab or wash with culture/PCR
What can you monitor if you are nervous an exposed horse will develop strangles?
Watch for a fever
How do we confirm a “cure” of strangles?
Three consecutive weekly PCR and culture by nasal swab or nasopharyngeal wash
If + = confirm source, Ex: guttural pouch wash
Is it a good idea to vaccinate in the face of a strangles outbreak?
No - could trigger purpura
Who do we vax and not vax?
- Horses previously infected = develop good immunity = don’t vax for at minimum, 1 year
- Vax healthy, afebrile horses w/ no nasal discharge
- Do NOT vax in the face of an outbreak
- OPTIMAL protection = systemic (IgG) and mucosal (IgA) responses
Which type of vaccine has been associated with purpura hemorrhagica?
Strangles extract vax
Similarities and differences between Strep equi and Strep zoo
+ BOTH = fever, nasal discharge, LN enlargment
- Pneumonia = zoo > equi
- Higher risk of outbreak = zoo
- Higher risk of purpura hemorrhagica = equi
Dx? 4 mo colt, cough, nasal discharge, abnormal bronchovesicular lung sounds, wheezes, crackles, fluid sounds in trachea, fever, tachypnea
Pneumonia - bacterial (Strep, R. equi)
Others = post-viral bronchiolitis, parasitic pneumonia (ascarids), inflammatory airway disease (wouldn’t have systemic signs)
