Test 3: 57 + 58 equine part 2 Flashcards
(36 cards)
appaloosa breeding farm
5/15 foals cough, fever, depression
1-5 months of age
1 foal has 3x joint effusion, no lameness
1 foal wierd eye
2 foals diarrhea
wheezes, crackles, dull areas
↑RR
↑ fibrinogen and WBC
3/10 unaffected foals have ↑ fibrinogen and ↑neutrophils
problem list
DDX
plan
problem list:
Lung disease, diarrhea, joint effusion, anterior chamber fibrin
DDX
rhodococcus- pneumonia
Plan
U/S
Rads- NAG (neoplasia, abcess, granuloma)
TTA- cytology (gram + rods), culture- not specific for VapA, PCR- VapA
serology- no
rhodococcus effects —
foals age 1-6 months
clinical signs of rhodococcus infection in horses
chronic suppurative pneumonia with abscessation
pulmonary signs:
* Fever
* Tachypnea, cyanosis
* Adventitial lung sounds
* Death! (subacute syndrome)
Extrapulmonary disease
* Diarrhea
* Colic → Typhlitis, enterocolitis→ LN abscess
* Uveitis/panophthalmitis
* Polysynovitis→ (not lame, don’t tap!)
* Septic arthritis / osteomyelitis / physitis
rhodococcus is caused by
gram + coccobacillus
found in the soil
inhaled into lungs, shed in feces
lives inside cell
VapA positive= virulent strain (2-23% of all environmental isolates
Not very “contagious” – most do not isolate affected foals
treatment of rhodococcus
Long-term antibiotics
Gram (+), good penetration+ lipid soluble
Macrolides +/- rifampin
* Azithromycin (PO SID)
* Clarithromycin (PO BID)
* Tulathromycin? IM depot. Less effective?
Now seeing some resistance to macrolides: worse prognosis. Scary.
* Doxycycline? Less effective.
Macrolides cause diarrhea in adults (including the dam!) and hyperthermia in foals (anhidrosis)
Co-infection?
* May need to add gram (-) coverage
prevention of rhodoccus
Screening
* PE, temp, CBC/fib, U/S
Environmental management
* Not proven to be effective
Chemoprophylaxis
* Macrolides? Arg. Bad idea. Why
* Gallium- bad
Passive immunization
* Hyper-immunized serum, days 1 and 30 (vaccinate moms, but expensive)
Vaccination?
* Exciting! Vaccine in development at Texas A&M
radiating heart sounds =
fluid → effusion
besides rhodococcus what are other causes of foal pneumonia
Strep. equi ssp zooepidemicus
R. equi
(Others: E.coli, Klebsiella, Actinobacillus etc.)
Interstitial -EMPF (idiopathic)
foal pneumonia presents with
sporadic
Fever, tachypnea, adventitial lung sounds, hypoxemia, nasal discharge, depression
pleural effusion is not as common as pneumonia in adults
diagnosis of foal pneumonia
Rads / U/S
TTA + culture
Inflam leukogram / ↑fibrinogen
treatment for foal pneumonia
Broad spectrum antibiotics
Ensure Strep coverage!
* Pencillin (narrow spectrum)
* Cephalosporins (e.g Ceftiofur)
* SMZ-TMS
* Macrolides (azithromycin)?- can cause hyperthermia in foals and diarrhea in adults
16 YP mare
severe respiratory distress
thick nasal discharge
occasional cough at exercise
exercise intolerant x 1 year
previous bout of dyspnea last month
T: 99.1 F, HR, 44 bpm, RR 55 bpm
marked expiratory effort, crackles and wheezes, grade III musical murmur on L
fibrinogen 450
problem list
DDx
Plan
Problem list
* Severe dyspnea, nasal discharge, cough, exercise intolernace, heart murmur
Differential diagnoses
* Pneumonia? Viral dz- no fever and normal fibrinogen
* Pneumothorax- crackles and wheezes, not decreased lung sounds
* Heart failure- HR normal, so prob not
* Asthma (“heaves”)- occasional cough, expiratory effort, older horse
Diagnostic plan
* Lung function testing?
* BAL?
severe equine asthma presents in — horses as —
Older horses
Clinical signs
* Severe, episodic occurrences (attacks) of dyspnea
* Expiratory effort
* Cough
* “Heave line”
* +/- nasal discharge
* signs at rest
also called heaves
mild equine asthma occurs in — horses and presents with —
Airway disease is second only to musculoskeletal injury in wastage
11-50% of TB and STB racehorses
young to middle-aged horses
Clinical signs:
* Cough
* Tracheal mucus
* Exercise intolerance
* No clinical signs at rest
previously called inflammatory airway disease (IAD)
how to diagnose mild equine asthma
Definitive diagnosis: BAL and/or pulmonary function testing (PFT)
Physical exam
* normal
Radiographs
* not accurate
Treadmill
* exercise intolerant
Endoscopy
* tracheal mucus
Blood gas
* Excessive hypoxemia during high speed work
BAL of horse with mild asthma will show
Mild Equine Asthma:
* >5% neuts, >0.5% eos, >2% mast
cells
Severe Equine Asthma (heaves):
* usually > 25% neutrophils
* Not eos or mast cells
BAL of horse with severe equine asthma will show
Mild Equine Asthma:
* >5% neuts, >0.5% eos, >2% mast
cells
Severe Equine Asthma (heaves):
* usually > 25% neutrophils
* Not eos or mast cells
pathophysiology of equine asthma
Environmental inhaled toxins
* Most cases are associated with barn dust/hay exposure
* Dust, mold spores
* Endotoxin (manure)
Pollens?
* In the SE US, some horses are triggered at pasture in summer (Summer-pasture associated heaves)
Genetics?
* Certain families of warmbloods have higher rates of heaves
NOT ALLERGIC →horses are extremely sensitive to dust
expiratory effort indicates upper or lower airway problem
lower
is equine asthma an allergic reaction
no- allergies cause increase eos/mast cells
equine asthma cause increase in neutrophils → horses are sensitive not allergic
what kind of bedding has the highest respirable endotoxin
straw > 2329
recommend changing to shavings or sawdust or move outside
what happens when the horse is exposed to an asthma trigger?
Airways are hyper-reactive (“twitchy”)
* Inhaled triggers (dust) cause bronchospasms that increased airway resistance
* Reversible
Airways become inflamed
* Neutrophils (pus) and mucus collects in the small airways
* Eventually, airways become fibrotic and cannot dilate
Airways become blocked
* mucus becomes stickier, remains in the airway
* bronchospasm increases work of breathing, dyspnea
inhaled triggers are not allergens! In horses most asthma is not an allergic disease
managment/treatment of asthma
Decrease barn dust, hay dust triggers
* 24/7 turnout →Out for >2hours after cleaning stall!
Shavings, not straw for bedding
Soak hay 5 minutes
* Buy excellent quality hay (no dust)
* Or use dustless bagged hay product: Dengie
Good ventilation
* End stall by the door
* No hay storage overhead
Avoid summer pasture? Only for Special-
asthma cases
medical treatment of asthma with steroids
steroids- corticosteroids
Oral steroids (tablets)
* Induce remission (most effective)
* Systemic side effects- can cause laminitis and GI issues
* Usually predniSOLONE or dexamethasone
Inhaled steroids (puffer)
* Maintain remission
* $$$ but fewer side effects
* Takes 2-4 weeks to show effect, need to use EVERY DAY, not just when you see clinical signs
* Fluticasone (Flovent) or beclomethasone (QVAR)
* Nebulized dexamethasone is NOT effective
