Test 3: 57 + 58 equine part 2

Question 1

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

Answer 1

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

Question 2

rhodococcus effects —

Answer 2

foals age 1-6 months

Question 3

clinical signs of rhodococcus infection in horses

Answer 3

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

Question 4

rhodococcus is caused by

Answer 4

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

Question 5

treatment of rhodococcus

Answer 5

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

Question 6

prevention of rhodoccus

Answer 6

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

Question 7

radiating heart sounds =

Answer 7

fluid → effusion

Question 8

besides rhodococcus what are other causes of foal pneumonia

Answer 8

Strep. equi ssp zooepidemicus
R. equi
(Others: E.coli, Klebsiella, Actinobacillus etc.)
Interstitial -EMPF (idiopathic)

Question 9

foal pneumonia presents with

Answer 9

sporadic
Fever, tachypnea, adventitial lung sounds, hypoxemia, nasal discharge, depression

pleural effusion is not as common as pneumonia in adults

Question 10

diagnosis of foal pneumonia

Answer 10

Rads / U/S
TTA + culture
Inflam leukogram / ↑fibrinogen

Question 11

treatment for foal pneumonia

Answer 11

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

Question 12

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

Answer 12

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?

Question 13

severe equine asthma presents in — horses as —

Answer 13

Older horses

Clinical signs
* Severe, episodic occurrences (attacks) of dyspnea
* Expiratory effort
* Cough
* “Heave line”
* +/- nasal discharge
* signs at rest

also called heaves

Question 14

mild equine asthma occurs in — horses and presents with —

Answer 14

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)

Question 15

how to diagnose mild equine asthma

Answer 15

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

Question 16

BAL of horse with mild asthma will show

Answer 16

Mild Equine Asthma:
* >5% neuts, >0.5% eos, >2% mast
cells

Severe Equine Asthma (heaves):
* usually > 25% neutrophils
* Not eos or mast cells

Question 17

BAL of horse with severe equine asthma will show

Answer 17

Mild Equine Asthma:
* >5% neuts, >0.5% eos, >2% mast
cells

Severe Equine Asthma (heaves):
* usually > 25% neutrophils
* Not eos or mast cells

Question 18

pathophysiology of equine asthma

Answer 18

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

Question 19

expiratory effort indicates upper or lower airway problem

Answer 19

lower

Question 20

is equine asthma an allergic reaction

Answer 20

no- allergies cause increase eos/mast cells

equine asthma cause increase in neutrophils → horses are sensitive not allergic

Question 21

what kind of bedding has the highest respirable endotoxin

Answer 21

straw > 2329

recommend changing to shavings or sawdust or move outside

Question 22

what happens when the horse is exposed to an asthma trigger?

Answer 22

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

Question 23

managment/treatment of asthma

Answer 23

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

Question 24

medical treatment of asthma with steroids

Answer 24

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

Question 25

what are treatments for asthma

Answer 25

clean/ decrease exposure to dust
steroids
bronchodilators

Question 26

bronchodilator treatment for asthma

Answer 26

NOT SOLE TREATMENT (BANDAID!)

Usually β-2 agonists, relax smooth muscle

Clenbuterol?
* FDA-approved oral syrup β-2 agonist
* NOT >14 DAYS UNLESS COMBINED W/ STEROIDS (LOSE EFFICACY!)

Inhaled bronchodilators
* Albuterol, salmeterol, ipratroprium
* +/- 30 minutes before exercise or before steroid puffer
* NO ORAL ALBUTEROL

Atropine/glycopyrrolate
* Rescue therapy only! 1 dose only!
* Can cause ileus → severe colic

Question 27

BAL shows 36% neutrophils

Diagnosis
treatment

Answer 27

severe equine asthma

Treatment
* Management changes (24/7 turn out, no hay)
* Prednisolone PO tapering course for 1 month
* Flovent to maintain remission if necessary

Question 28

6 YO TB stallion
chip fracture (R carpus 3 years ago)
receives anabolic steroids- occasionally
30 mins post race- blood from nostrils
HR 52 bpm, RR 40 bpm, T 102.9 F
lungs clear

problems
DDX

Answer 28

problems: epitaxis, increased temp: hyperthermia (not fever- just ran a race)

Exercise-Induced Pulmonary Hemorrhage (EIPH)

Question 29

Exercise-Induced Pulmonary Hemorrhage (EIPH) is caused by —

Answer 29

speed

Question 30

clinical signs of Exercise-Induced Pulmonary Hemorrhage (EIPH)

Answer 30

• Tracheal blood after exercise
• Severe cases: epistaxis
• Rarely: death
• Poor performance?

80-87% of racehorses have some EIPH
Caused by SPEED!

Question 31

pathophysiology of EIPH

Answer 31

Alveolar capillaries in caudodorsal lung from the pulmonary circulation rupture during exercise. Why?

First theory: increased transmural pressure, 2 components
* Increased pulmonary artery pressure during exercise: 90 mmHg vs. ~20mmHg at rest
* Very negative pleural pressures during exercise: -64 mmHg vs. ~5mmHg at rest

Second Theory: locomotory pressures
* Horses’ forelimbs have no boney attachment to axial skeleton.
Forces transmitted while galloping The alternate expansion and compression creates shear stress and capillary disruption.

Still a bit of a mystery…

Question 32

how to diagnosis EIPH

Answer 32

endoscopy
* blood visible for 30-120 mins - 3 days post exercise

BAL
* RBC up to 7 days
* Hemosiderophages for > 21 days

Radiographs
* Not sensitive
* Caudodorsal location

Question 33

treatment of EIPH

Answer 33

furosemide/lasix
give before race
causes dehydration
* reduces blood volume so decrease PA pressure
* reduces weight so horses run faster
* Increases blood viscosity → more shear force?!

Question 34

21 YO irish sporthorse gelding- grey horse
3 month hx of weight loss, exercise intolerance
temp 101.7
normal CBC/chem
black masses

ddx

Answer 34

melanoma- perianal, sheath, carotid area

Question 35

primary pulmonary neoplasia in horses are —

Answer 35

rare

Question 36

secondary pulmonary neoplasms are —

Answer 36

more common than primary

• melanoma
• gastric squamous cell carcinoma
• hemangiosarcoma