LAM I Exam I Material Flashcards
These are responsible for directing controlled detachment of laminae as required for growth of the hoof:
MMPs
- matrix metalloproteinases, metal-cofactor enzymes*
- Some factors (many proposed, such as direct action of endotoxin) trigger excessive uncontrolled activation of these enzymes such that widespread disruption of laminar attachment occurs.*
What is the maximum rate of intraosseus fluid administration in the horse?
2 L/hr
This rate sufficient in many cases for foals, barely compatible with maintenance in an average adult horse; More applicability with local treatment administration
Why must you be careful when administering Polymyxin B to a dehydrated horse?
can cause renal compromise/toxicity
What are the major contraindications to oral administration of fluids?
gastric distension, “reflux” and ileus
What is the most common cause of profuse hemorrhage of nasal origin in the horse?
Trauma (nasogastric tube)
T/F: Sinking is a clinical diagnosis based on depressing coronary band while rotational disruption is a radiographic diagnosis
True
T/F: Once a horse develops DIC, it is almost always a terminal event
True
What is the determinant of the chronic stage of laminitis?
mechanical disruption/collapse
Disruption involves rotational displacement and vertical displacement (sinking), of the distal phalanx with relation to the hoof wall. This phase is often associated with vascular insufficiency, localized sepsis, metabolic and growth dysfunction
T/F: In an anorexic horse, it is typical to see total body depletion of Ca2+
True
- Typically large amounts ingested in horses diet, thus large amount excreted each day*
- Regulation: geared to excrete large amounts of Ca2+ losses: net result is that suffer substantial losses as soon as intake decreases*
T/F: Unilateral nasal discharge is associated with upper and lower respiratory disease
False
Unilateral nasal discharge is associated with upper airway disease
What is the approximate gastric fluid capacity in a horse?
~15 L
What is the goal of intervention in the acute phase of laminitis?
limit the severity to optimize the progression into subacute phase rather than into the chronic phase
T/F: Endotoxin is generated during both death of gram negative bacteria, as well as during the rapid multiplication phase
True
T/F: Tachycardia is seen with both the hyperdynamic and hypodynamic stages of endotoxemia
True
What structure is responsible for most of the deleterious effects of endotoxin?
Lipid A
IV Mg sulfate should not be given to horses in hypotensive conditions. Why?
has vasodilator properties
What is a major contraindication for administering bicarbonate to an acidotic horse?
respiratory compromise (hypoventilation)
Will result in worsened acidemia through development of respiratory acidosis in addition to already present metabolic acidosis
What is the goal of intervention in the subacute phase of laminitis?
to limit progression into the chronic phase of the disease (i.e. prevent mechanical disruption)
During this phase the hoof is healing but still very weakened, and can still structurally fail
__________ is the highly variable, antigenic region of LPS
polysaccharide O
Synchronous diaphragmatic flutter [SDF] in horses is usually treated with intravenous fluids supplemented with moderate amounts of:
calcium
__________ is the most important factor in rapid fluid flow rate
radius (or diameter) of the catheter
Determinants of flow rate: diameter (“gauge”), length of system components, pressure differential, and viscosity of fluid administered
In what state of clinical endotoxemia do you expect to see a “toxic line” on the oral mucous membranes?
hypodynamic state
In an endotoxemic horse, you will often clinically recognize an apparently normal CBC except for presence of __________
lymphopenia
In an endotoxemic horse, you will often clinically recognize an apparently normal CBC except for presence of lymphopenia
A 12-year-old gelding presents for bilateral fowl-smelling epistaxis. What is your most likely diagnosis?
ethmoid hematoma
Common in older horses (most often 10-12 years) and often is associated with a fowl-smelling epistaxis
T/F: Fever is associated with the hyperdynamic state of endotoxemia
True
What is the most commonly used buffer base to treat metabolic acidosis in the horse?
Lactate
__________, a dietary supplement, can be given as a treatment for endotoxemia to alter the amount of arachidonic acid in cell membranes, thus decreasing inflammatory responses
Linseed oil
Which limbs in the equine have more Type I muscle fibers?
Forelimbs
These are the major weight bearing muscles. They are adapted to constant oxygen supply and therefore have tons of capillaries and low amounts of stored glycogen. Not very powerful, but fatigue slowly
What flow rate (L/hr) can be acheived with a 14 G catheter?
13.1 L/hr
T/F: All cases of endotoxemia will result in shock presentation
False
Has to do with the AMOUNT of endotoxin that gets in the blood stream. There will always be some because mucosa of the GIT is never 100% intact in any animal (wear and tear)
Describe the clinical signs associated with early endotoxemia:
tachypnea, pale mucous membranes
Within 90 minutes: depression, restlessness, inappetance, increasing temperature
Using the following, what is the correct progressive order of respiratory structures from rostral to distal?
- Pharynx
- Nares
- Larynx
- Trachea
- Ethmoid
- Guttural Pouch
- Nasopharynx
- Nasal passage
- Nares
- Nasal passage
- Ethmoid
- Nasopharynx
- Guttural Pouch
- Larynx
- Trachea
Horses don’t have a pharynx
Calculate maintenance fluid amount for a 400 kg horse
~24 L
- Maintenance = 50-60 mL/kg/day*
- 400kg x 60mL = 24,000mL ÷ 1000 = 24 L*
On a routine prepurchase exam, a potential buyer requests you to scope the horse. You note fungal plaque-like lesions near the internal carotid artery. What is the treatment of choice?
Transarterial coil placement
A horse with 2 days duration of laminitis is found to have absence of indentation at the coronary band, and this image on radiographs. Stage the laminitis.
Chronic
Margination of __________ accounts for the leukopenia found in most horses with endotoxemia
neutrophils
TNF and IL-1 act on neutrophils and endothelial cells. Margination of neutrophils accounts for the leukopenia found in most horses with endotoxemia.
Once activation of neutrophils and endothelial cells occurs the process becomes self-sustaining and malignant
What cell is the ‘major player’ in endotoxemia?
macrophages
Interaction with macrophages is the initiating event from which most all other steps flow
In horses, development of DIC is most typically associated with __________
endotoxemia
In horses, development of DIC is most typically associated with endotoxemia; activation of coagulation cascade by various inflammatory factors, mediators, kinins, and vascular endothelial disruption
T/F: Bronchoalveolar lavage (BAL) is typically indicated if a culture is necessary for evaluation
False
Bronchoalveolar lavage (BAL) is NOT indicated if a culture is necessary for evaluation. BAL is a non-sterile procedure.
T/F: Cough is associated with upper and lower respiratory disease
True
A 3-year-old Thoroughbred presents to you with unilateral epistaxis; no prior history of trauma. Last race was 7 days ago. What is your most likely diagnosis?
guttural pouch mycosis [GPM]
What solution is most typically used to treat metabolic alkalosis in the horse?
an acidifying solution – most typically NaCl
Metabolic alkalosis is characterized by increased HCO3 and increased pH; fairly rare to see in horses
What is the pattern in which muscle fibers are recruited?
Type I → Type IIA → Type IIAX → Type IIX
Type IIX only recruited near maximal intensity (sprinting, jumping) and during extremely prolonged submaximal exercise
What is considered the most thrombogenic catheter material?
polypropylene
What are the three most common causes of reduced performance in horses?
musculoskeletal, respiratory and cardiovascular dysfunction
How do you diagnose DIC in the hypercoagulable (prothrombotic) stage in a horse?
D-dimers
- Increase in D-dimer indicates excessive amounts of fibrin formation within the vascular; increases in many situations but is a reliable indicator of DIC, deep vein thrombosis, pulmonary embolism and catheter associated venous thrombosis*
- Elisa test for D-dimer (one of many tests) seems to have highest sensitivity*
T/F: Cold extremities correlate with the hypodynamic state of the horse
True!
What is ozena?
an atrophic rhinitis marked by a thick mucopurulent discharge, mucosal crusting, and a strong odor
What is the preferred medical treatment for ethmoid hematoma in a horse?
intralesional formalin
- Intralesional formalin causes protein hydrolysis which desiccates and coagulates the tissue.*
- The preferred surgical treatment would be surgical ablation*
What is the most common acid-base disturbance in the equine patient?
metabolic acidosis
T/F: In an adult horse, you would not want to give aminoglycosides before binding the endotoxin because it will release more endotoxin when it kills off the bacteria
False
This is only a concern in foals
A horse presents with cold extremities, tachycardia, congested membranes that are dark near the teeth and lighter above, CRT of > 5 seconds and HR of 128. What is your diagnosis?
Shock, likely due to endotoxemia
MM description is that of a “toxin line”. HR is with in the shock range of 120-140.
As endotoxemia progresses, HR peaks at time of __________
maximal GIT depression
As endotoxemia progresses, HR peaks at time of maximal GIT depression (2 hrs post-endotoxin)
What are the main complications associated with catheter use in a horse?
thrombosis, cracking, breaking, air embolism, extravasation
T/F: In the hypodynamic state of endotoxemia, a horse’s extremities are expected to be cold
True
You scope a 2-year-old Thoroughbred colt for recurrent mild spontaneous intermittent unilateral epistaxis of 2 week duration. What is your top differential?
guttural pouch mycosis [GPM]
What is the most common clinical sign associated with guttural pouch mycosis [GPM]?
epistaxis
It is often the only clinical signs seen in affected adults
Which of the following is associated with abnormal lung sounds on auscultation: upper airway disease or lower airway disease?
lower airway disease
There are NO abnormal lung sounds in upper airway disease
When would you associate laminitis with a grave prognosis?
when sinking is present
If you’re unable to use the jugular vein to administer IV fluids to a horse, what are your other best options?
lateral thoracic, cephalic, saphenous
What is the ‘shock organ’ in the horse?
lungs
Endotoxin-LBP complexes bind to CD14 receptors on intravascular macrophages which are found in specific locations in each animals, known as the shock organ
A horse presents with tacky MM, HR of 56 bpm, and CRT slightly prolonged. What percentage of dehydration is present?
8%
T/F: The most common cause of renal failure in the horse is endotoxemia
True
What flow rate (L/hr) can be acheived with a 10 G catheter?
36.5 L/hr
Development of edema, swelling, cell death which can be self-perpetuating as swelling occurring in closed space:
Compartmental Syndrome
Mechanism of oxygen-radical injury; production of oxygen free radicals which contribute to cellular destruction and inflammation upon return of circulation in a previously hypoxic environment
reperfusion syndrome
This is a cationic polypeptide antibiotic that exerts its effect by binding (forming a stable complex) with lipid A, thus preventing its interaction with inflammatory cells
Polymyxin B
Epistaxis is the most common clinical sign associated with guttural pouch mycosis [GPM]. What is the second most common clinical sign?
dysphagia
slow or sudden onset
T/F: Rate of energy production when using FFAs is slower than when using carbohydrates
True
In a horse performing at 50% VO2 max (moderate exercise) for several hours, the major substrate responsible for generating energy is:
FFA
FFA oxidation is highest at 40-60% VO2 max. Above 60% VO2 max, oxidation of carbohydrates (mostly glycogen) is mostly responsible.
What is the normal respiratory rate in a horse?
8-12 bpm
What size needle is typically used for IV injections in the horse?
18 G 1-1/2” needle
No less than 19 G 1-1/2” needle
T/F: Most cases of EIPH have no clinical signs
True
What type of acid/base disturbance would you typically expect to find in an endurance horse?
metabolic alkalosis
Sweat in horses is hypertonic with high concentrations of chloride. In the case of endurance horses, large losses will result in dehydration and hypochloremic metabolic alkalosis.
pH is expected to be > high range of normal (in general > 7.45)
A horse presents with tacky mucous membranes, heart rate of 64 bpm, and CRT of 5 seconds. What percentage of dehydration is present?
10-12%
HR and CRT fit into the 10-12% range. Even though the MM are tacky, that is more of an interpretation, whereas the other two are quantitative values
What drug is used to treat EIPH and has been found to decrease pulmonary capillary pressure?
Furosemide
Given pre-race, most widely used and recommended
T/F: Bilateral nasal discharge can be associated with upper or lower respiratory disease
True
What flow rate (L/hr) can be acheived with a 12 G catheter?
26.9 L/hr
What is a major disadvantage to using the cephalic vein in a horse for IV fluid administration?
easily plugs/clots due to placement against gravity and tendency for blood to back into catheter when no flow
This pathway generates tremendous amounts of ATP and is the first pathway engaged when starting exercise, however it is only sustained for a few seconds to allow the anaerobic pathway to take over:
Phosphocreatine (PCr) Pathway
Which one of the following indicators is not reliable in the horse to determine if DIC is present?
- PT
- Fibrinogen
- FDPs
- APTT
- Thrombocytopenia
Fibrinogen
- In small animals it would be decreased in DIC but since horses have such a high increase during inflammation often times you will get normal fibrinogen levels even in DIC horse.*
- Also remember FDPs should be >3-4 to indicate significant DIC*
What three factors predispose a horse to developing synchronous diaphragmatic flutter (SDF), aka “Thumps”?
hypocalcemia, hypokalemia, metabolic alkalosis
If it is due to one disturbance alone, it is likely hypocalcemia
T/F: If a horse is only 4% dehydrated, you would not tend to see PCV changes
True
You normally do not see changes until the horse is more than 5% dehydrated. For each 2-3 % increase in percent dehydration over 5%, the PCV will increase 5%
Why would you apply DMSO to the coronary band of a horse with laminitis?
Dimethyl sulfoxide (DMSO) helps resolve local edema
anti-inflammatory and free radical scavenger
This drug reduces endotoxin-induced production of cytokines, thromboxane and tissue factor while increasing that of prostacyclin
Pentoxifylline
mostly used to minimize the development of laminitis
At rest, breathing 21% O2 in the air, normal PaO2 in a horse is approximately __________
100 mmHg
T/F: The attachment of LBP to CD14 results in increased pulmonary arterial pressure
True
Endotoxin-LBP complex binds to CD14 cell surface receptor of intravascular macrophages (IVMs), which are responsible for variability in ‘shock organs’ in various species. The ‘shock organ’ in the horse is the lung.
T/F: Exercise induce pulmonary hemorrhage [EIPH] is directly related to the duration of exercise
False
Exercise induce pulmonary hemorrhage is related to INTENSITY of exercise rather than duration of exercise or breed
T/F: Sinking is the result of tensile forces while rotational movement is the result of vertical forces
False
- Sinking = vertical forces (look @ weight of horse and hoof size)
- Rotation = tensile (from DDF pressure)
Once endotoxin gains access to the circulation, it interacts with and activates __________. This is the initiating event from which most all other steps follow.
macrophages
Once endotoxin gains access to the circulation, it interacts with and activates _macrophages_. This is the initiating event from which most all other steps follow.
T/F: Circumferential detachment of soft tissue laminae from P3 is associated with vertical displacement
True
Warm extremities are seen in __________ state of endotoxic shock
hyperdynamic
In equines, we usually do not treat metabolic acidosis specifically with bicarbonate administration unless HCO3 drops to less than __________
17-18
(or pH<7.2, BE< -10 mEq/L after initial volume resuscitation)
-
NEVER treat empirically to correct
- Need to measure actual level
- Calculate deficit: deficit X distribution X bwt in kg = __mEq
-
Factor to use for distribution of HCO3
- 0.5 younger animals
- 0.4 typical
- 0.3 conservative
- Methodology: administer 1/4-1/2 of deficit calculated deficit, traditionally half of deficit, fairly rapidly (over 60 minutes) as isotonic solution (1.35% solution) then reevaluate if continued need to re-administer
- If need more administer remaining deficit (recalculated) over 12-24hrs
- A major contraindication to treating: presence of respiratory compromise (hypoventilation) - will result in worsened academia through development of respiratory acidosis in addition to already present metabolic acidosis
Which is a more specific indicator of dehydration in the equine: TP or Albumin?
albumin
albumin is not affected by changes in globulins and/or fibrinogen as is TP
The ONLY possible cause of hyperalbuminemia is dehydration
Chronic, unilateral recurrent intermittent mild-to-moderate epistaxis with occasional ozena best describes what disease if found in a 12 year old Warmblood breeding stallion?
ethmoid hematoma [EH]
T/F: Epistaxis is observed in the majority of cases of Exercise induce pulmonary hemorrhage [EIPH]
False
Only in a small percentage of cases (1-10%) of horses show epistaxis. In most recent study only 0.8% showed epistaxis and these were usually higher grade EIPH (grade 4).
T/F: Endotoxin is normally present in enormous amounts in the normal cecum and LI
True
Within the GIT lumen, endotoxin is inhibited from being absorbed to some extent due to binding to bile salts . Damage to intact epithelium in the face of gram-negative infection can result in systemic absorption of endotoxin
What do you expect to see with regard to CRT in the hyperdynamic state of endotoxemia?
CRT = normal
What measurement gives you the best estimate of a horses athletic ability?
VO2 max
VO2 max is a measure of the maximum volume of oxygen that an athlete can use
A 17 year-old 950 lb Arabian gelding has completed an endurance race successfully. You are asked to evaluate him 2 hrs post-race as he seems to have developed “thumps”. Which of the following abnormalities would be expected in this horse?
- Hyperkalemia
- Hypocalcemia
- Hypokalemia
- Metabolic acidosis
- Metabolic alkalosis
- Respiratory acidosis
- Respiratory alkalosis
hypocalcemia, hypokalemia, metabolic alkalosis
In the average endurance horse manifesting thumps, hypocalcemia, hypokalemia and metabolic alkalosis would be expected.
Though these are the three abnormalities which predispose the horse to thumps, the endurance horse typically develops all 3 at the same time, thus the higher likelihood of seeing synchronous diaphragmatic flutter (SDF) in this population of horse compared to other horses.
What size needle is typically used for IM injections in the horse?
18-19-20 G 1-1/2” needle
No less than 21 G 1-1/2” needle
T/F: Hemosiderophages can be recovered in respiratory secretions for up to 150 days after a known episode of EIPH
True
Why are glucocorticoids contraindicated for treatment of laminitis?
thought to potentiate vasoconstrictive activity associated with shock and stress
A 6-month-old foal presents to you with digital pulses, increased digital temps and sore toe areas on both forelimbs.
T/F: Laminitis is an acceptable diagnosis
False
< 1 year of age it is virtually impossible to see the typical clinical syndrome of laminitis. This is likely due to weight loading of the feet
__________ is the most commonly given drug to inhibit the synthesis and effects of endotoxin-induced mediators
flunixin meglumine (Banamine®)
Blocks production of inflammatory mediators and blocks receptors
T/F: Large intestinal impactions are a major contraindication for administration of oral fluids in a horse
False
Oral administration of fluids is especially helpful in large intestinal impactions
T/F: When using Pentoxifylline in an endotoxemic horse, you must beware of the potential for development of severe laminitis in an already high-risk patient
False
When using _dexamethasone_ in an endotoxemic horse, you must beware of the potential for development of severe laminitis in an already high-risk patient
T/F: The hypodynamic state of endotoxemia is overall vasodilatory
True
What is the normal pulmonary artery pressure [PAP] in a horse at rest?
25-30 mmHg
PAP at intense exercise can increase to 125 mmHg
A 5 yr-old, 450 kg, Thoroughbred gelding with 8 hr of severe colic is found with the following on PE: T = 98.5 F, HR = 88 bpm, RR= 24/min, MM dry, red to purple with CRT = 4 sec. skin tenting persists, ears and legs cold, weak thready pulses. GI sounds absent.
What is the expected acid base abnormality in this horse?
metabolic acidosis
Based on GI disease and shock state, expectation is for this horse to manisfest metabolic acidosis
Describe the epistaxis associated with guttural pouch mycosis:
Several bouts of mild unilateral epistaxis weeks usually preceding fatal hemorrhage
What clinical signs are associated with the developmental stage of laminitis?
none
- This is the time spanning from the occurrence of the causative event and the development of any acute identifiable lameness; thus prior to the development of clinical signs of laminitis*
- Goal of intervention at this stage is to prevent development rather than treat an affected patient*
What respiratory noise is expected to be heard associated with laryngeal hemiplegia?
roaring
What is the most common cardiovascular disease causing poor performance in the horse?
Atrial Fibrillation
T/F: A horse can manifest a neutrophilic leukocytosis and hyperfibrinogenemia with either upper or lower respiratory disease
True
What is the most common underlying cause of laminitis?
GIT disturbances
T/F: Palpating a digital pulse in the fetlock area of a horse is helpful for diagnosing laminitis
True
What antibiotics are usually given to endotoxemic horses to target Gram-negative bacteria?
potentiated sulfas and aminoglycosides
Recognize that rapid death of Gram negative organisms due to antimicrobial therapy can temporarily worsen the endotoxemic state. This is not considered typically clinically significant in the adult horse.
T/F: Endotoxin is released during times of growth of G [+] bacteria and times of death
False
Endotoxin is released during times of growth of _Gram-negative_ bacteria and times of death
Which form of laminitis carries a poorer prognosis:
vertical displacement or rotational displacement
vertical displacement (sinking)
What is the amount of water able to be given per os in an hour?
12-16 L/hour
What is considered the least thrombogenic catheter material?
polyurethane
T/F: Presence of hemosiderophages on BAL is supportive of a diagnosis of guttural pouch mycosis (GPM)
False
Presence of hemosiderophages on BAL is supportive of a diagnosis of exercise induced pulmonary hemorrhage (EIPH)
Guttural Pouch Mycosis (GPM) is a fungal invasion of tissue resulting in erosion of the wall of the arterial structures of guttural pouch, most notably the __________
internal carotid artery
- Erosion of the ICA results in aneurysm and eventually rupture (some postulate presence of aneurysm may precede mycotic plaque – uncertain)*
- Can involve ICA, external carotid artery (ECA), and/or maxillary artery (MA)*
What signalment is associated with progressive ethmoid hematoma (PEH, EH) in horses?
- Older than 4 yrs, most often > 8 yrs (10-12 yrs) of age
- Thoroughbred, Warmbloods Arabians
How do you diagnose exercise-induced pulmonary hemorrhage (EIPH)?
endoscopy
Direct observation of blood in tracheobronchial tree
On endoscopy, a horse has multiple, distinct streams of blood covering more than 1/3 of the tracheal circumference; no blood pooling at the thoracic inlet. Grade the EIPH:
Grade 3
At what % dehydration do we expect to see dry MM in a horse?
10-12%
At what % dehydration do we expect to see reduced jugular fill in a horse?
10-12%
What heart rate is typically associated with 10-12% dehydration in the horse?
40-60 bpm
Neuronal cells can decrease osmolality by destroying __________ in cases of hyponatremia
osmoles
Neuronal cells can decrease osmolality by destroying ”osmoles” in cases of hyponatremia
T/F: Animals with hyperinsulinemia are thought to be more susceptible or at increased risk of developing laminitis
True
- this may or may not directly involve the hoof vasculature*
- Hyperinsulinemia also results in vascular dysfunction, as well as inducing SIRS which then can contribute from a inflammatory mechanism*
All of the following contribute to the mucous membranes in an endotoxemic horse in the hypodynamic stage except?
- Vasoconstriction due to Thromboxane A2
- Vasodilation due to Prostacyclin
- Decreased circulatory volume
- Decreased CO
vasoconstriction due to thromboxane A2
this occurs in the hy_per_dynamic stage. The hy_po_dynamic stage is an overall vasodilatory stage
T/F: Endotoxemia is characterized by a neutrophilic leukocytosis and a lymphocytosis
No.
- Often clinically you will recognize an apparently normal CBC except for presence of lymphopenia*
- In pure endotoxic pattern and severely affected individuals, you may see leukopenia due to early profound neutropenia - usually with left shift and toxic cells*
- If you see leukopenia & neutropenia –> very severe*
- If you see myelocytes and metamyelocytes –> poor prognosis*
Which of the following is correct with regard to bicarb administration in the horse?
- Bicarb is adminstered if it falls bellow 20
- Administer ½ over the first hour and then reevaluate and give the rest over the next 24 hours.
- Give no more than 0.5 mEq/kg/hr
Administer ½ over the first hour and then reevaluate and give the rest over the next 24 hours
