Pharmacology

Question 1

Mechanism of action of Mannitol when used to decrease ICP

Answer 1

Mannitol is osmotically active, leading to a decrease in blood viscosity and reflexive vasoconstriction of arterioles within the CNS. If given too fast it has the opposite effect. Administration should be performed over at least 30 minutes

Question 2

List four antibiotics that readily penetrate the central nervous system

Answer 2

Third generation cephalosporins
Fluoroquinolones
Metronidazole
Chloramphenicol

Question 3

You are about to anesthetize a hyper thyroid patient but noticed that he is tachycardic and hypertensive. What drugs can you use for a few days before considering anesthetic induction in order to improve his anesthetic status? Give three examples and justify your answer

Answer 3

 “Metabolic and cardiovascular abnormalities associated with hyperthyroidism make anesthesia risky; therefore cats should be made euthyroid preoperatively by administering methimazole (Tapazole) (Box 22.20). Generally, administration for 1 to 3 weeks before surgery is sufficient; however, measurement of the TT4 concentration should be repeated to ensure that it is within the normal range before surgery is performed (see comment on side effects earlier). If preoperative therapy with methimazole is not tolerated, propranolol, a β1- and β2-blocker, may be given for 1 to 2 weeks before surgery (see Box 22.20) to reduce the HR. Propranolol may be discontinued 24 to 48 hours before surgery because of its β-blocking effects, which may interfere with treatment of hypotension; however, this increases the risk of tachycardia and hypertension, especially at induction. Another preanesthetic choice would be to use metoprolol, a specific β1-blocker, and continue antihypertensive therapy until the morning of surgery. ”

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Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Question 4

What is “thyroid storm“

Answer 4

“Thyroid storm is a condition caused by excessive thyroid hormone production due to excessive catecholamine release. Clinical signs of thyroid storm may include marked elevations in HR, blood pressure, and temperature, as well as cardiac arrhythmia and shock.”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Question 5

List three drugs known to cause splenic enlargement, as well as one opioid and one sedative known not to cause this issue

Answer 5

“Acepromazine, thiopental, and propofol have been shown to cause splenic enlargement; however, hydromorphone and dexmedetomidine do not. ”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Question 6

Why should Acepromazine be avoided In patients with splenic enlargement and DIC?

Answer 6

“Acepromazine should also be avoided in these patients because of the possibility of RBC sequestration, hypotension, and impact on platelet function. ”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Question 7

What antibiotics should you avoid in patients with kidney disease? Which antibiotic classes are concentrated in urine and whats their spectrum of activity?

Answer 7

Avoid aminoglycosides, tetracyclines (except Doxycycline) and sulfonamides

Penicillins and cephalosporins are concentrated in urine, And are effective against most gram-positive organisms. Second and third generation Cephalosporins also have enhanced gram-negative spectrum
Fluoroquinolones also have broad activity against aerobic gram- negative bacteria

Question 8

What precaution should always be taken when administering enrofloxacin IV?

Answer 8

It should always be diluted 1:1 with Saline and administer very slowly

Question 9

What are the advantages of vasopressin over epinephrine during CPR?

Answer 9

Epinephrine is a potent vasoconstrictor which acts in all areas of the body including brain and heart, thereby decreasing perfusion in these organs.
Vasopressant is also a potent vasoconstrictor but acts predominantly in the periphery of the body (muscles), sparing cerebral and cardiac vasculature

Question 10

What are the most common adverse effects observed after the administration of a cholinergic agent such as bethanechol?

Answer 10

SLUDGE-M
salivation, lacrimation, urination, defecation, G.I. distress, emesis, miosis. 

Question 11

Phenoxybenzamine is frequently used to improve urination in pstients with recent (resolved) urethral obstruction. What is the mechanism of action in most likely adverse effect with this drug?

Answer 11

Adrenergic blocker (alpha one) on smooth muscle, promoting relaxation

Potent vasodilator. May cause prolonged hypotension. Used cautiously in patients with cardiovascular disease

Question 12

Diazepam is occasionally used to improve urination in patients with urethral spasms. What is the mechanism of action? Why is this drug contraindicated in cats?

Answer 12

Benzodiazepines are CNS depressant that also promote muscle relaxation.

Idiopathic fetal hepatic necrosis has been reported in cats

Question 13

Bethanechol is occasionally used in patients with urinary bladder atony. What is the mechanism of action? What are possible adverse effects?

Answer 13

Muscarinic cholinergic agonist, promoting detrusor muscle contraction

Highly contraindicated if urinary or a gastrointestinal tract obstruction is still present (may lead to rupture)

Can cause cholinergic adverse effects in sensitive patients (SLUDGE-M: Salvation, lacrimation, urination, defecation, G.I. distress, emesis, meiosis)

Question 14

Cisapride is frequently used as part of the treatment for feline megacolon and to increase the tone of the lower esophageal sphincter in brachycephalic dogs. What is the mechanism of action? Are there concerns for colinergic adverse affects (SLUDGE-M)?

Answer 14

Cholinergic agonist
Adverse effects are minimal and rare

Question 15

List 4 possible clinical signs associated with serotone syndrome

Answer 15

hypertension, hyperthermia, myoclonus, mental status changes

Question 16

What are the two “class 1 anti-rhythmic drugs “commonly utilized in veterinary medicine?

Answer 16

 “class I antiarrhythmic drugs (i.e., lidocaine and procainamide).”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
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Question 17

What drug classes (give examples) are utilized for the treatment of Supraventricular tachycardia?

Answer 17

“Supraventricular tachycardia may require β-adrenergic blockers (e.g., esmolol, propranolol, atenolol) or calcium channel–blocking drugs (e.g., diltiazem) before surgery.”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Question 18

What drug combination is typically used for the treatment of atrial fibrillation? What alternative drug can be used if the initial approach fails?

Answer 18

“Atrial fibrillation should be controlled before surgery with a β-blocker or a calcium channel blocker with or without digoxin to lower the ventricular response rate to below 140 beats/min. Alternatively, amiodarone may be used to control the ventricular response rate, and in a small percentage of cases, to convert atrial fibrillation to normal sinus rhythm.”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Question 19

Bradyarrhythmias are usually treated with anticholinergic agents (atropine or glycopyrrolate). How do you treat a bradycardia not responsive to these drugs?

Answer 19

“If bradycardia is not responsive to atropine or glycopyrrolate, temporary transvenous pacing or constant intravenous (IV) infusion of isoproterenol (see management of bradycardia on p. 828) may be required.”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Question 20

What is the most common adverse effect associated with IV lidocaine therapy when approaching the high end of the normal range (> 8 mg per kilogram)?

Answer 20

Seizures

Question 21

What is the most common adverse effects associated with the use of intravenous benzodiazepines when utilized alone?

Answer 21

“Some patients may have an unpredictable behavioral response (e.g., excitation, aggressiveness) to benzodiazepine administration; therefore they are often used in combination with an opioid”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
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Question 22

Opioids can be used for the induction of anesthesia and very sick and compromised patients, but intubation can be quite difficult. Why?

Answer 22

“Opioids can be used for induction of very sick and compromised dogs; however, opioids do not induce hypnosis, so intubation may be difficult.”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
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Question 23

List the dose-dependent effects of dopamine, including which receptors are likely being stimulated at each given dose range

Answer 23

“The effects of dopamine may be dose related, with dopaminergic vasodilatory effects predominating at low dosages (1 to 3mcg/kg/min), β effects predominating at medium dosages (5 to 10mcg/kg/min), and α effects predominating at high dosages (>15mcg/kg/min)”

Excerpt From
Small Animal Critical Care Medicine
Deborah Silverstein & Kate Hopper
https://books.apple.com/us/book/small-animal-critical-care-medicine/id903782830
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Question 24

What is the expected clinical effect of dobutamine?

Answer 24

“Dobutamine is a synthetic analog of dopamine with strong β1-agonist activity as well as some effects on β2- and α1-receptors, but without dopaminergic effects. When dobutamine is given to critically ill humans,6,13 septic dogs7 (in the author’s experience), anesthetized dogs,8-10,14 anesthetized cats,12,15 and anesthetized foals,16,17 it generally causes modest vasodilation and a marked increase in cardiac output with little change in blood pressure.”

Excerpt From
Small Animal Critical Care Medicine
Deborah Silverstein & Kate Hopper
https://books.apple.com/us/book/small-animal-critical-care-medicine/id903782830
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Question 25

What is the mechanism of action of ephedrine? What clinical effects can be expected?

Answer 25

Sympathomimetic amine (not strictly a Catecholamine)

General cardiovascular stimulant and bronchodilator that functions by stimulating the release of norepinephrine from sympathetic nerve endings.

Prolonged use can deplete norepinephrine stores, resulting in tachyphylaxis.

Can be administered as boluses or CRI

Question 26

What are the pharmacological and clinical effects of norepinephrine?

Answer 26

“Norepinephrine is primarily an α-receptor agonist and is associated with arteriolar and venous constriction. It also exhibits minimal β1-receptor agonist activity (in contrast to phenylephrine and vasopressin, norepinephrine may increase heart rate and contractility). Norepinephrine generally causes vasoconstriction and increases blood pressure, with variable effects on heart rate; cardiac output may increase,16,19-24 decrease,17,24 or remain unchanged.2”

Excerpt From
Small Animal Critical Care Medicine
Deborah Silverstein & Kate Hopper
https://books.apple.com/us/book/small-animal-critical-care-medicine/id903782830
This material may be protected by copyright.

Question 27

What are the pharmacological and clinical effects of vasopressin?

Answer 27

“Vasopressin is a noncatecholamine vasoconstrictor acting via the vasopressin V1 receptor that increases intracellular calcium and vasomotor tone (see Chapter 158). It is a pure vasoconstrictor with no direct effect on the heart. Its administration is usually associated with an increase in systemic vascular resistance, a baroreceptor reflex decrease in heart rate, no change in contractility, and no change or a decrease in cardiac output.13,16,29,30-36 Arterial blood pressure is usually increased”

Excerpt From
Small Animal Critical Care Medicine
Deborah Silverstein & Kate Hopper
https://books.apple.com/us/book/small-animal-critical-care-medicine/id903782830
This material may be protected by copyright.

Question 28

Epinephrine is a potent beta-1, beta-2, alpha-1 and alpha-2 receptor agonist. it is a potent inotrope, chronotrope, arteriolar and venoconstrictor as well as bronchodilator. Why is this drug reserved for emergency situations and not commonly used to support the cardiovascular system?

Answer 28

“Epinephrine can be used to support cardiovascular dysfunction in critically ill patients, but its therapeutic margin may not be as liberal as that of the other catecholamines (higher incidence of sinus tachycardia, ventricular arrhythmias, and increased lactate level) and it is a potent vasoconstrictor”

Excerpt From
Small Animal Critical Care Medicine
Deborah Silverstein & Kate Hopper
https://books.apple.com/us/book/small-animal-critical-care-medicine/id903782830
This material may be protected by copyright.

Question 29

What are the pharmacological and clinical effects of isoproterenol?

Answer 29

“Isoproterenol is a potent β-receptor agonist with no α-receptor activity. As such, it is a potent vasodilator and hypotensive agent. In anesthetized dogs, isoproterenol increases heart rate and cardiac output, and decreases blood pressure.8 If isoproterenol is administered very carefully while blood pressure is monitored and maintained, it can provide potent augmentation of forward blood flow and tissue perfusion.”

Excerpt From
Small Animal Critical Care Medicine
Deborah Silverstein & Kate Hopper
https://books.apple.com/us/book/small-animal-critical-care-medicine/id903782830
This material may be protected by copyright.

Question 30

Between dopamine and dobutamine, which drug is considered a “pressure drug“ and which one is a “flow drug“.?

Answer 30

“Consequently, when hypotension is the problem, dopamine is the drug of choice; dopamine is the “pressure” drug of the two. When blood pressure is acceptable, dobutamine is the drug of choice to augment forward flow; dobutamine is the “flow” drug of the two. ”

Excerpt From
Small Animal Critical Care Medicine
Deborah Silverstein & Kate Hopper
https://books.apple.com/us/book/small-animal-critical-care-medicine/id903782830
This material may be protected by copyright.

Question 31

Discuss the mechanism of action of Heparin. How is it dosed (monitoring) when used to treat PTE?

Answer 31

“Heparin acts primarily to limit the conversion of fibrinogen to fibrin by accelerating the action of antithrombin III in inhibiting activated coagulation factors (II, IX, X, XI, and XII). Unfractionated heparin (UFH) has been most commonly used because of its widespread availability and low cost. It should be dosed to prolong the activated partial thromboplastin time (aPTT) 1.5 to 2 times that of baseline. ”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 32

Elimination half-life of Fentanyl

Answer 32

“Fentanyl is commonly used as a constant-rate infusion (CRI) for analgesia in dogs and cats because it has an elimination half-life of approximately 45 minutes”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 33

Describe the role and rationale of dexmedetomidine in pain management. How does it work and what are the downsides?

Answer 33

“Dexmedetomidine, an alpha-2 agonist, is an effective sedative and analgesic (see Chapter 12 and Tables 13.2 and 13.4). Due to its cardiovascular depressant effects, it is typically given as an adjunct with other analgesics. Its effects the alpha-2 receptor in the dorsal horn of the spinal cord, brain stem, and in the periphery. It provides excellent visceral analgesia with a duration of 1 to 2 hours. A microdose CRI (see Table 13.2) can offer a constant and titratable level of analgesia; however, decreased cardiac output may still be seen. Alpha-2 agonists are synergistic with opioids. The effects of alpha-2 agonists can be reversed with atipamezole (see Chapter 12 and Table 13.2).14”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Question 34

What is Tepoxalin?

Answer 34

“Tepoxalin (Zubrin) inhibits COX-1, COX- 2, and lipoxygenase, preventing the synthesis of leukotrienes. It is administered orally as a wafer that dissolves in the mouth”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 35

What is the mechanism of action of Amantadine? How can this drug contribute to the development of serotonin syndrome?

Answer 35

“Amantadine is a dopamine agonist and NMDA receptor antagonist. The potential analgesic effect is mediated through NMDA antagonism. It appears to be most effective in cases of chronic pain and with central sensitization. It undergoes renal excretion in dogs. When used at higher doses, monitor for CNS excitement (see Table 13.2). CNS stimulation is a side effect of the dopamine agonist activity, and it should be used with caution in patients receiving other dopaminergic agents, such as the monoamine oxidase inhibitor selegiline, or agents inhibiting the reuptake of serotonin (i.e., the tricyclic antidepressant amitriptyline and the selective serotonin reuptake inhibitor fluoxetine). When used together, there is the risk of serotonin syndrome. This syndrome can be fatal and is characterized by CNS stimulation, muscle tremors, tachycardia, tachypnea, and hypertension. Hepatic dysfunction may enhance this risk as these agents are metabolized by the CYP 450 pathway. Meperidine, fentanyl, tramadol, and methadone increase the CNS concentration of serotonin and may contribute to serotonin syndrome, although the risk is unknown.20”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 36

What is the mechanism of action of amitriptyline? How does it contribute to a multimodal analgesic protocol?

Answer 36

“Amitriptyline is a tricyclic antidepressant. It is a selective serotonin reuptake inhibitor leading to increases in synaptic levels of serotonin and norepinephrine. Other actions including sodium channel blockade, NMDA receptor antagonism, and antihistamine activity may contribute to the analgesic effect. Sedation may be a side effect. Overdose may lead to tachycardia, ventricular tachyarrhythmias, hypersalivation, and vomiting. In dogs, hepatic metabolism produces the active metabolite nortriptyline; both it and amitriptyline are excreted unchanged in the urine.20”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 37

Where should local anesthetic be deposited prior to feline onychectomy?

Answer 37

“For cats undergoing a declaw procedure, a bupivacaine nerve block can provide analgesia into the postoperative period (see Table 13.2). It is injected subcutaneously, lateral and proximal to the accessory carpal pad to block the dorsal branch of the ulnar nerve, and medial to the accessory pad to block the median nerve and palmar branch of the ulnar nerve. The third site is the dorsal-medial aspect of the proximal carpus to block the superficial branch of the radial nerve.23”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 38

Lactulose is frequently utilized as part of the medical management of hepatic encephalopathy. What is the mechanism of action of this drug? What are the most common adverse effects?

Answer 38

“Lactulose is a synthetic disaccharide that acidifies colonic contents and traps ammonium ions in the lumen (see Box 20.2). It is also an osmotic cathartic that shortens intestinal transit time and reduces the production and absorption of ammonia. Lactulose may be given orally or as a retention enema. Side effects of lactulose administration may include diarrhea, vomiting, anorexia, and increased gastrointestinal loss of potassium and water. ”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 39

Prostaglandin F2alpha can be used as part of the medical management of pyometra in high value bitches. What are the effects of this drug? How long does it take to work? Adverse effects? Alternative forms?

Answer 39

“Prostaglandin F2α causes contraction of the myometrium and relaxation of the cervical canal, leading to expulsion of exudate from the uterine lumen. There is a 48-hour lag time before treatment effects are noted; clinical deterioration may occur during that time. Response to treatment consists of a decrease in uterine diameter, cessation of uterine discharge, and resolution of WBC abnormalities. Side effects associated with PGF2α include abdominal pain, emesis, defecation, tachycardia, hypersalivation, dyspnea, panting, and fever. Low-dose treatment with a natural PGF2α such as dinoprost tromethamine is effective in resolving pyometra and has fewer side effects than higher doses. Intravaginal administration of PGF2α was reported successful in 13 of 15 bitches with pyometra and was also associated with less side effects.Synthetic prostaglandins such as cloprostenol have fewer side effects than natural compounds but also produce less uterine contraction and slower evacuation of uterine exudate.”

Excerpt From
Veterinary Surgery: Small Animal Expert Consult
Spencer A. Johnston VMD, DACVS & Karen M. Tobias DVM, MS, DACVS
https://books.apple.com/us/book/veterinary-surgery-small-animal-expert-consult/id1250368401
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Question 40

What is the ONLY route of administration of vitamin K1?

Answer 40

SQ

Question 41

What consideration should be made when determining the kind of opioid to be used in a patient with biliary obstruction prior to surgical treatment?

Answer 41

“An additional concern in patients with obstructive biliary disease relates to the effect of mu-agonists (e.g., hydromorphone, morphine) on smooth muscle tone. In human beings with biliary obstruction, these drugs increase both sphincter tone and pain. Mixed agonist-antagonists (e.g., butorphanol; see Tables 12.1 and 13.2) may be preferable as premedicants and analgesics in these patients. After corrective surgery of the biliary obstruction, mu-agonists can be utilized for postoperative analgesia.”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 42

Possible adverse effect of enrofloxacin in cats if the dose exceeds 5 mg/kilogram

Answer 42

Blindness

Question 43

What are the main advantages and disadvantages of triple antibiotic ointment for the treatment of skin wounds?

Answer 43

“Triple antibiotic ointment (bacitracin, neomycin, polymyxin) is effective against a broad spectrum of pathogenic bacteria commonly infecting superficial skin wounds. However, its efficacy against pseudomonads is poor. Zinc bacitracin is responsible for enhancing reepithelialization of wounds but can retard wound contraction. Because these drugs are poorly absorbed, systemic toxicosis (nephrotoxicity, ototoxicity, neurotoxicity) is rare. The ointment is more effective for preventing infections and treating mildly infected wounds.”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 44

What are the beneficial properties and downsides of silver sulfadiazine ointment or dressing?

Answer 44

Effective against most gram-positive and gram-negative bacteria

Penetrates necrotic tissue

Enhances wound Epithelialization Open friend drug of choice for burn wounds)

Dressings may be left in place for seven days. Silver is released slowly, is non-staining, non-irritating and nonsensitizing.

Maintains a moist wound environment for Autolytic to bridement

Downside:

In vitro human studies showed toxicity to keratinocytes and fibroblasts, as well as inhibition of neutrophils and lymphocytes (the addition of aloe vera minimizes this effect)

Question 45

What is the clinical use of Mafenide? What’s the antibacterial spectrum of this drug?

Answer 45

“Mafenide (hydrochloride or acetate) is a topical sulfa compound available as an aqueous spray most commonly used for burn wounds in humans. It has a broad spectrum against many gram-positive and gram-negative bacteria, including Pseudomonas spp., Clostridium spp., and methicillin-resistant Staphylococcus aureus; it is particularly useful on severely contaminated wounds.”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 46

How is topical gentamicin used in the treatment of open contaminated wounds? What’s the preferred form? Spectrum of action?

Answer 46

“Gentamicin sulfate is available as a 1% ointment or powder (Garamycin), but solutions are preferred. Products with an oil-in-water cream base slow wound contraction and epithelialization. It is especially effective in controlling gram-negative bacterial growth (Pseudomonas spp., Escherichia coli, Proteus spp.). It is often used before and after grafting and for wounds that have not responded to triple antibiotic ointment. However, gentamicin in an isotonic solution does not inhibit contraction, and it promotes epithelialization.”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Question 47

What is the clinical use of Acemannan? Discuss its mechanism of action, best time/phase of healing for application and potential downside.

Answer 47

“Acemannan is available as a topical wound hydrogel or a freeze-dried gel form. It is indicated for managing superficial and deep partial-thickness burns, lacerations, dermal ulcers, abrasions, and nonhealing wounds. Acemannan is a β-(1,4) acetylated mannan derived from the aloe vera plant that enhances early stages of healing. Acemannan stimulates macrophages to secrete interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF-α), which enhance fibroblast proliferation, neovascularization, epidermal growth and motility, and collagen deposition to form granulation tissue. Acemannan may also bind growth factors, prolonging their stimulating effect on formation of granulation tissue. The freeze-dried form enhances healing over exposed bone and has hydrophilic properties, which help cleanse the wound and reduce wound edema. The most effective time to begin topical application is in the early inflammatory stage of healing with daily application under a bandage, continuing into the repair stage of healing. The greatest effects are seen in the first 7 days of application. Excess granulation tissue can occur, especially with the freeze-dried form, which inhibits wound contraction.”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 48

Discuss the clinical use of Aloe Vera. Agains what kind of bacteria is it most useful? Effects on wound bed? Cellular effects?

Answer 48

“Aloe vera gel is extracted from the aloe vera leaf and contains 75 potentially active constituents. Aloe vera has been used on burns because of its antibacterial activity against Pseudomonas aeruginosa. It also inhibits fungal growth. The antiprostaglandin and antithromboxane properties of aloe vera medications are beneficial in maintaining vascular patency and thus helping avert dermal ischemia. Aloe vera medications may also stimulate fibroblastic replication. Aloe vera has the ability to penetrate and anesthetize tissue”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 49

How do carboxypenicillins and ureidopenicillins compare to aminopenicillins regarding spectrum of activity?

Answer 49

“The carboxypenicillins (e.g., piperacillin/tazobactam) have better gram-negative and anaerobe spectrums than the aminopenicillins, whereas the ureidopenicillins (e.g., mezlocillin) have the best gram-negative spectrums of all the penicillins. ”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 50

Chloramphenicol- mechanism of action, spectrum of activity, bacterial resistance, penetration, potential adverse effect

Answer 50

“Chloramphenicol (Table 9.2) has broad-spectrum activity against most anaerobic and aerobic bacteria, as well as Ehrlichia spp. and Rickettsia spp., but poor activity against Pseudomonas spp. It is highly lipophilic and penetrates most organs (e.g., CNS, eye, prostate). Although considered bacteriostatic, it often achieves tissue levels high enough to make it bactericidal. It is eliminated by hepatic metabolism and urinary excretion. The drug may cause idiosyncratic fatal anemia in people, but dogs and cats experience only a mild, transient anemia, if that. It inhibits hepatic P450 cytochromes and can thus affect hepatic metabolism of certain other drugs (e.g., propofol, opiates, barbiturates).”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 51

Tetracyclines
Preferred drug
Spectrum of activity (specific bacteria most commonly targeted)
Typically not effective against…
Preferred drug type
Penetration
Interaction with food products?
Excretion
Potential adverse effect/precautions



Answer 51

“Tetracyclines are effective against many gram-positive and gram-negative bacteria, including Chlamydia spp., rickettsia, spirochetes, Mycoplasma spp., bacterial L-forms, and some protozoa. They are usually ineffective against staphylococci, enterococci, Pseudomonas spp., and Enterobacteriaceae. Doxycycline (see Table 9.2) is usually the preferred tetracycline in small animal practice because it has fewer side effects, penetrates cells better, and has less resistance develop to it compared with other tetracyclines. It is well distributed to most tissues and achieves good intracellular concentrations, although not to the CNS. Products containing calcium chelate and tetracyclines interfere with oral absorption. Binding of the drugs to calcium can be a problem in young or pregnant animals, and tooth discoloration and inhibited bone growth can occur. Doxycycline is primarily eliminated through the intestines in the dog. Typical indications include tick-borne diseases as well as respiratory and prostatic infections. Doxycycline causes hepatotoxicity in some patients, but its main adverse side effect is related to causing esophagitis after oral administration.NoteTetracyclines are caustic, and it is critical that the patient drink water immediately after swallowing a tablet or capsule (in the case of doxycycline, the patient may eat nondairy food). Otherwise the tablet may lodge in the esophagus[…]”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 52

Erythromycin (inhibits bacterial protein synthesis)
Drug class and most common forms utilized and clinical practice
Where does this drug usually accumulate and how is it eliminated?
Spectrum of activity, including specific organisms typically targeted
Advantages concerning absorption, distribution and frequency of dosing

Answer 52

“Erythromycin is a macrolide that is readily absorbed from the upper gastrointestinal system and diffuses well throughout most tissues. All macrolides tend to accumulate in phagocytic cells and are usually eliminated in the bile. Erythromycin has a narrow spectrum of activity and may be associated with nausea and vomiting because of its prokinetic activity. New derivatives include clarithromycin and azithromycin. Azithromycin (see Table 9.2) is active against aerobic bacteria, such as staphylococci and streptococci, and anaerobes. It also has good activity against Mycoplasma spp. and intracellular organisms, such as Bartonella spp., Toxoplasma spp., and atypical mycobacteria. Absorption of azithromycin after oral administration is high, and it is well tolerated. The drug achieves extremely high tissue concentrations and only needs to be given once daily.”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 53

Clindamycin
Drug class
Where does this drug usually accumulate /concentrate and how is it eliminated?
Spectrum of activity, including specific organisms typically targeted
Common clinical uses
Most common concern /adverse effect

Answer 53

“Clindamycin (see Table 9.2) is a lincosamide that is primarily eliminated by biliary excretion and achieves excellent concentrations in the skin and bones, as well as high concentrations in white blood cells. It is effective against most anaerobic bacteria, plus it is active against many gram-positive pathogens. Typical indications include intra-abdominal infections, osteomyelitis, discospondylitis, and oral/dental disease. Clindamycin can be used in combination therapy directed at Pseudomonas aeruginosa; it inhibits bacterial adherence to epithelial cells, making it more susceptible to other antibiotics. Clindamycin is effective against toxoplasmosis and Neospora, and it can cause esophagitis if the pill stays in the esophagus (especially in cats).”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 54

Beta lactamase and aminoglycosides are frequently used together for their synergistic affect. Can these drug classes be mixed in the same syringe for IV administration? Why?

Answer 54

“A β-lactam drug should never be mixed in the same syringe, vial, or intravenous (IV) line with an aminoglycoside; mixing the two can result in a chemical reaction that inactivates one or both of the drugs.”

Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.

Question 55

Levetiracetam
Mechanism of action
Safe to use in PSS patients? Why?

Answer 55

Broad- spectrum anticonvulsant. Blocks SV2A, a synaptic vesicle protein. Minimal protein binding and excreted via kidneys, so safe for liver disease.

Question 56

Mechanism of action of lactulose for the treatment of hepatic encephalopathy

Answer 56

Ammonia is produced by G.I. microbiotita it is typically converted to urea and glutamine via the urea cycle in the normal liver. The abnormal blood flow associated with PSS results in ammonia accumulation. Lactulose is metabolized by colonic bacteria, resulting in the formation of carbon dioxide, lactic, formic and acetic acids. The resulting acidic environment promotes the conversion of ammonia to ammonium, which is not readily absorbed and becomes ion trapped and expelled in the feces.

Question 57

Antibiotics like metronidazole and ampicillin are frequently used to reduce the intestinal load of urease producing bacteria in cases of portosystemic shunt. What are the advantages of one versus another?

Answer 57

Metronidazole - broad coverage against urease-producing bacteria; concentration dependent.

Ampicillin - time dependent, not as broad-coverage against urease-producing bacteria as metronidazole but no concerns over neurotoxicity.
Ampicillin is preferred over amoxicillin due to its lower oral bioavailability (Minimizes systemic absorption)

Question 58

Post atenuation seizures may occur in up to 20% of dogs undergoing surgery for PSS. Midazolam is favored over diazepam as the drug of choice for seizure control. Why?

Answer 58

Intravenous diazepam contains a propyleneglycol carrying agent that requires hepatic metabolism

Question 59

Propofol is considered an adequate drug for induction of general anesthesia and and control of post- attenuation seizures in patients with PSS. Why? What precautions should be considered?

Answer 59

Post attenuation seizures are believed to be caused by an imbalance in the endogenous inhibitory CNS benzodiazepine agonist levels.
Propofol undergoes hepatic microsomal enzyme metabolism, like many drugs, but also has extrahepatic metabolic sites. It is believed to be beneficial for the treatment of status epilepticus because of it GABA activity at a different site from benzodiazepines.
 propofol is protein-bound. Those adjustments must be made in patients with low albumin.

Question 60

Why is phenobarbital not considered a first choice drug for the treatment of post attenuation seizures in patients with PSS?

Answer 60

Phenobarbital has a lower lipid solubility and may take up to 30 minutes to reach therapeutic concentrations (benzodiazepines are much faster).
Phenobarbital has also been shown to cause hepatic injury after long term administration in dogs.

Question 61

What commonly used postoperative drug is absolutely contraindicated in a patient operated for the attenuation of a PSS?

Answer 61

Nonsteroidal anti-inflammatories

 One study found a 38.5% mortality rate in dogs with intrahepatic shins treated with NSAIDs perioperatively, compared with 2.4% in dogs not treated with NSAIDs. All dogs in the study died because of confirmed or suspected gastroduodenal ulcerations. 

Question 62

What is the reported impact of omeprazole on gastric acid secretion?

Answer 62

Omeprazole has been reported to reduce gastric acid secretion by 80 to 95%

Question 63

What drug has been reported as potentially most useful reducing the incidence of the most common life-threatening complication following attenuation of PSS?

Answer 63

Omeprazole. Studies regarding intrahepatic PSS have demonstrated that up to 21% of dogs have lifelong risk for GI ulceration  with significantly shorter survival time. Specifically for dogs undergoing treatment of intrahepatic PSS Prior to anti-acid therapy, 50% of deaths were attributed to G.I. bleeding. Lifelong anti-acid therapy reduced this rate to 4%

Question 64

S-Adenosyl-Methionine (SAMe) is frequently prescribed for the therapy of patients with liver disease. Why?

Answer 64

SAMe is an endogenous coenzyme necessary for various hepatic functions including transmethylation and decarboxylation, as well as the production of glutathione, a crucial hepatic antioxidant.

Question 65

Cerenia
Mechanism of action

Answer 65

Neurokinin 1 receptor antagonist. Binds Substance P in emetic center in brain.

Question 66

Mirtazepine
Drug class
Mechanism of action

Answer 66

Tricyclic antidepressant
Alpha-2 adrenergic receptor antagonist

Blocks presynaptic alpha-2, serotonin (5HT) and histamine receptors

Question 67

Clinical signs of baclofen toxicity

Answer 67

Lack of gag reflex
Vocalization
Tremors
Sialorrhea
Stupor
Bilateral miosis
Intermittent hippus (rhythmic oscillation of the pupil)

Question 68

Intravenous Lipid Emulsion (ILE) is considered safe. What adverse effects can be observed in cases of gross overdosage?

Answer 68

Cardiovascular dysfunction
Coagulopathy
Hemolysis
Thrombocytopenia
Acute kidney injury
Hypertension (due to increased catecholamines?)

Question 69

Mechanism of action and proposed advantages of Theophylline versus other bronchodilators in the therapy of bronchitis

Answer 69

Phosphodiesterase III receptor inhibitor, increasing amounts of circulating cyclic AMP and co sequently epinephrine.

Also suppresses the production of inflammatory mediators and histamine release. May stimulate mucocilliary system and help clear mucous.

Question 70

Theophylline may cause CNS stimulation. How?

Answer 70

Appears to suppress Adenosine receptors (like caffeine), leading to CNS stimulation in dose-dependent fashion

Question 71

Elura (Capromorelin Oral Solution) for cats
Mechanisms of action (2)
Advantages over Cerenia and Mirtazepine (2)

Answer 71

Stimulates metabolic changes via GH and IGF-1
Mimics the effect of ghrelin, a naturally occurring hormone
Approved for long term use in cats
Tested and approved for use in cats with CRD
Increases food intake

Question 72

Pimobendan - two main effects and mechanism of action for each

Answer 72

Positive inotrope - increases Ca++ binding to myofibrils

Vasodilator - phosphodiesterase inhibitor

Question 73

Which of the following medications, at higher doses to treat systemic hypertension, may paradoxically activate the Renin Angiotensin Aldosterone System in the dog?

Amlodipine
Benazepril
Spironolactone

Answer 73

Amlodipine

Question 74

According to Gallaher et al. 2019 (Veterinary Surgery), what was the effect of NSAID therapy on bone healing following osteotomies?

Answer 74

No effect up to two weeks, but delayed healing if extended to 8 weeks.

Radiographic healing did not differ between dogs without carprofen and those with 2-week administration of carprofen (P =.9923).However, tibias of dogs without carprofen and those with 2-week administration of carprofen were more healed compared with those in the 8-week-carprofen group at 4 and 8 weeks after surgery (P = .0011). No treatment effect was detected by cartilage:callus ratio or BMD.

Question 75

How rapidly does prednisolone sodium succinate reach the cellular level and how rapidly is it removed from the circulation?

Answer 75

1 minute
90 minutes

Question 76

How rapidly does methylprednisolone sodium succinate reach the cellular level and how rapidly is it removed from the circulation?

Answer 76

1 minute

240 minutes

Question 77

Define the principles of “oral tolerization” and “Clonal Anargy” as they apply to oral collagen supplements.

Answer 77

1) Oral tolerization: The exposure of the GI tract Payer patches to small amounts of antigen leading to gradual desensitization through bystander suppression.

2) Clonal Anargy: The exposure of the GI tract Payer patches to large amounts of antigen, converting overactive Th1 lymphocytes into a state of non-reactivity.