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Level 3 Pharmacology-CH25-Antimicrobials/Antibiotics
CH 25- Pharmacology Notes - Antimicrobial Agents (Antibiotics) pp. 834-838
A. Antimicrobial Agents
-antibiotics initially produced by microorganisms, which destroy OR
inhibit growth of other microorganisms
-kill life-threatening infections
Can be produced chemically
B. Antibiotics Specific
-each antibiotic effective against specific groups of microorganisms
-some are BACTERICIDAL: destroy bacteria
-some are BATERIOSTATIC: inhibit bacteria growth
**some antibiotics are BOTH bactericidal AND bacteriostatic
-species of bacteria affected by antibiotic= SPECTRUM
(broad spectrum antibiotics are effective against a wide range of microorganisms)
G+ and G-
C. Classifying Bacteria- Gram Stain
-ability of bacteria to absorb dye (Gentian violet) into the cell wall
-GRAM stain results:
G+ (absorb dye-dark blue cell walls)
G- (do NOT absorb dye-light pink cell walls)
D. Effective Antibiotic
-must be able to reach site of infection
-concentration must be maintained over period of time to destroy ALL bacteria OR
inhibit bacterial growth so natural defenses can take over
**Length of antibiotic therapy depends UPON: the microorganism (pathogen),
site of infection, duration of infection
-Minimum length of antibiotic therapy is usually 5 days
-stopping an antibiotic too soon may cause under-exposed pathogens to become
resistant to the antibiotic
**Nosocomial antibiotics are antibiotics which originate in a clinical setting
E. Choices of Antibiotic Treatment
-BEST: culture bacteria (grow on petri dish, then test several antibiotic discs)
**if bare space occurs-bacteria sensitive to antibiotic patch(disc)
-HOWEVER: sometimes time/money a concern-treat with antibiotic which seems the
BEST: Empiric Treatment
**WHEN selecting an antibiotic, one should, chose an antibiotic which destroy/inhibit the pathogen BUT NOT DISTURB the normal bacterial flora (good bacteria in body)
WHY would you not want to harm the normal-existing flora of bacteria?
CAREFUL: Over-use of potent broad-spectrum antibiotics can lead to resistant strains of bacteria
Name: _______________________ Date: ________
ANTIBIOTICS
XXXXXXXX
History
Components
Forms
Effective
1. Penicllins
2. Amino-
Glycosides
3. Cephalo-
Sporins
\
4. Quinolones
5. Chloram-
phenicol
6. Tetra-
cyclines
**Erythromycin
**Azithromycin
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Disease Prevention-CH 15-Level 2 (10th)
NOTES: CH 15 DISEASE PREVENTION –pp. 242-244
A. Animals resistant to disease because of:
- immunity
-good nutrition
-skin/mucous membranes protect from invading pathogens
- normal bacteria flora-inhibit growth of other organisms
-adhesion sites-pathogen must adhere to animal’s cells before infection begins
B. How to maintain normal bacteria flora:
-reduce stress (see below)
-proper nutrition
-medication
C. Stress in animals:
-stress considered a threat/animal (animal increases epinephrine and cortisol production)
**cortisol can help animal in stress ( increases carbohydrate metabolism, more glucose to brain, reduces inflammation to damaged tissue)
***adverse effect of cortisol- weakens immune system, increases risk of diabetes, muscle weakness) /Cushing’s Disease-(hyperadrenocorticism) = CHRONIC elevated cortisol levels
-stress increases activity of sympathetic nervous system
D. Nutrition and Stress:
-nutrition maintains immune system
Vitamins (ex. Vitamin E) and minerals (ex. selenium) keep immune system strong
Antioxidants (oxidation-inhibiting vitamins/minerals0 play role in healthy immune
system
-sudden changes in diet: (decrease normal flora in intestinal tract)
allows for pathogen invasion
**flora = good bacteria pathogen = bad(disease-causing bacteria)
**antibiotics can decrease normal flora-CAREFUL
p. 2
E. Other forms of stress in animals:
-over-crowding: increases competition for food and comfort, animals too close
(spread diseases)
-increased urine/feces contaminate animal’s environment
-humidity higher in crowded areas/allows pathogens to survive outside body
**VENTILATION: air exchanged from inside of building to outside
Without ventilation- animals exhale (add heat, moisture, pathogens to air)
Ammonia/hydrogen sulfide released from urine/feces
**the above irritate mucous membranes of animals, LOWER respiratory tract defense systems/easier for pathogens to invade respiratory tract
ALSO: without ventilation-animals stir up dust which carries pathogens and irritates respiratory tract
F. HOW to prevent Disease- FRESH AIR
-bring fresh air from outside INTO inside barn area; reduce moisture, dust, etc.
VENTILATION methods:
1. some barns built for natural air flow (IN/OUT)
2. some barns use fans to move air/keep clean
3. some barns, fans on ONE end of barn, air outlets on OPPOSITE end = TUNNEL VENTILATION (a breeze of 3-5 miles/hour can be created)
**PROBLEM- in cold weather, less air exchange can take place (heat issues) BUT..
At least 4 air exchanges per hour should STILL take place
In summer, up to 30 air exchanges may be necessary
G. OTHER:
-older animals, have a higher level of immunity than the young (WHY?) BUT..
older animals could be carriers for pathogens-THEREFORE:
**IDEAL air flow in barns should flow from the youngest to the oldest-
(young animals not exposed to possible pathogens exhaled by older animals)
**ALSO: young animals should not mingle with older animals
-keep all bedding clean/dry-this keeps animal’s fur clean/dry/ -
Level 3-Pharmacology Addendum (Anthelmentics)
Pharmacology- CH 25- Addendum Notes
Treatment of Internal Parasites
ANTHELMINTICS (de-wormers) -IMPORTANT
-parasites SHORTEN life span of animal
-parasites REDUCE quality of life for host
**Current anthelmintics eradicate the parasite and are less toxic to host
Also more convenient to give since come in chewable and paste forms
Some types of Anthelmintics:
A. Benzimidazoles- large class of anthelmintics which interfere with parasite
metabolism
1. Albendazole- fights liver flukes (flatworm in liver)
2. Fenbendazole/Mebendazole- used in small animals to eradicate
roundworms, hookworms, whip worms and SOME tapeworms
**NOTE-Adverse effects (toxicity) not usually seen at recommended dosages
B. Organophosphates- affect neurotransmitters (ACh ) of parasites
(Ex. Trichlorfon)-can be dangerous to humans
Signs of toxicity- salivation, breathing difficulties, vomiting, muscle effects
Treatment: Atropine
C. Tetrahydropyrimidines: effective against adult nematodes, not effective against
larvae
1. Morantel- used in sheep and cattle (feed additive)
2. Pyrantel- horses: pinworms, strongyls, ascarids(round worms)
Dogs: hookworms, ascarids
**NOTE: Safe and non-toxic at recommended doses
D. Imidazothiazoles- used in most species to treat parasites (equine as well)
Product packaged as (Drontal Plus, Bayer)
E. Milbemycins- paralyze parasites-
1. Moxidectin- oral dewormer/boticide for horses
2. Doramectin- injectable drug /treats roundworms and arthropod parasites
in cattle and swine
p. 2
F. **Ivermectins- paralyze nematodes by blocking motor neuron transmission
-used in a number of animal species against a wide variety of internal/external
parasites
Cattle, swine, sheep, goats: injectable ivermectin treats roundworms,
lungworms, cattle grubs, sucking lice, mites
paste/oral liquid forms treat strongyls,
pinworms, bots
Dogs/cats-mainly used to prevent heartworm, but higher dosages used to treat
Scabies(skin mites)
**CAREFUL- Pure-bred collies tend to be sensitive to ivermectin, therefore, careful
dosages must be used
Over dose symptoms-blindness, ataxia, death
****Heartworm Treatment****
AVMA recommends the following treatment strategy:
-eliminate adult heartworms first (in heart tissue) THEN
-eliminate microfilaria (immature heartworm which migrate)
-before starting HW preventive, a dog must be free of adult and microfilaria
Treatment: melarsomine dihydrochloride (arsenic agent)
given by deep IM injection
CAREFUL: cage rest required to risk of blood clots (esp. in lungs)
Severe reactions may occur: abdominal bleeding,
hematuria, tachypnea,
icterus(yellowing of skin)
****Heartworm Prevention****
Ivermectin/Milbemycin-given ONCE a month/if more than 45 days between treatments, RETEST for Heartworm
1. Milbemycin- (Interceptor by Novartis) 2. Ivermectin/Pyrantel (Heartgard Plus)
by Merial –fights hookworms too
3. Moxidectin (ProHeart, Fort Dodge)
paralyzes adult heartworm/larvae in dogs 6 months or older/injectable-last 6 mos
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Level 3-Pharmacology Addendum (Cardiac Drugs)
NOTES- CH 25- Pharmacology- Addendum: pp. 829-831
I. Diuretic and Cardiovascular Drugs
-prevent reabsorption of sodium (Na) and Water
-increase urine output and sodium excretion
A. Diuretics- relieve fluid in tissue (edema)
used for kidney, heart, liver diseases
1. Furosemide (Lasix)- prevents sodium (Na) and chloride (Cl) to reabsorb
back into the kidney
Effect: rapid, produces loss of fluid (diuresis) within 5 minutes
of IV injection
Forms: oral, injectable
**CAREFUL: lowers potassium (K) levels in blood serum- MONITOR
2. Mannitol-produces diuresis
Form: injectable
**CAREFUL: produces crystals in bottle, dissolve crystals before
administering-warm water bath
B. Cardiac Glycosides- most potent, hazardous, used to treat heart disorders
**CAREFUL-calculate, administer, observe patient OR death could
result
1. Digoxin-used to treat chronic heart failure (CHF) -esp. dogs and cats
Form: oral, tablet, liquid, injectable
Effect: reduces heart’s demand for energy/oxygen
**CAREFUL- over dose can be toxic, especially to those with existing
liver/kidney problems
symptoms of overdose: vomiting, diarrhea, loss of appetite, depression
p. 2
C. Antiarrhythmia Drugs
1. Quinidine- used to treat arrhythmias in horse/large dogs
2. Lidocaine-used as a local anesthetic, can treat ventricular tachyarrhythmias
**CAREFUL- ALL antiarrthymia drugs are toxic to heart
TOXICITY SYMPTOMS:
-horses: anorexia, colic, diarrhea, edema of nasal mucosa, dyspnea, laminitis
-dogs: vomiting, depression, lack of coordination, convulsions
***NOTE: Lidocaine if given IV in large dosages, drops blood pressure
D. Angiotensin Converting Enzyme Inhibitors (ACE) drugs
-vasodilators (enlarge blood vessels)
-primarily used to treat canine CHF
1. Hydralazine- used to treat CHF in small animals (esp. mitral valve)
**side-effect: sodium/water retention-SHOULD be given with a
diuretic
2. Pimobendan- new drug on market to treat CHF
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Level 3-Pharmacology-Addendum(Neuropharmacology)
Neuropharmacology -Addendum
Overview: CNS includes brain and spinal cord
CNS divided into:
Autonomic Nervous System- (involuntary)
Somatic (motor) Nervous System (voluntary)
Neurons relay information from CNS to rest of body using NT’s
(neuro-transmitters)
ACh is a neurotransmitter
I. AUTONOMIC DRUGS-
A. Cholinomimetic Agents: (mimic ACh)
1. Bethanechol- smooth muscle stimulant (ex. stomach, intestines, bladder)
-side affects: vomiting, diarrhea, salivation, anorexia
-over-dose: arrhythmias, hypertension, asthma
2. Cholinesterase inhibitors-prevent ACh from breaking down, -exaggerated
(used mostly to treat internal/external parasites) OR restore rumen/GI tract
back to normal after surgery)
-over-dose: nausea, vomiting, diarrhea, salivation, sweating,
increased bronchial secretions, bronchospasms,
cardiac arrest, muscle cramps, weakness
B. Anticholinergics; (inhibit/stop action of ACh)
1. Atropine- derived from belladonna plant, stop ACh
-effects: decrease salivation/bronchial secretions (low doses)
Decrease movement in GI/urinary tract (high doses)
**used to dilate (open) eye pupil
used to treat poisoning from insecticides/parasiticides/mushrooms
C. Neuromuscular Blockers/NMB’s: (paralyze skeletal muscle)
1. Vecuronium/Atracurium- newer
-effects: relax skeletal muscles, used with surgical anesthesia
-overdose: respiratory paralysis
D. Sympathomimetics: (affect sympathetic nervous system = heart rate, blood pressure,
bronchial airways)
1. Epinepherine- (released from adrenal gland when stressed) –FIGHT or FLIGHT
-effect(treats): allergic reactions, bronchospasms, cardiac issues
**not available in oral forms-destroyed by stomach acid
Short-acting
2. Isoproterenol- used as bronchodilator, cardiac stimulant
E. Phenothiazines: (used as sedatives/tranquilizers)
1. Acepromazine- (takes “the edge off”)
-used to prolong effects of anesthesia, reduces anxiety/motion sickness
**prolonged use may promote seizures in dogs
F. Others:
1. Xylazine-used widely in horses/cattle-sedative and analgesic
**CAREFUL: Causes muscle tremors, respiratory changes in horses
Cattle extremely sensitive-require 1/10 dosage used in horses
In dogs/cats-causes immediate vomiting
2. Propofol- used to introduce anesthesia, (5-10 minutes-metabolized quickly)
**CAREFUL: weakens muscular contractions, esp. respiratory actions
G. Steroids: (extremely active, effect all organ systems)
-used to treat inflammation/auto-immune diseases
**LONG-TERM EFFECTS: GI bleeding, infection risk, inability
for wounds to heal, irregular heartbeat, muscle cramps, behavioral
changes (EX: Prednisolone, Dexamethasone)
H. Non-Steroidal Anti-inflammatory Drugs (NSAIDs) -less side affects
1. Phenylbutazone- original NSAID, used more in horses
**CAREFUL: dogs metabolize drug quickly, difficult to keep in system
cats metabolize drug slowly, can become TOXIC
2. Carprofen- approved to use in dogs with arthritis (relieve pain/inflammation)