Presented by-
Sindhu K,
M. V. Sc. Scholar, Dept. of VPT, COVAS, Pookode.
Greek: an = without
aesthesia = sensation
Anesthesiology is defined as art & science of administration of anesthesia.
Anesthesia term coined (1846) by an American physician Oliver Wendell Holmes, Sr. (1809-1894)
In 1975, The American College of Veterinary Anesthesiologists was officially recognized by the American Veterinary Medical Association as the body to certify veterinarians as specialists in veterinary anesthesia.
To apply methods to
minimize / eliminate pain,
relax muscles,
Facilitate patient restraint during surgical, obstetrical, medical, diagnostic & therapeutic procedures.
To monitor & support
Life functions in patients during the operative as well as in critically ill, injured, / seriously ill patients.
Elimination of sensibility to noxious stimuli.
Humane restraint (protect animal, facilitate diagnostic/surgical procedure).
Technical efficiency (protect personnel, facilitate diagnostic/surgical procedures).
Specific biomedical research tool (sleep time).
Control convulsions.
Euthanasia.
Prevention of the perception of noxious stimuli (pain) during surgery is the primary justification for anesthesia.
A noxious stimulus = stimulus that potentially damages the body tissue.
Nociception has no emotional/perceptional connotation.
Pain is an unpleasant sensory & emotional experience; it is a perception, not a physical entity.
Perception of pain depends functioning cerebral cortex.
• Sensory
• Discriminative
• Motivational
• Affective
Anesthesia is produced by
Chemicals (drugs)
Physical (sensory nerve destruction)
According to route of administration:
Topical.
Injection.
Gastrointestinal tact.
Respiratory system.
I. Cutaneous.
II. Mucous membrane.
I. Intravenous
II. Subcutaneous
III. Intramuscular
IV. Intraperitoneal
V. Intraosseous
Oral
Rectal
I. Inhalation
Based on extent of loss of sensation
1. Local/regional: drugs placed in close proximity to nerve membranes, causing conduction block.
Eg: topical, area infiltration, perineural, peridural, subarachnoid.
2. General anesthesia: state of controlled, reversible CNS depression including unconsciousness produced by one/multiple drugs.
Eg: injectable, inhalation, balanced.
Administered usually to conscious or mildly sedated animals, to desensitize a localized or regional area of the body.
It is deposited in close proximity to nerve membrane causing nerve conduction blockade.
GA is a condition induced by pharmacological or other means that results in controlled, reversible CNS depression.
Basic elements of GA:
I. Reversibility
II. Unconsciousness
III. Amnesia
IV. Analgesia
V. Muscle relaxation
VI. Immobility
A favorable anesthetic course begins with good plan – a plan based on sound pharmacological & physiological principles.
Anesthetic management = physiology of respiration + circulatory + central + autonomic nervous system.
Pre-anesthetic period.
Anesthetic period/ peri-anesthetics period.
Post-anesthetic period.
Tranquilizer-sedative (Acepromazine, benzodiazepines).
Hypnotic sedatives (pentobarbital & chloral hydrate).
Opioid (agonist-morphine & meperidine, agonist-antagonist-butorphanol).
Alpha-adrenergic agonist (xylazine, detomidine, medetomidine).
Dissociative (ketamine)
Parasympatholytics (atropine & glycopyrrolate).
Sedative drugs (telozol = tiletamine + zolazepam).
Administration of anesthesia requires a combination of knowledge + skill+ ingenuity.
Given by inhalation / injections.
Classification
Hypnotic sedatives
Dissociative
Opioid
Tranquilizer-sedatives
Balanced anesthetics.
Also known as anesthetic recovery period.
Hazards of immediate postanesthetic period:
Circulatory system complication arterial hypo- & hypertension, cardiac dysrhythmias.
Respiratory system complications hypoxemia, hypercapnia
Pain nociception
Emergency excitement physical trauma
Hyper-/hypothermia
Vomiting
Delayed awakening.
• Used clinically act by interfering with the effectiveness of the endogenous neurotransmitter Ach to activate nicotinic cholinergic receptors of skeletal muscle cells, thereby inhibiting receptor-coupled transmembrane ion movements necessary for muscle contraction. (Bouzat et al. 2004: Unwin 2005).
• End result = skeletal muscle paralysis + muscle relaxation.
• Most often used as adjuvants to anesthesia to facilitate tracheal intubation, abdominal muscle relaxation, orthopedic manipulations & as a part of balanced anesthesia procedure to reduce the amount of GA required in high-risk patients.
A direct alteration of the effectiveness of Ach to activate postjunctional receptors.
According to the mechanisms of postjunctional action, neuromuscular blocking agents are classified as
I. competitive (nondepolarising) agent.
II. depolarizing agent.
Drugs compete with Ach for available cholinergic receptors at postsynaptic membrane & by occupying these receptors, prevent the transmitter function of Ach.
Prototype: d-tubocurarine (Tubocurarine chloride, USP, Tubarine).
Metocurine Iodide, USP (Metubine).
Gallamine Triethiodide, USP, (Flaxedil) gallamine.
Pancuronium Bromide, Pavulon, Pancuronium.
Synthetic compound: alcuronium, atracurium.
Vecuronium, a derivative of pancuronium.
Drugs exert their skeletal muscle paralyzing effects by interfering with Ach-mediated depolarization of the post synaptic membrane.
Prototype: Succinylcholine chloride USP (quelcin, anectine, sucostrin, suxamethonium).
Decamethonium bromide, USP (syncurine, C-10)
Muscle paralysis head & neck muscles (head drop) tail limb muscles deglutition & laryngeal muscles abdominal muscles intercostal muscles diaphragm.
Recovery usually proceeds in the reverse sequence (Hall, 1971).
Unique among anesthetic drugs
because of ease in administration & in large part removed from the body, via the lungs.
Used widely for anesthetic management of animals due to their pharmacokinetic characteristics favors predictable & rapid adjustment of anesthetic depth.
Specialized apparatus is used to deliver the inhaled agents, helps minimize patient morbidity/mortality facilitates accurate & controlled anesthetic delivery, lung ventilation & improved arterial oxygenation.
Group I : agents in current use for animals.
Volatile halothane, isoflurane, desflurane, sevoflurane.
Gas nitrous oxide (N2o)
Group II : gaseous agent under investigation
Xenon
Group III : volatile agents of immediate past use/ interest.
Enflurane
Methoxyflurane
Diethylether
Provide rapid means of producing sedation/anesthesia in veterinary patients.
Advantage of injectable anesthetic over inhalation the ability to proceed more rapidly through stage II anesthesia (the excitement stage).
These agent allows a more rapid control of airway, smooth induction of anesthesia, rapid control & reduction in CNS activity, unobstructed visualization of URT for surgical procedures.
For large animal (horses), preventing the excitement stage is paramount for the animal’s safety + medical personnel.
Physiological properties unconsciousness, amnesia, analgesia & skeletal muscle relaxant.
Pharmacological properties margin of safety/ therapeutic index, short duration of action & noncumulative, readily metabolized & excreted ideally by > one route, a specific & complete reversal of anesthesia.
Ideal drug chemically stable, long shelf life, physiological pH, nontoxic vehicle & inexpensive.
I. Barbiturates. (thiopental, pentobarbital, amobarbital & phenobarbital.)
II. Non barbiturates – non dissociative anesthetics.
a. Phenol derivatives (propofol & fospropofol)
b. Imidazole derivatives (etomidate & metomidate)
c. Neurosteroids (alfaxalone-alfadolone & alfaxalone-CD)
d. Benzodiazepines (midazolam, diazepam & lorazepam)
e. Opiods, neuroleptanalgesics & neuroleptanalgesthics.
(fentanyl, fentanyl+droperidol, methadone+acepramazine+nitrousoxide.)
f. Miscellaneous i/v anesthetics [chloralhydrate, Guaifenesin (triple drip), chloralose, propranidid, tribromoethanol, urethane]
III. Dissociative anesthetics (ketamine, phencyclidine & tiletamine).
Classification Compounds Clinical
applications
Ultra short acting Thiopental, thiamylal,
thialbarbital, hexobarbital,
methohexital.
As general anesthetic
Short acting Pentobarbital, secobarbital. As hypnotic, pre-anesthetic &
emergency management of
seizures.
Intermediate acting Amobarbital, aprobarbital,
mephobarbital.
As hypnotic, pre-anesthetic &
emergency management of
seizures.
Long acting Barbital, phenobarbital. As anticonvulsant &
sedatives.
An anesthetic state caused from interruption of
ascending transmission from the unconscious to conscious part of the brain.
Characterized by catalepsy.
somatic analgesia.
intact ocular+laryngeal+pharengealreflexes.
control of the airway may not be complete, intubation with a cuffed endotracheal tube is recommended.
Commonly used induction + maintenance of anesthesia in cats & dogs.
CNS acting drugs which decreases activity, moderate excitement, produce drowsiness & calm the recipient.
Drugs having capacity to decrease the CNS activity calming & drowsiness.
Clinical indication to produce restrain.
to facilitate handling + transport.
to modify behavior of animals.
Sedative = non specific ~ general CNS depressants.
I. Hypnotic-sedatives/ Classical sedatives.
II. Tranquilliser-sedatives/Tranquillisers (ataractics, neuroleptics).
I. Benzodiazepines diazepam, midazolam, lorazepam.
II. Alpha2 adrenoceptor agonists xylazine, detomidine, medetomidine, romifidine & clonidine.
III. Barbiturates barbital, phenobarbital, amobarbital, secobarbital, pentobarbital.
IV. Chloral derivatives chloral hydrate.
V. Aldehydes paraldehyde.
VI. Inorganic salts sodium bromide, potassium bromide & magnesium sulphate.
VII.Miscellaneous agents ethyl alcohol, ethchlorvynol, glutethimide, methyprylon, ethinamate & meprobamate.
I. Phenothiazines chlorpromazine, acepromazine,
promazine, piperacetazine, triflupromazine.
II. Thioxanthenes chlorprothixene, clopenthixol, thiothixene.
III. Butyrophenones azaperone, droperidol, fluanisone.
Diverse group of drugs used primarily in the treatment of epilepsy.
It is important to 1st approach epilepsy as a manifestation of an underlying disease.
When the underlying cause of disease cannot be identified (idiopathic epilepsy) or treated management of epilepsy is primarily based on control of seizures with anticonvulsant drugs.
Major molecular target of commercially available drugs
Voltage gated sodium channels.
GABA a receptors.
The GAT-1 GABA transporter.
GABA transaminase.
I. Barbiturates phenobarbital, pentobarbital & mephobarbital.
II. Deoxybarbiturates primidone
III. Hydantoins phenytoin, mephenytoin, ethotoin, fosphenytion.
IV. Benzodiazepines clonazepam, diazepam, lorazepam, oxazepam, clorazepate.
V. Aliphatic carboxylic acids valoproic acid & sodium valproate
VI. Bromides potassium bromide & sodium bromide
VII.Succimides ethosuximide, methsuximide, phensuximide & mesuximide
VIII.GABA analogues gabapentin, vigabatrin, pregabalin, progabide
IX. Dicarbamates felbamate & meprobamate
X. Sulphonamides zonisamide, acetazolamide, methazolamide & sultiame
XI. Pyrrolidines levetiracetam, brivaracetam & seletracetam
XII. Carboxamides carbamazepine, oxcarbazepine, eslicarbazepine& rufinamide
XIII. Oxazolidinediones trimethadione, paramethadione & etadione.
XIV. Miscellaneous agents topiramate, lamotrigine, valpromide, beclamide, lacosamide, paraldehyde, tiagabine, stiripentol & valnoctamide.
Veterinary clinical ethology A relatively new branch of vet. Medicine dealing with study of customs & behaviour of animals in their natural habitat.
Behaviour is a complex phenomenon.
It is not easy to define in terms of normal & abnormal behaviour.
Adverse behaviour in animals disease condition (neural disorders).
lack of socialization & training.
genetically determined.
Classification of behaviour disorders on basis of their origin.
Genetic problems, developmental & age related problems, instinctive & species related problems, socialization/ social behaviour related problems, disease related problems & adaptation problems.
Sr. no. Behaviour disorder Etiology
1 Aggression Dominance, competition, fear, learned, idiopathic &
feeling of uncertainty.
2 Anxiety Separation, travelling, new place & unfriendly
environment.
3 Fear/phobia Thunderstorms, gunshots, fireworks, heavy vehicle’s
engine noise.
4 Destruction Fear anxiety, over activity & reaction to arousing
stimuli.
5 Excessive vocalization Frustrated social/sexual environment, aggression &
reaction to external stimuli.
6 Elimination behaviour
(urination/defecation)
Marking territory, urine spraying (cats), submission,
excitement, lack of training & separation.
7 Sexual behaviour Hyper-sexuality, lack of libido, false pregnancy.
8 Self mutilation Attention getting & stress response.
9 stereotypies Stress response & compulsive behaviour.
Abnormal behaviour in man/animal is closely related to alterations in concentrations of various neurotransmitters
Biogenic amines
Acetylcholine
Excitatory AA
Inhibitory AA
A wide variety of drugs from different pharmacological classes are employed to modify abnormal behaviour in animals Psychotropic drugs, anticonvulsants, hormonal preparations, CNS stimulants, artificial pheromones & miscellaneous drugs.
Algesia = ill-defined, unpleasant sensation,
usually evoked by external / internal noxious stimulus.
Physiological pain nociceptive pain.
Pathological pain neurogenic & cancer pain.
Opioids potent analgesic agents, which induces analgesia by stimulation of central opioid receptors.
Classified into
I. Opioid agonists.
II. Opioid mixed agonist-antagonists & partial agonists.
I. Natural opium alkaloids morphine & codeine.
II. Semi-synthetic opioids diacetylmorphine, hydromorphine, oxymorphone, hydrocodone, oxycodone, etorphine.
III. Synthetic opioids
1. Phenylpiperidines (pethidine, ketobemidone, prodine, allylprodine, anileridine).
2. Anilidopiperidines (fentanyl, alfentanil, carfentanil, sufentanil).
3. Diphenylpropylamine derivatives (methadone, propoxyphene, dextromoramide, dipipanone, loperamide & diphenoxylate).
4. Morphinans (levorphanol & levomethorphan).
5. Benzomorphans (phenazocine).
6. Miscellaneous drugs (tramadol, tapentadol & tilidine).
I. Semi-synthetic opioids (buprenorphine & nalbuphine).
II. Synthetic opioids
1. Morphinans (butorphanol).
2. Benzomorphans (pentazocine, dezocine & cyclazocine).
3. Miscellaneous agents (meptazinol).
Drugs which stimulate the CNS/improves specific brain functions.
Classification pyscostimulants / cerebral stimulants
brain stem stimulants / analeptics
convulsants
psychotomimetics / hallucinogens
Small animal clinical pharmacology: D. M. Boothe. (2nd ed.)
Veterinary Pharmacology and Therapeutics: Jim E Riviere & Mark G Papich. (9th ed.)
Veterinary pharmacology and therapeutics: H. R. Adams. (8th ed.)
Essentials of veterinary pharmacology & therapeutics: H. S. Sandhu. (2nd
ed.)
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