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Boards: Species > Birds > Flashcards

Birds Flashcards

1
Q

Temperature Regulation of Birds

A

○ Core body temps 39-42℃ (102-107.6℉) indicate HIGH metabolic rate
○ Low tolerance for low temps; significant effect of hypothermia

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2
Q

Functions of the Avian Respiratory System

A

○ Gaseous exchange
○ Vocalization
○ Thermoregulation

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3
Q

Main Features of Avian Respiratory System

A

Small lungs that undergo little change in volume when breathing

Air sacs DO not participate to gas exchange

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4
Q

What are the two main components of the avian pulmonary system?

A

Separate, distinct components

One for ventilation, one for GE

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5
Q

Tracheal Variations btw Species of Birds

A

1.Inflatable sac-like diverticulum
2. Double trachea (penguins, petrels)
3. Complex tracheal loops or coils within caudal neck in keep or within thorax/keel
–Fxn: large booming calls with low driving pressures

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6
Q

Larynx in Birds

A

○ Tracheal opening located at the base of the tongue
○ No epiglottis → easy visualization when tongue is gently pulled forward

Exception: Flamingo due to ventroflexion beak, large fleshy tongue

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7
Q

Trachea in Birds

A

Complete cartilaginous rings

Connects nares and mouth to the bronchi

Functions: warming, moisturizing, and screening particulate matter from inspired gas

Difference in trachea in between species:

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8
Q

Effect of Different Tracheal Anatomies in Birds?

A

Significant increase in tracheal dead space

Typical avian trachea vs trachea of comparably sized mammals 2.7 times longer BUT 1.29 times wider
= tracheal resistance to gas flow comparable
● Tracheal dead space volume in birds is ~ 4.5 times larger than that of comparably sized mammals, BUT relatively low respiratory frequency + larger tidal volume of birds decreases effect of larger tracheal dead space volume
● Avian minute tracheal ventilation = 1.5-1.9 times that of mammals

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9
Q

Syrinx

A

● Sound-producing organ
○ At junction of trachea and mainstem bronchi
○ Intubated birds can produce sounds, especially during PPV

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10
Q

Bronchi in Birds

A

3 orders of bronchial branching before gas exchange tissue reached
1. Primary bronchus (extra- and intrapulmonary)
2. Secondary bronchi
3. Tertiary bronchi or parabronchi

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11
Q

Role of Parabronchi, Surrounding Mantle of Tissue

A

Parabronchi, surrounding mantle of tissue (parabronchial mantle) = where gas exchange occurs, air capillaries within walls

Serve to connect ventrobronchi to dorsobronchi, laterobronchi

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12
Q

Primary Bronchi

A

–Enters junction of cranial, middle thirds of lung

–Gives rise to abdominal air sac, secondary bronchi

–Low columnar pseudostratified epithelium + well-developed internal circular smooth muscle layer + longitudinally oriented smooth muscles → contraction changes internal diameter

Movement of air only, no GE

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13
Q

Secondary Bronchi

A

–Arise from primary bronchus, same histology

–Arranged in four groups:
1. medioventral**
2. mediodorsal
3. lateroventral**
4. laterodorsal

Medioventral: gives rise to cranial air sacs
Lateroventral: gives rise of caudal thoracic air sacs

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14
Q

Air Sacs in Birds

A

9 Total

Arise from medioventral secondary bronchi: clavicular (1), cervical (2), cranial thoracic (2)

Arise from lateroventral secondary bronchi: caudal thoracic (2)

Arise from intrapulmonary bronchus (ie continuation of primary bronchus): abdominal (2)

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15
Q

How Group Air Sacs

A

-Cranial = cervical, clavicular, cranial thoracic
-Caudal = caudal thoracic, abdominal

Volume equally distributed btw cranial, caudal groups

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16
Q

Air Sac Structure and Function

A

Thin-walled structures composed of simple squamous epithelium, vessel poor
● Air sac do not contribute to gas exchange

Function: provide tidal flow of air to the relatively rigid avian lung [avian lung changes in volume by only 1.6%]

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17
Q

Air Sac Role During Movement of Gases

A

only volume-compliant structures in body cavity

inspiration → negative pressure within air sac →air flows from atmosphere into pulmonary system (air sacs + gas exchange surface areas of the lungs)

expiration → positive pressure within air sac →air flows from pulmonary system, air sacs to atmosphere

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18
Q

IInspiration in Birds

A

Contraction of Abdominal M
Elevation of Keel
Internal vol, thoracolumbar cavity increase
Negative intracoelomic pressure - air enters

BOTH INSPIRATION, EXPIRATION ACTIVE IN BIRDS

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19
Q

Intubation in Birds

A

can be difficult in small birds

Glottis can be difficult to visualize

Commercially available endotracheal tube manufactured for small birds do not exist

UNCUFFED TUBES

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20
Q

Use of IVC To Intubate Birds

A

do not possess same degree of flexibility, thermoplasticity of a commercially available ET tube

Can cause tracheal trauma (abrasion or puncture)

Must be of appropriate circumference: it needs to allow some degree of gas leak between tracheal wall and the catheter to avoid air sacs volutrauma or lung barotrauma

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21
Q

Bird Intubation: tube occlusion

A

Why:
–Small ETT diameter
-_Cold, dry FGF makes mucus thicker, more tenacious

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22
Q

Detection of Tube Obstruction in Birds

A

–Prolonged expiratory phase
–Gurgling on auscultation

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23
Q

Management of Airway Obstruction in Birds

A

● Extubating patient, cleaning tube, re-intubating, or by replacing with clean one
● Anticholinergic IM (atropine, 0.04 mg/kg, or glycopyrrolate 0.01 mg/kg) to reduce mucus production

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24
Q

Endotracheal Intubation and Risks in Birds

A

Because of complete cartilaginous tracheal rings, overly inflated cuff will injure tracheal mucosa or rupture tracheal rings
● Avian tracheal rings tend to rupture longitudinally

Larger birds (ostriches, emus) will need larger tubes: 10-18, 9-14

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25
Q

Ventilation in Emus

A

Tracheal cleft in emus does not complicate intubation, may make PPV difficult: can be overcome by placing snug wrap around distal third of neck

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26
Q

Body Position and Muscle Relaxation in Birds

A

body position may adversely affect ventilation (depending on species)
■ DORSAL RECUMBENCY IN CHICKEN (large breast muscles)

Weight of abdominal viscera →compress abdominal air sacs →reduced tidal volume

Anaesthesia causes myorelaxation → difficult to generate sufficient muscular effort to lift keel against gravity (in particular in birds with large heavy pectoral muscles) → reduced tidal volume

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27
Q

Sternal Recumbency in Birds

A

Sternal recumbency appears to be detrimental

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28
Q

How Manage Ventilation Challenges in Birds

A

Maintain light plane of anesthesia

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29
Q

Role of the Parabronchi

A

Increase total gas exchange, surface area

Basic unit for gas exchange: = Tertiary bronchus (parabronchus) + surrounding tissue (air capillaries + blood vessel)

Long, narrow tubes that anastomose profusely
■ Entrances guarded by smooth muscles

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30
Q

Tubular Parabronchi Subunits

A
  1. Atria
  2. Infundibula
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31
Q

Atria

A

opens into chambers, separated from one another via interatrial septa
–Bundle of SmM at opening, allow for SNS/PSNS control of air flow through parabronchi

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32
Q

Infundibula

A

funnel shaped duct arising from floor of atria, leads to air capillaries/meshwork with blood capillaries = site of GE

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32
Q

Infundibula

A
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33
Q

LaPlace’s Law and Avian Lungs

A

High surface tensions = air capillaries of small diameter → generate significant negative pressure across blood-gas barrier
■ This could lead to influx of fluid or collapsed tubules

Air, blood capillaries possess structural elements that preserve anatomy/gas exchange

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34
Q

What are the two types of parabronchial tissue?

A
  1. Paleo-pulmonic
  2. Neo-pulmonic
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35
Q

Paleo-pulmonic Parabronchial Tissue

A

found in all birds, consisting of parallel stacks of profusely anastomosing parabronchi
○ Unidirectional Gas Flow (aerodynamic valves)

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36
Q

Neopulmonic Parabronchial Tissue

A

meshwork of anastomosing parabronchi located in caudolateral portion of the lung; its degree of development = species-dependent
○ Bidirectional Gas Flow

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37
Q

What species only have paleopulmonic tissue?

A

Emus, penguins

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38
Q

Which species have 10-12% neopulmonic tissue?

A

Storks, swans, ducks, geese

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39
Q

Which species have 20-25% neopulmonic parabronchi?

A

Chickens, sparrows, other song birds

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40
Q

Gas Exchange Efficiency in Birds vs Mammals

A

More efficient, despite 27% smaller lung volume

41
Q

MOA Increased Gas Exchange in Birds vs Mammals

A

Specific surface area of blood-gas tissue barrier is 15% greater

Ratio of tissue surface area to volume of exchange tissue is 17-35% greater

Mean thickness of tissue barrier in birds 56-67% less = less resistance to gas diffusion
○ Pulmonary capillary blood volume is 22% greater

42
Q

Movement of Gases, Blood within Parabronchi

A

● Movement of gas within parabronchi, outwards into atria, infundibulae → convective flow and then by diffusion

● Blood flow from periphery → interparabronchial artery, arterioles → blood capillary → outward moving air

● Multicapillary serial arterialization system increases duration over which respiratory media (air and blood) exposed to each other

43
Q

What creates the counter current exchange system?

A

○ inward flow of deoxygenated blood
○ outward flow of air from parabronchial lumen

44
Q

Do birds have alveolar gas?

A

● No equivalent of alveolar gas because parabronchial gas continuously changes in composition as flows along length of parabronchus

45
Q

Gas Flow through the PB as it relates to PO2, PCO2

A

As gas flows along a parabronchus, it receives CO2 and gives off O2

→ At INFLOW end of parabronchus, gas has low PCO2 and high PO2

→ At OUTFLOW end of parabronchus, gas has high PCO2 and low PO2

46
Q

PeCO2 in End PB Gas

A

Can exceed PaCO2

47
Q

PeO2 in End PB Gas

A

Can be less than PaO2

48
Q

Cardiovascular System of Birds

A

Heart: four-chambered muscular pump that separate venous blood from arterial blood

Sympathetic, parasympathetic innervation
● NE, epi principal sympathetic NTs
● ACh principal parasympathetic NTs

49
Q

Bird vs Mammal Hearts

A

Larger heart, lower heart rates, larger stroke volumes and slightly lower peripheral resistance = higher cardiac output

Total blood volume: 5-13% of body mass of birds

Higher blood pressure: arteries are stiffer → increased risk of fatality due to aortic rupture, heart failure and hemorrhage in stressed patients**

Higher oxygen demand

50
Q

Do birds have a diaphragm?

A

liver lobes surround the apex of the heart

51
Q

Conduction System in Birds

A

Sinoatrial node → atrioventricular node and its branches →Purkinje fibers

Purkinje fibers distribution within ventricular myocardium (complete from endocardium to epicardium), responsible for QRS morphology

Pattern of ventricular activation: Type2b → facilitates synchronous beating at high heart rates

52
Q

Renal Portal System in Birds

A

Renal portal system like reptiles

53
Q

CV Disease in Birds

A

Cardiovascular disease common in pet birds, 10%–15% prevalence

Atherosclerosis is considered the most common vascular disease in captive psittacine birds, with histological lesions appearing similar to those seen in people).

54
Q

Clinical Signs of CV Dz in Birds

A

■ Dyspnoea
■ Lethargy
■ Weakness
■ Exercise intolerance
■ Abdominal distension
■ SUDDEN DEATH

55
Q

Anesthetic Considerations for the Avian CV Stream

A

Avoid excitement because excitement = release epi, norepinephrine

In birds inhalant anesthetic (+++ halothane) synthesize myocardium to catecholamines induced arrhythmias

Birds ECG can be mistaken for ventricular tachycardia

56
Q

Physical Exam of Birds - Distant Assessment

A

● Bird’s awareness of and attention to its surrounding environment
● Body form and posture
● Feather condition
● Respiratory rate

57
Q

Hands on PE in Birds

A

● nares and mouth
● Heart and lung auscultation
● Sharpness of keel (good indicator of muscle mass and body fat)

58
Q

Fasting in Birds

A

-Controversial: risk of hypoglycemia DT high metabolic rate vs risk of regurgitation

-Healthy birds: withhold food long enough for upper GI tract to empty
○ Overnight in large birds
○ 4-6 h in smaller birds (probably even less)

-Emergency procedure: bird with a full crop should be held upright during induction with a finger positioned below the mandible to block the esophagus
● Once anesthetized, empty crop
● At end of anesthesia check oral cavity

59
Q

Fasting Guidelines: healthy birds

A

withhold food long enough for upper GI tract to empty
○ Overnight in large birds
○ 4-6 h in smaller birds (probably even less)

60
Q

Fasting Guidelines in Emergency Situations/Sick Birds

A

bird with a full crop should be held upright during induction with a finger positioned below the mandible to block the esophagus
● Once anesthetized, empty crop
● At end of anesthesia check oral cavity

61
Q

Physical Restraint in Birds

A

Improper restraint can cause trauma (wing/leg fracture) and/or physiologic stress

Excessive handling can cause overheating

Good restraint = wings and legs are controlled and not allowed to flap or kick
● long-necked birds: the neck must be gently controlled

62
Q

Intubation

A

Patient should be intubated for most procedure
○ Maintain airway patent
○ Provide oxygen
○ Permit PPV

For brief procedure < 10 min, face mask sufficient
○ An ETT should always be ready

63
Q

Air Sac Cannulation

A

Reduce o2 flow by 1/3

Can cannulate caudal thoracic or abdominal with placement of cannula just cranial or caudal to last rib

64
Q

Induction

A

–Injectables rarely used as sole agents
–Mask or induction chamber - if chamber, can injure selves during involuntary excitement phase

Sevo preferred: less irritation, faster induction/recovert

65
Q

Breathing Systems in Birds <10kg

A

○ Bain circuit
○ Norman elbow (Jackson Rees modification of Ayres T piece)
● Minimal resistance to patient ventilation
● Light weight (++ Bain)
● Oxygen flow 100-200 ml/kg/min

66
Q

Breathing Circuits in Birds >10kg

A

○ Small animal breathing system (Emu and ostriches under 130 kg)
○ Large animal breathing system for larger

67
Q

MAC in Birds

A

Differs to MAC minimal ALVEOLAR concentration as meant in mammals
○ Birds do not have alveolar lungs so MAC = minimal ANESTHETIC concentration

○ Defined as Minimal Anesthetic Concentration required to prevent gross purposeful movement in response to a painful stimulus and usually determined via a bracketing technique

68
Q

MAC of Specific Agents in Birds

A

Similar to Mammals

Halothane: 0.85-1.05%
Isoflurane: 1.06-2.05%
Sevoflurane: 2.21-2.9% (2.39-3.94% not by bracketing technique)

69
Q

Inhalant Maintenance of Anesthesia

A

Halothane, isoflurane and sevoflurane depress ventilation in birds in dose dependent manner

Hypoventilation: difficult to control plane of anesthetic, variety effects on cardiopulmonary function (arrhythmias)

When possible assist or control ventilation*

70
Q

Apneic Index

A

measure of tendency of inhalant anesthetic to cause respiratory depression
● AI = [EtAA] / MAC
● LOWER the AI for anesthetic, GREATER its depressant effect on ventilation

71
Q

Inhalant Effects on BP

A

–Iso: dose dependent decrease
–Halothane, Sevo: variable

72
Q

N2O in Birds

A

● Not suitable as sole anesthetic
● 30% oxygen = generally accepted as minimum fraction of inspired oxygen

NO DIVING BIRDS

73
Q

Contraindications for N2O in Birds

A

Do not use on diving birds (pelicans)
● Subcutaneous pockets of air that do not communicate with the respiratory system
● Use of N2O can results in subcutaneous emphysema

74
Q

Injectable Drugs for Anesthesia - General Considerations

A

Risk of overdosing!!!
● Measure accurately the weight of the bird
● Dilution of drug concentration with sterile saline, insulin syringes

Other consideration:
○ They may delay onset of anesthesia
○ Species and individual variability
○ Cardio-respiratory depression
○ Slow induction
○ Prolonged recovery

75
Q

Alfaxalone in Birds

A

○ Can be administered by several routes
○ IV = most predictable anesthesia with good muscle relaxation
○ Cardiac abnormalities reported

76
Q

Propofol in Birds

A

○ Narrow safety of margin
○ 10 mg/kg to induce anesthesia and incremental doses of up to 3 mg/kg may be used to prolong anesthesia
○ Metabolised rapidly = rapid recovery
○ Respiratory depression and apnoea from overdose

77
Q

Ketamine in Birds

A

Used in combination with other drugs to produce chemical restraint, analgesia

Anesthesia of 10-30 minutes duration 3-5 minutes after IM administration
○ Recovery variable from 30 minutes to 5 hours

Cardio-respiratory depression, thermoregulation affected

Careful in patients with hepatic and renal dysfunction

78
Q

BZD + KET

A

○ Deep sedation or anesthesia with good muscle relaxation
○ Respiratory depression

79
Q

NMBA in Birds

A

Two purposes in birds:
○ Whole-body SkM paralysis to facilitate surgical procedures
○ to produce mydriasis striated m in pupil

Vecuronium 0.2 mg/kg optimizes mydriasis

**DO NOT combine with agents promoting corneal penetration! -enhanced systemic uptake with potentially fatal effects

80
Q

Local Anesthetics in Birds

A

Do not exceed 4mg/kg lido, 2mg/kg bupivacaine

○ Risk of seizures and cardiac arrest in small birds (inappropriate doses)
○ Provide local analgesia but do not relieve stress associated to physical restraint

81
Q

Injection Sites in Birds: SQ

A

○ area of the back between the wings, the wing web, and the skinfold in the inguinal region

82
Q

Injection Sites in Birds: IM

A

Pectoral, Thigh M

83
Q

Injection Sites in Birds: IV

A

dorsal metatarsal vein and jugular vein (right jugular is larger and more visible)

84
Q

Injection Sites in Birds: IO

A

○ Tibiotarsal (easier to place; harder to maintain)
○ Ulnar (harder to place; easier to maintain)

Do not place in pneumatic bones

85
Q

Opioids in Birds

A

Butorphanol may be a more effective analgesic in birds then a µ-opioid such as morphine

Morphine seems to produce hyperalgesia

Butorphanol = analgesia and MAC sparing effect (2-4 mg/kg IV)

Fentanyl CRI - useful MAC reduction (3155%) in red tailed hawks

86
Q

NSAIDS in Birds

A

Meloxicam: useful, muscle necrosis at doses needed to obtain analgesia, did not cause renal lesions

Ketoprofen: low bioavailability, tubular necrosis, mortality with eiders

Preferred NSAID = carprofen

87
Q

Fluid Therapy in Birds

A

● Birds tend to have higher plasma Na, osmolality compared to mammals
● Fluids with close osmolarity to 300-320 mOm/L recommended
○ Normosol-R
○ Plasmalyte-R
○ Plasmalyte-A
○ NaCl 0.9%

88
Q

Respiratory Monitoring in Birds

A

-High RR not assoc with depth: associated with small VT, greater proportion of dead space ventilation

–Monitor frequency, degree of motion of sternum, movements of reservoir bag

–Capnometry

89
Q

Birds: Respiratory Pauses

A

Respiratory pauses > 10-15s treated by lightning plane of anesthesia and when possible, ventilate bird manually or mechanically

90
Q

IPPV in Birds

A

When doing so do not exceed 15-20 cmH2O to prevent volutrauma to air sacs

RR 8-10 breaths/min, airway pressure of 10 cmH2O generally achieve desired goal to produce stable plane of anesthesia, acceptable minute volume for oxygenation/elimination of CO2

91
Q

Oxygenation in Birds

A

-SpO2: designed to measure mammalian Hgb, subject to artifact

-Color and capillary refill time of mucous membrane, color of the cere, beak or bill, as well as coloration on head where lack of feathers

92
Q

HR, Rhythm in Birds

A

■ Color and CRT of MM
■ Palpating peripheral pulse
■ ECG via hypodermic needles inserted through the skin at base of each wing, through skin at the level of each stifle

93
Q

Blood Pressure in Birds

A

■ In birds > 4 kg
■ Doppler = values closer to mean arterial pressure

94
Q

Temperature Monitoring in Birds

A

Electronic thermometer, long flexible thermistor probe into esophagus

Clinically acceptable range of core body temperature 38.3º-40.6º

95
Q

Depth Assessment in Birds

A

M Relaxation

96
Q

Recovery in Birds

A

● birds must be kept from flopping around
● lightly wrap the bird with a towel
● potential regurgitation risk: keep animal intubated until head control

97
Q

Pneumatic Bones in Birds

A

skull, humerus, clavicle, keel (sternum), pelvic girdle, and the lumbar/sacral vertebrae, femur

98
Q

Ketamine in Raptors

A

Avoid -no ketamine in vultures, caution with owls

99
Q

PNBs in Birds

A

perform sciatic-femoral NB in raptors undergoing sx for pododermatitis
 Motor responses following ENS both nerves consistent with those reported in mammalian species

BP blocks via palpation, US, nerve locators used with varying success

100
Q

Epidurals in Waterfowl

A

Epidurals: synsacrococcygeal space, 55’ spinal ax with bupivacaine, 18’ with lidocaine
 Lido 0.5-2mg/kg
 75mm, 23g needle directed 10-20* cranially btw synasarcum, first free coccygeal vertebrae  onset 1.5’, duration dose dependent
 No AEs , all birds retained motor function

Boards: Species (12 decks)

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