Exam 1 Learning Objectives

Technical Procedures – Administration of Drugs and Other materials, Technical Procedures – Sample Collection, Surgical Techniques, Sutures and Suturing, Anesthesia & Euthanasia, Confounding Factors / Variables Affecting Animal well Being and Research Outcomes, Lab Animal Diseases / Conditions

Identify several routes of Enteral administration

In food; in water; by mouth; by oral gavage

Identify several routes of Parenteral administration

Dermal/topical; Inhalation; Injections (IM, SC, IP, IV, intracardiac, intranasal)

IM

Intramuscular

SC

Subcutaneous

IP

Intraperitoneal

IV

Intravenous

Intracardiac

IC

What is the angle for an Intradermal (ID) injection

10-15°

What is the angle for an Subcutaneous (SC or SQ)  injection

45°

What is the angle for an Intramuscular (IM) injection

90°

What is the angle for an Intravenous/ intravascular (IV) injection

10-25°

Describe the steps in performing gavage in rodents

1. Measure from corner of mouth to last rib for proper length/depth of insertion

2. restrain the animal

3. using needle, push back on hard palate to rock head back so that passage is straight

4. ensure that maximum recommended volume does not exceeded

What are the appropriate dose/volume ranges for a gavage in a Mouse

For Average Adult Body weight: Mouse .5-1 mL

What are the appropriate dose/volume ranges for a gavage in a Rat

For Average Adult Body weight: 3 mL

What are the appropriate dose/volume ranges for a gavage in a Hamster

For Average Adult Body weight:

1-1.5 m

Identify variables/concerns related to whole-body inhalation exposure

besides being inhaled, also deposits on fur and skin, and can then be ingested orally– thus greater dose than originally calculated

Identify variables/concerns related to nose-only inhalation exposure

limits to just inhaled dose

Describe why one might choose a luer-lock syringe over a standard syringe

With thick liquids, pressure may build when pushing plunger, and needle may shoot off. With a luer-lock syringe, the needle is screwed on and won’t fly off

For the Diameter (gauge) the lower number means (16 ga,18ga), and who would you use it on?

large gauge, cat/dogs

For the Diameter (gauge) the higher number means (23 ga,27 ga) and who would you use it on?

Smaller gauge: rodents

Standard needle sizes for Rodents?

23-27 gauge

Standard needle sizes for Rabbits?

23 gauge

Provide several reasons why re-use of needles should be discouraged

Tissue trauma; contamination; pain

Discuss why commercially manufactured (USP) drugs are better than non-pharmaceutical grade agents?

Purity, sterility, acid-base balance, longer storage/shelf-life, absence of pyrogens (produced by bacterial contaminants)

IM common injection sites in rodents

(thigh muscles of hind limbs) -

< 0.05 ml mouse, < 0.1 ml hamster, < 0.3 ml rats

IM common injection sites in Rabbits

(thigh muscles of hind limbs; epaxial muscles which parallel the spine)

< 0.5 ml

SC common injection sites in rodents

(over the back)

< 1 ml mice, < 2 ml rats

IP common injection sites in rodents

(ventral abdomen – near midline of upper portion of lower two quadrants)

< 1.5 ml mice, < 3 ml rats

IM common injection sites in Rabbits

(thigh muscles of hind limbs; epaxial muscles which parallel the spine)

< 0.5 ml

IV common injection sites in Rabbits

marginal ear vein

What should always do before injection in order to prevent Hypothermia?

Warm to near body temperature

IV common injection sites in rodents

(lateral tail veins of rats and mice)

< 0.15 mice, < 1 ml rats

safe blood collection volumes for Mice

less than or equal to 0.3 ml

safe blood collection volumes for Rat

less than or equal to 3 ml

safe blood collection volumes for Hamster

less than or equal to 1 ml

safe blood collection volumes for Rabbit

less than or equal to 30 ml

why the use of a vacutainer for blood collection in rodents may not be successful

Collapses vessel, prevents collection of blood

Identify the location of the common vessels used for blood collection: Tail

lateral tail veins (rats and mice)

Identify the location of the common vessels used for blood collection: Ear

marginal ear vein, central artery (rabbit)

Identify the location of the common vessels used for blood collection: Face

submandibular and facial veins (rats and mice)

Identify the location of the common vessels used for blood collection: Eye

retro-orbital sinus (rats, mice, hamsters)

Identify the location of the common vessels used for blood collection: Front Legs

cephalic vein (rabbit)

Identify the location of the common vessels used for blood collection: Hind legs

lateral and medial saphenous veins (rat, mouse, hamster, gerbil); metatarsal vein (gerbils, guinea pigs)

Describe several methods for promoting vasodilation to facilitate blood collection

Warm the whole animal or the area where blood will be collected. Heating pad, heat lamp, warm water in glove, dipping tail in warm water

Why is indwelling catheter maintenance required

To maintain sterility and prevent contamination; to prevent clot (thrombus) formation; to prevent release of emboli.

steps to take to prevent thrombus formation

After administration or blood collection, use a “heparin lock” solution to prevent clot formation

Describe proper “surgical scub” procedures practiced at the site of the skin incision

Three alternating scrubs of Betadyne solution and alcohol. Start at center, and spiral outward with scrub

Describe the approach for the invasive procedure: laparotomy

1. clip site

2. surgical scrub

3. Incise skin with scalpel (NOT scissors – they crush cells and delay healing)

4. Use rat-tooth forceps to handle skin and abdominal muscles (less trauma, less crushing of tissues)

5. Elevate abdominal muscles

6. cut along linea alba to open abdomen

Describe the approach for the invasive procedure: thoracotomy

1. Insert endotracheal tube.

2. Clip site

3. surgical scrub Incise skin with scalpel (NOT scissors – they crush cells and delay healing)

4. Use rat-tooth forceps to handle skin and intercostal muscles (less trauma, less crushing of tissues).

5. Cut intercostal muscles (between ribs). NOTE –loss of negative pressure in chest cavity results in collapse of the lungs. Need to manually inflate lungs or use a mechanical ventilator

Appropriate use of several surgical instrument, and explain why other instruments may be inappropriate for the same use: rat-tooth forceps

Skin and muscle – to prevent excessive crushing of cells

Appropriate use of several surgical instrument, and explain why other instruments may be inappropriate for the same use: Scalpel

Skin and Muscle-as cut causes less trauma to cells

Appropriate use of several surgical instrument, and explain why other instruments may be inappropriate for the same use: Scissors

Skin and Muscle-crush cells/tissue and delays healing

Appropriate use of several surgical instrument, and explain why other instruments may be inappropriate for the same use: Hemostats

Skin and Muscle-are used for blunt dissection of subcutaneous tissues, and for clamping off bleeding vessels

What are swedged needles, why is one better than the other?

have the suture contained within the end of the needle – does not stick out beyond cross-section of needle, less drag, les trauma to tissues

What are non-swedged needles, why is one better than the other?

needles have eyelet, and suture must be looped through/around it, and thus has a wider diameter than the needle itself, allowing dragging/friction/trauma to the tissues, delaying healing

Recognize when taper point should be used

are used for hollow organs, as cutting needles would allow suture to tear through the tissue

Recognize when cutting points should be used

are used for skin, to facilitate passage of the needle through the denser tissue

Why is “perfect” apposition of the wound margin appropriate?

allows faster healing with minimal scar tissue formation

what happens when eversion or inversion of the wound margin occurs?

results in scarring – scar tissue is not as strong as normal tissue

Recognize (in general) which tissues have greater or lesser tensile strength (e.g., fat, muscle, muscle fascia, skin)

Skin > muscle fascia > muscle > subcutaneous fat

proper techniques for suture removal to prevent contamination under the skin

Elevate suture

Elevate suture

cut portion that was underneath the skin, then remove – this prevents entry and tracking of bacteria/contaminants under the skin surface

Recognize the types of anesthetic methods used

Local; Regional; General

Simple Interrupted Suture Pattern (image)

Simple Interrupted Suture Pattern

• Advantages:  

  • Good apposition of the margins 

  • Loss of one suture has minimal effect 

• Disadvantage 

  • Takes a little longer to do than continuous suture patterns 

  • May tear through tissue when tension present 

Horizontal Mattress Suture Pattern (image)

Horizontal Mattress Suture Pattern

• Advantages: 

  • Good for areas where tension tries to pull the margins apart 

  • Loss of one suture has minimal effect 

• Disadvantages: 

  • Takes a little longer to do than continuous suture patterns 

  • Causes eversion of the margins 

  • May "strangulate" blood flow and affect healing 

Vertical Mattress Suture Pattern (image)

Vertical Mattress Suture Pattern

• Advantages: 

  • Good areas where tension tries to pull the margins apart 

  • Loss of one suture has minimal effect 

  • Not as likely to restrict blood flow 

• Disadvantages: 

  • Takes a little longer to do than continuous suture patterns 

  • Causes eversion of the margins 

Simple Continuous Suture Pattern (image)

Simple Continuous Suture Pattern

• Advantages: 

  • Very fast to complete 

  • Fair apposition of the margins 

• Disadvantages: 

  • May tear through tissue when tension present, or will break 

  • Breaking a suture allows entire wound to gape open 

Continuous Interlocking Suture Pattern (image)

Continuous Interlocking Suture Pattern

• Advantages: 

  • Very fast to complete 

  • Fair apposition of the margins 

  • Good for tension relief 

• Disadvantages: 

  • Breaking of suture allows entire wound to gape open 

Use of Stents for Wound Closure (image)

Use of Stents for Wound Closure

• necessary in areas where significant tension is present

• provides a measure of tension relief to prevent sutures from tearing through the skin

rat toothed forceps (image)

Hemostats (image)

factors affecting anesthesia, identifying the different factors which affect metabolic rate

Size, age, gender, recent feeding, fear and activity, tranquilizers, concurrent disease

Differing Metabolic Rates (BMR): Age

neonates have low ___; old & young differ from "adults"

Differing Metabolic Rates (BMR): Sex Male

7% higher than

Differing Metabolic Rates (BMR): Sex female

increases with pregnancy

Differing Metabolic Rates (BMR): Recent feeding

increase, chylomicrons (fat globules in blood to which anesthetic can be bound rendering it ineffective)

Differing Metabolic Rates (BMR): Fear & activity

increase, so sedate initially

Differing Metabolic Rates (BMR): Tranquilizers

Lower

Differing Metabolic Rates (BMR): Fever

increases

Differing Metabolic Rates (BMR): toxemia

decreases

Differing Metabolic Rates (BMR):liver disease

decreases

Differing Metabolic Rates (BMR): shock

decreases

Differing Metabolic Rates (BMR): Vit. C deficiency in guinea pigs

decreases

Differing Metabolic Rates (BMR):hyperthyroidism

increases

Differing Metabolic Rates (BMR): thyroidectomized

decreases

List 4 methods of anesthetic delivery.

Dermal/topical; Injectable (IM, IV, IP, SC); Inhalant

Describe 2 body systems affected by "anesthetic emergencies"

Cardiac; Respiratory

List the 4 stages of anesthesia and the appropriate plane of anesthesia

Stage I – rising pain threshold

Stage II – excitement phase

Stage III – surgical anesthesia – Plane 3

Stage IV – respiratory paralysis

List methods for assessing adequate anesthesia/analgesia

Jaw tone;

swallowing reflex,

withdrawal reflex (“toe pinch”),

palpebral (eyelid) reflex;

corneal reflex

Signs Used to Assess Depth of Anesthesia: Jaw Tone

open the animal’s mouth; if jaw is relaxed and easy to open, then the animal is adequately anesthetized. If there is resistance, then the animal is too light

Signs Used to Assess Depth of Anesthesia: Swallowing Reflex

gently pull on the tongue; if chewing and swallowing can be seen, the animal is too light. When the tongue is not retracted, the animal is adequately anesthetized

Signs Used to Assess Depth of Anesthesia: Withdrawal Reflex (“toe pinch”)

gently extend one leg and pinch the web of skin between the toes or the footpad with your fingernail; a positive reflex is indicated by the flexion (pulling back) of the leg.

Note: this reflex may be preserved in some anesthetized animals

Signs Used to Assess Depth of Anesthesia: Palpebral Reflex

gently touch the medial canthus of the eye (the corner of the eye nearest the nose); the animal will blink its eyelids if not adequately anesthetized

Signs Used to Assess Depth of Anesthesia: Corneal Reflex

gently touch the cornea of the eye with a moistened gauze pad or Q-tip swab; the animal will blink its eyelids if not adequately anesthetized