L7: Wounds

Question 1

Epidermis composition & function

Answer 1

Avascular keratinized stratified squamous epithelium & it has protective function

Question 2

What kind of tissue dermis is? Function?

Answer 2

Thicker and vascular, tough fibroelastic tissue. It has a supportive and nourishing function.

Question 3

What is subcutis composed of?

Answer 3

Adipose tissue, cutaneous trunci muscle, and direct cutaneous arteries & veins

Question 4

Wound (term)

Answer 4

Injury to the body that results in disruption of the continuity of the body structure. Can be classified in several ways (clean, contaminated etc.)

Question 5

Open wounds (8 types)

Answer 5

1.Surgical incision
2.Laceration
3.Abrasion
4.Avulsion
* Degloving
* Shearing
5.Puncture
* Bite/sting: cat/dog; snake; insect; tick
* Firearm
6.Burn: thermal; chemical; electrical; radiation
7.Pressure sores
8.Cast- and bandage-related

Question 6

Closed wounds (4 types)

Answer 6

1.Contusion
2.Hematoma
3.Crush injury
4.Hygroma

Question 7

Incisional injuries & lacerations

Answer 7

Are usually surgical or traumatic. Edges generally clean and free from tissue damage, tend not to get infected. Surgical management.

Question 8

Abrasions

Answer 8

Superficial damage not extending beyond dermis. Frictional forces when moving parallel to a rough surface. Generally heavily contaminated. In severe cases with ongoing necrosis => avulsions. Surgical or open wound management.

Question 9

Avulsions (degloving)

Answer 9

-Avulsion is the separation of tissue from the deeper attachments.
-In degloving skin and deeper tissues torn from an extremity just as a glove is removed from a hand.
-Initially may be free from bacterial contamination but without proper management rapid colonization and infection of nectoric tissue will occure
-Surgical & open wound management together

Question 10

Avulsions (shearing)

Answer 10

-Usually involve loss of deeper tissues (tendons, muscle, even bone)
-Joints of distal limb
-Heavily contaminated, extremely prone to infection
-Open wound management

Question 11

Puncture wounds

Answer 11

-Caused by any sharp object that pierces the skin to create a relatively small deficit or a hole
-Bite wounds (also insects or snake)
-Impalement (full penetration)
-Oropharyngeal or firearm wounds
-Contamination and infection variable
-Damage assessment
- Risk of abscessation

Question 12

Burns

Answer 12

-Caused by extreme temperature or by contact with a chemical substance, electricity or radiation
-May require prolonged treatment
-Treatment depends on the case

Question 13

Pressure sores

Answer 13

-Caused by pressure typically on the elbows and hocks of larger dogs
-Can be open or closed
-Open sores prone to infections (bone & joint)
-Medical/surgical treatment
-Hygromas best treated medically, can’t really treat surgically

Question 14

Cast- and bandage-related wounds

Answer 14

-Iatrogenic wounds are common
(Overtight application, inadequate padding, excessive exercise => bandage slipping, wet or dirty bandages)
-Serious wounds may lead to loss of digits or limbs

Question 15

Wound healing 4 distinctive phases

Answer 15

1.Acute inflammatory
2.Debridement (breakdown)
3.Proliferation (reparation)
4.Maturation (remodelling)

Question 16

Inflammatory phase

Answer 16

-Characterized by: redness, pain, heat, swelling, loss of function
-Approximately 5 days
1.Filling with blood & lymph
2.Immediate vasoconstriction of damaged vessels (5-10min)
3.Vasodilation (dilutes toxins, provides nutrients, results blood clot)
4.Epithelial cells migrating from wound periphery to exposed tissue
5.Blood clot dries to form a scab
6.WBC leaking into wounds initiate debridement phase

Question 18

Debridement phase

Answer 18

-Starts usually 6-12h after injury
-Inflammatory exudate provides all the necessary phagocytic cells and proteolytic enzymes to deal with the demarcation
-An exudate (WBC, dead tissue, wound fluids) forms on the wound
-Necrotic tissue impedes wound healing
-Phase ends with rejection of nonvital tissue
-Sometimes combined with inflammatory phase

Question 18

Proliferation phase

Answer 18

-Repair phase
-3-5days after injury
-Signs of inflammation subside
-Neovascularization
1.Granulation
2.Wound contraction
3.Epithelialization

Question 19

Proliferative granulation

Answer 19

-Red irregular surface
-Fragile tissue
-Barrier to infection
-Granulation tissue forming at each wound edge at a rate of 0.4 to 1 mm/24H

Question 20

Proliferative wound contraction

Answer 20

-Surface and cavity of wound become smaller
-Adjacent skin pulled closer
-5-9days after wounding
-Stops when edges connected or tension is too high
-Risk of contracture
(temporarily thinner skin surrounding)

Question 21

Proliferative epithelialization

Answer 21

-Proliferation of basal epithelial cells from the adjacent skin edges and their moving over and adhesion to the surface of the wound
-Prevent excessive formation of granulation tissue
-Duration can range from days to weeks
-Surface of the wound that has become epithelialized is known as the epithelial scar = thin and fragile

Question 22

Maturation phase

Answer 22

-Increasing strength of the scar as a result of remodelling of tissue
-Newly formed collaged is arranged parallel to the tension lines of the skin
-Duration from weeks to over a year
-Healed wound will never regain original strength

Question 23

Chronic wounds

Answer 23

-Lack of orderly progression of wound healing through four phases
-Infection that causes sustained inflammatory phase
-Factors influencing: Malnutrition, radiation, use of corticosteroids, underlying metabolic disease

Question 24

Differences between cats and dogs

Answer 24

-Research more in dogs
-Formation of granulation tissue takes longer and first appear only at the edges
-Pseudohealing more common in cats