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113 Cards in this Set

  • Front
  • Back
What is the average skin thickness?
Average thickness of the body skin is 3.8 mm, 3.3 near body openings, and 6.2 mm near the mane and tail.
What are the layers of the epidermis?
Stratum basale, stratum spinosum, stratum granulosum, and stratum corneum
What is the function of the stratum corneum?
Slows water loss, barrier against harmful substances
What are the layers of the dermis?
Superficial papillary layer, deep reticular layer in most areas, with a collagenous layer along the lumbar, sacral and gluteal regions
What is the function of the dermis?
Support epidermis, houses vascular network
What are the functions of the dermal vascular network?
Temperature regulation, nutrient supply, absorption and delivery of medications, and wound healing
What type of gland is the skin sweat gland?
Apocrine
What region does the primary nerve and blood supply to the skin originate?
Subcutaneous region
What are the benefits of wound debridement?
Decrease bacteria #s and necrotic tissue, change wound classification from infected to contaminated or clean-contaminated
What effect does foreign material have on infection risk?
Reduces bacteria necessary from infection by a factor of 10 (from 105 to 104)
What are the types of debridement?
Sharp, mechanical, chemical, biological, autolytic
What are the tools for sharp debridement? Which is the best?
Scalpel*, scissors, laser
What is the benefit and disadvantage of sharp debridement?
least traumatic debridement, can remove too much
How is mechanical debridement performed?
Woven gauze, lavage, wet to wet or wet to dry dressings
What is the disadvantage of mechanical debridement?
Often too aggressive, very traumatic
What pressure should lavage be performed at?
10-15 psi
What are methods to attain correct pressure lavage?
19 gauge needle on 35 cc syringe, 4 16 gauge holes in cap of 1L saline bottle
How should antiseptics be used in wound debridement? Why?
Around wound (on skin) not on wound. Concentrations needed for bacterial killing in presence of necrotic tissue have a negative impact on the cells involved in wound healing
What is a wet to wet dressing?
Dressing intended to stay moist during the entire time it is applied to the wound
What is the benefit and disadvantage of wet to wet dressing?
More effective and less traumatic removal of necrotic tissue causing less epithelial and fibroblast damage. Very time consuming, often having to moisten up to 6 times a day to prevent drying out.
What is a wet to dry bandage?
Dressing is applied to the wound while wet but is allow to dry. Secondary absorbent dressing will pull fluid from primary dressing as primary dressing pulls fluid and exudate from the wound. Primary dressing dries and when removed, debrides the surface of the wound.
What is the disadvantage of wet to dry dressing?
Debridement is non-selective and can remove epithelial or fibroblast cells.
What are some examples of chemical debridement products?
Dakin’s solution (dilute hypocholoride), hydrogen peroxide, acetic acid, hypertonic saline
What type of wounds is chemical debridement used for and why?
Very contaminated, early phases of healing, because debridement can be non-selective
What are some examples of enzymatic debridement?
Streptokinase/ streptodornase, collagenase, DNase/fibrolysin, papain/urea, trypsin
What is biological debridement?
Application of lucilia sericata (green bottle fly) larva to wounds.
What is autolytic debridement?
Leaving wound fluid which contains WBC and enzymes released from dead WBC on the wound.
What is the advantage and disadvantage of autolytic debridement?
least traumatic, reduces bacterial count, wound must stay moist, ineffective in presence of large volumes of necrotic tissue
What are the stages of wound healing?
Inflammatory, debridement, proliferation, maturation
What determines the duration and intensity of inflammation?
Extent of injury
When does the debridement phase start and what is involved?
Debridement begins during the inflammatory phase. WBC phagocytize bacteria and enzymatically remove necrotic tissue
What does the proliferation phase involve?
Fibroblast migration & proliferation, epithelialization
What is the function of fibroblasts?
Secretion of ground substance and collagen
What is the function of myofibroblasts?
Draw full thickness skin together by contraction similar to smooth muscle cells
When does wound contraction stop?
When cells of the same type contact each other or the skin tension equals the contraction of the myofibroblast
What factors halt epithelialization?
Infection, dry wound surface, exuberant granulation tissue, frequent bandage changes
When does maturation occur?
Equal collagen degradation and production
What is the classification of wounds by contamination?
Clean: surgical wounds not involving the respiratory, alimentary or urogenital tract, Clean-contaminated: surgical wounds involving the respiratory, GI, or UG tract, Contaminated: traumatic wounds with necrotic debris, Infected: wounds with large amounts of bacteria, inflammation, edema, and pus
Define bacterial contamination:
Presence of bacteria without multiplication or trauma to host
Define bacterial colonization:
Presence of bacteria with multiplication but without trauma to host
Define bacterial infection:
Invasion of healthy host tissues with multiplication and trauma to host
What is qualitative bacterial assessment?
Bacterial identification and antimicrobial sensitivity
What is quantitative bacterial assessment?
Estimation of the number of bacteria colonizing a wound
How many bacteria indicate infection?
>105
What factors reduce the number of bacteria needed for active infection?
Foreign material, increased bacterial virulence, impaired host resistance
What is the difference between topical antiseptics and topical antimicrobial agents?
Antimicrobials are effective against bacteria within the wound bed, can target specific bacteria, and have no negative side effects on wound healing
What factors affect what wound closure is selected?
Cause and extent of injury, time from injury, degree of contamination, dead space, veteriniarian’s skill
What is primary closure?
Wound is closed immediately, completely, aseptically
When is primary closure acceptable?
Minimal tissue loss, bacterial contamination, tension on wound edges
How can dead space be managed in primarily closed wounds?
Suture, meshing the skin, passive or active drains, pressure bandages
What are the rules for suture selection for management of dead space?
Select smallest diameter suture possible, use monofilament, absorbable suture, and limit surgeon’s knots or interrupted sutures when suture is buried
What is delayed primary closure?
Wound is initially treated as an open wound to allow debridement and is closed completely or partially at a later time
When is delayed primary closure used?
Wounds with mild to moderate bacterial contamination, minimal tissue loss, minimal tension on wound edges
What is second intension healing?
Healing by contraction, granulation and epithelialization only
When is second intension healing selected?
Grossly contaminated wounds or those with moderate to severe tissue loss
What is moist wound healing?
Occlusive dressing keep wound exudate near wound to provide cells and substrate rich in enzymes, growth factors, chemotactic factors which controls infection and provides appropriate environment for healing
When are hypertonic dressings used?
Contaminated, infected wounds with necrotic tissue requiring some debridement; abscesses, draining tracts
How do hypertonic dressings work?
Osmotic removal of necrotic debris and bacteria
What are the proposed benefits of honey?
Bacteriocidal, possible growth factor like effects
What type of honey is most effective?
Makuna honey from nectar of leptospermum scoparium
What is the active agent in kerlix antimicrobial dressings?
Polyhexamethylene biguanide
What is the MOA of polyhexamethylene biguanide?
Destabilization of the cytoplasmic membrane resulting in microbial death
What is the benefit of polyhexamethylene biguanide?
Restrict bacterial penetration, reduce bacterial numbers in/ near wound
What is the function of hydrogel?
Provide moisture to a dry wound
What phase of healing are calcium algenate dressings used in?
Granulation (proliferation)
What is the function of calcium algenate dressings?
Ca interact with wound Na to stimulate myofibroblasts and epithelial cells, Ca modulates epithelial proliferation & migration
What phase of healing are collagen or maltodextrin dressings used?
Granulation (proliferation)
When are collagen or maltodextrin dressing no longer used?
Once adequate granulation tissue is present
What are the effects of small intestinal submucosa?
Unlikely to be rejected, reduction in exuberant granulation tissue, improved drainage
What are the effects of amnion?
Reduces wound retraction and exuberant granulation tissue, improves epithelialization
What is the benefit of platelet derived growth factor?
Chemotactic and mitogen for fibroblasts, smooth muscles cells, inflammatory cells
What is the function of tissue growth factor beta?
Encourages granulation formation, profibrotic
When are semiocclusive foams used?
Mildly exudative wounds
What is the benefit of semiocclusive foam?
Moist environment, thermal regulation, minimize exuberant granulation tissue
What are the benefits of negative pressure wound therapy?
Increased blood flow, increased angiogenesis, increased rate of granulation, improved skin flap survival, decreased bacterial numbers, decreased edema formation
What are the disadvantages of using corticosteroids in wound management?
Upregulation of plasminogen activator inhibitor and downregulation of plasminogen activator resulting in inhibition of proteolytic matrix degradation and reepitheialization; interfere with synthesis and degradation of collagen I and III; decrease vascular growth and formation of granulation tissue
How does the wound fluid of chronic wounds differ from acute wounds?
Chronic wound fluid inhibits the growth of fibroblasts by affecting cell cycle, acute wounds have active plasminogen activator but chronic wounds have urokinase plasminogen, chronic wounds have decreased levels of PDGF, FGF, VEGF and their receptors compared to acute wounds
Fistula:
abnormal passage or communication between 2 internal organs or leading from an organ to the surface
Sinus tract:
cavity or channel that may or may not be normal
Sarcoid:
cutaneous fibroblastic neoplasm with proliferative epithelial component
Subtypes of sarcoids:
occult, verrucous, nodular fibroblastic, ulcerative fibroblastic, mixed, manevolent
Most aggressive subtype of sarcoid:
manevolet (infiltrate along fascial planes & vessels, rapid growth, high recurrence after excision)
Cause of sarcoids:
host genetic, viral, and environmental factors
What genes as associated with sarcoid development?
Equine leukocyte antigens (presence of A3 or W13 increases risk, absence of W13 confers resistance)
What viral factors are associated with sarcoid development?
Presence of bovine papilloma vius with expression of E5 (or E6) protein, BVP can be in normal skin of affected horses, E5 is expressed by tumor tissue but not normal tissue
What environmental factors are associated with sarcoid development?
Previous sites of trauma or injury
Treatment options for sarcoids:
surgical excision or laser ablation +/- cryotherapy, hyperthermia, radiotherapy, immunotherapy, chemotherapy
Examples of immunotherapy:
immunostimulants such as mycobacterium cell wasll extracts, live whole cell bacilli Calmette Guerin, propionibacterial cell wall extract
How do immunotherapy agents work?
Thought to stimulate cell mediated immunity to lead to recognition of tumor cell specific antigens
Examples of chemotherapy:
intralesional cisplatin injection, topical 5-fluorouracil, AW3 or AW4-LUDES
Benefits of oil repositol cisplatin:
prevent significant systemic levels, maintains effective local tissue levels of drug
Dose of cisplatin:
1mg per cubic cm of tumor, in 4 treatments
Treatment options from SCC:
surgical excision, irradiation, chemotherapy
MOA of cisplatin:
binds directly to DNA to inhibit synthesis of dividing cells
Sarcoid Recurrence rate with surgical excision:
15-82%
Sarcoid Recurrence rate with laser:
38%
Sarcoid recurrance rate with cryotherapy:
0-40% but maybe be as high as 91% for periorbital sarcoids
Sarcoid recurrence rate with radiotherapy:
0-6%
Sarcoid recurrence rate with cisplatin:
13%
Predispositions for SCC:
UV light exposure, topically applied irritants, poorly healing wounds, poorly pigmented breeds,
Types of melanoma:
melanocytic nevi, dermal melanomonas, dermal melanomatosis, malignant melanoma
What are melanocytic nevi?
Large pleomorphic melanocytes with increased mitotic figures
Composition of dermal melanomas and melanomatosis:
homogeneous dendritic cells with dense pigmentation but no mitotic figures
MOA of cimetidine in melanoma therapy:
immunomodulation of lymphocyte activity via histamine receptors
Histology associated with nodular necrobiosis:
granulomatous reaction with eosinophils, lymphocytes, histiocytes and collagen degeneration
Causative organisms of cutaneous habronemiasis:
habronema muscae, microstoma, draschia megastoma
Carriers of cutaneous habronemiasis:
musca domestica, stomoxys calcitrans
Treatment goal of cutaneous habronemiasis:
resolve inflammation & allergy, prevent reinfestation
Causative agent of pythiosis:
pythium insidiosum (fungus-like oomycete)
how does pythiosis occur?
Invasion through small wounds when in contact with lakes, swamps, or flooded land
what is kunker?
Necrotic vessels, inflammatory cells, pythium hyphae
treatment of pythiosis:
surgical excision, antifungals (amphotericin) systemically & topically, NaI
dentigerous cyst:
congenital defect from incomplete closure of the 1st branchial cleft, contains dental elements with epidermal lining