Exam 2 Flashcards
(55 cards)
Infectious and Non-infectious diseases and disorders of the skin
Explain the cause of equine Sarcoids, describe the various types, diagnostic and treatment options
What is the most common skin tumor in the horse?
Is it malignant/benign?
What are the most common locations where it develops?
What age group is most affected?
Are multiple sessions common?
Which breeds have a genetic component?
Etiology
-The most common equine skin tumor fibroblastic
-Non-metastatic
-Bovine papilloma virus (BPV)
-Viral E5 protein = malignancy
-Vector vorne?
-Genetics: QH»_space; TB
Young adults 2-9 yo
Head & ears, ventral abdomen
-Previous trauma areas predisposed
-Multiple lesions common
Types of Sarcoids
- Earliest form, circular, hairless area, thickened skin, may be stable for years
- Grey, scaly, warty appearance. Possible ulceration, small nodules, “occult halo”
- Occult
- Verrucous
Types of sarcoids
- Firm, discrete, nodule under skin. Eyelid, axilla, inner thigh, groin. Can ulcerate and bleed. Skin may or may not be firmly attached
- Do not heal like granular tissue, though looks like it. Fleshly, aggressive, can have a narrow pedicle attaching it to the body. Attractive to flies
- Nodular
- Fibroblastic
Types of Sarcoids
- Mixed
- Malignant
- Common to have more than one type. Seen in areas of repeated trauma or inappropriate treatment. May or may not be able to tell the primary type
- Malignant: rare. Extensive through skin and underlying tissues. Aggressively invades locally but not into organs
How do sarcoids behave?
Should you always biopsy a sarcoid?
What is the best treatment?
Which treatment requires 4-8 sessions and general anesthesia?
What type of sarcoids respond best to BCG and Aldera treatments?
Which treatment has the highest success rate? is it commonly used or not?
-They can regress spontaneously occult» verrucous» fibroblastic
-Biopsy makes them angry!
Treatment
-Depends!!
-They do not always work
- Surgery
-Sharp incision, Laser, Cryosurgery
-Need > 1.6 cm margins
-Common recurrence
-Best combined with other therapy
-Laser»_space; success than scalpel, but higher wound dehiscence (thermal damage)
-Cryotherapy: necrosis of tumor, good only for small tumors (-20 C temp) - Chemotherapy
-Very expensive for large animals to do systemic chemo
-Topical: Acyclovir, 5-FU
-Intralesional: Cisplatin beads, 5-FU
-Electrochemotherapy: high voltage pulses and chemo combo Very effective requires 4-8 treatments and general anesthesia - Immunotherapy
-Spontaneous resolution
-BCG: Cell wall of Mycobacterium bovis = immunostimulant B & T cells
First debulk
-Multiple injections required
-Best for small, periorbital or fibroblastic tumors.
-Aldera: immune modulator, 3x per week, expensive. - Gene therapy
-Remove tumor and section of 3mm pieces frozen in liquid nitrogen for 10 min
Implant into the neck
-Autologous vaccination - Radiotherapy
-Iridium-192, Gold-198, Cobalt-60, Radon-22, Radium-226
-86.6-100% success rate
-General anesthesia, expensive - Photodynamic and phototherapy
- Others
XXterra
-Blood root/zin chloride mixtures
-some success, but not as good as advertised
-clients can get it online
Should you remove an occult, verrucous, or nodular sarcoid that is not interfering?
Should you remove an occult, verrucous, or nodular sarcoid that is interfering? what if it is <10 cm, or 10-20 cm, or >20 cm? What is the best treatment?
Should you remove a fibroblastic sarcoid that is non-interfering or interfering? what if it is <10 cm, or 10-20 cm, or >20 cm? What is the best treatment?
Should you remove a malevolent sarcoid that is interfering or not interfering? what if it is <10 cm, or 10-20 cm, or >20 cm? What is the best treatment?
Describe guidelines for mass removal in horses
Rules
> 5mm margins (usually 1cm)
-Limb: use tourniquet, graft, immobilize
-Near orifice/anus: may need reconstruction, partial closure, +/- gift, scarring may interfere with function
-Body: +/- graft, usually do not need closure
Bleed a lot, prepare for hemostasis
Describe how to perform skin grafting: pinch, punch, tunnel, sheet/mesh.
Primary closures always best when possible
Grafting Indications
-Extensive tissue loss, not enough skin to close
-Excessive granulation impeding wound contraction
-Contraction/epithelialization will be sufficient to close
Requirements for success
- Good vascular supply
-Won’t work over exposed bone, tendon, ligament, fat, etc. - Free of infection
-Pseudomonas sp. exudate interferes, other bacteria too - proteolytic enzymes - Competent post-graft care
-Proper bandaging - NO motion
- Flat healthy bed of granulation tissue
-Proud flesh should be removed before graft
Pinch Graft
-Small section of skin elevated with a needle and removed with scalpel
-Soaked in saline gauze before implantation
-Insert into granulation tissue bed
-Donor sites are left open or closed with a single suture
Areas of higher motion appropriate
-Wounds over joints or high motion areas
Punch Grafts
-Full thickness grafts
-Biopsy punch
-Usually mane on the neck or ventral abdomen or thorax donor site
-1-2 mm (smaller) prep punch site on receiving site prepared
-Want a tight fit
Pay attention to the direction of hair growth
-Close donor sites with monofilament
-Use in wound < 10 cm diameter, joints
Tunnel/Strip Grafts
-Partial or full thickness
-Partial - dermatome (hurts!!)
-Full - parallel incision 2mm apart
-Tunnel graft 6mm below surface of the granulation tissue, suture on the other side
-Place 2cm apart
-Granulation tissue over them sloughs or is removed in 7-10 days
-Use in large wounds with thick granulation tissue: good graft acceptance
Sheet Grafting
-Partial thickness obtained with a dermatome
-Very painful
-Need general anesthesia
-Removes partial thickness skin as a sheet: can be suture in place as a sheet or meshed
-Mesh: turns a large wound into lots of tiny ones, prevents fluid accumulation, improves acceptance
-Bandage as with other grafts
Describe types of skin grafting used for equine wounds and advantages/disadvantages of each
Skin Flaps
-Horses skin has less stretch than SA skin
Skin Grafts
- Split thickness
2.Full thickness - Autograft: most common
- Isograft: from identical twin or highly inbred animal
- Allograft: another animal same species
- Xenograft: another species
Describe how utilized methods pre and post grafting can increase graft acceptance
Bandaging
-Distal limbs best
-Areas of motion need cast
-Prevents examination of the wound
-Advantage: prevents motion
-Remove is there is heat, swelling above the cast, increased lameness, excessive discharge
Understand the causes of graft failure
- Poorly prepared recipient bed
- Poor perfusion
- Hemorrhage displacing pinch or punch grafts
- Motion
- fluid accumulation under graft
- Bacterial infection: Fibrin enzymatic destruction - usually holds graft into place
Prevention of failure
- Antibiotics
-Broad spectrum
-Timentin (ticarcillin with potassium clavulanate) - Inflammation
-Systemic NSAIDs
-Phenylbutazone
-Flunixin meglumine - Movement
-First bandage change at 4-5 days
-Confine to stall
-RBJ, cast, imobilize limb - Fluid accumulation
-Use meshed graft
-Hemostasis for punch graft cotton swabs
Dentigerous Cysts & Nodular Necrobiosis
Dentigerous Cyst (ear tooth)
-Congenital defect
-Draining tract near the ear
-Cystic lining around a tooth in an abnormal location
Nodular Necrobiosis
-Eosinophilic granulomas
-Trauma, insect hypersensitivity
-0.5-1cm firm nodules
-Can be seen anywhere
-Cosmetic: if needed inject steroids (triamcinolone, methylprednisolone) into lumps
-Can reoccur
Equine Wound management
Describe the etiology, diagnosis, treatment, and prognosis for
- Fistuluos withers
- Cellulitis
Fistulous withers
Etiology
-Inflammation and infection of the bursa below the supraspinatus ligament along the dorsal spinous processes
-Head trauma history: horse flipping over backward
Brucella abortus - zoonotic & reportable
-Other bacteria
Poll evil = supra-atlantan bursa
Diagnosis
-C/S: draining tract over withers
-Pain on palpation
-Radiographs to assess spinal processes
-Culture
Treatment
-Establish drainage: can be difficult
-Debride wound, spinous processes, bursa
-Antimicrobials
-Lots of lavage
Prognosis
-Fair with early intervention
-$$ prolonged treatment
Cellulitis
Etiology
-Infection of the subcutaneous tissues
-Diffused edema in affected limbs
-Common bacteria: Staphylococcus or Streptococcus, negative anaerobes too
-C/S: Significant swelling, lameness 4 or 5/5, fever, small scab, wound, weep fluid from skin, sloughing in severe cases
Diagnosis
-Based on clinical signs
Treatment
-Broad spectrum antibiotics
-Gentamicin, ceftiofur/penicillin, enrofloxacin (resistance in refractory cases), SMZ/doxycycline in mild cases
-May be able to aspirate fluid and get culture/sensitivity
Sweat bandages
-Anti-inflammatories
Magna-poultice topical
Emergency within 12-24 hours
Prognosis
-Prone to recurrence: 44%
-Refractory treatment in some cases: chronically thick leg
-Decreased survival with development of laminitis
Pigeon Fever Lymphangitis
Etiology
Corynebacterium pseudotuberculosis
-Uncommon sequelae
Diagnosis
-Nodular lesions
-Abscesses
Treatment
-Broad spectrum antibiotics
-Bandaging
-Takes months to resolve
Determine which wounds are candidates for primary closure, delayed primary closure, and secondary healing, explain why a certain method was choses
- Initial evaluation
- Check synovial structures if applicable
- History, PE, Distance exam
- Initial evaluation
-Clip the wound: sterile lube to keep hair from sticking
-Clean the wound: DILUTE betadine or chlorhexidine
-Wound lavage: 15 psi (19 g needle, 35 ml syringe)
-Sedation: xylazine 0.2-1 mg/kg (150-250 mg average horse). Detomidine (3-5 mg), Butorphanol labeled dose or (5-10mg)
-Local anesthesia: nerve blocks best
-Radiographs: check for foreign body, fracture - Synovial structures
-Aseptic prep away from wound for communication check
-Insert needle into synovial structure: sample fluid, Amikacin instilled broadspectrum.
-Lavage
-If it communicates refer. Initially not very lame, but 3-5 days later severe lameness bacteria sealed in wound
Treatment
-Antibiotics broad spectrum
-Systemic NSAIDs
-Local antibiotics: Regional limb perfusion, intraosseous perfusion.
-Lavage: arthroscopic, needle under anesthesia, standing.
Regional limb perfusion
-Get high concentration of antibiotic to the sire of infection
-Tourniquet above the site of infection: above and below if mid-limb
-25-27 g needle or catheter in a peripheral vessel
-1g Amikacin or Gentamicin qs to 30-60 ml
10-20 ml Carbocaine first
-Leave tourniquet in place for 30 minutes
-Aminoglycosides concentration dependent
Lavage
-Under general anesthesia
Lavage
Chronic Sepsis
-Hyperemia: bacteria hide
-Adhesion formation
-Cartilage thinning
Determine which wounds are candidates for primary closure, delayed primary closure, and secondary healing, explain why a certain method was chosen
Primary Closure
-Wound is closed immediately and completely
-Strict aseptic technique
When:
minimal tissue loss, minimal bacterial contamination, minimal tension
Mesh expansion/relief incisions
-Minimize tension
-Small incisions “gap” and heal by second intention
-Allows for drainage of fluid
Never cut skin off if it is still alive/bleeding
Delayed Primary Closure
-Initially debride
-Close within 3-5 days, before granulation tissue forms
When:
-Mild/moderate contamination present
-Minimal tissue loss
-Minimal tension
-Can place drain if needed to evacuate fluid after closing
Secondary Closure
-Less common
-After granulation tissue is covering wound bed
1-2 weeks after wound
-Tension sutures usually needed (button or rubber tubing)
Second intension healing
-Heal by contraction, granulation, epithelialization
-Complications: bone sequestration, exuberant granulation tissue
When
-Wounds can not be sutured
-Gross contamination
-Moderate to severe tissue loss
Exposed Bone
-Sequestrum
-C/S: draining tract from healed wound
-Prevention: cover bone with skin
-Tx: surgical removal
Describe pathophysiology of the development of exuberant granulation tissue on distal limbs of horses
-Occurs on distal limbs only
-Related to: local hypoxia, bandaging, prolonged inflammation
-Delayed healing: epithelialization can not migrate across the wound
Treatment
-Sharp debridement: very vascular, no nerve endings, trim if >dime diameter. From bottom to top
-Topical corticosteroids
-Skin grafting
-Equine amnion dressing (depends on study)
