Surgical equine dermatology Flashcards
What is the most common skin tumor in the horse?
sarcoid
What are differential diagnoses for sarcoid?
- squamous cell carcinom
- melanoma
- parasitic lesions
- ringworm
- equine papilloma
- granulation tissue
Where do squmaous cell carcinomas tend to be?
head or genital
Where do melanomas tend to be?
muzzle? under tail?
Where can parasitic lesions and ringworms be?
anywher
What can granulation tissue look like?
- sarcoid
2. squamous cell carcinoma
What are the characteristics of dry, flat sarcoid
dry, flat–hair loss, skin is normal underneath, ressembles ringworm but not silvery. palpate bmps and irregularities at edge of lesion–true edge of lesion
What are the features of a mixed sarcoid
hyperpigmentation
not itchy or painful
ddx staph folliculitis–but PAINFUL
What are the classifications of sarcoids?
- dry, flat
- mixed
- nodular (type A, Type B)
- verrucose–feel like warts
- fibroblastic
- occult
How common are periorbital sarcoids
common
What is the etiology of sarcoids?
- can occur one-off
- can occur in groups of horses–“outbreak” then go away without treatment
these have different etiologies
What are the features of fibroblastic sarcoids?
highly aggressive
can be primary but usually secondary to inadequate intervention
will invade!!
Tumors on the head are what until proven otherwise?
squamous cell carcinoma
How do you diagnose a skin lesion?
take a biopsy and send to someone that has experience looking at horse skin!!!
Why do you not want to biopsy a sarcoid?
may turn fibroblastic because you upset it
What are treatment options for sarcoids?
- surgical removal
- surgical removal and cryptherapy
- crypotherapy
- laser therapy
- immunotherapy
- chemotherapy–cisplatin
- brachytherapy–radiation
How do you correctly surgically remove a sarcoid?
- don’t prep–take surface active cells and scrub over surgical field then cut through and seed them into your margins
- don’t clip
- make big square line block and cut inside square
- pick up skin margin with towel clamps, not thumb forceps
- often don’t have to go very deep (dermal based tumors)
- horses have many myofibril cells in skin–as soon as make any sized hole, will become 30% bigger v/ quickly–warn client!
- put big tacking sutures across the wound. near far, far near, tight! if a few days will be loose–massively improve bandage, treatment time
- smear vasoline down the side of the horse (and have fly spray)
- time it with spring, late fall so there a fewer flies because these wounds are fly magnets!
How should you do cryotherapy on sarcoids?
do 3 cycles
What are the steps of cryotherapy
rapidly freeze tissue–ice crystals
slow thaw–aggregation of ice crystals so ice block in cell gets larger
rupture of cell
microthrombus formation–avascular necrosis of remaining tumor cells left behind–tell client that more will die!!!
What is CO2 laser therapy?
a treatment for sarcoid
What is the problem with treating sarcoids on the ear?
very unforgiving tissue, could damage cartilage and disrupt proper structure of ear
What is the BCG vaccine?
a vaccine for sarcoids
What is the issue with the sarcoid vaccine?
some animals have a major anaphylactic reaction and drop dead (second time?) may pretreat with dex but given risk and success rate probably don’t use this
What drug is used with immunotherapy?
cisplatin
can inject into mass (use luer lock syringe)
cisplatin beads–make small incision in sarcoid and drop beat in and cruciate suture over it–works quite well but the beads are a pain–small, quite fragile
multiple treatments
if first injection doesn’t work, could try a second but no more than that if second does not work
What is the current definitive treatment for sarcoids?
brachytherapy (radiation) inject grains, or wires don't want in a midthoraxic, axillary region!!! gold strontium wand etc
Why might you not be able to get a good freeze with cryotherapy after surgery?
the blood flowing can thaw the tissue faster than you can freeze it
Why do you want to get a very good freeze on sarcoid after surgery?
because want to penetrate deeply
What are topical therapies for sarcoids?
AW4-LUDES
5-fluorouracil and oil of rosemary
ok, not great
Xterra: not FDA approved, not for sale in canada. No controlled trials!!!
blood root extract
Melanomas are most ocmmon in…
grey horses
What are the 3 types of melanoma
- classical benign
- benign-malignant-benign
- malignant
Where can the melanomas under the tail metastasizze to (rare)
to the spine and cause ataxia
What is the appearance of melanomas?
hard spherical nodules
How do melanomas typically spread?
locally
Where can melanomas be found?
tailhead
salivary gland?
What is a differential for melanomas at salivary gland region?
enlargement of salivary gland with low grazing?
What are the features of squamous cell carcinomas?
- invasive tumor of squamous cells of skin, resporatory mucosa etc etc
- most common are eyelid/nictitating membrane and penis
- high U/V levels and smegma thought to be inciting causes
- penile condition more common in geldings
What may be the initial sign of squamous cell carcinoma in eyelid/nictitating membrane?
epiphora
prolapse nictating membrane and look underneath for grey fleshy mass that could be early SCC
Why should you feel inguinal lymph nodes?
SCC from penis may go there (can feel very rectal)
but just because not enlarged does not mean they have not metastasized there
Does granulation have nerves (before maturation)
no
Why can it be difficlt to differentiate granulation tissue and sarcoid?
because can be similar in appearance and becuase sarcoid can arise from previous region of trauma
