Shared Flashcard Set

Details

skin tumours and chronic wounds
asdf
29
Veterinary Medicine
Graduate
02/29/2016

Additional Veterinary Medicine Flashcards

 


 

Cards

Term
Sarcoids
Definition

 

most common neoplasm affecting horse. Benign but can be locally aggressive. Fibroma-type structures. Aetiology is unknown but BPV or similar viral cause suspected. Some evidence that they can be spread by flies.

Clinical features: Distribution can grow anywhere but common on head, groin, prepuce, axillae, neck. >80% of horses with sarcoids have more than 1 lesion. Often can be slow growing/quiescent for months/years, then rapid growth.

Lesions types: See: http://pcwww.liv.ac.uk/sarcoid/ for photos or Knottenbelt, Diseases and Disorders of the horse, Mosby. 

Term
Occult: sarcoids
Definition
Area of slightly thickened skin with a roughened surface, often hairless and very slow growing.
Term

 

  •   Verrucous (warty) Sarcoid: 

Definition

 

  • Dry, horny and cauliflower-like, hairless and can have either a broad base or a stalk (pedunculated) 

Term

 

  • Fibroblastic Sarcoid:  

Definition

 

  • Resembles proud flesh; can be firm and nodular and its surface may be ulcerated. 

Term

 

  • Mixed Sarcoid 

Definition

 

  • This is a mix between any types of sarcoid. 

Term

 

  • Nodular Sarcoids:  

Definition

 

  • Entirely under the skin, easily shelled out 

Term

 

  • Malevolent sarcoids: 

Definition

 

  • Rare, most aggressive type - tumours spread extensively

    through the skin with cords of tumour tissue interspersed with nodules and ulcerating fibroblastic lesions. 

Term
Treatment for sarcoids
Definition

 

  1. Difficult. Many tx’s available suggests no one is very effective. N.B. draw a lesion map so all lesions on horse at time of start of tx are documented. Lesions may increase in size and number after any interference. Choice of tx depends on site and type of sarcoid, cost issues etc. Lesions may occur at same or distant sites. Effective treatment is more certain if lesions are treated early, and if the horse is under 4 - 6 years of age. N.B. when comparing treatment ‘success’ must consider length of post-treatment evaluation.

    1. Do Nothing: If do not cause interference e.g. with tack, are not ulcerated. Very occasionally sarcoids can be self-resolving.

    2. Surgery: Up to 40% recurrence reported but better results (80%) if wide margins (8mm) taken or when used to ‘debulk’ large lesions which are then also tx’d with other therapy e.g. cisplatin. Laser surgery may also be useful (seals bv’s and lymphatics as it cuts). Ligation or elastration of stalks of pedunculated sarcoids sometimes effective.

    3. Cryosurgery: Only effective for lesions with limited size and depth, may cause extensive damage to surrounding structures and scarring. High reported rate of recurrence.

      1. BCG injection: Very successful for periocular sarcoids (>85%), very poor rate of success elsewhere. Need 2-3 injections several weeks apart. Unknown mechanism of action. Can get severe anaphylactic reaction on repeat tx’s.

      2. Radiation -gives the best results but very expensive and very restricted (Liverpool only). Therefore, it is reserved for difficult lesions such as around the eye or over joints. 90-100% success at 1 year

      3. Topical cytotoxic therapy: AW4-LUDES (‘Liverpool sarcoid cream’) = secret formula applied topically on several occasions. Obtained on case by case basis from Leahurst Equine Hosptial. Causes skin necrosis and scarring. CARE: fly strike in tx’d areas in summer.

      4. Intralesional chemotherapy: Cisplatin (N.B. CARE when handling). 5-flourouracil.

      5. Combination therapy: usually gives best results. 

       

Term
Melanoma
Definition

 

Prevalence: 4% of all tumours in horses, 10% of skin tumours in horses, 80% of grey horses >15y.o have them.
Classification: N.B. may change from benign malignant

  •   benign tend to be dermal melanoma = discrete, slow growing, only cause probs if distorting normal function e.g. around anus, in guttural pouch.

  •   Malignant often metastasise. Grey horses = dermal melanomatiosis (>17 y.o.) or non-grey coloured horse = anaplastic malignant melanoma (>20 y.o.)

    Appearance: Black lesions, solid or soft, black on cut surface, aggressive melanomas can occasionally be amelanotic i.e. unpigmented.

Term
MElanoma treatment
Definition

 

  1. Benign:

    •   Leave alone unless causing a problem

    •   Excision wide and check margins. May be curative for discrete dermal lesions or

      helpful for de-bulking large lesions that are causing a physical obstruction.

    •   Cryotherapy may need to repeat. Combine with de-bulking surgery? Don’t use if

      near any vital structures

    •   Cimetidine systemic oral tx. Only works in horses with lesions that are increasing

      fast in size or number. Poor client compliance because TID administration for 3

      months required. Expensive and very questionable success rate

    •   Chemotherapy intralesional cisplatin on at least 2 occasions. Cisplatin = v. toxic to

      the administrator so CARE when handling. 

Term
squamous cell carcinoma
Definition

 

  1. Aetiology: UV radiation, chronic irritation, previous wound, smegma (penile SCC) Distribution: Usually around head/eye (esp 3rd eyelid) or external genitalia (vulva, penis), particularly non-pigmented skin.
    Appearance: lesions are productive (papillary appearance) or erosive (nodular plaques +/- ulceration). Locally invasive, slow to metastasize, maylocal lymph nodes then lung. 

Term
SCC treatment
Definition

 

  1. Treatment:

    •   Excision: wide, deep, check margins often difficult around head, 55% recurrence rate. Good success for SCC of 3rd eyelid.

    •   Cryotherapy (see above)

    •   Radiation therapy: specialised centres only iridium wire implants (U of Liverpool),

      strontium wands

    •   Chemotherapy: topical 5% 5-flourouracil 90% success rate reported but have to

      apply daily for weeks. Cisplatin injection (see above) 65% success rate, when

      used in conjunction with surgical debulking 89% success.

    •   Malignant lesions: only attempt to treat if reasonably sure have not metastasised. 

Term
Papillomatosis
Definition

 

  1. common disease of young horses (<2 y.o.) due to papovavirus infection. Occasionally in older horses if immunologically naïve. Often on face/head, particularly around muzzle. Regress spontaneously in 3-4 months therefore NO NEED TO TX. Virus also causes aural plaques see medicine skin lectures. 

Term
Mast cell tumour
Definition

 

rare in horse. Typically benign c.f. small animals. Arabs over represented. Surgical removal is usually curative. 

Term
THink about why the wound is not healing?
Definition

1. Infection

2. Excess movement

3. Large skin defect

4. presence of FB/necrotic tissue

5. excessive granulation tissue= proud flesh

6. systemic disease of patient

7. combo of above 

Term
Infection
Definition

 

Definition = >105 bacteria/gram of tissue
o Bacteria prolong inflammatory phase of wound healing
o Bacteria may produce collagenases decreased wound strength
o Predisposed to by devitalised tissue, foreign bodies, haematoma, seroma,

dead space, movement and excessive oedema.

Remove necrotic tissue, foreign bodies etc
o Topical +/- systemic antibiotics - bacterial culture and sensitivity will save

you wasting lots of money on inappropriate drugs. 

Term
Excess movement
Definition

 

particularly over high motion joints in the limbs

Robert jones bandage +/- splint
o Cast bandage cast (cast material placed over soft bandage) safest to use if

not in hospital situation and also allows dressing changes (bi-valve the cast

material) 

Term

 

Large skin defect 

Definition

 

May just require more time if epithelisation is occurring

o May require skin graft (particularly on limbs where contraction effect = less)

If epithelisation is already occurring, may simply require more time o Skin graft -see below

o Delayed secondary closureskin to skin contact 

Term

 

Presence of foreign body/necrotic tissue 

Definition

 

Stake wounds
o Inadequately debrided wounds
o Bone fragment remaining
o Bony sequestrum formation post-injury

 

Ultrasound/radiography etc to help identify if necessary then REMOVE 

Term

 

Excessive granulation tissue = ‘Proud flesh’ (N.B. predisposed to by 1-4)

Definition

 

Limbs>>trunk wounds, Horses>> ponies
o Once granulation tissue protrudes higher than wound edge, v. difficult for

epithelium to grow over it.

 

use treatments for 1-4 as appropriate +
o Bandage with moderate pressure CARE injuries to tendons, skin rubs etc o Excision of excess tissue cut back to just below the surrounding skin

surface note, granulation tissue can bleed a lot, be prepared!
o Topical steroids CARE if infected wound. Reduces granulation tissue but

also slows epithelisation too so don’t use for too long.
o Biological dressings e.g. amnion, skin grafts can reduce granulation tissue

production
o Cauterising compounds copper sulphate, silver nitrate, salysilic acid

DON’T USE. V. old fashioned. Cause necrosis and slough of tissue and ++++ irritation to wound surface retards contraction and epithelisation. 

Term

 

Systemic disease of patient N.B. has to be quite severe to affect wound healing 

Definition

 

Nutritional status of horse (i.e. cachexia)

o Cushings

Term
Skin grafting
Definition

 

Skin grafting not uncommonly required in horses due to poor wound healing in distal wounds and predisposition to exuberant granulation tissue. Reconstructive surgery/pedicle grafts difficult in horse due to practical considerations (little spare skin, difficult to mobilise etc.) 

Term
Type of skin graft
Definition

 

Depends on:

  •   Size and location of defect

  •   Facilities and equipment available e.g.:

o Require GA e.g. to harvest split thickness grafts
o Specialist equipment e.g. dermatome
o Aftercare require immobilisation/frequent bandage changes?

Expertise available

Term

 

Preparation of recipient site (for all types of graft) 

Definition

 

  •   Need a fresh or granulating wound

  •   If granulating, debriding granulation tissue prior to grafting reduces bacterial

    contamination of surface

  •   DON’T consider grafting if infection present may be obvious clinically or could do

    qualitative bacteriology on sample of granulation tissue (>105/g)

  •   Consider topical tx of recipient site after initial debridement for 1 or 2 bandage

    changes prior to grafting (poor penetration of gran tissue by systemic abios). Beta- haemolytic streps and pseudomonads often a problem therefore consider silver sulfadiazine, nitrofurazone. 

Term

 

  1. 1. Pinch/Punch grafts: 

Definition

 

  •   Easy to do can be done in general practice on the yard having another vet or nurse around speeds the process immensely.

  •   Good for relatively small recipient sites

  •   Donor site usually on dorsal aspect of neck, side hidden by mane

  •   Reported up to 50% graft ‘take’ in horses – manage owner expectations 

Term

 

  1. 2. Tunnel grafts: 

Definition

 

  •   Useful for large skin defects at highly mobile sites e.g. dorsal hock, or sites that are difficult to bandage e.g. thorax/abdomen/gluteal areas.

  •   Technically simple

  •   Donor site = neck, leaves more of a scar than pinch/punch 

Term

 

  • 3. Split thickness grafts: 

Definition

 

  •   Very painful to harvest therefore horse usually requires GA

  •   Need specialist equipment (dermatome)

  •   Technically difficult but higher % ‘take’ than full thickness graft

  •   No adnexal structures (hair etc) transferred (usually)

    4. Full thickness grafts: 

Term

 

  1. 4. Full thickness grafts: 

Definition

 

  •   Good cosmetic and functional result make sure hair is going correct direction!

  •   Limited amount of donor skin available (usually take from brisket) can mesh graft

    to make it cover larger area

  •   Reduced survival c.f. split thickness. 

Term
Reasons for graft failure
Definition

 

  1.  Excessive movement and infection = most common. Both fluid accumulation between graft and recipient site prevent/disrupt adherence. Also inadequate preparation of graft (too thick?) or recipient site. 

Supporting users have an ad free experience!