SA Dermatology and wounds Flashcards
Where is the best place to test for sarcoptic mange?
Ear margin
Small orange-red colonies are likely to be which yeast?
Malassezia pachydermatitis
What is the most common cause of anal gland disease?
Impaction
May be associated with loose stools
What would you expect to see with anal gland carcinoma?
Hypercalcaemia
What is onychomadesis?
Sloughing of claws
What is paronychia?
Inflammation or infection of the claw folds
What is onychogryphosis?
Claws growing inwards
Where would you see scale associated with Cheyletiella?
Along back
What histological findings would you see with pemphigus foliaceus?
Subcorneal pustule with acanthocytes
What clinical sign in cats is a good indicator of pemphigus foliaceus?
Caseous paronychia
What do lots of follicular casts on a histological sample indicate?
Sebaceous adenitis
How long is the epidermal turnover?
21 days
What is pigmentary incontinence?
Loss of melanin from the epidermis, and accumulation in melanophages in the upper dermis.
Associated with immune-mediated and inflammatory diseases
What is CAD?
Genetically predisposed inflammatory and pruritic allergic skin disease, with characteristic features associated with IgE antibodies most commonly against environmental allergens
What is atopic-like dermatitis?
An inflammatory and pruritic skin disease with clinical features identical to those of CAD, but in response to non-environmental allergens
Describe the pathogenesis of CAD
Complex, multi-factorial Genetic predisposition: -Skin barrier dysfunction -Immune dysregulation Environmental factors: -Specific allergen sensitisation -Enhanced microbial colonisation
How do you diagnose CAD?
Clinical signs: pruritus with skin lesions of characteristic distribution (ears, eyes, muzzle, feet, axilla, inguinal, perianal)
Ectoparasite/food trials
How do you manage CAD?
Improve skin barrier function (eg EFAs)
Anti-inflammatory drugs
Allergen avoidance and ASIT
Control microbial infection and other flare factors
How can we improve skin barrier function when treating CAD?
Non-irritating shampoos (eg emollients)
Oral EFAs
Topical formulations containing EFAs
How long does it take essential fatty acids to be incorporated into cell walls?
8-12 weeks
How are topical lipid formulations useful in treating CAD?
Help to normalise existing stratum corneum defects
However, likely to be of little benefit in addition to oral EFAs
Which anti-inflammatory drugs can you use to treat CAD?
Glucocorticoids (eg prednisolone,0.5mg/kg once to twice daily)
Calcineurin inhibitors (eg atopica)
Novel Janus Kinase inhibitor (eg aopquel)
Antihistamines
Recombinant interferons
Give some adverse effects of using systemic glucocorticoids (anti-inflammatories) to treat CAD
Polyphagia, PUPD, behaviour changes, panting, iatrogenic hyperadrenocorticism, increased risk of UTI
Which topical glucocorticoid could you use to treat CAD?
Where is it metabolised?
Give a side-effect
Hydrocortisone aceponate
Metabolised within the dermis so minimal systemic effects
Side effect: skin-thinning, so use intermittently
How do oral calcineurin inhibitors work in the treatment of CAD?
Give some adverse effects
Inhibit T lymphocyte function via blocking calcineurin
Adverse effects: GI signs, gingival hyperplasia, viral papillomas, hirsutism
When are janus kinase inhibitors contra-indicated when treating CAD?
<12 months old or <3kg BW
Breeding dogs or dogs with serious infections, underlying neoplasia or immune suppression
What dose of janus kinase inhibitor should you use when treating CAD?
0.4-.0.6 mg/kg twice a day for 2 weeks
Then once a day for maintenance
What is primary wound closure?
Direct suture closure
What is delayed primary wound closure/tertiary closure?
Leave part/all of wound, then close 1-5 days later before full granulation has occurred
What is secondary wound closure?
Wound edges cannot be apposed, so wound is left open. Involves repeated bandaging and debridement. Before granulation tissue develops, use wet-to-dry dressings. Once granulation tissue develops, use dry non-stick dressings so as not to disrupt granulation.
May be closed over 5 days later; granulation will have occurred so excise granulated edges
What are the aims of skin reconstruction?
- Square skin edges
- Accurate apposition
- No overlapping
- Slight eversion of wound edges (ensure base of epidermis is touching on both sides)
- Follow Halsted’s principles (follow the tension lines-want wound to run parallel to tension lines to make it easier to close)
When would you undermine and advance the skin when closing a wound?
Indicated when wound is too large for closure using tension-relieving sutures, but too small for a flap
What are the 2 ways of undermining and advancing skin to close a wound?
- Blunt (scalpel handle, scissors)
- Sharp (scalpel blade, scissors)
Why might we undermine and advance skin to close a wound?
Frees skin from its subcutaneous attachments to allow us to stretch it over the wound
What must we remember to do when we undermine and advance skin to close a wound?
- Maintain vascular supply (direct cutaneous arteries/veins)
- Undermine deep to the panniculus muscle layer where present (ie neck, thorax, abdomen). If not, undermine in loose areolar fascia deep to dermis
What are walking sutures?
Tension-type sutures that can be used to close large skin defects in areas where sufficient skin surrounds the wound that can be moved or stretched to close the wound
Used to eliminate dead space
Why do we not want walking sutures to go through the skin?
Possible route of infection
Give some possible disadvantages of using multiple punctate relaxing sutures to close a wound (making multiple stab incisions in skin to allow it to stretch)
- Damages subdermal plexus (blood supply to edge of wound)
- Holes would heal by 2nd intention -> patches of hairless skin -> fragile, prone to damage
- Too many (or too closely-placed) stab incisionsmay damage the circulation to the wound edges -> ischaemic necrosis
- Hence this technique not used much now
Which suture material should you use when doing walking sutures?
Where should they be placed?
- Absorbable 2/0 or 3/0 sutures between the dermis and the subcutaneous fascia in rows no closer than 2-3cm apart
- Place as few as possible
What is the ‘Z-plasty’ method of wound closure?
-Incisions are marked at 60 degrees to the original wound
-Creation of 2 triangular skin flaps
-Transposition of the skin flaps
-Wound is closed, giving a length gain
of approximately 75%
What is the ‘V-Y plasty’ method of wound closure?
A V-shaped incision is created perpendicular to the wound and closed in the shape of a Y
This technique will only relieve tension over a relatively limited area
How can you close crescent-shaped wounds where the 2 sides are of unequal length?
By spacing sutures further apart on the longer side of the crescent shape
(Or by excising dog ears that form at the corners)
How would you close triangular/square/rectangular-shaped wounds?
Begin suturing at the corners and proceed to the centre