Derm Flashcards
1
Q
What is the main biting louse of the dog?
A
Trichodectes Canis
2
Q
What is the main biting louse of the cat?
A
Felicola Subrostratus
Feel-ic- oh- la Sub-row-stratus
3
Q
What is the main sucking louse of the dog?
A
Linognathus setosus
Pronounce:
Lino-(g)nathus setosus
4
Q
What are the 3 long-legged mites of small animals?
A
Cheyletiella
Otodectes
Trombicula
5
Q
What are the short legged mites of small animals?
A
Sarcoptes
Demodex
6
Q
which mite has a ‘lemon’ shaped egg?
A
Demodex Canis
7
Q
Which parasite may be found on a hair pluck?
A
Demodex
8
Q
What are the 2 main derm conditions seen in dogs <1y old?
A
Parasites
Food induced atopy
9
Q
Which derm condition is commonly seen in dogs 6m-3y old?
A
Environmental allergen induced atopy
10
Q
What are the 2 main causes of dermatological dz in adult dogs?
A
Immune mediated
Endocrinopathy
11
Q
What are 2 common signs of demodex overgrowth?
A
Greasy hair and pruritis on dorsum
12
Q
Which mite leads to extreme pruritis, crusting and excoriation?
A
Sarcoptes
13
Q
Which mite causes “walking dandruff” w/pruritis and erythema.
A
Cheyletiella
14
Q
Which canine/feline mites are zoonotic?
A
Cheyletiella
Sarcoptes
15
Q
Which mites cause a dark brown, waxy discharge?
A
Otodectes
16
Q
Which flea/mite/lice treatment is best for small furry exotics?
A
Ivermectin/milbemycin
17
Q
What can be used to treat otodectes in cats?
A
Imidacloprid + moxidectin
OR
Selamectin
IMID ACLO PRID
18
Q
Which SA parasite is a possible vector of anaplasma and borrelia?
A
Neotrombicula
19
Q
How is uncinaria treated?
A
Fenbendazole/milbemycin
20
Q
What is the most common cause of bacterial pyoderma?
A
Staph pseudintermedius
21
Q
What can be seen on cytology of superficial pyoderma?
A
Degenerative neutrophils
Phagocytosis of bacteria
22
Q
What are the main clinical signs of superficial pyoderma?
A
Macules Papules/pustules Collarettes Hyperpigmentation Erosion
23
Q
What are the main clinical signs of deep pyoderma?
A
systemically unwell Furuncules, nodules, plaques Crusts, ulcers, sinus tracts Heat/erythema/swelling Haemorrhagic bullae Haemo-purulent exudate
24
Q
Which breed of cat is predisposed to malassezia overgrowht?
A
Devon Rex
25
What are the signs of malassezia dermatitis?
Alopecia
Seborrhoea
Hyperpigmentation
26
How is malassezia dermatitis treated?
Chlorhexidine + miconazole shampoo
If unsuccessful: systemic anti-fungals
27
What are the key signs of atopic dermatitis?
Pruritis
Alopecia
Acral lick
Recurrent otitis externa
28
What are favrots criteria for cAD?
DOG PENN
Dog lives indoors
Onset <3yo
Glucocorticoid-responsive pruritus
Pruritus at onset
Ear pinnae +/- front feet
Nonaffected ear margins
Nonaffected dorso-lumbar area
29
How is canine food allergy diagnosed?
+ response to 6-8w diet trial w/novel or hydrolysed protein
30
What is the onset of improvement for allergen-specific immunotherapy?
3-9m
MUST DO FOR 12m
31
How can we control allergies medically?
```
Glucocorticoids (low dose)
JAK inhibitor (oclacitinib)
```
32
What are the 2 contraindications for apoquel use?
<12m
| <3kg
33
Name 3 glucocorticoids used to treat cAD.
Hydrocortisone
Ciclosporin
Tacrolimus
34
How would self-induced alopecia appear on a trichogram?
frayed/broken tips
35
What is the main cause of ringworm in dogs and cats?
Microsporum Canis
ALSO: M. gypseum & T. mentagrophytes
36
What is the gold standard test for ringworm in cats/dogs?
External lab fungal culture.
woods lamp and trichography have false +/-'s.
37
Which antifungal treatment can be given to cats?
Itraconazole
38
Which antifungal treatment(s) can be given to dogs?
Itraconazole
| Ketoconazole
39
What treatment is given for juvenile onset demodicosis?
None - most spontaneously resolve
40
What treatment is given for adult onset demodicosis?
Aggressive Tx:
Manage underlying Dz.
ABs as often 2e infection.
41
What are the two mites causing feline demodicosis and how do they differ?
D. Cati: non-pruritic, usually due to immunosuppresive drugs.
D. gatoi: pruritic and infectious.
42
How is feline demodicosis treated?
treat pyoderma
| Imidacloprid 1st
43
When should demodicosis tx be stopped?
2-3 consecutive skin scrapes (4w apart)
44
What are the clinical signs of alopecia areata?
Focal to MF alopecia
| Variable hyperpigmentation
45
Which breeds are predisposed to dermatomyositis?
Collies
| Shetland sheepdogs
46
How does dermatomyositis present?
```
6m old
patchy alopecia on face/extremities
erythema
scale
hyperpigmented
```
47
How is dermatomyositis treated?
Preds
Pentoxifylline
Vit E
48
What is sebaceous adenitis?
autoimmune attack on sebaceous glands
49
What are the derm signs of an endocrine Dz?
generalised alopecia
dull/dry/scaly
comedones
atrophic skin/poor healing
50
Which endocrine Dz presents with weight gain, tragic expression and truncal alopecia?
hypothyroidism
51
Which cancers cause feline paraneoplastic alopecia?
pancreatic/bile duct carcinoma
52
How does feline paraneoplastic alopecia present?
shiny, translucent skin.
| Alopecia ventrum & legs.
53
How is alopecia X diagnosed?
Breed - plush coat
| Exclude Ddx
54
Which 2 dog breeds are prone to pattern alopecia affecting the pinnae?
YRT
| Daxie
55
Which 2 breeds are predisposed to sebaceous adenitis?
Akitas
| Poodles
56
Clinical signs of sebaceous adenitis are...
Alopecia
Dry/Dull coat
Large adherent scales
Bacterial folliculitis
57
What is the treatment for sebaceous adenitis?
Skin care
Intense moisturisation
Manage 2e infection
58
What are the 5 main causes of head and neck pruritis in the cat?
```
FBH
Otodectes
Neotrombicula
Bacteria
Malassezia
```
59
What are the 3 presentations of eosinophilic granuloma complex in the cat?
Eosinophilic plaque
Eosinophilic granuloma
Eosinophilic ulcer
60
What is a feline Eosinophilic plaque?
Raised, alopecic, erythematous, erosive to ulcerative plaque
| HIGHLY PRURITIC
61
What is a feline Eosinophilic Granuloma?
Raised, alopecic, erythematous, erosive to ulcerative plaque.
Non-pruritic!!!
62
What is a feline Eosinophilic Ulcer?
Well circumscribed, red/brown ulcer with raised border on upper lip.
Non-pruritic, non-painful.
63
What is atopic dermatitis?
Genetically predisposed inflammatory & pruritic allergic skin disease - commonly environmental or food associated
64
Which type of hypersensitivity reaction is CAD?
```
Type I (IgE)
Type IV Th2
```
65
What is an atopic flare?
Inc in staph and malassezia pyoderma due to defective skin barrier function
66
What are the 4 key features of cAD treatment?
Improve skin barrier
Allergen avoidance/AST
Control inflammation and pruritis
Control flare factors
67
How does Food-Induced Atopy differ for CAD?
Younger onset
Concurrent GI signs present
Not seasonal
68
What is the gold std Tx for FIA?
Home cooked diet trial with novel protein (min 6w)
69
What ways can we improve skin barrier function?
Non-irritating shampoos
Supplementation of EFAs
Topical EFA containing formulations
70
Name 2 topical lipid formulations that can aid skin barrier function.
Alladerm Spot on
| Dermoscent
71
Via which 2 route can glucocorticoids be given in CAD? Give examples of each.
Systemic: Preds, methypreds
Topical: Betamethasone, hydrocortisone
72
What systemic calcineurin inhibtors can be given in CAD?
Ciclosporin
73
What topical calcineurin inhibtors can be given in CAD?
Tacrolimus
74
How does oclacitinib work?
Janus Kinase Inhibitor
75
What is Lokivetmab?
Monoclonal Antibody against IL-31 (pruritic IL)
76
How should Glucocorticoids be used in CAD?
Crisis busting - relieve flares
77
Why is topical hydrocortisone a low-risk Tx for CAD flares?
MEtabolised in skin so very little drug reaches circulation
78
How do calcineurin inhibitors work?
Inhibit Tc function
79
How is oclacitinib (apoquel) given?
BID 2w then SID
80
What are the 2 contraindications of oclacitinib?
<12m
| <3kg
81
What is the CI for lokivetmab?
<3kg
82
Which 2 anti-histamines show some effect at relieving CAD when combined?
Chlorpheniramine and hydroxyzine
83
What is the most important source of environmental allergen for CAD and how can we reduce this?
House Dust mites
Environmental Flea Sprays and cleaning!
84
What is ASIT?
Expose dog to gradually increasing allergen dose over 12m
85
What is the Tx for ear margin seborrhoea?
Emollient rinse
VAseline
Propylene Glycol
Backup: surgery
86
What are the 3 Ps of otitis?
Primary (pathogen/disorder)
Predisposing (hair, morphology)
Perpetuating Factors
87
What is the best Tx for localised otodectes cyanosis?
Selamectin/moxidectin spot on
88
What is the best Tx for secondary Dz to otodectes cyanosis?
Cleaner +/- steroids
89
What are the signs of otitis externa?
Malodour
Head Tilt
Aural pruritis
Deafness
90
What are the signs of otitis media?
Pain
Concurrent OE
Deafness
Pain Eating
91
What are 3 potential complications of Otitis Media?
Conductive Deafness
Horners
Vestibular Syndrome
92
What is the first diagnostic method used to asses OM?
Video otoscopy - assess drum
93
What Tx is indicted in cases of chonric OM or evidence of TM bulging/fluid behind it?
Myringotomy (w catheter)
+ swabs
+ saline flush
94
What is the best method for assessing internal damage caused by OM?
MRI
95
What are the clinical signs of Otitis Interna?
Ipsilateral head tilt
rotatory nystagmus
asymmetric ataxia/falling
Vomiting +/- anorexia
96
What is the underlying cause of "dry coffee ground" exudate from the ears?
Otodectes cyanotis
97
What is the underlying cause of "moist brown" exudate from the ears?
Staph spp/Malassezia
98
What is the underlying cause of "purlent yellow/green, malodorous" exudate from the ears?
Gram negative infection
99
What is the underlying cause of ceruminous discharge from the ears?
Allergy
Endocrinopathy
Bacteroides Spp
100
How should wax samples be stained?
Methylene blue only
101
How should purulent ear samples be stained?
Diffquick
102
How should parasites from the ear be prepared for microscopic exam?
Mix in LP
103
Which 3 flushing solutions are most commonly used in canine medicine?
Saline
Dilute Chlorhexidine
Povidone Iodine
104
What 3 medications are sued to treat otitis?
AB + Anti-inflam + Anti-fungal
105
Which drugs are ototoxic? (4 ABs, 2 cleaners)
Gentamicin
Polymixin B
Ticarcillin
Imipenem
Propylene Glycol
Chlorhexine (conc)
106
What is the best method of identifying the pathogen responsible for otitis?
Charcoal Swab and Culture
107
Why does pseudomonas otitis cause ear drum rupture?
Bacteria produces collagenase
108
What 2 Tx cane be used for a multi-resistant otitis?
Flamazine 1:9 in sterile water
| Ticarcillin solution
109
What are the 4 Tx for stenosis?
Potent topical steroids
Oral steroids
Tacrolimus ointment BID
Intralesional steroids
110
What is the Tx of choice for an end-stage ear?
TECA
111
What are the 3 signs of surface bacterial pyoderma?
Hotspots
Intertrigo
Bacterial Overgrowth
112
How should Malassezia be sampled?
If dry: acetate tape
If greasy: indirect smear w/cotton bud
113
What can be seen on cytology with superficial pyoderma?
Degen neutrophils and phagocytosis of bacteria
114
What are the signs of superficial bacterial pyoderma?
```
Papule/Pustules/Colarettes
ALopecia
Erythema
Hyperpigmentation
Lichenification
```
115
What are the signs of DEEP pyoderma?
```
Inflammation
furuncules/nodules/bullae
plaques
sinus tracts
ulcers/exudation/crusts
```
Sytemically unwell!!
116
How should a direct impression smear be performed on a pustule?
Pop it/lift crust - then apply slide SEVERAL times
117
How should acetate strips be stained?
Eosin and Basophil stains ONLY - no fixative
118
What size needle and syringe should be used for an FNA?
21G
| 2-5ml
119
What is the 1st line Tx for malassezia dermatits?
Chlorhexidine + miconazole shampoo
120
What is the Tx for chronic malassezia dermatits?
systemic antifungals
121
How longs should ABs be prescribed for a superficial pyoderma?
2-3w past clinical cure
122
How longs should ABs be prescribed for a deep pyoderma?
3m past clinical cure
123
How is the skin a protective barrier?
Strength of the skin is provided by factors including epithelial and dermal structures
124
How is the skin a chemical barrier?
Lipid barrier
125
How does the skin inhibit infectious agents?
Normal flora
Lipids-> fatty acids for the flora
Microbial proteins for epithelial cells and commensal bacteria support the microbiome
126
How does the skin regulate temperature?
Altered blood flow in the superficial plexus allows regulation of the temperature of the skin
Sweating in horses and other
Hair is insulation
127
How does the skin provide photoprotection?
Melanin in skin protects epidermal cells
Nuclear capping prevents damage of the basal cell nuclei
128
How does the skin carry out immunosurveillance?
Langerhans cells are crucial antigen presenting cells in cutaneous diseases
129
How is vitamin D produced in the skin?
Vit D conversion with UV light
130
What is the mechanism for Type I hypersensitivity reactions?
Mediator release from mast cells following cross linkage of IgE by allergen causing swelling, itching and inflammation
131
What is the mechanism for Type II hypersensitivity?
Complement or cellular damage to target bound by IgG
132
What is the mechanism for type III hypersensitivity?
Immune complexes of IgG or IgM and antigen are deposited and then complement or cellular damage follows
133
What is the mechanism for type IV hypersensitivity?
T cells orchestrate specific immune responses through production of cytokines (Th1 and Th2)
or through direct cell contact
134
Type I hypersensitivity time until onset
<30 minutes
135
Type II hypersensitivity time until onset
5-10 hours
136
Type III hypersensitivity time until onset
4-8 hours
137
Type IV hypersensitivity time until onset
24-72 hours
138
What type of hypersensitivity is Hives?
I
139
What type of hypersensitivity is insect bite reactions?
I
140
What type of hypersensitivity is pemphigus foliaceus
II
141
What type of hypersensitivity is drug reactions in the skin due to sulphonamides?
ii
142
What type of hypersensitivity is vasculitis?
III
143
What type of hypersensitivity is tuberculin response?
IV - uses Th1
144
What type of hypersensitivity is late phase allergic reactions?
IV uses Th2
145
What is the pathophysiology of atopic contact dermatitis?
Allegen -> skin
allergen penetrates the stratum corneum and is taken up by langerhans cells
Langerhans-> lymph nodes
Antigens taken up are incontact with T lymphocytes
Clonal expansionn and cytokine induced proliferation = antigen specific T lymphocytes
T cells-> blood-> epidermis
This is the sensitisation phase
146
What follows the sensitisation phase of allergic contact dermatitis?
Provocation phase = after rexposure
Langerhans cells containing antigen interacts with the specific T cells for that antigen
Initiaites cytokine induced proliferation
Causes a localised inflammatory response
147
In Atopic contact dermatitis how does the T cell proliferation affect the outcome?
Clonal expansion -> Th2 cell = allergic response = IL4-IL5- IL31-> IgE
Clonal expansion -> Th1 = non allergic response = IL2, IFNy = IgG
148
What promotes Th2 response in allergic contact dermatitis?
Thymic stroma lymphopoeitin (TSLP)
Works via the langerhans cells
149
What factors affect the response influenced by the APC in allergic dermatitis?
the amount and type of antigen
Via toll like receptors
Via lipid content of antigens
Cytokine environment
Microbiome
Antigens are presented to T cells in the local lymph node after migration from the epidermis
150
What does tissue inflammation result in, in cAD?
Skin thickening through hyperplasia
Increase in numbers of langerhans cells
Reduced cutaneous barrier function
INcreased bacterial numbers on or in the skin
151
Define dermatophyte
a pathogenic fungus that grows on skin, mucous membranes, hair, nails, feathers, and other body surfaces, causing ringworm and related diseases.
152
What samples could be used to investigate demodicosis in a lively puppy with periocular lesions?
Hair plucj
153
What samples would be the most appt to detect demodicosis on the thick of a well behaved dog?
Deep skin scraping
154
What is demodicosus?
deep follicular mites
155
What is not suitable for detection of dermatophytosis?
Unstained acetate tape strip
156
WHat is cheyletiellosis?
Surface mites
157
What is the best staining technique for cytological examination of an acetate strip sample?
Eosin and methylene blue
158
Which cells increase with chronicity of skin inflammation?
Macrophages
159
Lowest magnification for viewing demodex canis
X4
160
Lowest magnification for malassezia
x40
161
Lowest magnification for rod bacteria
x100
162
What is the Mckenzie coat brushing used for?
Sampling dermatophyte culture
163
What does a woods lamp detect?
Some but not all strains of microsporum canis
164
Best area to sample for skin scraping
Primary lesion
165
What is a DTM plate?
Dermatophyte test medium
based on sabourauds dextrose agar with added cycloheximide to inhibit saprotrophic growth. Has an antibiotic to inhibit antibiotic growth
Phenol red pH indicator= sacrophytic fungus present
166
What causes colour dilution alopecia?
Macromelanosomes
167
How will hair appear when there is self trauma?
Broken off hair tips
168
How will hair appear when there is endocrine disorders or inflammation involving the follicle?
Tapered hair tips
Hair loss is caused by events within the follicle
169
How will hair appear when in anagen phase?
roots of anagen hairs are rounded, curled, bent
Often smooth and pigmented
170
How will hair appear when in the telogen phase?
Lancet shaped and lack pigmentation
Base of the hair may show a roughened brush like edge
171
How will hair appear when there is dermatophysis?
Covered with spores and penetrated with hyphae?
172
How will hair appear when there is colour dilution alopecia?
Melanin clumped in the hair shaft
173
Appearance of demodex canis
lives in the hair follicles of dogs. Under the microscope, this mite is shaped like a cigar with eight legs. Demodectic mange, sometimes just called 'Demodex' or 'red mange', is the most common form of mange in dogs.
174
When should unstained acetate tape tests be used?
Plain tape strips can be used to collect hair and skin debris to detect ectoparasites
175
Define pruritis
Unpleasant sensation that elicits the desire or reflex to scratch (rub, lick, chew)
may be acute or chronic
176
What is the role of pruritis?
Pruritis is a physiological self protective mechanism that is designed to remove the agent causing the sensation from the skin
177
What is pruriceptive pruritis?
due to stimulation of peripheral receptors in skin (in presence of healthy nervous system
usually due to skin disease
178
What is neuropathic pruritis?
Generated in the CNS in response to
Circulating pruritogens
pharmacological mediators
anatomical lesion of PNS or CNS
179
What receptors are involved in the somatosensory activity of the skin?
Mechanoreceptors
Thermoreceptors
Nociceptors
180
What is pruritis mediated by?
Unmyelinated slow conduction C fibres
A-delta fibres
181
What are the chemical mediators of the cutaneous itch?
- various proteases/leukotrienes and neurotropins
- peptides
- prostaglandins
- cytokines - such as IL4, IL13, IL31 and IL33
- histamine
182
Where do chemical mediators of the skin originate?
- Keratinocytes
- leukotriene B4
- endogenous cannabinoids
- thymic stromal lymphopoietin
- mast cells
- Histamine
- LTB-4
- IL2
- nerve growth factor
- skin leucocytes
- T cells - IL 31
- eosinophils - NGF
183
What are the 3 different ways that mediators can act?
1. Direct stimulation of intraepidermal nerve fibres
2. stimulate mast cells
3. stimulate other mediators/transduction cascades
184
What produces IL31 and what is its role?
produced by activated T cells in allergic skin disease
bnds to recepotrs on surface of neurons in skin leading to the activation of JAK enzymes which stimulated the pruritic impulse to the brain
185
What are the neural pathways for itch
1. Sensory afferent from skin
1. mainly C neurones - slow conducting
2. Dorsal nerve root to spinal cord
3. Dorsal horn- synapse with spinal interneurones
4. Cross and ascend in lateral spinothalamic tract
5. Thalamus to the internal capsule
6. To the sensory cortex (left hemisphere dominance, cf pain)
186
Which cranial nerves carry the sensory fibres in from the head?
Trigeminal
Facial
Glossopharyngeal
Vagus
187
How does scratching suppress pruritis?
Scratch -> fast conducting A beta neurones-> activation of inhibitory neuronal circuits -> widespread surround inhibition
188
How does distraction suppress pruritis?
Distraction-> increased activity in descending pathways from reticular formation -> activation of inhibitory circuits in dorsal horns of spinal cord-> close gated mechanisms-> diminishes afferent itch messages
189
Outline peripheral sensitisation of chronic pruritis
Scratching → increase local inflammation → production of pruritogens by inflammatory cells → INCREASE C FIBRE RESPONSIVENESS
190
Outline the central sensitisation of chronic pruritis
chronic inflammation of skin→ altered perception of gentle mechanical/ other stimuli→ percieved as pruritis (allokinesis)
191
What are the 3 responses to skin damage?
Epidermal responses
Dermal responses
Alopecia
192
What is hyperkeratosis?
Increase depth of cornified layer
Scaling = production of abnormal or excessive scale
193
What is ichthyosis?
Primary keratinisation defects
194
What might non specific signs of secondary defects be indicative of?
Increased turnover of epidermis
Imbalance between turnover and desquamation
195
Follicular hyperkeratosis
-
- keritinaceous plugs in hair follicle infundibula
= comdefo/ comedones (blackheads)
196
What is a keratinaceous collar around hair emerging called?
Follicular cast
197
What is acanthosis?
Increased depth of the whole epidermis
198
What causes acanthosis?
1. repeated lowgrade blunt trauma
2. release of cytokines from keratinocytes
3. increased division of basal epidermal cells occurs
4. increases the depth of the epidermis
199
Which cytokines stimulate the epidermal growth that leads to acanthosis?
- PDGF released by keratinocytes
- TGF- alpha released by keritanocytes
- TGF- beta released by fibroblasts
- EGF released by platelets and macrophages
200
What is lichenification?
thickening and hardening of the skin characterised by exaggeration of the superficial skin markings
201
When do vesicles usually occur?
- with viruses
- foot and mouth disease
- Autoimmune diseases - autoantibodes attach intercellular proteins → this leads to separation of the keratinocytes
202
What is a pustule
- small circumscribed elevation of the epidermis that is filled with pus
- usually associated with infection but some are sterile
- such as bacterial pyoderma caused by staphylococcus pseudintermedius infection
203
What causes hyper or hypopigmentation?
Feature of diseases affecting the basal epidermis and dermoepidermal junction in the dog
204
What is crusting?
formed when dried exudate, serum, pus, blood, cells, scales or modifications adhere to skin surface
Caused by multiple exudate and ulcerative diseases
205
How is erythema caused?
Damage leads to release of proinflammatory mediators including histamine
this causes vasodilation of dermal vessels
causing erythema
206
What causes oedema?
Mediated by histamine and other cytokines which increases vascular permeability leading to leakage of tissue fluid
this leads to urticarial lesions
Type I hypersensitivity
207
What is dermal thickening associated with?
Longer standign allergic reactions
Chronic inflammatory conditions
208
What is alopecia a result of?
Failure to grow hair properly
Damage to hair follicles or shafts
209
How may a testicular tumour lead to alopecia?
Sertoli cell tumour produces oestrogens causing alopecia
210
Diplococci
bacteria- of various spherical Gram-positive bacteria that occur in pairs
211
Escherichia coli
acteria Gram-negative and its envelope has three layers: cytoplasmic membrane, peptidoglycan, and outer membrane
. The peptidoglycan is rigid determining the rod shape
212
Actinomyces
Gram postive bacteria
Filamentous
Rod
213
Clostridium spp
anaerobic, Gram-positive, spore-forming bacteria belonging to the family Clostridiaceae- vibrion
214
What cells are involved in the defence against parasites?
Basophils and mast cells - surface recetors for IgE, contain histamine, prostaglandins, leukotrienes and proteases
215
What cels are involved in phagocytosing pathogens?
monocytes, macrophages, neutrophils, dendritic cells, osteoclasts, and eosinophils
216
What term is used to describe a solid elevation of the skin greater than 1cm in diameter associated with cellular infiltration and or proliferation?
Nodule
217
Is a papule a primary or secondary lesion?
primaru
218
what is the name of a lesion that results from self trauma?
Excoriations
219
What lesion results from loss of the epidermis and the basement membrane (ie. exposing the dermis)
ulcer
220
What name is given to an elevated oedematous area of skin often caused by an urticarial reaction?
Wheal
221
What name is given to a flat, solid elevated lesion of >1cm often considered to be an accumulation of papules?
plaque
222
What lesion is composed of an enclosed cavity with a solid membranous linign that contains a liquid or semi solid material?
cyst
223
Which term is used to describe the thickening of the skin and exaggerated skin markings?
lichenification
224
Is crusting a primary or secondary lesion>
Secondary
225
What makes the physical protection of the skin?
Poor conditions
Low pH
Competition by normal flora
Physical barrier and desquamation
226
What secretions protect the skin>
- Antimicrobial peptides
- Protective substances such as mucus
- soluble proteins such as complement
- secretory immunoglobulins
227
What makes up cell mediated immunity of the skin
- Phagocytic cells
- Intraepithelial lymphocytes and natural killer cells
- Mast cells
- cytokines and chemokines
- the development of inflammation
228
What makes up the adaptive immunity of the skin?
Immunoglobulins
229
How does bacteria adapt to evade immune response on the skin?
- Antigenic variation
- inhibiton of antigen processing
- Inhibition of complement activation
- Resistance to phagocytosis
- Inactivation of reactive oxygen species
- Escape from the phagolysosome
- Production of cytokine receptor homologues
230
Why do commensals proliferate and cause pathogenic disease?
Usually due to a primary cause such as
- Hypersensitivity
- Systemic disease
- Damage of compromise of defences
231
Define (in relation to microbiology) resident
Can replicate on the skin and persist
232
Define (in relation to microbiology) nomad
Nomad organisms can colonise and reproduce on the skin for short times
233
Define (in relation to microbiology) transient
can not replicate so stay for a short time on the skin
234
Define (in relation to microbiology) pathogens
Organisms that become established and can proliferate in the skin surface and deeper that are deleterious to normal physiology of the skin
235
What do bacterial niches colonise based on?
Local secretions
pH
Contamination from local structures
Moisture
236
What transient bacteria can be found on dog skin?
- Staphylococcys psuedintermedius
- S. aureus
- E coli
- Proteus mirabilis
- Corynebacterium spp
- Bacillus spp
- Pseudomonas spp
237
What are the most common microbes on canine skin?
Staphylococcus
malassezia
238
What are the most common microbes in canine ears?
staphylococcus
malassezia
but can also get
pseudomonas sp
proteus sp
239
What bacteria is high risk around the anus?
Enteric bacteria
240
What is would you expect to find on canine skin>
Malassezia and gram positive cocci
241
What should not be on canine skin?
Gram negative or rod bacteria
242
Properties of the staphylococcus species
- Gram positive, facultative anaerobes that occur in pairs, tetrads or clusters
- Non motile opportunistic pathogens
- There are at least 30 different species on skin of mucous membranes as commensals
Use baird parker selective indicator agar
243
Which virulence factors are expressed by staphylococcus sp?
coagulase
Lipases and elastase
Protein A inhibits opsonisation
Range of toxins
244
How do staphylococcal super antigens lead to hypersensitivity?
1. Stimulation by super antigens (staphylococcus sp)
2. Super antifens over activate T lymphocytes by bypassing the normal processes
3. Activation by binding MHC and lymphocytes by not through the peptide binding cleft
4. This can lead to cytokine production and an inflammatory response
5. Uncontrolled immune response contributes to pathology
245
What is an abscess?
- A collection of pus formed by tissue destruction in an inflamed area of localised infection
- A defensive reaction of the tissue to prevent the spread of infectious material
Attract WBC - inc regional blood flow
246
Example of surface infection
Secondary bacterial colonisation of lesions on the skin surface
- Acute moist dermatitis
- Eczemas
- intertrigo
247
Example of superficial infection
Infection involves skin and hair follicle epithelium
- Impetigo
- superficial bacterial folliculitis
- dermatophilosis
- pyotraumatic folliculitis
- mucocutaneaous pyoderm
248
Example of deep infection
Infection involves the dermis and subcutaneous tissue
- furnculosis
- cellulitits
- furunculosis
- acral lick furnculosis
- subcutaneous abscess
249
Pathogenesis of dermatophilosis?
1. Zoospres attracted to sites on the skin due to respiratory low levels of carbon dioxide
2. Germinate to produce hyphae which penentrate into the living epidermis and subsequently spread in all directions from the initial focus
3. Penetration causes an acute inflammatory reaction
4. In most acute infections the filamaentous invasion of the epidermis ceases in 2-3 weeks and the lesions heal spontaneously
5. in chronic infections the affected hair follicles and scabs are sites from which intermittent invasions of non infected hair follicles and epidermis occur
250
What is coagulase?
Enzyme produced by staphylococcus aureas that converts fibrinogen to fibrin
Reacts with prothrombin
Staphylothrombin complex is formed which causes blood to clot by converting fibrinogen to fibrin
251
What is the coagulase test?
Rabbit plasma is inoculated with a staphylococcal colony
incubated at 37 degrees celsius for 60-90 mins
positive serum will coagulate while the negative plasma remains liquid
