Equine dermatology Flashcards
1
Q
what should be obtained from a general history?
A
age gender breed colour management feed
2
Q
what is a common skin condition seen in young horses that will disappear over time?
A
papilloma
3
Q
what should be discussed with regards to the management when obtaining a history?
A
other horses present other animals stabling feeding work
4
Q
with regards to the history of the current problem, what needs to be determined?
A
when it started
has it improved or gotten worse - changes? treatment?
what has been done to treat it - results? duration?
5
Q
with regards to the lesions present, what needs to be established?
A
type
distribution
extent/severity
whether it is primary/secondary
6
Q
what ways can samples be collected on a primary basis? (simple)
A
skin brush/scrape
hair pluck
adhesive tape
skin biopsy
7
Q
what ways can samples be collected on a secondary basis? (second stage)
A
skin biopsy
intradermal skin test
blood test
8
Q
what is skin brushing good for looking for?
A
parasites
9
Q
what are hair plucks useful for looking for?
A
lice eggs - white dots
10
Q
what are the reasons to do a skin biopsy?
A
if there are papules or pustules
neoplastic lesions
11
Q
when is skin biopsy not useful?
A
immune-mediated and autoimmune disorders
ulcers and crusts
chronic lesions
12
Q
what are the golden rules for skin biopsies?
A
try not to clip
do not scrub the skin
place small amount of local anaesthetic subcutaneously
rotate biopsy punch in one direction
13
Q
what areas should a skin biopsy not be taken from?
A
over the coronary band
14
Q
define pruritus
A
unpleasant sensation that provokes the desire to scratch/itch
15
Q
what are the two things that make horses pruritic?
A
parasitic skin disease
hypersensitivity (allergies)
16
Q
what is the most common louse found on horses?
A
Werneckiella
17
Q
where on the horse is Werneckiella found?
A
dorsolater trunk
neck
face
18
Q
what type of louse is Werneckiella?
A
biting
19
Q
what does Werneckiella feed on?
A
epidermal debri
20
Q
what sucking louse is seen on horses?
A
Haematopinus asini
21
Q
where is Haematopinus asini seen on the horse?
A
mane
tail
fetlock
pastern
22
Q
what does Haematopinus asini feed on?
A
blood (sucking louse)
23
Q
what horses is Werneckiella seen in?
A
housed younger/older houses in the winter
24
Q
how are lice transmitted?
A
direct/indirect contact
25
how can lice be diagnosed?
coat brush or hair pluck
26
what can be used to treat lice?
pyrethrins, pyrethroids, permethrin, fipronil
27
where is Chorioptes equi found on the horse?
distal limbs
28
what is the major clinical sign of Chorioptes equi?
intense pruritus with stamping/scratching/chewing of feet
29
what is a common clinical sign of Psoroptes equi in horses?
headshaking - mite present in ears
30
how can mites be diagnosed?
skin brushing
31
what can be used to treat mites?
inject macrocyclic lactones
topical macrocyclic lactones
topical shampoos - lime sulphur, selenium sulphate, topical ivermectin
32
when do injectable MLs need to be administered to treat mites?
2 injections 2 weeks apart
33
how often do topical MLs need to be administered to treat mites?
once every 4 weeks
34
what is the name of the poultry mite that can effect horses?
Dermanyssus gallinae
35
where on the body does the poultry mite effect the horse?
head and legs
36
what are some nematodes that can cause pruritus in horses?
Oxyuris equi
habronemiasis
Onchocerca cervicalis
37
what is Oxyuris equi also known as?
pinworm
38
what body area does the pinworm cause pruritus in?
perianal
39
what is used to treat Oxyuris equi?
anthelmintics - none specifically designed for Oxyuris
40
what is habronemiassis spread by?
flies that lay their larvae under the skin
41
what season is habronemiassis seen in?
spring/summer
42
what are the clinical signs of habronemiassis?
ulcerative nodules
| granulation tissue with yellow granules
43
what can be used to treat habronemiassis?
ivermectin
| corticosteroids - control hypersensitivites that may develop when larvae die under the skin
44
where do adult Onchocerca cervicalis live?
nuchal ligament
45
how can Onchocerca cervicalis cause hypersensitivity?
microfilarie migrate to the skin surface
46
what season is Onchocerca cervicalis worst?
spring/summer
47
where on the horses body is Onchocerca cervicalis usually seen?
face, neck, ventral chest, abdomen
48
what can be done to treat Onchocerca cervicalis?
ivermectin
| corticosteroids - protect against potential hypersensitivity reaction caused by the death of the worm
49
what are the hypersensitivities that can be seen in horses?
```
insect hypersensitivity
food allergy
contact allergy
atopy
urticaria
```
50
where on the animal is insect bite hypersensitivity seen?
main, back, tail ventrum
51
what are the risk factors that can increase the likelihood of insect bite hypersensitivity?
standing water
| dusk/dawn
52
what are the clinical signs of food allergy?
pruritus
diarrhoea
respiratory disease
53
how are food allergies diagnosed?
diet elimination
54
what is done do diagnose atopy?
exclusion
| intradermal skin testing can be helpful
55
what can be done to teat atopy?
avoid allergen
immunotherapy
corticosteroids/antihistamines
improve skin barrier function
56
what are the clinical signs of urticaria?
wheals
oedema
pruritus
57
what is urticaria also known as?
hives
58
what can be used to treat urticaria (hives)?
corticosteroids
| antihistamines
59
what are some common skin diseases that cause crusting, scaling erosion and/or ulceration?
```
dermatophilosis (rain scald)
bacterial folliculitis
dermatophytosis (ringworm)
photosensitisation
leukocytoclastic vasculitis
pastern dermatitis
pemphigus foliaceous
```
60
what bacteria causes dermatophilosis?
Dermatophilus congolensis
61
what is dermatophilosis also known as?
rain scald
62
describe the bacteria Dermatophilus congolensis
gram positive
| facultative anaerobe
63
what factors causes dermatophilosis?
chronic moisture
| skin damage
64
describe the lesions associated with dermatophilosis
crusts
| moist mats of hair
65
where on the body is rain scald seen?
back, gluteal area, face, neck extremities
66
how can dermatophilosis be diagnosed?
cytology using a pus smear
67
what can be used to treat dermatophilosis?
```
topical antimicrobials (mild cases)
systemic antimicrobials (severe cases)
```
68
what bacteria can cause bacterial folliculitis?
Staphylococcus
| Streptococcus
69
how can bacterial folliculitis be diagnosed?
cytology and culture
70
what is used to treat bacterial folliculitis?
topical and systemic antimicrobials depending on severity
71
what is dermatophytosis more commonly known as?
ringworm
72
what causes the pruritus in pinworm infections?
the substance used to glue the eggs onto the outside of the anus
73
how can Oxyuris equi be diagnosed?
clinical signs and tape strip
74
why are ticks a worry in horses?
due to the transmission of disease - lyme disease, babesiosis...
75
what can be used to treat tick infestations?
fipronil spray
ivermectin
topical pyrethroids
76
what is another name for insect bite hypersensitivity?
sweet itch
77
what it insect bite hypersensitivity a hypersensitivity to?
female Culicoides spp. saliva
78
how can insect bite hypersensitivity be treated?
avoid midge contact - fly repellents and rugs
| reduce immune reaction - steroids (can lead to laminitis)
79
what is hives?
small patches of oedema under the skin surface
80
what does scaling looking like?
it is seen as dry and grey
81
what is the appearance of crusting?
yellow, red and brown
usually wet and damp
from serous ooze
82
what is the difference between erosion and ulceration?
erosion is superficial and ulceration is deep
83
what are the characteristics of bacterial folliculitis lesions?
pain
| oozing/wheeping lesions
84
what are the two most common fungi that cause ringworm in horses?
Trichophyton and Microsporum
85
what horses is dermatophytosis most commonly seen in?
young and immunocompromised
86
what do the lesions of dermatophytosis look like?
circular well demarcated patches of alopecia with an ashy appearance
87
how can ringworm be diagnosed?
fungal culture, PCR, microscopy
88
what is used to treat ringworm?
topical antfungals - miconhzole, natamycin
89
what are the two possible causes of photosensitisation?
hepatogenous - liver failure...
| ingestion or application of photodynamic agent
90
on what areas of skin is photosensitisation most common?
areas of white hair
91
what is used to treat photosensitisation?
treat liver disease
| removal of photodynamic agent
92
what lesion could be linked to photosensitisation?
leukocytoclastic vasculitis
93
where does leukocytoclastic vasculitis effect?
the lateral distal limbs of horses (white hair)
94
what can be done to diagnose leukocytoclastic vasculitis?
clinical signs
| skin biopsy
95
what can be done to treat leukocytoclastic vasculitis?
avoid exposure to light
| corticosteroids
96
what is meant by pastern dermatitis?
a skin condition seen on the pastern - can have many causes
97
what type of disease is Pemphigus foliaceous?
autoimmune disease
98
what is the major clinical sign of Pemphigus foliaceous?
severe crusting
99
what is used to treat Pemphigus foliaceous?
immunosuppressive drugs (steroids)
100
what are the most common cutaneous swellings, nodules and tumours seen in horses?
```
viral papillomatosis
warbles
genetic/developmental
eosinophilic granuloma
tumours - sarcoid, melanoma, squamous cell carcinoma...
```
101
what are two examples of viral papillomatosis?
grass warts
| Pinnae Acanthosis
102
what is the treatment of grass warts and pinnae acanthosis?
no need to treat, regress on their own and is purely cosmetic
103
what are the species of warbles that cause nodules on the skin?
Hypoderma bovis and lineatum
104
what is used to treat warbles?
ivermectin
| surgical removal
105
what nodular skin condition is notifiable?
warbles
106
what are some genetic/developmental skin masses/nodules?
dentigerous cyst
atheroma
dermoid cyst
vascular hamartoma
107
what is a dentigerous cyst?
small cyst of an embryonic remanent around the head area of the house, often containing teeth or hair
108
what is an atheroma?
a growth on the inside of the false nostril - don't normally cause problems but can be removed because of cosmetics
109
what can cause an eosinophilic granuloma?
hypersensitivity reaction to insect bites, trauma or anything else causing necrosis of collagen
110
what are some common skin tumours?
sarcoid
melanoma
squamous cell carcinoma
111
what are sarcoids made of?
fibroblasts
112
what are thought to be possible risk factors/causes of sarcoids?
bovine papillomavirus 1/2
genetic predisposition
flies
113
how many clinical presentations of sarcoids is there?
6
114
what are the 6 clinical presentations of sarcoids?
```
occult
verrucose
nodular
fibroblastic
mixed
malignant
```
115
describe an occult sarcoid
alopecic faded area of skin that turns scaly/dark
116
describe a verrucose sarcoid
alopecic faded area of skin that turns scaly/dark with a lumpy/warty appearance
117
describe a nodular sarcoid
small growths under the skin
118
how can sarcoids be diagnosed?
biopsy
| clinical presentation
119
why should care be taken when taking a biopsy of a sarcoid?
can exacerbate then - be prepared to treat quickly
120
what can be used to treat sarcoids?
```
brachytherapy
surgery/laser removal
cytotoxic
photodynamic therapy
(lots of therapies because none of them work very well)
```
121
what are the general rules for sarcoid prognosis?
more they have the more they get
multiply over summer and grow in winter
single sarcoid indicates genetic susceptibility
122
what horses are melanoma most common in?
grey horses over 15 years old
123
where are most melanomas located in horses?
perineum, tail head, parotid region
| can appear anywhere
124
are melanomas benign or malignant?
mostly benign but some are malignant
125
how care melanomas diagnosed?
clinical signs and biopsy
126
what can be done to treat melanomas?
surgical excision - sooner rather than later
| immunotherapy
127
where do squamous cell carcinomas commonly grow on horses?
external genitalia
eye
(other locations possible)
128
how are squamous cell carcinomas treated?
surgical excision
cryotherapy
chemotherapy
129
where are cutaneous lymphomas most commonly seen on horses?
trunk and neck
