Skin Flashcards
Collagen defects may be genetic. There are also four dietary causes, list them
Vitamin C deficiency, Iron deficiency, Copper deficiency, sweet pea poisoning (aminoproprionitrite)
What are the ratios of scondary to primary hair in Merinos and meat sheep?
20:1 and 5:1
Which two hormones cause involution of the sebaceous glands (leading to dry coats)
Oestrogen, corticosteroids
What dermatological consequences can hyperthermia of the dam have on the offspring?
Hypertrichosis
What is the incubation period for orf
3-14 days
Described the histopathology seen with orf
Ballooning and degeneration of keratinocytes with eosinophilic intracytoplasmic viral inclusions.
What lesions are seen in malignant orf?
Non-contagious lesions on feet/legs
What is the cause of ulcerative dermatosis?
virus related to parapox
Which regions are affected in ulcerative dermatosis (3)?
Face, limbs, genitals
How does Dermatophilus congolensis appear on cytology
Gram positive branching filaments of parallel cuboidal coci (“railroad tracks”)
What agent causes fleece rot. What lesions does it cause. What areas does it affect. How is it treated?
Pseudomonas aeuruginosa. Foul, green exudative dermatitis. Back and withers. Shearing and drying
Which agents can cause malignant oedema. What toxins are involved?
Clostridium sordellii, novyi, septicum and chauvoei. Alpha-toxin and Large clostridial toxin
Which bacetria is associated with pyogranulomatous infection with sulfur granules
Actinobacillus lignieresii
What is the classic location for staphylococcla dermatitis in sheep
Above upper eyelid
Which bacteria has been decsribed as the cause of a systemic infection in a pygmy goat similar to greasy pig disease
Staphylococcus hyacus
What gram stain is Corynebacerium pseudotuberculosis? What shape is it?
Gram positive. Usually rods but can be coccoid
What proportion of UK terminal sire flocks are positive for CLA?
34%
What proportion of carcases in the UK have signs of CLA?
<1%
What are the sensitivty and specificity if the CLA ELISA?
Se 87%, spec 98%
At a prevalenec of 2% what are the sensitivity and specificity of bulk milk tan ELISA for CLA
se 73%, spec 89%
What is the sensitivity of IFNy testing for CLA?
91%
Can CLA be treated?
Closed lavage systems have been described but cullig is the sensible option.
12 weekly testing and culling for CLA for 2 years had what effect on prevalence?
Reduced from 10% to 0.4%
List most common dermatophyte pathogens of small ruminants
Trichophyton verrucosum, T. metagorphytes, Microsporum canis
Why are show breeds prediposed to ringworm?
Frequent washing strips lanolin.
Do trychophyton fluoresce?
No
What culture medium is used for ringworm
Sabouraud’s agar
Described treatment options for ringworm
Griseofulivn (ILLEGAL), Topical enilconazole, 4 times 72h apart, Topical lime sulfur - 5% daily for 7 days then weekly for a month.
What is the prevalence of lice in the UK? When do infections peak?
10-20%. Peak in winter-early spring.
List the species of lice affecting sheep (3+2)
Bovicola ovis
Linognathus ovillus
Linognathus pedalis
(Bovicola bovis)
(Bovicola caprae)
List the species of lice affecting goats (5+1)
Bovicola caprae, crassipes and limbata
Linognathus africanus and stenopsis
(Bovicola bovis)
Can lice survive off the host?
Yes for a few weeks, but epidemiologically insignificant
How long do louse eggs take to hatch?
1-2 weeks
Howlong do lice take to develop to adults?
2-4 weeks
How long post-infection is alopecia commonly seen with louse infestations?
5 weeks
How can lice be treated? Can these be used in lactating animals
Deltamethrin (lasts 5 weeks) - no, Cypermethrin (lasts 8-12 weeks) - no,
eprinomectin (injectable for sucking, pour-on for biting) - yes
Is louse resistance heritable? What beed was this studied in?
Yes - Romney
Describe the microscopic appearance of Psooptes ovis
Elongated head, Firts pair of legs jointed. First two pairs of legs have 3-segmented pedicles with funnel-shaped suckers.
How long is the intergenerational interval of Psoroptes of ovis?
11-19 days.
For how long are Psoroptes ovis infectious off the host?
15-16 days
How soon after infection can the sheep scab ELISA be used? What is its sensitivity and specificity?
2 weeks. 98% se, 96% sp
How long do diazinon dip and moxidectin 2% persist against sheep scab? Can they be used in milk sheep?
63 days and 60 days. No, have to use repeated eprinomectin treatments.
What experimental vaccine is there against sheeo scab? How effective is it?
7 subunit cocktail vaccine, reduces clinical signs and mite numbers but not sterile immunity.
Describe the appearance of sarcoptes scabei
ROund head. Long non-jointed pedicles.
How long is sarcoptes scabei life-cycle?
10-17 days
Described the lesion distribtuion for sarcoptic mange
face and non-wooled areas in sheep. Generalised in goats
How is sarcoptic mange treated?
Ivermectin injection every 7 days.
Which species cause chorioptic mange? Describe their appearance
Chorioptes ovis and caprae. Short unsegmented pedicles, oval body.
What are the prediliction sites for chorioptes?
Scrotum, lower limbs
How long is the chorioptes life cycle? How long can they presist off-host?
2-3 week life ycle. A few days survival off host
Hich bacteria is secondarily associated with chorioptic mange? Are there any other secondary effects of chorioptic ange
Staphylococci.
Heat -> temporary ram infertility
How is chorioptic mange treated
Topical eprinomectin - paint on to lesions to maxmise concentrations. Fipronil effective but illegal.
How many demodex species infect small ruminants?
Two - ovis and caprae
How is demodecosis treated?
Repeated macrocyclic lactones or weekly amitraz baths (10-12 weeks treatment reqd for both).
Which two fly species are associated with flystrike in most of Europe? Which species is present in Eastern Europe, Spain and Greece, and how does it’s pathology differ?
Lucillia sericata and Protphormia terranovae.
Wohlfahrtia magnifica - more aggressive, focuses on anus/genitals.
How do Lucilia sericata penetrate the skin?
Proteolytic enzymes and mouth hooks
How long do flystrke larvae infect the host before pupating?
4-5 days
What proportion of farms in the UK and Netherlands are affected by fly strike annually?
UK: 75%. NL: 50%
Describe the treatment options and duratiosn for flystrike
Cypermethrin 6-8 weeks
Alpha-cyperpethrin 8-10 weeks
Deltamethrin no persistence
Cyromazine - 9 weeks
Dicyclinil - 16 weeks+
Diazinon - 6 weeks
Has drug resistant fly strike been reported in Europe?
No but permethrin resistance reported in L. cuprina in Australia and IGR resistance shown in lab.
Which biological control options have been proposed for flystrike? Are they effective?
Bacillus thurigiensis and various entomopathogenic fungi. Limited duration effect in lab studies.
Tea tree oil is an effective repellant in the housed sheep but not clear how it persists in rain etc.
How effective are fly traps for flystrike?
1 synthetic-baited trap per 100 sheep can reduce fly populations 60%. Liver-baited sticky paper shown to reduce flystrike in SW England 80%. However non-specific offal baited traps may kill competitors and increase Lucillia populations.
Name the main two species of small ruminant ear mite. For what bacteria might they act as a vector?
Psoroptes cuniculi and Raillietia caprae. Mycoplasma spp.
What is the latin name for the sheep ked. Which notifiable disease can they act as a vector for?
Melophagus ovinus. BTV
Which parasite can cause hide damage in goats in Mediterranean countries
Goat warble fly (Przhevalskiana silenu)
Against what antigen is the type-ii hypersenstivity reaction medaited in Pemphigous Foliaceous?
Keratinocyte glycocalyx
What is seen on histopathology in Pemphigus Foliaceus?
bilsters, acantholytic keratinocytes
Name the endophyte that causes fescue toxicity.
What are the dermatological signs?
Epichloe coenophialum.
Vascular constriction leading to necrosis of extremities, especially in winter.
Which two mineral deficiencies are associated with poor quality hair/wool?
Copper, Iodine
What are the signs of zinc deficiency?
Parakeratosis, wrinkled skin, swollen hocks, alopecia, dental pad overgrowth, small testes.
Excesses of which minerals can lead to zinc deficiency?
Calcium and Phspshorous
What are the signs of vitmain A deficiency? What feedstuff predisposes?
Hair loss, bight blindness, overgrown hooves, corneal ulceration.
Hay stored for a long time
Name two primary photosensitizing toxins
Phyloerythrin. Hypericin (St John’s Wort)
Which fungus causes secondary photosensitization (facial eczema). What is the toxin? What is the pathology?
Phythomyces chartarum
Sporedesmin
Biliary fibrosis and duct occlusion
Name three plant/algal causes of secondary photosensitization
Pyrrolizidine alkaloid plants (ragwort, heliotrope)
Bluegreen algae
Bog asphodel (Narthecium ossifragum)
Name three sheep breeds with inherited photosensitization
Southdown, Corriedale, Santa-Ines
Name two breeds of sheep with an inherited collagedn dysplasia
Norwegian and White Dorper
Which type of collagen is lacking in Epidermolysis bullosa / Epitheliogenesis imperfecta cases?
Type VII collagen
Which sheep breeds have heritable epidermolysis bullosa / epthitheliogenesisimperfecta
Weisses Alpenschaf, Suffolk, South Down
Which gene is assocaited with eptheliogenesis imperfecta in sheep. Which layer of the skin is affected? Which layer can also be affected by an unknown mutation in sheep and goats
LAMC2 frame shift
Lamina Lucida
Sublamina Densa
Which breed of sheep has an inherited hypotrichosis?
Dorsets
