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| <br> | | <br> |
− | ==Mites==
| |
− | ===Demodicosis===
| |
− | *[[Suborder: Astigmata, astigmatid mites|''Demodex'']] are normal inhabitants of hair follicles and sebaceous glands
| |
− | *Have to have increased number of immature mites to classify as infestation
| |
− | *Host-specific
| |
− | *Occurs in dogs, cattle, sheep, goats, pigs, horses and cats
| |
− | *Transmits during nursing from dam to offspring
| |
− | *''Demodex canis'' in dogs:
| |
− | **Generalised or localised
| |
− | **Mainly young dogs affected or adults with other disease ([[Adrenal Glands - Pathology#Adrenal Hyperfunction|hyperadrenocorticism]], [[Thyroid Gland - Pathology#Hypothyroidism|hypothyroidism]])
| |
− | **Often inherited in pure bred
| |
− | **Grossly:
| |
− | ***Localised: scaly, erythematous, macular, alopecic areas; usually face or front legs
| |
− | ***Generalised: large, coalescing lesions, patches, erythema, alopecia, scales, crusts
| |
− | **Microscopically:
| |
− | ***Localised: lymphoplasmacytic perifolliculitis with hyperkeratinisation, sebaceous adenitis, low pigment, intraluminal mites
| |
− | ***Generalised: perifolliculitis and follicular hyperkeratosis, follicular pluggingf, bacterial proliferation, bacterial neutrophilic folliculitis
| |
− | ****May cause folliculat rupture -> furunculosis, cellulitis, lymphadenitis and septicaemia
| |
| | | |
| + | ==Fleas== |
| | | |
− | ===Scabies===
| |
− | *Caused by [[Suborder: Astigmata, astigmatid mites|''Sarcoptes scabiei'']]
| |
− | *Highly contagious
| |
− | *Mainly in pigs, dogs, also horses, cattle, sheep, goats and cats
| |
− | *Intense pruritus due hypersensitivity to mites borrowing through stratum corneum
| |
− | *Usually starts with external pinnae -> head -> neck -> generalised
| |
− | *Grossly:
| |
− | **Erythematous [[Skin Glossary - Pathology|macules, papules, crusts]]
| |
− | **If chronic -> [[Skin Glossary - Pathology|lichenified]], hairless
| |
− | *Microscopically:
| |
− | **Hyperplastic, spongiotic, superficial perivascular dermatitis
| |
− | **Crusting, eosinophil infiltration
| |
− | **Mites are not commonly seen, but eggs and feces may be found in stratumn corneum
| |
− |
| |
− |
| |
− | ===Notoedric mites===
| |
− | *Rare but very contagious
| |
− | *Caused by [[Suborder: Astigmata, astigmatid mites|''Notoedres cati'']]
| |
− | *Grossly:
| |
− | **Erythematous papular rash -> scales, crusts, alopecia -> lichenification when chronic
| |
− | **Start on neck and ears -> head, face, paws -> generalised
| |
− | *Microscopically:
| |
− | **Epidermal hyperplasia, spongiosis, crusts
| |
− | **Superficial perivascular dermatitis
| |
− | **Eosinophils
| |
− |
| |
− |
| |
− | ===Otodectic mites===
| |
− | *Caused by [[Suborder: Astigmata, astigmatid mites|''Otodectes cynotis'']]
| |
− | *In external ear canals of carnivores, occasionally elsewhere
| |
− |
| |
− |
| |
− | ===Psoroptic mites===
| |
− | *Occurs in cattle, sheep, horses, goats, rabbits and other animals
| |
− | *Host-specific
| |
− | *[[Suborder: Astigmata, astigmatid mites#Psoroptes cuniculi|''Psoroptes cuniculi'']] in ear canals of rabbits, horses, goats and sheep
| |
− | *[[Suborder: Astigmata, astigmatid mites|''P.equi'']] at base of mane, ttail and forelock in horses
| |
− | *[[Suborder: Astigmata, astigmatid mites|''P.ovis'']] in sheep ('''sheep scab''')and cattle
| |
− | **Thickened skin and dry scales and crusts
| |
− | **Starts at withers and spreads due to self trauma
| |
− | **Microscopically:
| |
− | ***Spongiotic, hyperplastic or exudative superficial perivascular dermatitis
| |
− | ***Eosinophils
| |
− |
| |
− |
| |
− | ===Chorioptic mites===
| |
− | *Host-specific
| |
− | *In cattle, horses, goats
| |
− | *Caused by [[Suborder: Astigmata, astigmatid mites|''Chorioptes'' spp.]]
| |
− | *Grossly:
| |
− | **Erythematous, papular, crusty lesions
| |
− | **Hairless, thickened skin
| |
− | **Areas usually affected:
| |
− | ***Horses: lower hind legs
| |
− | ***Cattle: lower hind legs, scrotum, perineum, tail, udder, thigh
| |
− | ***Sheep: lower hind legs and scrotum
| |
− | ***Goats: lower hind legs, hindquarters, abdomen
| |
− |
| |
− |
| |
− | ===Cheyletiellosis===
| |
− | *Caused by ''Cheyletiella'' sp.]]
| |
− | *Occurs in dogs, cats, rabbits, humans and wild animals
| |
− | *In dogs and cats: hyperkeratosis - dry, white, scaly dandruff along back
| |
− | *May be asymptomatic
| |
− | *Grossly:
| |
− | **Focal, multifocal or generalised red papules or crusts
| |
− | *Microscopically:
| |
− | **Superficial perivascular dermatitis
| |
− | **Eosinophils
| |
− |
| |
− |
| |
− | ===Trombiculidiasis===
| |
− |
| |
− | *Harvest mite infestation (chiggers) - [[Suborder: Astigmata, astigmatid mites|''Trombicula'' sp.]]
| |
− | *Form tunnels in epidermis by injecting saliva - eat digested tissue fluid
| |
− | *Intense pruritus
| |
− | *Grossly:
| |
− | **Small, red [[Skin Glossary - Pathology|papules or crusts]]
| |
− | **Orange to red larvae
| |
− | **On skin close to plants or the ground
| |
− | *Microscopically:
| |
− | **Hyperplastic, superficial perivascular dermatitis
| |
− | **[[Eosinophils - WikiBlood|Eosinophils]], [[Mast Cells - WikiBlood|mast cells]]
| |
− | **Intraepidermal mites
| |
− |
| |
− | ==Ticks==
| |
− |
| |
− | *Local reaction depends on host hypersensitivity and [[Suborder: Metastigmata, ticks|tick's]] secretions
| |
− | *Grossly:
| |
− | **Focal erosions, erythema, crusted ulcers, sometimes alopecia and nodules
| |
− | *Microscopically:
| |
− | **Epidermal and dermal necrosis
| |
− | **Perivascular of diffuse inflammation and necrotic margins
| |
− | **Eosinophils, macrophages and lymphocytes in exudate
| |
− | **May form granulomas containing collagenous fibres and lymphoid follicles within dermis
| |
− |
| |
− | ==Lice==
| |
− |
| |
− | *Infestation is called '''pediculosis'''
| |
− | *May cause anaemia (sucking lice), weakness, discomfort and damage to hair or wool
| |
− | *More common in low temperatures when hair is longer
| |
− | *Host-specific
| |
− | *Spread by direct contact
| |
− | *Most lesions are due to self-inflicted trauma
| |
− | *Grossly:
| |
− | **Papules, crusts, secondary excoriations
| |
− | **Eggs and lice visible in lesions
| |
− |
| |
− | ==Fleas==
| |
| *Occurs in cats and dogs mainly | | *Occurs in cats and dogs mainly |
| *Irritation caused by enzymes, anticoagulants and histamine-like substances | | *Irritation caused by enzymes, anticoagulants and histamine-like substances |
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| *Grossly: | | *Grossly: |
| **Red papules and secondary excoriations | | **Red papules and secondary excoriations |
− |
| |
| ==[[Insecta|Flies]]== | | ==[[Insecta|Flies]]== |
| *Bites may cause irritation, anaemia, toxicity or hypersensitivity | | *Bites may cause irritation, anaemia, toxicity or hypersensitivity |
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| **Larvaae are deposited in wounds | | **Larvaae are deposited in wounds |
| **Penetrate and liquify tissue | | **Penetrate and liquify tissue |
| + | |
| | | |
| ==Helminths== | | ==Helminths== |
− |
| |
− | ===Hookworms===
| |
− | *Caused by [[Ancylostomatoidea|''Ancylostoma'' or ''Uncinaria'']]
| |
− | *Grossly:
| |
− | **Red papules -> lichenified alopecic areas
| |
− | **Mainly of dog feet
| |
− | **Foot pads may soften with keratinised area separation
| |
− | **Possible secondary bacterial dermatitis and [[Skin Glossary - Pathology|paronychia]]
| |
− | *Microscopically:
| |
− | **Hyperplastic spongiotic perivascular dermatitis
| |
− | **Eosinophils
| |
− | **Crusts
| |
− | **Migration tracts
| |
| | | |
| ===Cutaneous habronemiasis=== | | ===Cutaneous habronemiasis=== |
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| **Larvae and necrotic tissue | | **Larvae and necrotic tissue |
| **Granulation tissue with neutrophils along ulcerated surface | | **Granulation tissue with neutrophils along ulcerated surface |
| + | |
| + | ===Hookworms=== |
| + | *Caused by [[Ancylostomatoidea|''Ancylostoma'' or ''Uncinaria'']] |
| + | *Grossly: |
| + | **Red papules -> lichenified alopecic areas |
| + | **Mainly of dog feet |
| + | **Foot pads may soften with keratinised area separation |
| + | **Possible secondary bacterial dermatitis and [[Skin Glossary - Pathology|paronychia]] |
| + | *Microscopically: |
| + | **Hyperplastic spongiotic perivascular dermatitis |
| + | **Eosinophils |
| + | **Crusts |
| + | **Migration tracts |
| | | |
| ===Onchocerciasis=== | | ===Onchocerciasis=== |
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| **Eosinophils, adult and microfilarial parasites | | **Eosinophils, adult and microfilarial parasites |
| **[[Skin Glossary - Pathology|Epidermal hyperkeratosis, parakeratosis, acanthosis]], eosinophilic microabscesses and crusts | | **[[Skin Glossary - Pathology|Epidermal hyperkeratosis, parakeratosis, acanthosis]], eosinophilic microabscesses and crusts |
| + | |
| + | |
| + | ==Lice== |
| + | |
| + | *Infestation is called '''pediculosis''' |
| + | *May cause anaemia (sucking lice), weakness, discomfort and damage to hair or wool |
| + | *More common in low temperatures when hair is longer |
| + | *Host-specific |
| + | *Spread by direct contact |
| + | *Most lesions are due to self-inflicted trauma |
| + | *Grossly: |
| + | **Papules, crusts, secondary excoriations |
| + | **Eggs and lice visible in lesions |
| + | |
| + | |
| + | ==Mites== |
| + | |
| + | ===Cheyletiellosis=== |
| + | *Caused by ''Cheyletiella'' sp.]] |
| + | *Occurs in dogs, cats, rabbits, humans and wild animals |
| + | *In dogs and cats: hyperkeratosis - dry, white, scaly dandruff along back |
| + | *May be asymptomatic |
| + | *Grossly: |
| + | **Focal, multifocal or generalised red papules or crusts |
| + | *Microscopically: |
| + | **Superficial perivascular dermatitis |
| + | **Eosinophils |
| + | |
| + | ===Chorioptic mites=== |
| + | *Host-specific |
| + | *In cattle, horses, goats |
| + | *Caused by [[Suborder: Astigmata, astigmatid mites|''Chorioptes'' spp.]] |
| + | *Grossly: |
| + | **Erythematous, papular, crusty lesions |
| + | **Hairless, thickened skin |
| + | **Areas usually affected: |
| + | ***Horses: lower hind legs |
| + | ***Cattle: lower hind legs, scrotum, perineum, tail, udder, thigh |
| + | ***Sheep: lower hind legs and scrotum |
| + | ***Goats: lower hind legs, hindquarters, abdomen |
| + | |
| + | ===Demodicosis=== |
| + | *[[Suborder: Astigmata, astigmatid mites|''Demodex'']] are normal inhabitants of hair follicles and sebaceous glands |
| + | *Have to have increased number of immature mites to classify as infestation |
| + | *Host-specific |
| + | *Occurs in dogs, cattle, sheep, goats, pigs, horses and cats |
| + | *Transmits during nursing from dam to offspring |
| + | *''Demodex canis'' in dogs: |
| + | **Generalised or localised |
| + | **Mainly young dogs affected or adults with other disease ([[Adrenal Glands - Pathology#Adrenal Hyperfunction|hyperadrenocorticism]], [[Thyroid Gland - Pathology#Hypothyroidism|hypothyroidism]]) |
| + | **Often inherited in pure bred |
| + | **Grossly: |
| + | ***Localised: scaly, erythematous, macular, alopecic areas; usually face or front legs |
| + | ***Generalised: large, coalescing lesions, patches, erythema, alopecia, scales, crusts |
| + | **Microscopically: |
| + | ***Localised: lymphoplasmacytic perifolliculitis with hyperkeratinisation, sebaceous adenitis, low pigment, intraluminal mites |
| + | ***Generalised: perifolliculitis and follicular hyperkeratosis, follicular pluggingf, bacterial proliferation, bacterial neutrophilic folliculitis |
| + | ****May cause folliculat rupture -> furunculosis, cellulitis, lymphadenitis and septicaemia |
| + | |
| + | ===Notoedric mites=== |
| + | *Rare but very contagious |
| + | *Caused by [[Suborder: Astigmata, astigmatid mites|''Notoedres cati'']] |
| + | *Grossly: |
| + | **Erythematous papular rash -> scales, crusts, alopecia -> lichenification when chronic |
| + | **Start on neck and ears -> head, face, paws -> generalised |
| + | *Microscopically: |
| + | **Epidermal hyperplasia, spongiosis, crusts |
| + | **Superficial perivascular dermatitis |
| + | **Eosinophils |
| + | |
| + | ===Otodectic mites=== |
| + | *Caused by [[Suborder: Astigmata, astigmatid mites|''Otodectes cynotis'']] |
| + | *In external ear canals of carnivores, occasionally elsewhere |
| + | |
| + | ===Psoroptic mites=== |
| + | *Occurs in cattle, sheep, horses, goats, rabbits and other animals |
| + | *Host-specific |
| + | *[[Suborder: Astigmata, astigmatid mites#Psoroptes cuniculi|''Psoroptes cuniculi'']] in ear canals of rabbits, horses, goats and sheep |
| + | *[[Suborder: Astigmata, astigmatid mites|''P.equi'']] at base of mane, ttail and forelock in horses |
| + | *[[Suborder: Astigmata, astigmatid mites|''P.ovis'']] in sheep ('''sheep scab''')and cattle |
| + | **Thickened skin and dry scales and crusts |
| + | **Starts at withers and spreads due to self trauma |
| + | **Microscopically: |
| + | ***Spongiotic, hyperplastic or exudative superficial perivascular dermatitis |
| + | ***Eosinophils |
| + | |
| + | ===Scabies=== |
| + | *Caused by [[Suborder: Astigmata, astigmatid mites|''Sarcoptes scabiei'']] |
| + | *Highly contagious |
| + | *Mainly in pigs, dogs, also horses, cattle, sheep, goats and cats |
| + | *Intense pruritus due hypersensitivity to mites borrowing through stratum corneum |
| + | *Usually starts with external pinnae -> head -> neck -> generalised |
| + | *Grossly: |
| + | **Erythematous [[Skin Glossary - Pathology|macules, papules, crusts]] |
| + | **If chronic -> [[Skin Glossary - Pathology|lichenified]], hairless |
| + | *Microscopically: |
| + | **Hyperplastic, spongiotic, superficial perivascular dermatitis |
| + | **Crusting, eosinophil infiltration |
| + | **Mites are not commonly seen, but eggs and feces may be found in stratumn corneum |
| + | |
| + | ===Trombiculidiasis=== |
| + | |
| + | *Harvest mite infestation (chiggers) - [[Suborder: Astigmata, astigmatid mites|''Trombicula'' sp.]] |
| + | *Form tunnels in epidermis by injecting saliva - eat digested tissue fluid |
| + | *Intense pruritus |
| + | *Grossly: |
| + | **Small, red [[Skin Glossary - Pathology|papules or crusts]] |
| + | **Orange to red larvae |
| + | **On skin close to plants or the ground |
| + | *Microscopically: |
| + | **Hyperplastic, superficial perivascular dermatitis |
| + | **[[Eosinophils - WikiBlood|Eosinophils]], [[Mast Cells - WikiBlood|mast cells]] |
| + | **Intraepidermal mites |
| | | |
| ==Protozoa== | | ==Protozoa== |
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| **Macrophages, some lymphocytes and plasma cells - periadnexal pattern, may affect sebaceous glands | | **Macrophages, some lymphocytes and plasma cells - periadnexal pattern, may affect sebaceous glands |
| **Organisms may be found extra or intracellularly | | **Organisms may be found extra or intracellularly |
| + | |
| + | ==Ticks== |
| + | |
| + | *Local reaction depends on host hypersensitivity and [[Suborder: Metastigmata, ticks|tick's]] secretions |
| + | *Grossly: |
| + | **Focal erosions, erythema, crusted ulcers, sometimes alopecia and nodules |
| + | *Microscopically: |
| + | **Epidermal and dermal necrosis |
| + | **Perivascular of diffuse inflammation and necrotic margins |
| + | **Eosinophils, macrophages and lymphocytes in exudate |
| + | **May form granulomas containing collagenous fibres and lymphoid follicles within dermis |