The approach to pruritus

Question 1

What is pruritus?

Answer 1

Unpleasant sensation that elicits the desire or reflex to scratch

Question 2

How does pruritus manifest in dogs?

Answer 2

*Scratching
*Rubbing (along furniture)
*Chewing
*Licking: often not perceived as pruritus by owners
*Rolling
*Temperament changes

Question 3

How does pruritus manifest in cats?

Answer 3

*Scratching
*Chewing
*Licking
*May be secretive and not noticed by owners

Question 4

What are common differentials of pruritus?

Answer 4

*Hypersensitivity reactions (allergic skin disease + parasite hypersensitivity)
*Microbial infections
Less common differentials =
-Epitheliotrophic lymphoma
-Pemphigus foliaceus
-demodicosis
-dermatophytosis

Question 5

What are the different parasitic infestations?

Answer 5

*Sarcoptic mange
*Cheyletiellosis
*Pediculosis (lice)
*Trombiculiasis (Harvest mites)
*Flea infestation
*Notoedric mange
*Hookworm dermatitis

Question 6

How would you differentiate the different diseases?

Answer 6

*History
*Dermatological examination
*Diagnostic tests

Question 7

Where does atopic dermtaitis affect?

Answer 7

Muzzle
Eyes
Ears
Paws
Ventral aspect

Question 8

Where does sarcoptic mange affect?

Answer 8

Ear margins
Ventral aspect

Question 9

Where does cheyletiellosis + pediculosis affect?

Answer 9

Dorsum

Question 10

Where does pemphigus foliaceus affect?

Answer 10

Nose
Eyes
Ears
Whole body

Question 11

Where does Epitheliotropic lymphoma affect?

Answer 11

Muzzle
Whole body

Question 12

Why are cytology tests important?

Answer 12

-very important to rule out secondary microbial overgrowth or infection (indicated in most cases)
*Direct/indirect impression smear
*Acetate tape impression (stained)

Question 13

How would you identify parasitic disease?

Answer 13

*Coat brushing and wet paper test
*Acetate tape impression (unstained)
*Skin scraping
*Hair plucks and trichography

Question 14

When would you use skin biopsy?

Answer 14

to rule out less common differentials for pruritus; Pemphigus foliaceus, Epitheliotropic Lymphoma

Question 15

What cats are more at risk of fleas?

Answer 15

*Outdoor cats
*Multi-cat household

Question 16

What is flea allergy commonly seen with in dogs?

Answer 16

Canine Atopic Dermatitis

Question 17

What are the primary and secondary lesions caused by fleas?

Answer 17

Primary lesions
*Pruritus
*Papules
*Erythema

Secondary lesions
*Crusted excoriations
*Alopecia
*+/- bacterial pyoderma
signs

Question 18

What is the typical distribution of fleas?

Answer 18

Caudodorsum (+ventral abdomen in dogs)

Question 19

What diagnostic tests can be taken to identify fleas?

Answer 19

*Direct observation
*Wet paper test
*Coat brushings: direct microscopy may reveal coiled faeces
*Serology/intradermal allergy testing: limited usefulness
*Treatment trial

Question 20

What is the most common flea in the UK?

Answer 20

Ctenocephalides felis

Question 21

How are fleas transmitted?

Answer 21

*Direct zoonosis
*Bartonella henselae
*Dipylidium caninum

Question 22

What and where are the primary + secondary lesions of sarcoptic mange?

Answer 22

Primary lesions
*Pruritus - severe
*Papules
*Erythema

Secondary lesions
*Excoriation
*Alopecia
*Crusts
*Pyoderma signs
Distribution =
*Pinnal margins, elbows, hocks
*Becomes more generalised with time

Question 23

What are diagnostic tests for sarcoptic mange?

Answer 23

*Pinnal-pedal reflex: often present but unreliable
*Superficial skin scrapes: high specificity (100%) & low sensitivity (50%)
*IgG serology: variable sensitivity and susceptibility, cross reaction with
house-dust mites!
*Treatment trial: often chosen above others as most reliable

Question 24

What is the main sarcoptes found in dogs?

Answer 24

Sarcoptes scabei var canis

Question 25

What is the feline form of sarcoptic mange?

Answer 25

Notoedres cati

Question 26

Where do female sarcoptes lay their eggs?

Answer 26

Tunnel into stratum corneum

Question 27

What is a common treatment for sarcoptic mange?

Answer 27

*Common topical and oral treatments are effective *Anti-pruritic therapy often needed to control severe pruritus

Question 28

What is the distribution of harvest mites (Trombicula)?

Answer 28

Henry's pocket - pinnae Ventrum - nipples Between footpads

Question 29

What are common treatments for harvest mites?

Answer 29

*Larval forms temporarily parasitise animals to feed then return to environment *Avoidance is best policy as killing following feeding fails to address irritation *Fipronil spray for the legs (not licenced) *Isoxazolines? *Prednisolone as before to control pruritus and inflammation

Question 30

What is the ear mite?

Answer 30

Otodectes Cynotis

Question 31

What is the distribution of the ear mite?

Answer 31

Usually in the ear But can leave canal and affect head/tail

Question 32

What is the treatment of otodectes?

Answer 32

Spot-on /oral therapies +Topical

Question 33

What diagnostic tests can be done for otodectes?

Answer 33

*Direct observation of mites using otoscope (photophobic) *Unstained ear wax examination (mount in liquid paraffin)

Question 34

What are the most common species of cheyletiellosis?

Answer 34

Cheyletiella yasguri C. blakei C. parasitivorax

Question 35

What is the distribution of cheyletiella?

Answer 35

Dorsal trunk Rarely head

Question 36

What diagnostic tests can be done for cheyletiella?

Answer 36

*Coat brushings: walking dandruff *Superficial skin scraping from scaly areas *Faecal flotation may be used in cats where excessive grooming present

Question 37

What is the treatment for cheyletiella?

Answer 37

*No licenced therapy *Fipronil spray or spot-on selamectin effective

Question 38

What are common chewing lice?

Answer 38

Felicola subrostratus Trichodectes canis

Question 39

What is a common sucking louse?

Answer 39

Linognathus setosus

Question 40

What is the normal distribution of lice? (Pediculosis)

Answer 40

Dorsum

Question 41

How can you diagnose lice?

Answer 41

Coat brushings - lice seen under microscope + eggs

Question 42

What animals are affected by epitheliotropic lymphoma?

Answer 42

*Disease of older animals (very rarely seen in young animals) *Lesions before pruritus

Question 43

What is the distribution of epitheliotropic lymphoma?

Answer 43

Anywhere on body Often mucocutaneous junction

Question 44

How is Epitheliotropic lymphoma diagnosed?

Answer 44

*Skin biopsy & histopathology

Question 45

What is the primary lesion of demodex?

Answer 45

Alopecia

Question 46

What are clinical features of demodex gatoi?

Answer 46

*Contagious (unlike all other forms of demodicosis) *Pruritus often seen (but not in all animals) *Self-induced alopecia ± excoriation (anywhere)

Question 47

How is demodex diagnosed?

Answer 47

*Surface dwelling mites so skin scrapes have very poor sensitivity *Tape impression more useful *Faecal floatation has been used successfully

Question 48

What is the treatment of demodex gatoi?

Answer 48

*Selamectin/sarolaner spot-on combo (Stronghold Plus) *Fluralaner (Bravecto) *Lime sulphur dip (weekly until 2 negative samples) *Treat in contact cats and investigate potential immunosuppressive disease

Question 49

What species are predisposed to demodex injai?

Answer 49

Terriers - Border, Welsh, Norfolk, WHWT