Diagnostic Approach to

the Pruritic Dog & Cat

Dr. Nuttawan SrifawattanaDermatology Clinic

Small Animal Hospital Chiang Mai University

Faculty of Veterinary Medicine, Chiang Mai University

Pruritic Skin Diseases in Dogs & Cats

Pathogenesis of Pruritus & Pruritic Threshold

Introduction01

Outline

Canine Pruritus & Canine Pruritic Score

Dermatological Approach, Differential Diagnosis & Management

Canine Pruritic Skin Disease02

Feline Pruritus & Dermatological Reaction Patterns

Dermatological Approach, Differential Diagnosis & Management

Feline Pruritic Skin Disease03

IntroductionPruritic Skin Diseases in Dogs & Cats

Pathogenesis of Pruritus & Pruritic Threshold

Canine

Pruritic

Disease

Ectoparasite

Allergic Dermatitis

Infectious Disease

Neoplastic Disease

Pruritic Skin Diseases

Feline

Pruritic

Disease

Ectoparasite

Allergic Dermatitis

Infectious Disease

Idiopathic

Pathogenesis of Pruritus

We Create

Quality Professional

PPT Presentation

Pathogenesis of Pruritus

https://www.researchgate.net/publication/275652472_Mediators_of_Chronic_Pruritus_in_Atopic_Dermatitis_Getting_the_Itch_Out/figures

Not a fixed level

Factors Raised threshold Lower threshold

Skin temperature Cooling Heating

Water content Moist skin Dry skin

Emotional status Calm Anxiety/Stress

Vary individually

Pruritic Threshold

Canine Pruritic

Skin DiseaseCanine Pruritus & Canine Pruritic Score

Dermatological Approach, Differential Diagnosis & Management

Canine Pruritus &

Canine Pruritic

Score

Dermatological Approach

Parasitic

Allergic

Autoimmune

Nutritional

Endocrine

Bacterial

Fungal

Degree of Pruritus

Differential Diagnosis

Ectoparasites

• Scabies

• Cheyletiellosis

• Fleas

Allergic dermatitis

• Flea allergy dermatitis

• Atopic dermatitis

• Food adverse reaction/Food intolerance

Infectious Disease

• Malassezia dermatitis

• Bacterial pyoderma

Neoplastic Disease

• Cutaneous lymphoma

Simple

Diagnostic

Test

The Skin Scraping The Scotch Tape Test Coat Brushing

Cytology Examination Trichogram Fungal Culture

Complex

Diagnostic

Test

An Elimination diet Intradermal Skin Testing Culture & Sensitivity Test

Skin Biopsy Blood Test Imaging Techniques

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Ectoparasite

D

DD

Sarcoptes scabieio Burrowing mite (Digging tunnel)

o Host: dog, pig etc.

o Location: epidermis (stratum corneum)

o Morphology:

Round

Unsegmented Pretarsi of legs I and II–

simple stalked pedicels and suckers

Dorsal spine with triangle shape of scale

Terminal anus

Clinical Signs

Picture

o Pruritus 10/10

o Positive pinna pedal reflex

o Papulocrustous eruptions

(Papules, yellow crust)

o Scaling , excoriation

o Erythema, alopecia

o Area : pinnal tips/margin, elbows,

ventral chest, abdomen, hock

o Hypersensitivity

(https://veterinarypartner.vin.com/default.aspx?pid=19239&catId=102899&id=4952007)

Diagnosis

o Skin scraping

o Serological test IgG

Sensitivity 83-92%

Specificity 89-92%

o Therapeutic trial

Kittichai wannasiri,DVM.

TreatmentEMA Approved Extra-label

Sarolaner (Simparica®) 2.5 mg/kg POIsoxazolines : Fluralaner,

afoxolaner , lotilaner

Selamectin (Revolution® ) Spot on

Moxidectin (Advantage multi®) Spot on

Ivermetin 0.2 mg/kg

q14ds SCOne application/administration : repeat

after one month

Cheyletiellosis

o Walking dandruff

C. blakei in cat

C. parasitivorax in rabbit

C. yasguri in dog

o Morephology: oval shape and the

body has a "waist"

o Cheyletiella dermatitis

o Length of life cycle: 3-5 wks

o In contact and Zoonosis

Clinical Signso Skin scales

o Moving dandruff

o Cat can induce dorsal crusting,

generalized miliary dermatitis

Diagnosis

o Scotch tape technique

o Superficial skin scraping

o Flea combing

o Hair plucking

http://www.pugdogclubofamerica.com/skin-5.html

Treatmento Milbemycin oxime 2 mg/kg weekly

o Selamectin weekly

o Moxidectin weekly

o Fipronil spray

o Amitraz 250 ppm

o Selenium sulphide washes

Flea

Life Cycle

5%

10%

35%

50%

Ctenocephalides canis

o 7-8 similar length of genal combs spine อนัแรกของ genal

ctenidium จะสัน้กว่า spine อนัท่ีสอง

o 16 pronotal combs

o Hind tibia; 2 long bristle between postmedian & apical setae

o Poor host for D. caninum

Ctenocephalides felis

o ช่ือสามญัว่า หมดัแมว (cat flea)

o พบได้ในแมวทัว่ไป แต่อาจพบได้ในสนัุขเลี้ยงด้วย

o มีหลาย subspecies Ctenocephalides felis felis

7-8 similar length of genal combs

16 pronotal combs

Hind tibia; 1 long bristle between postmedian & apical setae

How important it is ???

oSucking blood causing Anemia

(puppy & kitten)

o Intermediate hosts of Rickettsia

felis & Bartonella spp.

o Itching and scratching (pruritis &

Dermatitis) and hair loss

oFlea bite allergic dermatitis

Stage 3

In animals that are allergic to the flea saliva, the

reaction is more pronounced, causing intense

itching. Scratching may

cause increased inflammation and hair loss.

Stage 1

Normal skin

Stage 2

When a flea bites, it injects a

small amount of saliva into the skin, causing

an inflammatory reaction

Stage 4

Bacterial infection is a common sequela to skin

trauma caused by scratching.

Clinical signs

o Non allergic animal

Irritation

Pruritus

o Allergic animal

o Flea bite allergy

Allergic Dermatitis

Caused by Flea

D

DD

Allergic Dermatitis

Flea triangle

Atopic Dermatitis

Adverse Food Reaction

Ctenocephalides felis

Ctenocephalides canis

Hypersensitivity to flea salivary

antigens (dose dependent

hypersensitivity)

Severity of flea bite allergy

depend on individual

hypersensitivity

Flea Allergy

Dermatitis

Rule Out Allergy Rule Out Flea

DD

D

Allergy

o Adverse food

reaction

o Atopy

o Flea bite allergy

Flea therapeutic trial for 4 weeks

May take until week 8-12 to see the improvement

in severe and chronic cases

Symptomatic anti-pruritic therapy is necessary

Lumbo-sacral region

All pets in the same household need to be treated

Flea Control

Adverse Food Reaction

Hypersensitivity type I (also III

and IV)

Allergen : Glycoproteins of MW

between 10-70 kD.

Most common : Beef , Daily

product, Chicken , wheat and soy

Young dog , all breed

Non seasonal pruritus

Only partially responsive to

steroid

Erythema , papule, secondary

lesions (periocular , ventral

pinnae , around mouth)

Abdomen, perianal area , legs,

paws

Otitis externa

GI sign 10-15%

Adverse Food Reaction

Diagnosis :

Elimination diet with New source of protein / carbohydrate or Commercial food based on hydrolyzed protein

Elimination diet

(8 weeks)

Improve response

Challenge (2 weeks)

Clinical signs re-appear

Food allergy

Remains without clinical signs

Rule out

No response

Rule out

Food allergy/ Intolerance

Favrot’s criteria5 criteria should be fulfilled

Age at on set<3 years

Mostly indoor

Alesional pruritus at onset

Corticosteroid responsiveness

Affected front feet

Affected ear pinnae

Non-affected ear margins

Non-affected dorso-lumbar area

Canine Atopic Dermatitis

D

DD

Infectious Disease

Canine

Pyoderma

Phylum: Firmicutes

Class: Bacilli

Order: Bacillales

Family: Staphylococcaceae

Genus: Staphylococcus

Facultative anaerobic

Gram-positive

Cocci in clusters (grape-like cocci)

Colonize at mucocutaneous junctions

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Staphylococcus pseudintermedius

Classification

Deep pyoderma

Surface pyoderma

Mucocutaneous pyoderma

Superficial pyoderma

Antibiotic TreatmentTopical Therapy Systemic Therapy

Antiseptic Shampoo

• Benzoyl peroxide

• Chlorhexidine

• Salicylic acid

First Tier

Cephalexin 22-30 mg/kg q8-12h PO

Amoxicillin-clavulanic acid 15-30 mg/kg q8-12h PO

Clindamycin 5.5-11 mg/kg q12h SC,PO

Sulfamethoxazole-trimethoprim 15-30 mg/kg q12h PO

Antibiotics Topical

• Mupirocin

• Polymyxin B

• Fusidic acid

• Amikacin gel

Secondary Tier

Cefovecin 8 mg/kg once SC

Enrofloxacin 5-20 mg/kg q24h PO

Marbofloxacin 2.75-5.5 mg/kg q24h PO

Doxycycline 5-10 mg/kg q12-24h PO

Alternatives

• Herbs, Fruits, etc.

Third Tier

Amikacin 15-30 mg/kg q24h SC

Vancomycin

Carbapenems

Malessezia Dermatitis

Yeast Infection

Medication

Itraconazole : 5 mg/kg sid duration at

least 1 month

Topical treatment

2% Ketoconazole cream

Shampoo

• 2% miconazole

• 2-4% chlorhexidine

• 2% ketoconazole

• 2% chlorhexidine +

1%ketoconazole

D

DD

Neoplastic Disease

Cutaneous Lymphoma

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Diagnostic Approach to the Pruritic Dog

Fleas or lesions suggestive of FAD

Rule out ectoparasite

Skin scraping

Hair microscopy

Serology/Treatment

Investigate secondary infections

Rule out Adverse Food Reaction

Atopic dermatitis

Test in vibo (IDST)

Test in vitro (serology)

Flea control

Scabies treatment

Specific treatment

Adequate treatment

Feed Adequate Food

Decide most

Adequate therapy

D

DD

Management of Pruritus

Multimodal ManagementShot term/Acute flare/ Supportive care Long term control

Antihistamine (30%)Oclacitinib acid/

ApoquelCorticosteroid/Prednisolone

Oclacitinib acid/ApoquelLokivetmab/

CytopointLokivetmab/Cytopoint

Control secondary infection Cyclosporine

Antihistamine

Antihistamine used in CanineAntihistamine Dose

Hydroxyzine HCl (Atarax®) 2.2 mg/kg q8-12h

Diphenhydramine (Benadryl®) 2.2 mg/kg q8-12h

Chlorpheniramine (CPM®) 0.2-0.8 mg/kg q8-12h

Clemastine fumarate (Tavist®) 0.05-0.1 mg/kg q8-12h

Amitriptylyne (Elavil®) 2.2 mg/kg q12h

Loratadine (Claritin®) 10 mg/kg q24h

Fexofenadine (Allergra®) 15-20 mg/kg q24h

Cetirizine (Zyrtec®) 1 mg/kg q12-24h

Oclacitinib acid/Apoquel

Lokivetmab / Cytopoint

Corticosteroid / Prednisolone

Corticosteroid / Prednisolone Prednisolone 0.5 mg/kg twice daily then reduce dose 50% every 7 days,

then alternate day

Safe annual dose: 30 x Body weight(kg) = mg of prednisolone per year

(need to divided to daily dose)

Be aware of PU/PD, Iatrogenic cushing’s, Cystitis, Hepatomegaly, DM, GI

ulcer, Calcinosis cutis

Cyclosporine

Feline Pruritic

Skin DiseaseFeline Pruritus & Dermatological Reaction Patterns

Dermatological Approach, Differential Diagnosis & Management

Reaction Patterns

D

DD

01 02 0403 05

Head and

neck pruritus

Self-induced

alopecia

Eosinophilic

plaque

Indolent

ulcer

Eosinophilic

granuloma

Reaction Patterns

D

DD

06 0807

Linear

granuloma

Miliary

dermatitis

Urticaria

pigmentosa like

dermatitis

Head and Neck Pruritus

Back

Self-induced Alopecia Back

Eosinophilic PlaqueEosinophilic Granuloma

Back

https://veterinary-practice.com/article/dealing-with-feline-allergic-

skin-disease

Indolent Ulcer

Back

https://veterinary-practice.com/article/dealing-with-feline-allergic-skin-disease

Linear Granuloma

Back

https://veterinary-practice.com/article/dealing-with-feline-allergic-skin-disease

Miliary Dermatitis

Back

https://www.cliniciansbrief.com/column/1000-words/miliary-dermatitis

Urticaria Pigmentosa-liked Dermatitis

Back

Differential Diagnosis

Ectoparasites

• Otodectes cynotis,Notoedres cati

• Demodex ,Trombiculid mite

• Flea , lice

• Sarcoptes

Allergic dermatitis

• Environmental , Food, Flea saliva

• Contact, Intestinal parasite (Immune

response : rare)

Infectious Disease

• Dermatophyte

• Bacteria

• Virus : Herpes virus

Idiopathic/Neurogenic

• No underlying cause

• Cannot identified

• Psychogenic

Ectoparasite

D

DD

Parasite cause of feline itching

Flea

Chyletiella

Demodex gatoi / Demodex Cati

Notoedres

Otodectes

Mosquitoes

Demodex Demodex gatoi

Short body

Stratum corneum

Scale ,alopecia, erythema

Demodex Cati

Follicular demodicosis

Eyelids, periocular,Head,neck

Treatment

Stop any Glucocorticoid

Bravecto

Lime sulfur

www.veterinaryimagebank.com

:Demodex cati

https://vet360.vetlink.co.za/training/diagnosis-treatment-of-demodicosis-in-dogs-cats/

Demodex gatoi

Demodex Cati

http://citeseerx.ist.psu.edu :

Demodex gatoi

Notoedres catiFeline Scabies

Morphology similar to Sarcoptes scrabiei

except the anus position (dorsal anus)

Skin hyperkeratinization

Treatment

Selamectin (6-12mg/kg every 4 week)

Moxidectin (2.5-5 mg/kg every 2-4 week)

Lime Sulphur dips

Fipronil spray

Week 4Week 2Week 0

OtodectescynotisLocation: Ear canal (external), Ear pinna

Length of life cycle: 3-4 weeks

Clinical signs

Pruritus and self induced alopecia

Associated with otitis externa

Dry blackish granules

Erythema and excoriations

Severity in TM rupture : vestibular signs

Diagnosis Ear swab (liquid paraffin mounts)

Treatment Topical otic preparations

***Thiabendazole ****

Monosulfiram

Permethrin

Selamectin (spot on labelled dosage)

Moxidectin (spot on labelled dosage)

D

DD

Infectious Disease

Fungal Infection

Microsporum Canis Microsporum gypseum

Trichophyton

mentagrophytes

Localized Infection Generalized Infection

1-5 small circumscribed

Treatment: Topical treatment

o Shampoo (miconazole,

ketoconazole, chlorhexidine

+ miconazole)

o Cream, Spray

5 or more lesions

Treatment: Topical and Systemic treatment

o Ketoconazole

o Itraconazole

Fungal Infection

D

DD

Allergic Dermatitis

Distribution pattern

Feline Food allergy

Genetic predisposition not require

• 0.22 to 6% of cats with dermatologic signs

• 17 to 22% of cats with GI signs •

Cats mean age 4-5 years (range 3 mo to 11 yr)

Allergen

> 4000 Dalton

Reported Food Allergens in cat

Proteins Grains Others

Beef Barleys Commercial food

Chickens Corn Clam juice

Fish Cod liver oil

Dairy product Food additives

Horse meat Food preservatives

Lamp

Pork

Diagnosis

R/O ectoparasites

R/O food allergies

R/O infections

• Investigate for “offending”

allergens

• Serum IgE testing

• Intradermal testing

Feline Atopic Dermatitis

D

DD

Idiopathic

Neurogenic

Idiopathic/Neurogenic

Twitchy cat syndrome

Neurologic ?

Behavioral?

Rippling of skin over back

Over grooming , Growling, hissing, biting at back or tail,

running and hiding

Rule out ectoparasites, allergies, neurological disease

Treatment trials

Gabapentin

Amitriptyline

Phenobarbital

D

DD

Management of Pruritus

Avoidance

Managing Microbial infection/overgrowth

Medical treatment of Itching

Antihistamine

Glucocorticoid

Cyclosporine

***Apoquel ***

Management of Feline Pruritus

Antihistamine used in cat

Antihistamine Dose

Chlorpheniramine (CPM®) 2-4 mg/cat q12h

Diphenhydramine (Benadryl®) 2.2 mg/kg q12h

Clemastine fumarate (Tavist®) 0.68 mg/cat q12h

Amitriptylyne (Elavil®) 0.5-1.0 mg/kg q12h

Cetirizine (Zyrtec®) 5 mg/cat q24h

Cyproheptadine 2 mg/cat q12h

Glucocorticoid used in cat

Prednisolone 2 mg/kg PO q 24h then EOD

Methylprednisolone 1.6 mg/kg PO q24h then EOD

Dexamethasone 0.2 mg.kg PO q24h then EOD

Cyclosporine

7 mg/kg SID (5-10 mg/kg)

Clinical improvement typically between 2-3 weeks

Steady state around 4-6 weeks

Recommended that cats have serology evaluated for

Toxoplasma , FeLV or FIV

Prior to initiating therapy and periodically during treatment

Oclacitinib acid

Janus kinase inhibitor

Decreases production of IL-31

At higher doses may cause bone marrow suppression

Precautions

Do not use in FeLV or FIV + cats

Indoor cats only and avoid feeding raw meats

Thank YouFor your attention