This document discusses bacterial pyoderma, Malassezia dermatitis, and flea control in pets. It provides information on: 1. The causes, clinical presentations, diagnosis, and treatment of bacterial pyoderma and Malassezia dermatitis. Surface cytology is important for diagnosis. Antibiotics or antifungals are used to first treat the underlying infection before addressing the primary disease. 2. Methicillin-resistant Staphylococcus pseudintermedius is an emerging concern, with resistance rates varying worldwide from 7-60%. Culture and sensitivity testing is important for treatment. 3. Historical clues can provide insights for diagnosing flea allergy in pets,

1. Pesky Pyoderma, Malodourous
Malassezia, & Fecund Fleas
Linda Vogelnest BVSc MACVSc FACVSc
Specialist Veterinary Dermatologist
Associate Lecture University of Sydney

2. www.sashvets.com
Bacterial Pyoderma
• Superficial &/or Deep
• 2° to
– Allergies – AD (can markedly  pruritus)
– Systemic immune suppression
• Immuno-suppressive therapies (e.g. pred)
• Disease (e.g. neoplasia, FIV)
– Hormonal – hypoT, hyperA (can cause pruritus)
– Keratinisation defects - primary seborrhoea,
sebaceous adenitis

3. www.sashvets.com
Bacterial Pyoderma
• Superficial &/or Deep - 2° disease
• Problems
– Diagnosis – variable presentations
– Treatment
• Clear current infection - duration key
– New antibiotic resistance – drugs
+ duration
• Manage 1° disease – AD common,
difficult
3

4. www.sashvets.com
Bacterial Pyoderma
• Historical clues
– Species/breed/age
• Dogs – any skin disease, age, breed
• Cats – young (allergies); aged
– Pruritus – absent to severe
– Poor/loss of steroid-responsiveness
– Recent illness, immuno-suppressive drugs
4

5. www.sashvets.com
Bacterial Pyoderma
• Clinical clues
– Lesions - superficial
• Pustules, papules;
epidermal collarettes
5

6. www.sashvets.com
Bacterial Pyoderma
• Clinical clues
– Lesions - superficial
• Pustules, papules; epidermal collarettes
• Alopecia – well-demarcated to patchy diffuse
6

7. www.sashvets.com
Bacterial Pyoderma
• Clinical clues
– Lesions - superficial
• Pustules, papules; epidermal collarettes
• Alopecia – well-demarcated (to patchy diffuse)
• Non-specific – erythema, erosions, scaling, crusting,
lichenification, hyperpigmentation
7

8. www.sashvets.com
Bacterial Pyoderma
• Clinical clues
– Lesions - superficial
• Pustules, papules; epidermal collarettes
• Alopecia – well-demarcated (to patchy diffuse)
• Non-specific – erythema, scaling, crusting, lich/hyperpigmentation
• Regional forms:
8

9. www.sashvets.com
Bacterial Pyoderma
• Clinical clues
– Lesions
• Pustules, papules; epidermal
collarettes
• Alopecia – well-demarcated (to
patchy diffuse)
• Non-specific – erythema, scaling,
crusting, lich/hyper
• Regional forms
• Other forms
9

10. www.sashvets.com
Bacterial Pyoderma
• Clinical clues
– Lesions - superficial
• Pustules, papules; epidermal collarettes
• Alopecia – well-demarcated (to patchy diffuse)
• Non-specific – erythema, scaling, crusting, lich/hyper
• Regional forms
• Other forms
10

11. www.sashvets.com
Bacterial Pyoderma
• Clinical clues
– Lesions – superficial
– Lesions – deep
• Nodules, draining tracts
11

12. 12

13. www.sashvets.com
Bacterial Pyoderma
• Clinical clues
– Lesions – superficial
– Lesions – deep
• Pseudomonas deep
pyoderma
13

14. www.sashvets.com
Bacterial Pyoderma
• Clinical clues
– Lesions – superficial
– Lesions – deep
• Solar deep pyoderma
14

15. 15

16. www.sashvets.com
Malassezia dermatitis
• 2° to
– Allergies – AD (can markedly  pruritus)
– Systemic immune suppression
• Immuno-suppressive therapies (e.g. pred)
• Disease (e.g. neoplasia, FIV)
– Hormonal – hypoT, hyperA (can cause pruritus)
– Keratinisation defects - primary seborrhoea, sebaceous adenitis
16

17. www.sashvets.com
Malassezia Dermatitis
• Historical clues
– Breeds - WHWT, Basset, Cocker, Shih Tzu,
Dachshund; Devon Rex
– Pruritus - often severe
– +/- Odour
– Poor/loss of steroid-responsiveness
– Concurrent illness, immuno-suppressive drugs
17

18. www.sashvets.com
Malassezia Dermatitis
• Clinical clues
– Lesions
• Erythema, scaling; brown nails
• Lichenification, hyperpigmentation, odour
18

19. 19

20. www.sashvets.com
Diagnosis
• Skin cytology
– Adhesive tape impression (all lesions)
• Diff-Quik stain (no fixative)
20

21. www.sashvets.com
Diagnosis
• Skin cytology
– Adhesive tape impression (all
lesions)
– Glass slide impression (moist
lesions)
21

22. 22
Tape Impression - Normal skin - 4X lens (40x magnification)
Keratinocytes dominate; normal flora very sparse

23. 23
Tape Impression – Pyoderma 4X lens (40x magnification)
Clumped keratinocytes; Neutrophil rims/clusters

24. 24
4X lens (40x magnification)

25. 25
Degenerate neutrophils with intracellular cocci – oif (1000x)

26. 26
Neutrophils with intracellular & colonising cocci – oif (1000x)

27. 27
Keratinocytes with melanin granules – oif (1000x)

28. 28
Tape Impression – MD 4X lens (40x magnification)

29. 29
MD – oil lens (1000X)
Dx = >1 yeast per oif

30. www.sashvets.com
Pyoderma & MD - Diagnosis
• Surface cytology
– Most important
– Not 100% sensitive (esp. pyoderma)
• Clinical appearance
– May be suggestive (papular lesions;
follicular moth-eaten alopecia;
nodules/discharge)
• Consider treatment trial
– Antibiotics or antifungals alone (3wks min
- superficial)
30

31. www.sashvets.com
Pyoderma & MD - Treatment
1. Treat the infection first (underlying dz 2nd)
Systemic most reliable (min. 3wk course)
 MD
Itraconazole 5-10mg/kg SID
Terbinafine 30mg/kg SID
Pulse tx: 2 consecutive days/wk
 Pyoderma
Cephalexin, amoxyclav
Doxycycline, TMS, clindamycin
Rifampicin, chloramphenicol, enrofloxacin
31

32. www.sashvets.com
Pyoderma & MD - Treatment
1. Treat the infection first (underlying dz 2nd)
 Systemic most reliable (min. 3wk course)
 Topicals can be useful
 MD - Enilconazole rinse, miconazole/terbinafine
cream
 Pyoderma - Mupirocin, fusidic acid, silver
sulphadiazine
 Both - Chlorhexidine solution (2-3%) sid-bid
Shampoos – adjunctive only (limited
residual effect)
Chlorhexidine, miconazole
Piroctone olamine, econazole
32

33. www.sashvets.com
Pyoderma & MD - Treatment
1. Treat the infection first (underlying dz 2nd)
• Systemics &/or topicals
• NO concurrent steroids
– Incomplete/delayed resolution of infections
– Encourages antimicrobial resistance
– Pruritus markedly reduced in 24-48 hours without steroids
 DON’T use pred & 5-10 days antibiotics !!
33

34. www.sashvets.com
Pyoderma & MD - Treatment
Diagnosis uncertain?
– Options
1. Antibiotic or antifungal treatment trial
(3wks; no steroids)
– Pruritic: pruritus & lesions should
improve by 5-7d
– Non-pruritic: lesions should resolve by
2-3wks
1. Steroid-treatment trial (2-7 days; no
antibiotics/antifungals)
– Pruritic: pruritus and lesions should
improve notably by 7d
– Non-pruritic: not indicated!
1. Referral?
DON’T use pred & 5-10 days
antibiotics !!
34

35. www.sashvets.com
Pyoderma & MD - Treatment
1. Treat the infection first – systemics &/or topicals (no steroids)
2. Address the underlying dz next – if possible!
3. Options for recurrent pyoderma/MD (e.g. immune suppression; AD)
1. Pulse antimicrobials – encourage development of resistance
2. Intensive topical therapies
» Chlorhexidine/piroctone olamine/azole shampoo 1-2 times wkly
» Bleach baths (0.005%) = 50ppm [6% bleach: 1ml per 1.2L]
» Chlorhex 2.5% spray, Resichlor® or Pyohex Leave on Lotion® -
SID?
1. Maximise Skin health
» Skin Barrier Repair – moisturising; fatty acids
» Balance Diets – fatty acids
» Shampoos – appropriate, non-drying
1. More aggressive disease control – cyclosporine for AD
35

36. www.sashvets.com
Methicillin-Resistant Pyoderma
= Resistance to
• β-Lactam Ab’s - Cephalexin, amoxyclav
• Often several other drug classes: MDR
–World Trends for S. pseudintermedius
• ~98% sensitive to cephalexin, amoxyclav for >20yrs
• First methicillin resistance (MRSP) – 1999 (Dogs: Illinois, USA)
• Increasing MRSP 2006 (healthy dogs + skin dz)#
– ~7% many countries – Canada, Europe, parts USA
– 10% Spain, 17% Korea
– 27-38% parts USA, 30-66% Japan
# van Duijkeren E, Catry B, Greko C et al. Review on methicillin-resistant Staphylococcus pseudintermedius. J
Antimicrob Chemoth 2011;66:2705-2714.
36

37. www.sashvets.com
Methicillin-Resistant Pyoderma
= Resistance to
• β-Lactam Ab’s - Cephalexin, amoxyclav
• Often several other drug classes: MDR
–World Trends for S. pseudintermedius
• Worldwide – 7-60% MRSP (more dogs than cats)
• Sydney, Australia
– 27 cases (Aug 2010-Sep 2012; no Ab’s previous 2wks)#
» 24 S. pseudintermeudius; 3 S. schleiferi
» 1 (4%) – MRSP + MDR; 26 (96%) sensitive cephalexin, amoxyclav
– 55 cases (Nov 2012-Jul 2013; no Ab withdrawal)
» 6 (20%) of 29 dogs – MRSP + MDR
# Ravens et al. Canine superficial bacterial pyoderma: screening for antimicrobial resistance in causal Staphylococcus
isolates, and comparison of culture sampling methods; AVJ in press.
37

38. www.sashvets.com
Methicillin-Resistant Pyoderma
= Resistance to
• Β-Lactam Ab’s - Cephalexin, amoxyclav
• Often several other drug classes: MDR
–World Trends for S. pseudintermedius
• Worldwide ~ 7-60% MRSP (more dogs than cats)
• Sydney, Australia ~20% (dogs)
• Small no. MRSP clones disseminated worldwide
– Prior Ab use; hospitalisation; urban areas = risk factors
» DON’T use pred & 5-10 days antibiotics !!
– Vet Hospital hygiene important to limit spread
38

39. www.sashvets.com
Methicillin-Resistant Pyoderma
1. Culture Samples
1. Pustules – 25g needle, dry swab sample
2. Other lesions – dry swab rubbed vigorously 5 sec
– Dry swab, saline-moistened swab, skin scraping similar#
» Minor variation in isolates with method (6/29 dogs)
» Interpret with care; in relation to skin cytology
» Repeat samples?
• # Ravens et al. Canine superficial bacterial pyoderma: screening for antimicrobial resistance in causal
Staphylococcus isolates, and comparison of culture sampling methods; AVJ in press.
39

40. www.sashvets.com
Methicillin-Resistant Pyoderma
1. Culture Samples
1. Pustules – 25g needle, dry swab sample
2. Other lesions – dry swab rubbed vigorously 5 sec
2. Sensitivity testing SP isolates Sydney#(27 dogs; 227
isolates)
• Cephalexin, amoxyclav, TMS (96%)
• Enrofloxacin, chloramphenicol (96%)
– Less to doxycycline (78%), clindamycin (88%),
cefovecin (90%)
• # Ravens et al. Canine superficial bacterial pyoderma: screening for antimicrobial
resistance in causal Staphylococcus isolates, and comparison of culture sampling
methods; AVJ in press.
40

41. Pyoderma & MD
QUESTIONS?
41

42. www.sashvets.com
Flea Allergy/Flea Control
• Flea problems common – cats, dogs
– Diagnosis of Allergy – sometimes missed
– Treatment – sometimes challenging
• Historical clues for Flea Allergy
– Signalment
• No breed predilections
• Age of onset - typically 3-5yrs
– Pattern of pruritus
• Severe; intermittent, suddenly flaring
• Typically seasonal - late summer/autumn worst
– Flea control history
• Regular monthly flea prevention
• No evidence fleas/flea dirt (more likely with regular control)
42

43. www.sashvets.com
Clinical Lesions - Dogs
• Lesions
– Acute
• Papules
• Self-trauma – alopecia, excoriations
• “Hot spots”
– Chronic
• Lichenification
• Hyperpigmentation

44. www.sashvets.com
Clinical Lesions - Dogs
Distribution
– Caudal ½ of body
• Dorsal lumbosacral area
• Flanks
• Caudomedial hindlimbs
• Ventral abdomen
• Umbilical area

45. www.sashvets.com
Clinical Lesions - Cats
• Lesions - variable
– Self trauma - mild to severe
• Alopecia, excoriations, crusting,
ulcers
– Non-inflammatory alopecia
– Miliary dermatitis
– EGC lesions

46. www.sashvets.com
Clinical Lesions - Cats
Distribution
– Caudal ½ of body
• Dorsal lumbosacral area
• Caudomedial hindlimbs
• Ventral abdomen
– Neck/shoulders
– Lips

47. www.sashvets.com
Flea Allergy Diagnosis
Response to flea treatment trial (4wks)
1. Affected pets -  control
2. In-contact pets - regular control
3. Environment - IGR treatment
 marked reduction in pruritus/clinical
signs by 4wks

48. www.sashvets.com
Response to flea treatment trial (4wks)
1. Affected pets -  control
2. In-contact pets - regular control
3. Environment - IGR treatment
– Product Choice - consider
– Product efficacy
– Coat length/density
– Frequency of bathing, swimming
– Ability of owner to apply effectively
– Cost
Flea Allergy Diagnosis

49. www.sashvets.com
Flea Allergy/Flea Control
• Flea Life Cycle
– Adults
• Feed <5min
• Mate 8-24hrs; lay eggs by 24-36hrs (40-50/day)
• Only 8-15% adults move to other hosts
– Eggs
• Fall off pet into resting areas
• Hatch 1-6d - RH>50%; 4-35°C
– Larvae
• Motile – “down, into dark” (moist, cool sites)
• Pupate in 8-14d – temp & food dependent (faeces, eggs)
– Pupae
• Very resistant
• Adult emergence in 2wks-6mnth- vibration, warmth
49

50. www.sashvets.com
Flea Allergy/Flea Control
– Flea control for flea allergy
• Adults – feed 5min; eggs by 24-36hrs
1. Quick reduction in flea numbers
2. Reduced flea feeding times
– Adulticides – kill rates/speed of kill/duration effect
• Nitenpyram - 100% kill by 3hrs (dogs), 4hrs (cats); 92% by
72hr
– Sig. less flea feeding within ≤ 15mins
• Spinosad - 100% kill by 24hrs; 85-100% kill + 100% less eggs
by 30d
– >90% kill by 2hrs (cats); 81-100% by 4hrs (dogs)
– 95-96% dogs flea free by 3mnth cf. 64%
selamectin cf. 38% fipronil#
– IVERMECTIN toxicity… beware!
#Dryden Vet Parasitol 2012
50

51. www.sashvets.com
Flea Allergy/Flea Control
• Flea control for flea allergy
1. Quick reduction in flea numbers
2. Reduced flea feeding times
– Adults – feed 5min; eggs by 24-36hrs
– Adulticides – kill rates/speed/duration effect
• Nitenpyram - 100% kill by 3hrs (dogs), 4hrs (cats);
92% by 72hr
• Spinosad - 100% kill by 4-24hrs; 85-100% + 100% less
eggs by 30d
• Imidacloprid - 95-100% kill by 8-12hrs; 95% by 30d
– 83% kill by 8hrs (cats)
– Reduced flea feeding by 3-5mins (cf 60min
fip/sel) – d7, d14
– Lower flea kill rates Advantix® vs Advantage®#
McCall, Int J Applied Research in Vet Med 2004
51

52. www.sashvets.com
Flea Allergy/Flea Control
• Flea control for flea allergy
1. Quick reduction in flea numbers
2. Reduced flea feeding times
– Adults – feed 5min; eggs by 24-36hrs
– Adulticides – kill rates/speed/duration effect
• Nitenpyram - 100% kill by 3hrs (dogs), 4hrs (cats);
92% by 72hr
• Spinosad - 100% kill by 4-24hrs; 85-100% + 100% less
eggs by 30d
• Imidacloprid - 95-100% kill by 8-12hrs; 95% by 30d
• Fipronil - 98-100% kill by 12-18hrs; 93-95% by 30d
– 63% kill (cats), 47% kill (dogs) by 8hrs
– 38% flea free by 3 mnths (cf. 64% selamectin;
95% spinosad)#
• Selamectin - >98% kill by 36-42hrs; 95% by 28d
– 74% kill by 8hrs
#Dryden Vet Parasitol 2012
52

53. www.sashvets.com
Flea Allergy/Flea Control
• Flea control for flea allergy
1. Quick reduction in flea numbers
2. Reduced flea feeding times
– Adults – feed 5min; eggs by 24-36hrs
– Adulticides – kill rates/speed/duration effect
• Nitenpyram - 100% kill by 3hrs (dogs), 4hrs (cats); 92% by
72hr
• Spinosad - 100% kill by 4-24hrs; 85-100% + 100% less eggs by
30d
• Imidacloprid - 95-100% kill by 8-12hrs; 95% by 30d
• Fipronil - 98-100% kill by 12-18hrs; 93-95% by 30d
• Selamectin - >98% by 36-42hrs; 95% by 28d
• Permethrin (dogs only) - data? – repellant action
• Indoxacarb (Activyl®) - 98% kill by 7d; 95+% by 30-45d
– Cf. fipronil/methoprene 85% kill by 7d; 50% by 30d#
– 100% less eggs (cats) by 72hrs*
Dryden; Parasites and Vectors #Dec 2013; *Mar 2013
53

54. www.sashvets.com
Flea Allergy/Flea Control
• Flea Allergy Control
1. Quick reduction in flea numbers
2. Reduced flea feeding times
– Adults – feed 5min; egg by 24-36hrs
– Adulticides – kill rates/speed/duration effect
• Multiple options 95-100% kill without environ. tx by 60-
90d (Florida)#
– Fipronil, Imidacloprid, Lufenuron (+pyrethrin or
nitenpyram), Selamectin
• New Options?
– Imidacloprid/flumethrin collar (Seresto®) – 95% kill
x 7-8mnth (d&c)
» 99.5-100% kill by 24hrs cf 73% for
fipronil/methoprene cf 66-83% for …..
– Deltamethrin collar (Scalibor®) – up to 6mnth flea
– Dinotefuran/Permethrin/Pyriproxyfen (Vectra®)
» 87% kill by 7d; 99% kill by 48hrs
#Dryden et al Vet Parasitol 2011; 182, 281-286
54

55. www.sashvets.com
Flea Allergy Diagnosis
Response to flea treatment trial (4wks)
1. Affected pets -  control
2. In-contact pets - regular control
3. Environment - IGR treatment
 marked reduction in pruritus/clinical
signs by 4wks

56. www.sashvets.com
Flea Allergy Diagnosis
Response to flea treatment trial (4wks)
1. Affected pets -  control
2. In-contact pets - regular control
3. Environment - IGR treatment
Product Choice - consider
 Product efficacy
 Coat length/density
 Frequency of bathing, swimming
 Ability of owner to apply effectively
 Cost

57. www.sashvets.com
Flea Allergy Diagnosis
1. Affected pets
• Spot-on or spray - every 2wks
• Imidacloprid (Advantage®)
• Fipronil (Frontline®) spray
• Oral
• Nitenpyram (Capstar®) - daily
• Spinosad (Comfortis®/Panoramis®) -
fortnightly
• Topical rinses
• Permethrin (Permoxin®) 1-2 times wkly
with Capstar® (DOGS ONLY!)

58. www.sashvets.com
Flea Allergy Diagnosis
1. Affected pets
2. In-contact pets
 Similar products – monthly
 Aim to prevent large burdens
1. Environment - all pet resting/laying/sleeping/travelling
areas
• Vacuuming
– Remove ~90% eggs/50% larvae
– Stimulates pupal emergence
• IGR treatment - Raid, Mortein, Baygon “egg
killer”sprays
– Methoprene (UV-degraded)
– Pyriproxyfen, Fenoxycarb (UV-stable)

59. Flea Control
Questions?
59

60. www.sashvets.com.au twitter: @SASHvets
Phone - (02) 9889 0289 Fax - (02) 9889 0431
Level 1, 1 Richardson Place, North Ryde 2113, Sydney, NSW