Derm 7 - more fungal

Question 1

often overlooked pathogen for chronic pododermatitis cases, and other referrals

Answer 1

Malassezia dermatitis

Question 2

nail biting dogs should be checked for what condition? what might we see?
Therapy?
vs other similar conditions?

Answer 2

Malassezia paronychia
- may present with nothing more than discoloured claws
- A closer look at the base of the claws may reveal a brown discolouration with a waxy exudate/film
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These patients often respond well to antifungal therapy, though many respond better to systemic therapy than topical treatment, likely a result of the difficulty in treating this area effectively
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Bacterial and fungal claw disease can also lead to nail biting of course, but these are usually associated with a more significant inflammatory reaction.

Question 3

malessezia - how many species, host preferences?
- which is most common? where does it live?

Answer 3

 There are now 14 species identified, with different preferences for host species.
- Malassezia pachydermatis is most commonly isolated
> a commensal isolated from skin of healthy dogs, primarily from seborrheic areas and skin fold regions (chin, interdigital, axilla, groin, ear canals, lip, buccal mucosa, anal sacs, anal mucosa, vagina)
> Less frequently isolated from cats

Question 4

malessezia growth enhanced when what other organism present?

Answer 4

 Growth of Malassezia enhanced when skin co-colonized with Staphylococcus pseudintermedius

Question 5

malessezia dermatitis clinical signs

Answer 5

 Pruritus
 Erythema, scale (honey-coloured to brown), greasy, crust
 Occasionally papular dermatitis
 Lichenification and hyperpigmentation with chronicity
 Often rancid odour
 Locations:

Question 6

malessezia common sites on dogs

Answer 6

 Paws most common (interdigital, palmoplantar)
 Paronychia (claw fold inflammation)
 Ear canals
 Ventral neck
 Axillary
 Lips
 Inguinal/medial thigh regions
 Perianal/perivulvar

Question 7

malessezia common sites on cats

Answer 7

 paronychia
 otitis
 chin acne
 facial dermatitis
 adherent brownish scale, ventral distribution
 Malassezia is commonly isolated from claws of Devon Rex cats

Question 8

malessezia diagnosis methods

Answer 8

 Cytology
 Culture – Many normal dogs will have some Malassezia on fungal culture
 Histopathology – insensitive - Malassezia lost in part with normal processing (as part of Stratum corneum is lost)
 Clinical and Historical Suspicion
 Response to antifungal treatment

Question 9

malessezia treatment, which are best? what do we need to do to ensure success?

Answer 9

1. Systemics (more effective)
   > Baseline liver enzymes and periodic monitoring with all azoles
   > Underlying disease must be addressed to prevent or reduce recurrences. Client education crucial.
   - Ketoconazole
   > numerous drug interactions
   - Fluconazole
   - Itraconazole (cats)
   - Terbinafine
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2. Topical
   - In milder cases where owner able to be diligent
   - Miconazole shampoo, ketoconazole, etc.
   - Acidifying ear canal beneficial

Question 10

Sporotrichosis
- organism
- type of disease, pathogenesis
- who is at risk?

Answer 10

• Sporothrix schenckii
   Subcutaneous mycosis
   Wound contamination- yeast phase establishes infection
• people and animals at risk > zoonosis, generally from felines to humans

Question 11

Sporotrichosis in dogs - clinical signs, forms of disease

Answer 11

• Uncommon to rare
• from puncture wounds, thorns, splinters
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  Cutaneous form (most common)
  o multiple firm nodules (may ulcerate, draining tracts) o ulcerated plaques with raised borders
  o head, pinnae, trunk
  o not painful or pruritic, healthy otherwise
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  Cutaneolymphatic form
  o nodule on distal aspect of limb
  o ascending infection through lymphatics
  o secondary nodules may be firm or fluctuant
  o regional lymphadenopathy
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  Disseminated (extremely rare): usually related to immunosuppressive medications

Question 12

Sporotrichosis
- clinical signs in cats

Answer 12

• Uncommon
• Inoculation by claws or teeth of another cat
• Head, distal limbs, tail base, mucosal involvement
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   May initially present with fight wound abscess, draining tracts, cellulitis
   Purulent exudate, crusted nodules, large areas of necrosis
   Suspect in cats with non-healing bite wound abscess
   Cats may have disseminated form- even though systemic involvement may not be obvious
   Lymph nodes may fistulate, +/- lethargy, depression, anorexia, fever
   Large numbers of organisms in draining fluids (unlike other species)

Question 13

Cryptococcus neoformans
- type of organism
- where it is found
- species most susceptible
- site of infection, symptoms
- zoonotic?

Answer 13

 Dimorphic, saprophytic, encapsulated yeast-like fungus
 Found in pigeon excrement, nitrogen-rich environments
 Global, but most often in humid, subtropical: Australia, Western US and Canada
 Cats most susceptible, including indoor
 Nasal cavity usually primary site of infection
 Converts to yeast form in tissues
 In cats, direct spread from nasal cavity across cribriform plate –> meningitis and may track along optic nerve–> eye
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Not zoonotic - as organism doesn’t aerosol from sites of infection

Question 14

Cryptococcus neoformans clinical signs, in dogs and cats

Answer 14

Dogs: very rare, CNS disease more common, 20% have cutaneous lesions
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Cats:
 most common deep mycosis of the cat
 upper respiratory (nasal cavity), cutaneous, lymph nodes, CNS (meninges), ocular, (peripheral blindness and
dilated pupils- marker for CNS involvement)
 intranasal granulomatous disease most common; cutaneous signs often a sequel to nasal infection (local
extension)
 less common lower respiratory signs, occasionally otitis media
 systemic signs with visceral or nasal disease- fever, anorexia, weight loss
 70% of cases with upper respiratory signs, polyp-like mass visible in nostril or firm, mushy SQ swelling over
bridge of nose
 association with FeLV, and FIV in cats is controversial; no longer appears to be a risk factor; may affect
prognosis

Question 15

cryptococcus neoformans diagnosis

Answer 15

 Cytology
 Histopathology
 Serology
 Culture

Question 16

Blastomycosis dermatitidis
- how common
- type of organism
- form, where found

Answer 16

 Most common systemic mycosis in small animal practice
 Dimorphic, saprophytic fungus
 Grows in a saprophytic mycelial form, which produces infective spores
 Ecologic niche includes moisture, soil type (sandy, acid), presence of wildlife, soil disruption
 Even in endemic areas, not widely distributed
 Endemic areas: Mississippi, Missouri, Ohio river valleys, Great Lakes region, Southeastern Canada
 Most people and animals in endemic areas show no serologic evidence of exposure and disease uncommon

Question 17

blastomycosis risk factors

Answer 17

o Proximity to a body of water
o Dirt-moving activities (excavation)
o Likely “point of source exposure”- seem to have multiple cases within brief period

Question 18

blastomycosis pathogenesis

Answer 18

 Inhalation of spores from environment–> enter terminal airway –> primary infection in lungs–> disseminates
 Organism transforms into yeast form at body temperature
 Yeast from body/coughing animal too big to enter terminal airway-thus transmission unlikely
 Skin lesions usually from disseminated disease. Rare cases of focal lesion from a puncture.

Question 19

blastomycosis clinical signs in dogs and cats

Answer 19

• dogs
   Young male large sporting breeds most common
   Most common affected organs after dissemination from lungs: skin, subcutaneous tissue, eyes, bones, lymph
  nodes, external nares, brain testes
   Exercise intolerance, coughing, dyspnea, anorexia, weight loss
   Uveitis (40% ocular signs), lameness (30% bone lesions)
   Skin lesions (20-50%)
   usually multiple lesions: papules, nodules, plaques, ulcers, draining tracts, subcutaneous abscesses - nasal
  planum, face and claw beds preferred sites
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  Cats: very rare - Dyspnea, draining skin lesions (especially digits), weight loss

Question 20

blastomycosis diagnosis

Answer 20

 Cytology: gold standard
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 Biopsy:
 Culture: not recommended for in hospital - danger of infection from mycelial form (advise commercial
laboratory of suspicion)
 Urine Antigen test
 Serologic testing:
 ELISA, agar-gel immunodiffusion antibody tests- low sensitivity, high specificity- no longer recommended -
antibodies persists once cured
 RIA better sensitivity- not readily available

Question 21

Histoplasmosis
- organism
- clinical findings in dogs and cats

Answer 21

Histoplasma capsulatum
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 Uncommon disease
 Young dogs- Pointers, Weimaraners, Brittany spaniels
 Seen in cats just as frequently - 2nd most common systemic mycosis in cats
 Dogs often local granulomatous disease in lungs
 Most cats disseminated disease
 Anorexia, weight loss, fever, coughing, dyspnea, gastrointestinal (especially dogs) , ocular, skin disease,
anemia
 Bone and skin involvement uncommon
 Skin lesions: usually multiple papules, nodules, ulcers, draining tracts

Question 22

Coccidiomycosis
- organism
- clinical signs, lesions

Answer 22

Coccidiodes immitis -
“San Joaquin Valley Fever”
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 Commonly affected organs: bone, eyes, heart, testicles, CNS, visceral organs
 Young male dogs, Dobermans and Boxers predisposed to disseminated infection
 Coughing, dyspnea, fluctuating fever, anorexia, weight loss, lameness, skin disease, ocular disease, CNS
(seizures), constricting pericarditis
 Bone lesions may become apparent years after initial exposure- initial respiratory signs may not have been apparent
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Skin lesions:
 Uncommon
 almost always over sites of infected bone
 multiple papules, nodules, abscesses, draining tracts, ulcers
 cats: rare, but skin lesions most predominant sign, without bone involvement