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The No Bueno Blasto

Abigail Schmidt

Blastomycosis

Signalment: 6 yr old MN German Short-

haired Pointer

History:Progressively

worsening cough over 3 week period

“Ruger” Walters

Thoracic Radiograph

Blastomyces spp. Antibody Test – Negative

Others (unknown)

Diagnostics Run

Thoracic Radiograph

**Highly characteristic of Blastomyces infection

What is Blasto??

Blastomyces dermatitidis

“Gilchrist’s Disease” 1894

Dimorphic fungus

Infective form: mycelial phase

Preferred environment: sandy, acidic soil

Lifecycle

Thermally dimorphic: mold & yeast phases

At 25oC: mycelia/microscopic conidia mould-like form that mammals can inhale; infectious

At 37oC (in the body): transform into yeast (8-15 microns)

Phase transformation mechanism unknown

Mycelial form

Big Blue Broad Based Budding

yeast

Pathogenesis

Immune system evasion changing of surface antigens

Dissemination to other locations

**Incubation Period in humans = 30-100 days

Geographic Distribution

Most reported cases from MS River basin, OH, MO, & western margins of Lake Michigan

International: South Africa, Zimbabwe, India

Most at Risk for Infection

Male Entire large breed dogs Sporting & Hound breeds

predisposed 2-4 years of age Endemic regions Late Summer & Early Fall

Clinical Presentation

Depends on site of infection… Lung Disease

increased RE, exercise intolerance, coughing

Loss of appetite, fever, weight loss

Bone lameness Skin ulcerated

lesions, draining abscesses

Eyes hyperemic, & painful with discharge

{ {Cutaneous Ocular

Typical Lesions

Diagnostics

Thoracic Imaging Cytologic or histologic

examination Wright’s-Giemsa Stain

Serologic Antibody Urinary Antigen PCR

Bloods

Ruger vs. Blasto

Chest Rads

Amphotericin B Intravenous administration Adverse effects: cumulative nephrotoxicosis**Don’t give with steroids!

Itraconazole Expensive, oral medication better absorbed

with food Lag time before clinical response Adverse effects: hepatotoxic

Ketoconazole Less expensive Resolution of disease <50% cases High rate relapse

Treatment**All interfere with ergosterol synthesis**Minimum of 60d treatment necessary**Lung disease requires 90d minimum

Amphotericin B Intravenous administration Adverse effects: cumulative nephrotoxicosis**Don’t give with steroids!

Itraconazole Expensive, oral medication better absorbed

with food Lag time before clinical response Adverse effects: hepatotoxic

Ketoconazole Less expensive Resolution of disease <50% cases High rate relapse

Can easily rack up $5,000 in treatment costs

Treatment**All interfere with ergosterol synthesis**Minimum of 60d treatment necessary**Lung disease requires 90d minimum

Good – EXCEPT in cases with Severe pulmonary infectionBrain infection

Deterioration often seen first 2-3 days therapy 50% dogs die within first 7 days treatment Inflammatory response against dying organisms in lungs

Geographic variation in strain virulence

Prognosis

Level 3 Biological Hazard Classification Human infection associated with occupation & recreational

activities Fishing Camping Outdoor professions i.e. Forest Ranger

Dogs with blasto *aren’t* considered infectious to their owners…however is ZOONOTIC

Can spread to humans from bite/puncture wounds

Veterinary Importance Disease in dogs evident prior to people Owner may have been exposed from same environmental

source as dog

Public Health Concerns

Thoracic radiograph highly suspicious of Blastomycosis

Tested negative Started treatment with

Ketaconazole and Oxygen cage therapy

Made it through 3 days of treatment before passing

Ruger’s Outcome

Don’t disregard chronic cough Don’t just treat with steroids No singular test guarantees positive diagnosis Gold Standard of diagnosis:

Combination of clinical signs & cytologic or histopathologic identification of organism from tissues

If disease suspected, make owner aware of exposure risk Recommend seeing own doctor immediately

Take Home Messages

Dr. Jess Walters-Wright for allowing me to share her boy Ruger’s tale with you.

Special Thanks to…

Baumgardner, D., Turkal, N. and Paretsky, D. (1996). Blastomycosis in dogs: A fifteen-year survey in a very highly endemic area near Eagle River, Wisconsin, USA. Wilderness & Environmental Medicine, 7(1), pp.1-8.

Botit.botany.wisc.edu, (2015). Blastomyces dermatitidis, cause of blastomycosis, Tom Volk's Fungus of the Month for January2001. http://botit.botany.wisc.edu/toms_fungi/jan2001.html.

Brömel, C. and Sykes, J. (2005). Epidemiology, Diagnosis, and Treatment of Blastomycosis in Dogs and Cats. Clinical Techniques in Small Animal Practice, 20(4), pp.233-239.

Cdc.gov, (2015). CDC - Sources of Blastomycosis. [online] Available at: http://www.cdc.gov/fungal/diseases/blastomycosis/causes.html.

DVM, S. (2015). Canine blastomycosis: A review and update on diagnosis and treatment. [online] dvm360.com. Available at: http://veterinarymedicine.dvm360.com/canine-blastomycosis-review-and-update-diagnosis-and-treatment.

Ettinger, S. and Feldman, E. (2005). Textbook of veterinary internal medicine. St. Louis: Elsevier Saunders.

Health.state.mn.us, (2015). Blastomycosis Basics - Minnesota Dept. of Health. [online] Available at: http://www.health.state.mn.us/divs/idepc/diseases/blastomycosis/basics.html.

Life with Llewellin Setters, (2013). Blastomycosis—What Every Dog Owner Needs to Know - Life with Llewellin Setters. [online] Available at: http://lifewithllewellins.com/blastomycosis-what-every-dog-owner-needs-to-know/.

López-Martínez, R. and Méndéz-Tovar, L. (2012). Blastomycosis. Clinics in Dermatology, 30(6), pp.565-572.

Spector, D., Legendre, A., Wheat, J., Bemis, D., Rohrbach, B., Taboada, J. and Durkin, M. (2008). Antigen and Antibody Testing for the Diagnosis of Blastomycosis in Dogs. Journal of Veterinary Internal Medicine, 22(4), pp.839-843.

VCA Animal Hospitals, (2015). Blastomycosis in Dogs. [online] Available at: http://www.vcahospitals.com/main/pet-health-information/article/animal-health/blastomycosis-in-dogs/437.

References