Disseminated Protothecosis in a dog (N07-610)

Francesco C. Origgi DVM, PhD Dipl ACVM

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Signalment and clinical history

• “Minnie me” canine. Boxer, female spayed, 6 years.

• Initially presented for rectal bleeding and bilateral uveitis.

• High titer for Rocky Mountain Spotted Fever (1:512).

• Patient started on doxycycline and metronidazole

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Clinical history

• Minnie me deteriorated progressively to complete blindness and deafness with head tilt and mild vestibular signs. Finally she was unable to walk and stand.

• Minnie me was euthanized on 10/26/07

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Gross examination and ancillary exams

• The liver, kidney and spleen: moderately to markedly congested.

• Pericardium: Thickened and cloudy.

• Colon: moderately distended with distal mucosa partially stained with blood and enlarged mesenteric lymph nodes.

• Aerobic and anaerobic cultures from the intestine: Mixed bacterial growth.

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Interstitial nephritis, granulomatous, chronic, severe, with intralesional algae, and mineralization, kidney

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•Within the cytoplasm of the macrophages and Within the cytoplasm of the macrophages and of the multinucleated giant cells there are large of the multinucleated giant cells there are large numbers of algal organisms.numbers of algal organisms.

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The organism

• Prototheca spp, is an unicellular achlorophyllic, aerobic algae, closely related to the genus Chlorella.

• They reproduce by endosporulation.

• Of the 5 species of Prototheca spp identified so far (P. moriformis, stagnora, ulemea, wickerhamii and zopfii) only P. wickerhamii and zopfii have been incriminated as pathogens.

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Epidemiology

• It is a rare worldwide disease reported both in people and animals.

• Prototheca spp can be found in multiple environmental (raw and treated sewage, trees, soil, flowing and standing water, food, cow’s milk, and human and animal feces) niches.

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Clinical findings and Pathogenesis

• In dogs: three clinical forms: a) cutaneous (P wickerhamii, b) systemic (P. zopfii) (single organ system), c) disseminated (hematogenous and/or lymphatic spread).

• Signs: Weight loss, bloody diarrhea, CNS signs and impaired vision. Skin lesions are rare in the dog (boxer and collie are markedly sensitive to the infection). Hallmark of Prototheca spp infection: large bowel, CNS and eye disease.

• Feline cutaneous form: large, firm nodules on the limbs or feet, head and base of the tail.

• Cattle: Mastitis.Presented at SEVPAC 2008 – Permission granted for use on

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Prototheca can be cultured on Blood agar, Sabouraud’s cyclohexemide-free dextrose agar at 25 to 37 C, forming white to light tan colonies within 2 to 7 days.

Diagnosis

Definitive diagnosis is by culture

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P. wickerhamii is susceptible to clotrimazole; P. zopfii is resistant.Final ID:P. zopfii

Biochemical test: Trehalose negative (P. wickerhamii uses trehalose as exclusive source of carbon)

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Thanks to:

• Mary Reinhard DVM, DACVP, DACLAM

• Jack Gaskin DVM, DACVM

• David Taylor BVSc, DACVP

• Fellow residents

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Questions?

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