Protothecosis in four dogs in New Zealand

Figures & data

Table 1. Signalment, diagnostic findings, details of case management and outcome in four dogs diagnosed with protothecosis in New Zealand.

	Case 1	Case 2	Case 3	Case 4
Signalment
Age (years)	6	9	4	8
Sex	Female, neutered	Female, neutered	Female, neutered	Male, neutered
Breed	Labrador Retriever	Crossbreed	Miniature Schnauzer	Crossbreed
Location	Lower Hutt, NZ	Franklin district, NZ	Hamilton, NZ	Ōamaru,NZ
First presenting signs	Left eye: retinal detachment, inconsistent menace response, panuveitis, subretinal exudate, glaucoma (IOP 38 mmHg). Right eye: normal Transient cough	Haematochezia, tenesmus, increased frequency of defecation	Intermittent diarrhoea and haematochezia, increased frequency of defecation	Multiple cutaneous nodules and thickened skin over olecranons with pyoderma, pruritus
Diagnostic findings
Clinical pathology	CBC: mild numbers of reactive lymphocytes, marginal monocytosis (1.7 × 10^9/L; RR 0.2–1.5 × 10^9/L)	CBC, serum biochemistry: WNL	CBC: mild lymphopenia (0.9 × 10^9/L; RR 1–4.80x 10^9/L), marginal mature neutrophilia (11.5 × 10^9/L; RR 3–11.5 × 10^9/L) Serum biochemistry: WNL ELISA (faeces): negative for Giardia/Cryptosporidium FEC: negative	FNA from cutaneous lesions: cytology consistent with Prototheca spp.
Imaging			Abdominal ultrasound: thickened colon and small intestinal wall
Histopathology	Intraocular contents: chorioretinitis, organisms consistent with Prototheca spp.	Enucleated globe: chorioretinitis, organisms consistent with Prototheca spp.	Gastrointestinal biopsies: caecal protothecosis with spread to regional LN	Skin biopsies: dermatitis and panniculitis, organisms consistent with Prototheca spp.
Microbiology	Faeces, kidney^a: negative for Prototheca spp.	Faeces: light growth of Prototheca spp. Urine: negative for Prototheca spp.	Faeces: negative for Salmonella, Campylobacter spp.	Lesion biopsies: isolates identified as P. zopfii by PCR + sequencing
Post-mortem examination	Rectal scraping: organisms consistent with Prototheca spp. Histopathology (eye, kidney, colon, mesenteric LN): evidence of protothecosis	NP	NP	NP
Case management^b
Progression of clinical signs	7 weeks: right eye: retinal detachment 9 weeks–19 weeks: intermittent haemorrhagic diarrhoea. 19 weeks: depression, dysphoria, head tilt	3 weeks: Left eye: ocular discomfort, panuveitis with retinal haemorrhage and focal detachments, secondary glaucoma (IOP 65 mmHg). Right eye: normal. 5 weeks: Right eye: mydriasis, absent PLR, scleral injection, vision decline. Reduced appetite, polydipsia, colitis ongoing but improved	1–9 months: ongoing colitis. 9 months: IOP 34 mmHg, cataract, absent menace response, vision loss	2 months: multifocal tracts on foot pad 7–29 months: progressive foot pad ulceration and multifocal cutaneous nodules, draining fistulae over olecranon 30 months: necrotic cutaneous lesions
Interventions	10 weeks: bilateral intraocular evisceration and prosthesis surgery	3 weeks: left eye enucleated	9 months: Abdominal ultrasound and exploratory laparotomy	7 months: FNA of nodules and surgical biopsies
Protothecosis diagnosed	10 weeks	3 weeks	9 months	7 months
Outcome	Euthanasia	Euthanasia	Euthanasia	Euthanasia
Survival time from first clinical signs	4.5 months	5 weeks	9 months	30 months

^a Samples collected post-mortem and frozen.

^bTimes are given since first presentation.

CBC: complete blood count; FEC: faecal egg count; FN: female neutered; FNA: fine needle aspirate; IOP: intraocular pressure; LN: lymph node: MN: male neutered; NP: not performed; PLR: pupillary light reflex; RR: reference range; WNL: within normal limits.

Figure 1. Photographs of a dog (Case 4) with (a) multiple foot pad ulcerations, (b) an ulcerated swelling of the left elbow and (c, d) firm nodular swellings within the skin of the metacarpi with ulceration of the swelling of the right metacarpus (c).

Figure 2. Photomicrograph of section from the (a) colon of Case 1 and (b) skin of Case 4 showing endosporulating algal organism (arrows) with internal septation in both locations and empty theca (arrow heads) in the section of skin (H&E; bar = 30 μm). These are magnified in the insets.

Figure 3. Fundic photograph of a dog with ocular protothecosis showing multifocal hypo-reflective areas of active chorioretinitis and an opaque, ventral, exudative retinal detachment. Image courtesy of Marnie Ford, Animal Eye Care, Melbourne, Australia.