Diarrhea and blindness in a dog

Diarrhea and blindness in a dog

Diarrhea and Blindness in a Dog
Written by the Internal Medicine Team at Peak

Maggie, a 2 year-old female spayed English Springer Spaniel presented to Vermont Veterinary Eye Care at Peak Veterinary Referral Center for evaluation of a recent onset of blindness. The owners also reported a one-year history of chronic diarrhea with frank blood. In spite of the chronic diarrhea, the owners reported an excellent appetite and no significant weight loss.

On the ophthalmology examination Dr. Vivian Jamieson (substituting for Dr. Sarah Hoy), identified panuveitis with exudative retinal detachment and an unusual white vitreal debris.  Based on the ophthalmologic findings and the history of diarrhea, a systemic disease was suspected and Maggie was referred to Dr. Dani Rondeau on the Internal Medicine Service.

On physical examination, Maggie was bright, alert and well-hydrated with a normal body condition. Rectal examination revealed watery stool containing frank blood.

Blood work including a CBC and chemistry panel was obtained. The following abnormalities were found on the chemistry panel:

  • mild hypoalbuminemia 2.2 g/dL (2.7-4.4)
  • hyperglobulinemia 4.8 g/dL (1.6-3.6)

The CBC showed:

  • mild mature neutrophilia
  • monocytosis
  • 4 nucleated red cells per 100 white blood cells

A rectal scraping was performed and cytology revealed:

  • moderate numbers of round to oval structures up to 10 microns in diameter with clear peripheral capsules and internal basophilic stippling
  • neutrophils, many with intracellular bacteria

The rectal cytology was submitted to a clinical pathologist who confirmed the presence of prototheca.

Microscopic appearance of prototheca (arrow) courtesy of Auburn University

Prototheca is a type of alga that is found in sewage, slime flux of trees and animal wastes. Maggie has lived on a dairy farm near the southern Vermont-New York border her entire life and was allowed to roam freely on the farm.

Most cases in North America are restricted to the Southeastern United States.  It has rarely been reported in our region. Dogs presenting with ocular lesions and a history of chronic (intermittent or protracted) bloody diarrhea should be suspected of having protothecosis, as these signs are typical of the disease. Ocular lesions are present in two-thirds of cases, and in some dogs blindness is the primary symptom. As the disease progresses, it disseminates beyond the eyes and intestines, most often involving the kidney, liver, heart and brain.

The prognosis is guarded to poor in dogs, as there is inevitable progression of the disease. Maggie’s owners declined treatment based on the poor prognosis for successful treatment. Amphotericin B and itraconazole  can slow disease progression, and survival of over a year has been reported in some treated dogs. In cats, only the cutaneous form of protothecosis has been reported, which manifests as firm cutaneous nodules, most often on the limbs or feet, which can potentially be surgically excised.

If you have questions about this case or any of your other internal medicine cases please contact Dr. Dani Rondeau or Dr. Marielle Goossens at the Internal Medicine Service at  Peak.