Incidental finding or cause of death?
An approximately 8-year-old miniature donkey mare had difficulty foaling. The referring veterinarian provided aggressive supportive therapy but unfortunately the foal and mare did not survive. To determine the cause of death both carcasses were submitted for necropsy.
Grossly, the mare was remarkably emaciated, and there were mild, chronic, multifocal ulcers in the stomach. Histologic examination of the stomach confirmed moderate, chronic-active, multifocal ulcerative gastritis with bacterial infection. Additionally, histologic examination of the mare’s kidney revealed multiple, variable sized parasites in the renal tubular epithelium (Figures 1-3). No abnormalities were detected grossly or microscopically in the foal.
Figure 1: Various parasite stages in the renal epithelial cells (indicated by arrows).
Figure 2: Multiple nuclei lie along the periphery – notice how they look like a flower, these are called “sporoblasts” (indicated by arrow).
Figure 3: Free/Mature sporoblasts (indicated by arrow) – each of these sporoblasts undergoes further divisions to form sporocysts.
Klossiella equi is a protozoan parasite observed in the kidney of equines. The life cycle has not been fully understood; however, it is thought to be a direct life cycle. Sporocysts are passed in the urine and infection takes place by ingestion of sporulated sporocysts. Klossiella equi infection is thought to be fairly common throughout the world but rarely seen.
Klossiella eqi is considered non-pathogenic and usually is not associated with clinical signs. In this case, K. equi infection was an incidental finding, and bacterial translocation from the gastric ulcers and subsequent septicemia was likely related to the death of the mare and foal.
Special thanks to Dr. Rory Chia-Ching Chien, DVM, MSc, Anatomic Pathology Resident at Oklahoma State University, Center for Veterinary Health Sciences for sharing his case and photos!
Taylor MA, Coop RL, Wall RL. Veterinary Parasitology (4thedition).
Gardiner CH, Fayer R. Dubey JP. An Atlas of protozoan parasites in animal tissues.
Ballweber LR, Dailey D, Landolt G. (2012). Klossiella equiInfection in an Immunosuppressed Horse: Evidence of Long-Term Infection. Case Reports in Veterinary Medicine. 2012, 4. doi:10.1155/2012/230398.
Reinemeyer CR, Jacobs RM, Spurlock GN. (1983). A coccidial sporocyst in equine urine. J Am Vet Med Assoc.182(11). 1250–1251.
A fluke finding: is it a fluke egg?!
An approximately 20-year-old, intact male African spurred tortoise was presented to an exotic animal practice with a history of bleeding from the cloaca. Centrifugal fecal flotation with Sheather’s sugar solution (specific gravity, 1.25) and a direct fecal smear with saline solution were performed. A moderate number of large (> 60 µm), brown and yellow/orange colored, oval shaped objects with a cap-like structure on one side (Figures 1 & 2) were observed on the direct fecal smear. Centrifugal fecal flotation revealed many similar looking objects but with a collapsed appearance (Figures 3 & 4).
Figure 1: Direct fecal smear with saline solution. 200X magnification.
Figure 2: Direct fecal smear with saline solution. 600X magnification.
Figure 3: Centrifugal fecal flotation with Sheather’s sugar solution. 400X magnification.
Figure 4: Centrifugal fecal flotation with Sheather’s sugar solution. 400X magnification.
Nyctotherus spp. cysts
Nyctotherus is a large ciliated protozoa commonly found in herbivorous reptiles such as tortoises and some species of lizards. Nyctotherus spp. cysts are often confused with trematode or oxyurid eggs due to the presence of a structure that resembles an operculum on one side. Although uniformly distributed cilia should be apparent on cysts, they are subtle and can be easily overlooked. Nyctotherus is usually harmless, and it was less likely that Nyctotherus caused the cloacal bleeding.
Nyctotherus cysts seem to be fragile, and centrifugal flotation tends to collapse the cysts making it difficult to observe the details of cyst morphology. Direct fecal smear seems to be the best diagnostic test to recover intact Nyctotherus spp. cysts.
A 2-year-old intact male Labrador Retriever dog was presented to a small animal emergency clinic in Sacramento, California, USA with a recent onset of lethargy and inappetence and a single episode of vomiting and bloody diarrhea. Physical examination revealed fever of 105.2°F, enlarged lymph nodes, and dehydration.
After providing supportive care, a centrifugal fecal flotation and fecal sedimentation were performed. Results are shown below.
Figure 1: Centrifugal fecal flotation. 100X magnification
Figure 2: Centrifugal fecal flotation. 400X magnification
Figure 3: Fecal sedimentation. 100X magnification
Figure 4: Fecal sedimentation. 400X magnification
Nanophyetus salmincola eggs
This is a case of “salmon poisoning” caused by Neorickettsia helminthoeca. The rickettsial agent responsible for disease is found within a fluke – Nanophyetus salmincola – that uses salmonid fish as an intermediate host. Dogs and other canids are extremely susceptible to this infection, and disease occurs by consumption of infected raw fish. Disease is most commonly associated with fish in coastal streams of the Pacific Northwest of the USA, including the states of Washington, Oregon, and northern California, and southern Vancouver Island in Canada. The prognosis with appropriate treatment for the N. helminthoeca infection (doxycycline) is good; however, dogs that do not receive appropriate antibiotics will deteriorate quickly and often die.
Note: Although a fecal sedimentation test is preferred to detect fluke eggs, it has been reported that N. salmincola eggs can often be found by a centrifugal fecal flotation test. However, eggs on flotation might be collapsed, folded, or deformed due to the high specific gravity solution (Figures 1 & 2).
Suggested reading: Sykes, J. E., et al. (2010). "Salmon poisoning disease in dogs: 29 cases." JVIM 24(3): 504-513.
An approximately 6-month-old, intact male, recently rescued, domestic short-haired kitten was presented to a small animal clinic in Oklahoma with a 2-week-history of intermittent coughing. A fresh fecal sample was submitted to a parasitology diagnostic lab for a general parasitology examination. Centrifugal fecal flotation with 33% zinc sulfate solution (specific gravity, 1.18) revealed a moderate number of nematode larvae (Figure 1 & 2). Larvae were approximately 400 microns in length, and the terminus of the tail has a characteristic kink and spine (Figure 3).
Figure 1: 100x magnification.
Figure 2: 200x magnification.
Figure 3: Focusing on the tail of the larva. Showing the distinctive kink with dorsal spine. 400x magnification.
Aelurostrongylus abstrusus first stage larvae.
Aelurostrongylus abstrusus is a feline lungworm, which distributes worldwide. Felids serve as a definitive host and acquire the infection by ingestion of an intermediate host (snail or slug) or a paratenic host (rodent and bird). Adult worms are located in the lung parenchyma of the definitive host. First-stage larvae are released in the airways, coughed up, swallowed, and passed out in the feces. Gold standard diagnostic test to recover A. abstrusus L1s is Baermann technique; however, a regular centrifugal fecal flotation test may also detect L1s. Infected cats may be asymptomatic or can have respiratory signs such as coughing, dyspnea, and tachypnea.
Click on the following link to watch a video of a live L1 of A. abstrusus! >>> www.youtube.com/watch?v=NGNPjBJBCoc
Zajac & Conboy, Veterinary Clinical Parasitology 8th ed.
Crawling bugs on a pot-bellied pig
A 1-year-old, free-range, pot-bellied gilt on a farm in southern Georgia presented with pruritus. The owner noted "bugs" crawling on the pig skin.
Haematopinus suis is the only louse species found on swine. Since this louse is a large species which can reach 6 mm in length, and it is easily detectable by gross examination. Infestations tend to be more severe during colder months.
Many thanks for a case with nice photos and move to Dr. Susan E. Little, Oklahoma State University & Dr. Kelsey Paras, University of Georgia.
Persistent mite eggs in feces of a dog?
A fecal sample from an approximately 9-month-old, intact female, collie-mixed dog was submitted to the parasitology diagnostic laboratory for recheck evaluation post-treatment against persistent Dipylidium caninum and Sarcocystis spp. infection. This dog had been rescued and imported from Ethiopia to the United States 3 month prior.
Centrifugal fecal flotation with Sheather's sugar solution (specific gravity, 1.25) was performed and revealed a low number of Sarcocystis spp. sporocysts and a moderate number of fairly large, oval-shaped, amber-colored, arthropod-like eggs (Figure 1 & 2). The egg shell outer wall were smooth, semi-thickened, and the embryo appeared to have 2-4 short appendages with pairs of chitinous hook-like structures visible using fine focus adjustment of the microscope at 400x magnification (Figure 2 & 3). A tentative diagnosis of pseudoparasite, most likely mite eggs, was made.
Two weeks post-treatment against Sarcocystis spp. infection, a fresh fecal sample was submitted for fecal examination. The same arthropod-like eggs were still detected in a moderate to high number in addition to a low number of Sarcocystis spp. sporocysts.
Figure 1: 100x magnification
Figure 2: Focused on the outer egg shell wall. 400x magnification
Figure 3: Focused on internal structure. Two irregularly arranged chitinous claws were seen inside the egg. 400x magnification
Linguatula serrata eggs.
Linguatula serrata uses carnivores, canids and rarely felids, as definitive hosts. The adult parasite can be found in the nasal airway, frontal sinus and tympanic cavity. Herbivores, such as ruminants and lagomorphs, become infected by ingesting eggs shed in the feces or nasal discharge of infected carnivores and serve as intermediate hosts by harboring encysted larvae (nymphs) in the internal organs and lymph nodes. Definitive hosts become infected by ingestion of the nymphal stages found in infected intermediate hosts. The prepatent period of this parasite is approximately 6–7 months, and adults live in definitive hosts for about 15 months. Eggs passed in the feces or nasal discharges are immediately infectious to intermediate hosts. Humans become infected by ingesting either eggs excreted by definitive hosts or nymphs in raw, undercooked viscera of intermediate hosts. Although the prevalence of this parasite is thought to be worldwide, most cases have been reported in Africa, the Middle East, and southern Asia.
Yoko Nagamori, et al. 2019. A zoonotic parasite, Linguatula serrata, infection in a dog imported from Ethiopia to the United States. Veterinary Parasitology: Regional Studies and Reports, 16, 100273.
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