A 4-month-old intact, male, calf was found dead and submitted to the state diagnostic laboratory for necropsy. Per owner, he was acting weak for a while, but he seemed to gain strength after having hay, protein and sweet feed. A centrifugal fecal flotation revealed the following larva as well as high number of trichostrongyle type of eggs and Eimeria multiple species oocysts. Baermann test was also performed on the fecal sample and recovered the same larvae.
Dictyocaulus viviparus first-stage larva. Characteristic dark food granules are observed in the intestinal cells. Although D. filaria larvae have a small knob at the anterior end, D. viviparus larvae do not have it.
First-stage larvae are passed in the feces of the host, and infective third-stage larvae develop on pasture and are ingested while grazing.
Click on the following link to watch a video of a live D. viviparus adult worm and first-stage larvae!: www.youtube.com/watch?v=ZfitLJPpgjc
Reference: Zajac and Conboy, Veterinary Clinical Parasitology 8th edition.
Diarrhea in a newly adopted kitten
Approximately 4-month-old domestic short-haired, intact female cat showed up to a small animal clinic with a 2-day history of soft stools/diarrhea and occasionally bloody diarrhea. This kitty was adopted from a local animal shelter a week ago, and besides diarrhea, she has been active and seemed happy. A centrifugal fecal flotation with 33% zinc sulfate solution was performed.
Numerous round to slightly oval-shaped objects with a thin, smooth, clear wall were observed. Original magnification, x100 (with x10 objective lens).
Size difference was also observed. Some were bigger - approximately 40-45 x 30 um, and some were smaller - approximately 20-25 x 20 um. Also some contained only a single, round cell inside, but some contained 2 round cells instead. Original magnification, x400 (with x40 objective lens).
A few of them even showed more details inside. Original magnification, x600.
Cystoisospora spp. oocysts - the bigger one was C. felis and the smaller one was C. rivolta.
This protozoan parasite is commonly called as "coccidia" of dogs and cats although other parasites, such as Eimeria, Sarcocystis, Toxoplasma, and Neospora, also fall into this taxonomic group. When oocysts are freshly passed in feces, they typically contain a single, round cell (called "sporoblast"). Developing process (called "sporulation") occurs in the environment - oocyst with a single sporoblast (C. rivolta in photo #2) > sporoblast multiplies into 2 sporocysts (C. felis in photo #2) > each sporocyst contains 4 sporozoites with a single large, round residual body (photo #3).
Cystoisospora infection is commonly found in young cats, and most of the time cats are asymptomatic. However, when kittens are stressed out due to weaning, change of owner, new environment, etc., clinical coccidiosis can occur and cause diarrhea, abdominal pain, and in a severe case, bloody diarrhea and anemia.
Anne M. Zajac & Gary A. Conboy. 2012. Veterinary Clinical Parasitology 8th ed.
Flotation solution matters
A 3-month-old dog presented to Riverside Animal Hospital in Miami, FL with a three-day history of watery diarrhea. The dog is indoor/outdoor and has a 1 year old canine housemate. A centrifugal fecal flotation with Sheather's sugar solution (specific gravity 1.25) was performed and revealed numerous half-moon shaped objects.
A centrifugal fecal flotation with Sheather's sugar solution revealed numerous half-moon shaped objects in the entire slide. Original magnification, 400x.
A centrifugal fecal flotation was repeated using a 33% zinc sulfate solution (specific gravity, 1.18).
A Centrifugal fecal flotation with a 33% zinc sulfate solution. Now more Giardia cysts were observed on the slide and most cysts showed details. Original, 400x.
Many thanks for a great case with nice photos to Dr. Kamilyah R. Miller, Tuskegee University, College of Veterinary Medicine & Dr. Yoko Nagamori, Center for Veterinary Health Sciences, Oklahoma State University.
They are Giardia spp. cysts.
Since this fecal sample was taken from a dog it could either be Giardia duodenalis Assemblage C and/or D (G. canis).
There has been suspicions of Giardia being zoonotic, but current research is now questioning that theory -- Giardia may be more species specific, and may not be zoonotic.
It is important to note the difficulties of identifying Giardia cyst on centrifugal fecal flotation. When performing a fecal flotation, it is important to use a zinc sulfate solution (specific gravity of 1.18) allowing the cyst to float showing with more details of internal structures. The slide must be prepared and read immediately following the centrifugal flotation so not allow the cyst to collapse. The cyst will have a green hue to them when using a zinc sulfate solution, you must fine focus in and out to identify the distinguishing features that make up the Giardia cyst.
What a Rare Find!!
An emaciated horse with no known previous history was rescued and presented to Large Animal Services at Oklahoma State University. The horse was humanely euthanized and sent to necropsy the next day. On necropsy, a pathologist found the severe local arteritis, especially in the cranial mesenteric artery, with a worm in the lesion.
The cranial mesenteric artery. The wall was very thickened and fibrous.
A nematode worm was also detected in the lesion of the cranial mesenteric artery.
A nematode worm detected in the cranial mesenteric artery of the emacinated horse.
The cranial end of the nematode. Note there was a big buccal cavity and 2 teeth in the bottom.
Special thanks to Dr. Kamilyah R. Miller at College of Veterinary Medicine, Tuskegee University & Dr. Yoko Nagamori at Center for Veterinary Health Sciences, Oklahoma State University.
Strongylus vulgaris -- This is a sheathed Strongylus vulgaris L5. There were 2 teeth in the bottom of the buccal cavity, which distinguish it from other Strongylus species.
Migrating S. vulgaris larvae can cause thickening of the cranial mesenteric artery, which impairs intestinal blood flow and leads to colic. Clinical signs include fever, anorexia, weight loss and depression. This case was a rare find of a fourth stage larvae molting into an adult Strongylus vulgaris worm. An infected animal sheds eggs, and under the right humidity and temperature the eggs develop into L3. A naïve animal ingests the L3 while grazing, the L3 penetrate the submucosa of the cecum and ventral colon, molt into L4 and penetrate smaller arterioles and migrate through the intima of the vessels to the larges branches of the cranial mesenteric artery. As the larvae grow larger, and occlude smaller vessels, the larvae travel to the cranial mesenteric artery and become encapsulated in nodules where they molt to immature adults. Some larvae are found in the arteries, before the fifth molt occurs, with the sheath still present. The immature adults travel back to the cecum and colon, mature and reproduce producing eggs 6 months after the animal becomes infected.
An adolescent, wild woodchuck was found ataxic with other neurologic signs in Stillwater, Oklahoma. The woodchuck was rescued and brought to the animal hospital for examination. Forebrain disease was suspected based on the neurologic examination. Possible etiologies, including rabies, organophosphate poisoning, encephalitis, meningitis, and lead toxicity, were considered clinically. The woodchuck was then euthanized due to the possibility of rabies infection and submitted to Oklahoma Animal Disease Diagnostic Laboratory (OADDL) for necropsy. Here are the microscopic findings in the brain of this woodchuck:
Special thanks to Dr. Rory Chia-Ching Chien, DVM, MSc, Anatomic Pathology Resident at Oklahoma State University, Center for Veterinary Health Sciences!!
Multiple nematode larvae are seen in the cerebral parenchyma and the morphology of the parasite is consistent with Baylisascaris spp. In the tissue sections, the parasites are 40-50 µm wide with variable lengths and are surrounded by eosinophilic and granulomatous inflammations. The parasites have several microscopic features that are characteristic for ascarids, including eosinophilic cuticle, thin hypodermis, polymyarian coelomyarian musculature, pseudocoelom, prominent lateral cords, and uni-cellular epithelium of the digestive tract. Multifocal randomly distributed foci of malacia are observed in the cerebrum, brainstem and cerebellum with gliosis and infiltrates of macrophages, eosinophils, and multinucleated giant cells. Multifocal and disseminated eosinophilic and granulomatous meningoencephalitis with intralesional nematode larvae is diagnosed.
Baylisascaris sp. infection and associated encephalitis has been reported in woodchucks, many other mammals, birds, and human. Baylisascaris procyonis and Baylisascaris columnaris are two of the most commonly reported species that can cause diseases in woodchucks. The usual definitive host of B. procyonis is a raccoon and the definitive host of B. columnaris is a skunk. Infection of Baylisascaris spp. occurs most likely due to ingestion of materials contaminated by raccoon or skunk feces.
A 3-month-old calf presented to a large animal clinic in Oklahoma for watery diarrhea. Other herd mates have tested positive for Corona virus, but this calf has been affected longer than the others. A centrifugal fecal flotation with Sheather's sugar solution (specific gravity: 1.26) was performed, and the following tiny parasites measuring approximately 5 micrometer in diameter were observed.
Small, round-shaped objects. Highly refractile and often appear to have a single black dot in the center. Original magnification, x400
Original magnification, x1000
Acid-fast staining was also performed on fecal sample.
Acid-fast stained sample. Original magnification, x1000
Many thanks for a great case with nice photos to Kamilyah R. Miller, DVM, Tuskegee University, College of Veterinary Medicine
They are Cryptosporidium spp. oocysts. It is important to note that Cryptosporidium is very difficult to find via routine fecal examination. Use of Sheather's sugar solution is a key to find them because that will give the oocysts a pink hue. When using the acid-fast staining, the oocysts will appear pink against a blue background.
Cryptosporidium is a one-cell protozoan parasite that causes diarrhea in calves and other mammals. Cryptosporidium parvum mainly affects calves younger than 30 days of age. Cryptosporidium ryanae more commonly affects older calves more than one year of age. Cryptosporidium bovis is often seen in adult cattle. There’s no approved treatment for cattle in the United States. The best treatment option is fluid therapy for dehydration, nutritional support and keep the animals in a clean and dry environment. However, halofuginon lactate (Halocur®) is the licensed product in the UK and Canada; it doesn’t cure the disease, but it reduces egg shedding and clinical signs. The best way to prevent cryptosporidiosis is to keep a clean environment where newborn calves are housed, don’t house older calves with newborn calves and keep feed and water off the ground to prevent fecal contamination.
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