​Theileria orientalis is a tick transmitted protozoan parasite that infects erythrocytes and leukocytes.  In the United States, native genotypes are usually non-pathogenic, however in the past few years an increase of T. orientalis genotype Ikeda that causes diseases, has been observed.  Clinical signs associated with this intracellular parasite are anemia, jaundice and weakness.   Haemaphysalis spp. ticks are the primary biological vector of T. orientalis and are considered essential for completion of the lifecycle.  This case was tested by PCR and DNA sequencing and detected as T. orientalis genotype chitose.

​Oesophagostomum sp.
Oesophagostomins are parasites of the large intestine of ruminants, swine and primates. The adults are 1 to 2 cm long and the eggs are 70 to 90 x 34 to 45 um. They are also called nodular worms because their larva can become encapsulated by a reactive inflammation in hypersensitive hosts.  Acute inflammation may lead to diarrhea that can be fatal. 

This calf also had high numbers of Moniezia sp. eggs, and Nematodirus helvetianus, with the last one being pathogenic in young animals that have no acquired immunity. (Image 2)

​​Image 2: Fecal centrifugation from small intestinal content

Knemidocoptes sp.  These mites burrow in the epidermis of the legs on birds, causing scales to lift and become loosened and the legs to become thickened and deformed. K. pilae is the species that commonly infest parakeets while K. mutans and K. jamaiciensis infest gallinaceous birds and canaries respectively. This case was resolved after oral administration of Ivermectin in drinking water.  ​

​Dentostomella translucida. Known as the “Gerbil Pinworm” is a threadworm found in the small intestine of gerbils. Females typically measure 1 cm to 3 cm in length and males are 0.6 cm to 1 cm. The identifying features of D. translucida include a mouth with no lips, five unequal teeth per esophageal sector, and a thick, translucent, transversely striated cuticle.
Typically, gerbils infected with D. translucida are asymptomatic and diagnosis may be difficult, as these parasites do not deposit their eggs around the perianal region.

​Ascarid larva migrans (likely Baylisascaris sp.)
Histologic evaluation reveals numerous up to 60 um diameter nematodes, determined to be the larval stage, given the absence of genital tracts within the examined sections. The presence of lateral alae (arrow), coelomyarian-polymyarian musculature, and a uninucleate intestine are consistent with ascarid larvae. While other ascarids, such as Toxocara canis cannot be ruled out, the most likely diagnosis in this case is considered to be Baylisascaris sp. There are many species of Baylisascaris affecting wildlife, including Baylisascaris columnaris in skunks, Baylisascaris transfuga in bears, and Baylisascaris laevis in woodchucks. The most commonly discussed species is Baylisascaris procyonis, which affects raccoons, and can cause visceral larva migrans in a wide range of hosts, including humans. Ascarid migration of the central nervous system, as in this case, can cause severe clinical signs. Although quick diagnosis and treatment with corticosteroids and albendazole can prove effective, this is not always plausible, as diagnosis can prove difficult.

Sarcocystis sp. oocysts.
Dogs and other carnivores are definitive hosts of Sarcocystis sp. while ruminants, horses, swine and rabbits can act as intermediate hosts.  Fully sporulated oocysts are eliminated thorough the dog’s feces and the schizogony and sarcocysts formation occurs in the intermediate hosts.  Definitive hosts usually do not display clinical signs but the schizogony in the endothelium of the herbivore may result in serious disease.  A known pathogenic species for equids is Sarcocystis neurona with opossums acting as definitive hosts.