Oh deer!A white-tail deer from a Northeast Oklahoma farm, was submitted for necropsy to the Oklahoma Diagnostic Laboratory during the month of August 2022. During necropsy the following larva was found on the esophagus. Images 1-3: Larva found in the esophagus Images 4-5: Posterior spiracles of recovered larva Hypoderma lineatum, also called heel flies or gadflies. The adult flies deposit eggs on the hair of cattle, deer and sometimes horses. The eggs hatch within a week and migrate through the connective tissues of the host. The larva of H. lineatum accumulate in the esophagus during migration and remain there for about 3 months. After, they migrate to the subcutaneous tissues of the back, forming lumps or warbles and cutting breathing holes in the skin of the host. When the larva emerges from the warble they measure approximately 25 mm long with a light brown color. Gerbil with an itchA Bushy Tailed Jird/Gerbil was presented to Texas A&M college of veterinary medicine with a two-week history of progressive pruritus on the left ear. The pruritus progressed to the point where the external ear was scabbed and scratched till it was raw (Image 1). The gerbil was not on any medication or prevention and no other animals in the same cage appeared affected. Several specimens, as the one observed on the following images were collected from the gerbil (Image 2-3). Image 1: Lesion on ear of gerbil Image 2-3: Specimens collected from gerbil This month’s case was a contribution of Tiana Sanders and Dr. Gui Verocai. Ornithonyssus bacoti. Known as the “tropical rate mite” is a bloodsucking mesostigmatid mite. They can be distinguished from Liponyssoides sanguineus, another mite that typically parasitizes rodents, by observing an anterior anus within the anal plate compared to a centrally located anus in Liponyssoides. Liponyssoides also has long whip-like chelicerae whereas Ornithonyssus have well-developed chelicerae that are the same in diameter throughout. Ornithonyssus is zoonotic and results in “Tropical Rat Dermatitis” in humans. It also harbors other pathogenic agents such as Francisella tularensis, Yersenia pestis, Borrelia burgdorferi and Rickettsia typhi. Annoying companionThe following parasites were recovered from the large intestine of a colony of prairie voles: Image 1-3: Key features for identification. Image 4: Egg image. Syphacia obvelata female. This parasite is a nematode of the order Oxyurida commonly found in mice and gerbils. Eggs can be detected by routine flotation techniques or found on the skin in the perineal region of infected animals. Infections are usually subclinical. For goat's sake!A herd of goats, from central Oklahoma submitted fecal samples to the Oklahoma Diagnostic Parasitology lab for fecal egg counts (FEC) and Trichostrongyles larval culture. Fecal samples look normal in appearance with FEC ranging between 500 to 2000 EPG. During larval identification the following parasites were observed:  Image 1: First stage larvae identified in culture.  Image 2: Tail of first stage larvae with dorsal spine. Muellerius capillaris This parasite is usually nonpathogenic, except when heavy infections occur. It is a Metastrongylid lungworm that infects sheep and goats, with adults living in the lung tissue or reactive nodules in the lungs. The first stage larvae are detected antemortem by the Baermann technique and characterized by having a tail with a dorsal spine. Bad beefA 3 year-old Aberdeen-Angus cow, from Northeast Oklahoma was submitted for necropsy examination to the Oklahoma Animal Disease Diagnostic Laboratory during the late month of May. The cow was found lying down with a body temperature of 104°F and was not able to recover. At necropsy marked acute, multifocal myositis was observed as well as the following structures (Images 1 and 2).  Image 1: Histologic muscle preparation.  Image 2: Histologic muscle preparation (40x objective). Cattle become infected when they ingest infective sporocysts discharged in dog feces. Two generations of schizogony occur in the vascular endothelium of cattle, with the first one happening in the mesenteric arteries and the second one in the endothelium of capillaries throughout the body. The merozoites released from second generation schizonts enter striated muscle cells and in certain cases, nerve cells to from sarcocysts. Sarcocyst formation is a slow process requiring several months. Dogs become infected when they ingest uncooked beef containing sarcocysts of S. cruzi. Even though bovine sarcocystosis is mainly subclinical, if high number of sporocysts are ingested over a short time a clinical disease can occur. In this case the finding of S. cruzi was incidental and not related to the cause of death. Always chick for parasitesA chicken less than 1 year-old, was submitted for necropsy to the Oklahoma Diagnostic Laboratory; the chicken belonged to a flock of mixed breeds with contact with ducks. During necropsy the following parasites were recovered.  Image 1: Specimen collected at necropsy. Dermanyssus sp.
These mites are infrequently found on the birds due to their feeding habits. They usually hide in nests and feed during the night. They are blood feeders and their life cycle can be completed in a week, adults can survive for months without having a blood meal. They can be differentiated from Ornithonyssus mites by observing the anal plate, the anus is located in the anterior half, while in Dermanyssus the anus is in the posterior half (Image 2). The chelicerae are long with minute chelae (Image 3). 
Image 2.
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