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.
Image 3. This is bullA cattle producer from northeast Oklahoma found several of his cows open during the last pregnancy check. The previous year he purchased a new bull with a breeding soundness exam performed before purchasing. Due to the high number of open cows, he submitted a preputial wash and requested a new fertility test. The following is a video of the culture after 48 hours of initiation. Video: Culture pouch after 48 hours of initiation. Tritrichomonas foetus trophozoites. This parasite is sexually transmitted, causing early abortions, endometritis, and occasionally pyometra. Bulls are asymptomatic and remain infected indefinitely. Diagnosis is confirmed by culture or qPCR and control measures should be focused on biosecurity protocols, culling, and artificial insemination.
Image: Stained T. foetus (arrow). Unwanted "Neigh"borTwo specimens, as the one seen in Image 1, were submitted to the parasitology diagnostic laboratory. The specimens were collected from a 5-year-old mare with history of pruritus and scaly coat on the back.  Image 1: Specimen removed from a horse. Werneckiella equi (Damalinia equi), is the horse biting louse that belongs to the suborder Ischnocera. Lice from this group are characterized by having salient three-jointed antennae in species that infest mammals, comparing to the five-jointed antennae that infest birds, they feed on epithelial cells and skin debris. Groups of horses with poor body condition and confined in small spaces are more likely to be affected. Dog down on his luckA fecal sample from a 2-year-old male dog with history of soft stools and vomiting was submitted to the parasitology diagnostic laboratory. The dog did not have history of deworming treatments. The following structures were observed after fecal centrifugation with sugar solution  Image 1: Specimen at 10x objective.  Image 2: Specimen at 40x objective. Adelina sp., is an apicomplexan parasite of arthropods and oligochaetes that could be confused with Ancylostoma sp. eggs if not measured or if examined by inexperienced personnel. In this case it is a spurious parasite of the dog which is passing the oocysts, after ingesting arthropods or earthworms infected with the coccidian parasite. Unhealthy RelationshipThe following images belong to an 8-month-old Quarter Horse colt from Kansas with a history of lethargy, inappetence, and abdominal pain that worsened over approximately 2 weeks. The colt died and a necropsy was performed. On gross examination, the large colon exhibited changes consistent with infarction. The cranial mesenteric artery contained a thrombus and on histopathology, the following was identified.  Image 1: 2X objective  Image 2: 10X objective Strongylus vulgaris, is a member of the Strongylinae. The 4th and 5th larval stages migrate through the arterial system and cause verminous arteritis with marked intimal thickening and thrombus formation that can block arteries, causing infarction of intestinal walls commonly associated with anorexia, pyrexia, colic and death. Foals and yearlings are most commonly affected. Case provided by Dr. Giselle Cino. |