Thankful for cattle parasites
A beef cattle herd located in central Oklahoma, started showing weight loss over the past few months. Five cows died during the last week of October. One of the cows was submitted for necropsy and the following parasites were found on the trachea.
Image 1: Anterior end of worm
Image 2: Caudal portion of a male worm.
Image 3: Larvated eggs recovered from adult females
Images 5–7: Larva hatching from an egg
Adults: Up to 3 inches long, white in color. Found in the bronchial tree, where they cause chronic bronchitis and localized occlusion of the bronchial tree. Adults of Dictyocaulus viviparus are the only parasites that reach maturity in the lungs of cattle.
Eggs: Contain a vermiform embryo that usually hatches before is eliminated in the feces (Images 5–7). While in the environment these larvae derive their energy from stored food materials ‘food granules’. Development to the infective stage requires about five weeks, and prepatent period is approximately one month.
A scary finding.
These larvae were found near the tail head of a stray dog. The dog is approximately 2 years-old but no other history was available. The larvae were submitted to the diagnostic lab for identification.
Image 1: Gross specimen. Lateral view (16 mm in length)
Image 2: Posterior end of larva showing spiracular plate.
Lucilia sericata third instar. Also called common green bottle fly. Found throughout the world, but is more specifically described as having a Holarctic (Northern Hemisphere) distribution, being widely distributed throughout the United States and southern Canada. The larvae feed exclusively on carrion and excrement where they develop after hatching from eggs. The larval stages can cause myasis in animals and humans.
Larvae: All stages are smooth, conical-shaped, and have a complete peritreme on the posterior spiracles. The larvae are white or yellowish through all three instars of development and reach a maximum of 12–18 mm before pupation.
Adults: The adults are usually a metallic green color and can also have a copper green hue. The back is hairy and the overall diameter is about 8–10 mm.
Posterior segment with two spiracles (three slits per spiracle = third instar), distance between each papilla (P) similar to distance between P1 and P2. Complete peritreme (black arrow) and central button (blue arrow).
Does this belong in a camel?
A routine fecal egg count was requested on a 2-year-old camel during the month of August. A Wisconsin was performed and the following parasite egg was observed:
Image 1: Egg measures 75 µM x 65µM
Spurious Toxocara cati
This camel ingested food contaminated with cat feces. The egg is fully larvated which means the egg has been in the environment for a few weeks. We know the egg is T. cati due to its size..
Camels have been reported to be infected with roundworms in other parts of the world, the species that infects them is Toxocara vitulorum (75 to 90 µM x 60 to 75µM), and it is commonly found in the small intestine of bovid calves in tropical and subtropical regions of the world.
Camels and adult bovines can become infected with Toxocara vitulorum after ingesting eggs from the environment. In calves the most common route of transmission is lactogenic. Treatment is recommended in young calves, however treatment in adult bovines is unlikely to be effective because of the inability of the drugs to affect hypobiotic larval forms.
Treating the camel for the spurious Toxocara cati egg is not necessary as it is not a true parasite of camels.
Eggs and worms and teeth, oh my!
A 4-month-old German shepherd was submitted for necropsy to the Oklahoma Animal Disease Diagnostic Laboratory. The dog had a history of hematochezia, anemia, and lethargy. The intestinal content was used to perform a centrifugal fecal flotation with Sheather’s solution. The following eggs and part of a worm were observed.
Image 1: 100X magnification
Ancylostoma caninum is the most common hookworm of dogs. Adults live in the small intestine, and their buccal cavity is armed with three pairs of teeth that are used to attach to the intestinal mucosa. They are voracious blood feeders, which gives them their dark colored appearance in fresh specimens. Peracute, acute, and chronic disease syndromes can occur. Transmission is via several routes: direct skin penetration or ingestion of infective third-stage larvae in the environment, ingestion of a paratenic host with infective larvae in its tissues, or transmammary transmission to pups.
The eggs can be detected by flotation techniques, and measure 60–79 x 30–55um.
Image 2: Anterior end of adult worm with an egg visible in its buccal cavity.
Somebunny has parasites...
A fecal sample from a 4 month-old intact male English lop rabbit was submitted for gastrointestinal parasite evaluation. According to the owner, the rabbit has not been doing well lately.
A centrifugal fecal flotation with Sheather’s sugar solution (specific gravity, 1.26) was performed, and a number of these eggs were observed (Images 1–3) sizes ranged from 97.5 x 40 µM to 105 x 47.5 µM
Image 1: 100x magnification
Image 2: 200x magnification
Image 3: 400x magnification
Passalurus ambiguus are Oxyurids, commonly called pinworms and are distributed worldwide. The adults live in the cecum of rabbits. The eggs are passed in the feces of infected rabbits, and the eggs become infective within a short period of time. Infections with this nematode are usually subclinical.
The eggs can be detected by flotation techniques, and measure 95-105 x 45 µM.
The chicken or the egg?
Three chickens were submitted for necropsy to the Oklahoma Animal Diseases Diagnostic Laboratory. A history of poor feather condition, decreased egg production, and increased mortality was reported. The ceca of the birds were submitted for fecal examination and parasite identification. During gross examination several adult parasites were observed in one of the chicken’s cecum (Figures 1–3).
The fecal content was pooled for a centrifugal fecal floatation using sugar solution and the following eggs were observed (Figures 4 and 5).
Heterakis spp. are common parasites in poultry and wild bird hosts. Adults are found in cecum. Eggs are passed in the feces of poultry and become infective in the environment.
How were the chickens infected? Ingesting eggs from contaminated environment or through ingestion of earthworms that act as transport host.
Is it pathogenic? Heterakis gallinarum is usually nonpathogenic, however they act as vectors of the protozoan Histomonas melagridis (blackheaded disease) which can be a life threatening infection, particularly in turkeys.
How do you treat it? Piperazine is an anthelmintic approved by the FDA for use in chickens to treat ascarids. Fenbendazole has also been shown to reduce the number of Heterakis gallinarum in infected birds by less than 90%. (1, 2)
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