Parasites by Host - Dog (Exam 5)

Exam 5 of Parasitology is Parasites by Host review, this is part 1 Dog. Blue text is testable material, black text is general info or potential extra credit. General note: Dr. Wu uses the class name Secernentea, but Modern genetic studies use name Chromadorea (Secernentea is deeply nested within Chromadorea, making them closely related in taxonomy. Secernentea is not considered a separate, co-equal class; it is now typically reclassified as the order Rhabditida under the class Chromadorea)

Thinking of all the parasites studied so far, What could be some differential diagnoses for an itching dog?

Sarcoptes

Ctenocephalides

Otodectes

Sarcoptes: morphological features

Arthropods > Arachnids > Acari > Astigmata > Sarcoptidae > Sarcoptes

Long, unsegmented pedicels

Anus on posterior edge of body

Sarcoptes causes what? (Disease/Clinical signs)

Causes mange in humans, dogs, foxes, horses, and cattle → Relatively host-specific, interspecies transmission uncommon

Burrow in tunnels under the epidermis → Begins in hairless areas (elbow, pinna), can progress to generalized

Causes Intense pruritus with papules, erythema, crusts, and excoriations develop, progresses to hyperkeratosis → Secondary bacterial infection common

Ctenocephalides: morphological features

Arthropods > Insecta > Siphonaptera (fleas) > Ctenocephalides

Genal and pronotal combs

Genal teeth run parallel to head

Which species of Ctenocephalides is more common: C. felis or C. canis?

Ctenocephalides felis

Ctenocephalides: how long does it take adults to emerge?

Eggs laid on host, fall off into environment

Adults emerge by weeks 3-4

Ctenocephalides is the intermediate host for what other parasites?

Intermediate hosts of tapeworm Dipylidium caninum and nematode Acanthocheilonema reconditum

Ctenocephalides: Disease

Can cause flea allergy dermatitis due to hypersensitivity

Can cause exsanguination of host (flea anemia)

Otodectes: morphological features

Arthropods > Arachnids > Acari > Astigmata > Psoroptidae > Otodectes > Otodected cynotis

Short, unsegmented pedicels

Where does Otodectes infest on host body?

Infests external ear canal and adjacent skin of dogs, cats, foxes, and ferrets, and sometimes humans

Otodectes: Disease/Clinical signs

Cause intense irritation, dark cerumen and tan flaky material in ear canal

Leads to head shaking that can cause aural hematomas

How would you treat a Sarcoptes infestation?

Sarcoptic mite treatments: Selamectin, moxidectin, fipronil, flumethrin, off-label isoxazolines

How would you treat a Ctenocephalides flea infestation?

Flea treatments: Isoxazolines (afoxolaner, fluralaner, lotilaner, sarolaner), nitenpyram, spinosad, selamectin, fipronil, imidacloprid, dinotefuran, flumethrin, indoxacarb

and Insect growth regulators (lufenuron, pyriproxyfen, methoprene) used to prevent development of larvae and pupae

Considering all of the parasites studied so far, what is a differential diagnosis for a vomiting dog?

Spirocerca lupi

Spirocerca lupi can cause what clinical signs?

Nematoda > Secernetea > Spirurida > Spirurina > Spirocerca > Spirocerca lupi

Mostly nonpathogenic

Can see dysphagia, coughing, and vomiting

Can cause aortic aneurysm or hypertrophic osteopathy

Can cause esophageal neoplasia (fibrosarcoma, osteosarcoma, chondrosarcoma)

Aberrant migration can cause neurologic signs

What features on this egg help identify it as Spirocerca lupi?

Small eggs with vermiform embryo passed in fecal flotation or sedimentation,

nodules on endoscopy

Considering all of the parasites we have learned so far, what are some differential diagnoses for a dog with diarrhea?

Cystoisospora

Giardia

Toxocara

Trichuris

Strongyloides