Parasites by Host - Dog PDF

PARASITES BY HOST: DOG  BY THE END OF THIS PRESENTATION, YOU SHOULD BE ABLE TO: Provide a differential list of parasites that cause the clinical signs reported in the host Generate a diagnostic plan to rule in or out parasites on the differential list, and what the e...

PARASITES BY HOST: DOG  BY THE END OF THIS PRESENTATION, YOU SHOULD BE ABLE TO: Provide a differential list of parasites that cause the clinical signs reported in the host Generate a diagnostic plan to rule in or out parasites on the differential list, and what the expected findings would be for each test Design a treatment plan depending on the parasite affecting the host Inform owners regarding methods of prevention of future infections by these parasites MY DOG IS ITCHING Arthropods > Arachnids > Acari > Astigmata > Sarcoptidae > Sarcoptes SARCOPTES Long, unsegmented pedicels Anus on posterior edge of body 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 Intense pruritus with papules, erythema, crusts, and excoriations develop, progresses to hyperkeratosis Secondary bacterial infection common Arthropods > Insecta > Siphonaptera (fleas) > Ctenocephalides CTENOCEPHALIDES Ctenocephalides felis much more common than Ctenocephalides canis Parasitize cats, dogs, cattle, and humans Genal and pronotal combs Genal teeth run parallel to head Eggs laid on host, fall off into environment Adults emerge by weeks 3-4 Can cause exsanguination of host Intermediate host of tapeworm Dipylidium caninum and nematode Acanthocheilonema reconditum Can cause flea allergy dermatitis due to hypersensitivity Arthropods > Arachnids > Acari > Astigmata > Psoroptidae > Otodectes OTODECTES Otodectes cynotis: Short, unsegmented pedicels Infests external ear canal and adjacent skin of dogs, cats, foxes, and ferrets, and sometimes humans Cause intense irritation, dark cerumen and tan flaky material in ear canal Leads to head shaking that can cause aural hematomas  ACTIVE LEARNING ACTIVITY What is an appropriate diagnostic method if you suspect Sarcoptes spp. mites? What about fleas? What are some potential treatments?  ARTHROPOD TREATMENTS Flea treatments: Isoxazolines (afoxolaner, fluralaner, lotilaner, sarolaner), nitenpyram, spinosad, selamectin, fipronil, imidacloprid, dinotefuran, flumethrin, indoxacarb Insect growth regulators (lufenuron, pyriproxyfen, methoprene) used to prevent development of larvae and pupae Sarcoptic mite treatments: Selamectin, moxidectin, fipronil, flumethrin, off-label isoxazolines MY DOG IS VOMITING Nematoda > Secernetea > Spirurida > Spirurina > Spirocerca SPIROCERC A 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 Diagnosis: Small eggs with vermiform embryo passed in fecal flotation or sedimentation, nodules on endoscopy Treatment: Milbemycin oxime, doramectin MY DOG HAS DIARRHEA Protists > SAR > Apicomplexa > Coccidians > Cystoisospora CYSTOISOSPORA SPP. Infection via ingestion of oocysts or paratenic hosts (in dogs and cats) Dog species: C. canis, C. ohioensis, C. burrowsi May cause diarrhea (hemorrhagic or nonhemorrhagic) in dogs (usually puppies) Usually resulting from change of environment Respiratory and nervous signs reported in some animals Treatment: Sulfadimethoxine Protists > Excavata (flagellates) > Diplomonadida > Giardia GIARDIA Common intestinal commensal organism Trophozoites can be passed in diarrheic feces but not considered infectious Cysts are immediately infectious when passed Assemblage C & D: Dog Dogs may be subclinical Puppies and debilitated dogs more likely to develop diarrhea Diagnosis: Cysts on direct smear or fecal flotation with zinc sulfate, ELISA Treatment: Metronidazole, fenbendazole Nematoda > Secernetea > Ascaridia (roundworms) > Toxocara TOXOC ARA Cream colored adults with cervical alae Live as adults in small intestine of mammals Toxocara canis in dogs Can infection puppies transplacentally Disease: Ill-thrift, pot-bellied appearance Intestinal rupture or obstruction can occur Diagnosis: Identification of adults in vomit or feces, eggs in fecal flotation Treatment: Benzimidazoles, macrocyclic lactones, pyrantel, piperazine Start as early as 2-weeks old in puppies, treat every 2 weeks to prevent environmental contamination Nematoda > Adenophorea (Enoplida) > Trichinelloidea > Trichuris TRICHURIS Aka whipworms Trichuris vulpis common among dogs in U.S. Adults found embedded within wall of large intestine and cecum Eggs with infective L1 highly resistant in environment Prepatent period: 3 months in dogs Heavy T. vulpis infections can cause weight loss and diarrhea with mucus and blood Diagnosis: Lemon shaped eggs with bipolar plugs and a single cell on fecal flotation Treatment: Macrocyclic lactones, benzimidazoles Every month for 3 months Nematoda > Secernetea > Rhabditida > Strongyloides STRONGYLOIDES Lives in mucosal crypts of small intestine Strongyloides stercoralis: humans and dogs Transmammary transmission occurs in dogs, horses, pigs, and ruminants Infection can be chronic due to autoinfection of larvae in Strongyloides stercoralis Can cause hyperinfection and death Diagnosis: L1 larvae in feces detected via Baermann Treatment: Ivermectin, oxibendazole, levamisole, doramectin THERE’S STUFF IN MY DOG’S POOP  CESTODES Dibothriocephalus latum Infection: Plerocercoids in fish Diagnosis: Whole tapeworm or long segment Taenia spp. Infection: Cysticercus or coenurus in sheep and rabbits Diagnosis: Square-shaped segments Mesocestoides spp. Infection: Tetrathyridium in snakes, birds, and small mammals Diagnosis: Small sesame seed-shaped segments Dipylidium caninum Infection: Cysticercoids in fleas Diagnosis: Pumpkin seed-shaped segments Treatments: Praziquantel  ACANTHOCEPHALANS AKA Thorny-headed worms White, flattened body (become cylindric when placed in water) Final host infected by ingesting arthropod or paratenic host Dung beetle for Macracanthorhynchus hirudinaceus Millipede for Macracanthorhynchus ingens Usually asymptomatic in dogs Diagnosis: Thick, multilayered eggs with a dark brown shell on fecal flotation or sedimentation Adults can be passed in feces Treatment: No approved treatment in dogs MY DOG IS SNEEZING Arthropods > Arachnids > Acari > Mesostigmata > Pneumonyssoides PNEUMONYSSOIDES Pneumonyssoides caninum: Mite of nasal and paranasal sinuses of dogs Can cause chronic sneezing and epistaxis, nasal discharge Diagnosis via rhinoscopy or nasal swabs Treatment: SQ ivermectin or topical imidacloprid + moxidectin Nematoda > Adenophorea (Enoplida) > Trichinelloidea > Capillarids > Eucoleus EUCOLEUS Found in airways of dogs, foxes, and cats Eucoleus boehmi in frontal sinus mucosa Eucoleus aerophilus in bronchi Life cycle may be direct or with earthworm intermediate hosts L1 infective stage Diagnosis: Bipolar eggs with a single cell detected in feces and tracheal mucus Treatment: ivermectin, imidacloprid+moxidectin Eucoleus boehmi on nasal turbinate in a dog MY DOG IS COUGHING  ACTIVE LEARNING ACTIVITY Name some parasitic differentials for coughing in a dog, and what diagnostic tests you would like to run to rule these in or out. Nematoda > Secernetea > Strongylida (bursates) > Metastrongyloidea (lungworms) > Crenosoma CRENOSOMA Cuticle thrown into crenated folds, especially anteriorly Crenosoma vulpis: Lives in bronchi and bronchioles of canids and foxes Definitive host infected by ingesting L3 in snails and slugs Disease: Can cause chronic bronchitis and bronchiolitis Diagnosis: Baermann technique for first stage larvae Treatment: Fenbendazole, macrocyclic lactones (milbemycin oxime, moxidectin) Nematoda > Secernetea > Strongylida (bursates) > Metastrongyloidea (lungworms) > Filaroides FILAROIDES (OSLERUS) OSLERI Forms nodules in the trachea and bronchi L1 passed in feces is the infective stage, not L3 Dogs can be infected via ingesting L1 in regurgitated stomach content, lung tissue, or feces Disease: Coughing, bronchitis Diagnosis: L1 recovered on fecal flotation, bronchoscopy No recovery on Baermann Treatment: Fenbendazole, ivermectin, doramectin Nematoda > Secernetea > Strongylida (bursates) > Metastrongyloidea (lungworms) > Filaroides FILAROIDES HIRTHI Lives as adult in lungs of canids Transmission via ingestion of L1 passed in feces Disease: Usually no clinical signs Fatal cases of hyperinfection can occur in stressed or immune-deficient animals Diagnosis: Larvae in feces or bronchoalveolar lavage No recovery on Baermann Treatment: Albendazole, ivermectin Nematoda > Secernetea > Spirurida > Spirurina > Filaroidea > Dirofilaria DIROFILARIA IMMITIS AKA heartworm Live as adults in pulmonary arteries of dogs, cats, and ferrets Disease: Pulmonary endarteritis and fibrosis Respiratory distress and hemoptysis Can develop fatal caval syndrome Nematoda > Secernetea > Spirurida > Spirurina > Filaroidea > Dirofilaria DIROFILARIA IMMITIS Diagnosis: Antigen test: Detects female heartworm antigens in blood by 5 months after L3 inoculation Heat treatment may dissociate antigen- antibody complexes pre-testing to eliminate false negatives Microfilariae in blood : Detected 6.5 months after exposure to L3 inoculation Can be confused with microfilariae of Acanthocheilonema reconditum, a nonpathogenic nematode Nematoda > Secernetea > Spirurida > Spirurina > Filaroidea > Dirofilaria DIROFILARIA IMMITIS Treatment of adult heartworms: Melarsomine dihydrochloride: Adulticidal Moxidectin+imidacloprid: Microfilaricidal Doxycycline: Bactericidial Prevention: Monthly administration of macrocyclic lactone Adults should be tested first with antigen test to prevent resistance development Platyhelminths > Trematodes > Paragonimus PARAGONIMUS Live in pairs or groups in cysts within lungs of mammal definitive hosts Cat and dog definitive hosts Infection through ingestion of metacercariae in crabs and crayfish Disease: Can cause chronic coughing Bullae can form and rupture, leading to pneumothorax Diagnosis: Large, vase-shaped, operculated eggs in feces or sputum on fecal sedimentation Treatment: Fenbendazole, albendazole, praziquantel MY DOG IS BEHAVING STRANGELY Protists > SAR > Apicomplexa > Coccidians > Neospora NEOSPORA C ANINUM Canid definitive hosts Oocysts shed in feces Dogs can also serve as paratenic hosts Transplacental infection in puppies by tachyzoites Progressive paralysis in newborns Adult dogs can develop neurologic signs Diagnosis: Dogs only shed oocysts once after become infected Serology and PCR aid in diagnosis Treatment: No approved treatment in cattle or dogs Nematoda > Secernetea > Ascaridia (roundworms) > Baylisascaris B AYLISASC ARIS Baylisascaris procyonis: Ascarid of raccoons Dogs can serve as final hosts Acquired through ingestion of infective eggs from raccoon feces contaminating environment Can cause fatal larva migrans in humans Larvae grow as they migrate, causing severe disease Diagnosis: Eggs similar to Toxocara canis but smaller Treatment: Albendazole with corticosteroids in humans Pyrantel pamoate, piperazine, fenbendazole, milbemycin oxime, moxidectin all work in raccoons  TICK TOXICOSIS Tick paralysis: Ascending paralysis due to absorption of toxins from saliva of tick Can occur with just one tick Occurs following at least 4 days of feeding Removal usually leads to recovery U.S. species most involved: Dermacentor andersoni, Dermacentor variabilis, Amblyomma americanum, Amblyomma macultaum PRACTICE QUESTIONS