Canine/Feline Nematodes Flashcards
Spirocerca lupi-Common Name
Esophageal Worm
Spirocerca lupi-Hosts
DH: Dogs
IH: Dung Beetles
PH: Chickens, birds and lizards
*Reported in humans also
Spirocerca lupi-Identification
Adults: pink/red in color, reach 8cm in length
Eggs: small, elongated, 30-35um
Spirocerca lupi-Life Cycle
Indirect. PPP = 6 mths
Egg with L1 passed in vomitus/feces→ingested by IH→L1 hatches and develops into L3 and encysts in IH→DH ingests L3 within IH/PH→L3 penetrates stomach wall of DH and migrates to thoracic aorta through celiac a.→3 mths later move into esophagus and form granulomas→adult
Spirocerca lupi-Site of Infection
Adults in granulomatous nodules in wall of esophagus/stomach of DH
Spirocerca lupi-Pathogenesis and Lesions
Lesions within wall of aorta due to migrating larvae
Osteosarcoma (bone cancer)
Spondylosis (immobility of joint) of the thoracic vertebrae
Osteopathy (bone disease) of long bones
Spirocerca lupi-Clinical Signs
Esophageal granulomas interfere with swallowing and can cause regurgitation
Weakness, emaciation, and rapid loss of condition
Spirocerca lupi-Diagnosis
Fecal floatation with sodium nitrate→only positive when the adults are releasing eggs from the granulomas
Endoscopy or radiography
Spirocerca lupi-Treatment and Prevention
Macrocyclic lactones are used extra-label
Physaloptera spp.-Hosts
DH: Dogs and Cats
IH: Beetles, cockroaches and crickets
PH: Snakes and birds
Physaloptera spp.-Identification
Adults: 4-6cm, resemble ascarids in size
Eggs: elongated, 45um, more oval than Spirocerca
Physaloptera spp.-Life Cycle
Indirect. PPP = 8-10 wks.
Egg with L1 passed in vomitus/feces→Ingested by IH→L1 hatches and develops into L3 and encysts→L3 in IH or PH ingested by DH→L3 develops into an adult in stomach of DH
Physaloptera spp.-Site of Infection
Stomach
Physaloptera spp.-Pathogenesis and Lesions
Small ulcers due to strong forcep-like teeth that attach to the gastric mucosa
Physaloptera spp.-Clinical Signs
Vomiting, catarrhal gastritis (inflammation of mucous membrane) and bloody stool
Physaloptera spp.-Diagnosis
Adults can be viewed in stomach with endoscopy
Elongate eggs thickened at either pole in vomitus/feces
Physaloptera spp.-Treatment and Prevention
No approved treatment
Control of IH–NOT PRACTICAL
Toxocara canis-Common Name
Common Roundworm, ascarid
Toxocara canis-Hosts
Dogs
*Zoonosis
Toxocara canis-Identification
Adults: large white nematodes 10-15cm, small finger-like process on tail of male
Egg: dark brown, round, thick pitted shell, 85 x 75 um
Toxocara canis-Life Cycle
Direct. PPP = 4-7 wks with direct infection following ingestion of eggs or larvae in a PH, 3 wks with prenatal infection
Per os, Transplacental or prenatal, Transmammary or Paratenic Hosts
Per os Life Cycle
Eggs with L2 infective in environ. in 2-4 wks. Infective eggs (L2) ingested by DH and hatch in small intestine→hepatic-tracheal migration→return to small intestine→mature to adult→eggs laid 4-5 wks.
This mode of infection occurs regularly in hosts under 5 wks. Older than 5 wks can still be infected but typically arrest at L3 stage due to acquired immunity
Transplacental or prenatal Life Cycle
Arrested L3 in pregnant bitch move across placenta at week 6 of gestation→brought to fetal liver by circulatory system→after birth nematodes migrate to stomach and mature in small intestine
Transmammary Life Cycle
Suckling pup may be infected with migration of L3 in the milk during first 3 wks of lactation. No further migration in pup
Paratenic Host Life Cycle
Rodents or birds may ingest infective egg→hatched L2 travel to tissues and remain until eaten by dog→further development confined to GI tract
Toxocara canis-Site of Infection
Small Intestine
Toxocara canis-Pathogenesis and Lesions
No apparent damage to tissue during larval migration
Little reaction in intestines from adults
Toxocara canis-Clinical Signs
Pneumonia from larval migration through lungs, eosinophilia from chronic infection, hypersensitization, digestive disturbances such as vomiting and diarrhea, intestinal obstruction from large numbers of adults, general malaise, anemia, pot belly appearance
No clinical signs with moderate infections
Toxocara canis-Diagnosis
Patent intestinal infection
Eggs in fecal floatation
Adults recovered in necropsy
Toxocara canis-Treatment and Prevention
Anthelmintics-Pyrantel and benzimidazole
Management of environ.
Removal of feces
Toxocara cati-Common Name
Common roundworm, ascarid
Toxocara cati-Hosts
Cats
*Zoonosis
Toxocara cati-Identification
Adults: large white nematodes 4-10cm, cervical alae shaped as an arrow head with the posterior margins almost at a right angle to the body
Eggs: thick pitted shell, colorless, 60 x 80 um.
Toxocara cati-Life Cycle
Direct.
Per os, transmammary (RARE), paratenic hosts
Transplacental or prenatal DOES NOT occur
Toxocara cati-Site of Infection
Small Intestine
Toxocara cati-Pathogenesis and Lesions
Little migration
Toxocara cati-Clinical Signs
Pneumonia from larval migration through lungs, eosinophilia from chronic infection, hypersensitization, digestive disturbances such as vomiting and diarrhea, intestinal obstruction from large numbers of adults, general malaise, anemia, pot belly appearance
Toxocara cati-Diagnosis
Eggs in fecal floatation
Toxocara cati-Treatment and Prevention
Anthelmintics-Pyrantel and benzimidazole
Management of environ.
Removal of feces
Control of ascarids should concentrate on kittens
Toxascaris leonina-Common Name
Ascarid
Toxacaris leonina-Hosts
Dogs and cats
Toxacaris leonina-Identification
Adults: large white nematode with prominent process 6-10cm
Eggs: slightly ovoid with smooth thick shell
Toxacaris leonina-Life Cycle
Direct. PPP = 10-11 wks.
Per Os, Paratenic hosts
Toxacaris leonina-Site of Infection
Small intestine
Toxacaris leonina-Pathogenesis and Lesions
None
Toxacaris leonina-Clinical Signs
Typically non-pathogenic.
Adults can cause vomiting/diarrhea, intestinal obstruction, general malaise, anemia and pot belly appearance.
Toxacaris leonina-Diagnosis
Eggs in fecal floatation
Adults in small intestine in necropsy
Toxacaris leonina-Treatment and Prevention
Anthelmintics-Pyrantel and benzimidazole
Management of environ.
Removal of feces
Ancylostoma caninum-Common Name
Hookworm
Ancylostoma caninum-Hosts
DH: Dogs and Foxes
*Zoonosis
Ancylostoma caninum-Identification
Adults: 1-2cm, characteristic “hook” posture, large buccal capsule with 3 pairs of marginal teeth
Eggs: thin-shelled, oval, 60 x 40 um
Ancylostoma caninum-Life Cycle
Direct. PPP = 2-3 wks.
Eggs hatch, molt and develop to L3 (infective stage)
Percutaneous or penetration of oral mucosa if ingested,
Per Os, Paratenic hosts, Transplacental, Transmammary
Ancylostoma caninum-Site of Infection
Small intestine
Ancylostoma caninum-Pathogenesis and Lesions
Acute or chronic hemorrhagic anemia caused by adults
Skin reactions at sites of percutaneous infection
Ancylostoma caninum-Clinical Signs
Acute infections cause anemia and lassitude (little energy). Severe anemia can be accompanied by diarrhea with blood/mucous.
Chronic infections cause weight loss, poor hair coat, loss of appetite.
Ancylostoma caninum-Diagnosis
Eggs on fecal floatation
Adults at necropsy in small intestine
Ancylostoma caninum-Treatment and Prevention
Anthelminthics such as mebendazole, fenbendazole and nitroscanate
With severe infection may require parenteral iron or blood transfusion
Keep kennel floors clean
Treat weaned pups every 3 mths.
Ancylostoma tubaeforme-Common Name
Hookworm
Ancylostoma tubaeforme-Hosts
Cats
Ancylostoma tubaeforme-Identification
Adults: 1-2cm, large buccal capsule with 3 pairs of marginal teeth
Eggs: thin shelled, oval, 60 x 40 um
Percutaneous or penetration of oral mucosa if ingested
Migrate by blood to the lungs, tracheal migration to the small intestine
Ancylostoma tubaeforme-Life Cycle
Direct.
Per Os, Percutaneous and Paratenic hosts
Ancylostoma tubaeforme-Site of Infection
Small intestine
Ancylostoma tubaeforme-Pathogenesis and Lesions
Acute or chronic hemorrhagic anemia caused by adults
Skin reactions at sites of percutaneous infection
Ancylostoma tubaeforme-Clinical Signs
Acute infections cause anemia and lassitude (little energy). Severe anemia can be accompanied by diarrhea with blood/mucous.
Chronic infections cause weight loss, poor hair coat, loss of appetite.
Ancylostoma tubaeforme-Diagnosis
Eggs on fecal floatation
Adults at necropsy in small intestine
Ancylostoma tubaeforme-Treatment and Prevention
Anthelminthics such as mebendazole, fenbendazole and nitroscanate
With severe infection may require parenteral iron or blood transfusion
Keep kennel floors clean
Treat weaned pups every 3 mths.
Ancylostoma braziliense-Common Name
Hookworm
Ancylostoma braziliense-Hosts
Dogs and Cats
*Zoonosis-severe cutaneous larval migrans in humans
Ancylostoma braziliense-Identification
Adults: 1-2cm, large buccal capsule with 3 pairs of marginal teeth
Eggs: thin shelled, oval, 60 x 40 um
Ancylostoma braziliense-Life Cycle
Direct.
Per Os, Percutaneous Infeciton
Rodents can act as paratenic hosts
Ancylostoma braziliense-Sites of Infection
Small intestine
Ancylostoma braziliense-Pathogenesis and Lesions
Less voracious bloodsucker than A. caninum hense less pathogenic
Ancylostoma braziliense-Clinical Signs
Mild digestive upsets
Occasional diarrhea
Ancylostoma braziliense-Diagnosis
Eggs on fecal floatation
Adults at necropsy in small intestine
Ancylostoma braziliense-Treatment and Prevention
Anthelminthics such as mebendazole, fenbendazole and nitroscanate
With severe infection may require parenteral iron or blood transfusion
Keep kennel floors clean
Treat weaned pups every 3 mths.
Uncinaria stenocephala-Common Name
Hookworm
Uncinaria stenocephala-Hosts
Dogs, cats and foxes
*Zoonosis
Uncinaria stenocephala-Identification
Adults: small nematode, 1cm, 2 cutting plates on border of the buccal capsule and at base a small pair of teeth
Eggs: thin shelled, oval, 80 x 40 um
Uncinaria stenocephala-Life Cycle
Direct. PPP = 15-21 days
Per os is usual mode of infection
Percutaneous infection is rare
Uncinaria stenocephala-Site of Infection
Small intestine
Uncinaria stenocephala-Pathogenesis and Lesions
Less voracious bloodsucker than A. caninum
Uncinaria stenocephala-Clinical Signs
Anemia, diarrhea, and interdigital dermatitis
Uncinaria stenocephala-Diagnosis
Eggs in fecal floatation
Larval culture
Uncinaria stenocephala-Treatment and Prevention
Anthelminthics and good hygiene
Strongyloides stercoralis-Common Name
Threadworm
Strongyloides stercoralis-Hosts
Dogs, cats, foxes
*Zoonosis
Strongyloides stercoralis-Identification
Adults: slender hair-like nematode less than 1cm in length
Eggs: with L1 30 x 40 um
Strongyloides stercoralis-Life Cycle
Direct.
Parasitic (homogonic) phase: eggs with L1 passed in feces→L1 develop to L3 in soil→infective L3 penetrates host’s skin or oral mucosa→migrate to heart→ lungs→ trachea and swallowed→intestine→adult FEMALE ONLY PPP = 10-14 days
Free-living (heterogonic) phase: favorable environ. conditions the free-living stage predominates. Larvae hatch from egg→devel. into adult (MALE OR FEMALE) in soil→females lay eggs→eggs devel. into free-living L3→infect percutaneously and per os
Prenatal and transmammary transmission
Strongyloides stercoralis-Site of Infection
Small intestine (adults), skin (larvae)
Strongyloides stercoralis-Pathogenesis and Lesions
Inflammation in small intestine with heavy infection
Erythrematous reaction with infective L3 in skin
Strongyloides stercoralis-Clinical Signs
Diarrhea, anorexia, dullness, weight loss, urticaria (hives)
Strongyloides stercoralis-Diagnosis
L1 and eggs with L1 in fecal floatation, Baermann technique
Strongyloides stercoralis-Treatment and Prevention
Anthelmintics
Trichuris spp.-Common Name
Whipworm
Trichuris spp.-Hosts
Dogs and Cats
Trichuris spp.-Identification
Adults: 4-6cm long, thick posterior end tapering rapidly to a long filamentous anterior end
Egg: lemon shape, yellow or brown, plug at both ends, 80 x 35 um
Trichuris spp.-Life Cycle
Direct. PPP = 6-12 wks.
Infective stage is egg with L1.
Ingestion of infective egg with L1→plugs digested→L1 penetrates the glands of the cecal mucosa→4 molts within the glands→adults embed in cecal mucosa.
Trichuris spp.-Site of Infection
Large intestine, particularly cecum
Trichuris spp.-Pathogenesis and Lesions
Usually light infection and asymptomatic
With heavy infection, can cause diphtheritic (leather-like) inflammation of cecal mucosa.
Trichuris spp.-Clinical Signs
Sporadic diseases with heavy infection.
Associated with watery, bloody diarrhea
Trichuris spp.-Diagnosis
Eggs in feces in fecal floatation
Trichuris spp.-Treatment and Prevention
Anthelmintics-benzimidazoles and macrolides
Eggs can survive for 3-4yrs without host and are a reservoir of infection
Capillaria spp.-Hosts
Dogs and Cats.
*Zoonosis-but not very common
Capillaria spp.-Identification
Adults: thin, hair-like nematodes, 1-5cm long
Eggs: resemble Trichuris eggs, bipolar plugs, barrel-shaped, lighter in color, 60 x 35 um
Capillaria spp.-Life Cycle
Direct and Indirect.
Infective stage: L1 in egg
Direct. Adults in airways embedded in the mucosa of trachea, bronchi and nasal passages produce eggs→eggs coughed up and swallowed→eggs in intestines→eggs excreted in feces→eggs ingested by host PPP = 6 wks
Indirect. Adults in urinary bladder produce eggs→excrete in urine→eggs ingested by host (direct) or eggs ingested by IH (earthworm) then IH ingested by host (indirect) PPP = 2 mths
Capillaria spp.-Site of Infection
Airways, intestinal tract or bladder
Capillaria spp.-Pathogenesis and Lesions
Relatively non-pathogenic
Capillaria spp.-Clinical Signs
Asymptomatic
Capillaria spp.-Diagnosis
Eggs found in feces, urine or bronchial swab-Incidental finding since they are non-pathogenic
Capillaria spp.-Treatment and Prevention
Anthelmintics (levamisole, fenbendazole, ivermectin)
Control IH is not practical
Dioctophyme renale-Common Name
Giant Kidney Worm
Dioctophyme renale-Hosts
DH: Dogs, foxes, minks
IH: Earthworm
PH: Frogs, fish
*Zoonosis
Dioctophyme renale-Identification
Largest nematode of domestic animals
Adults: females 60-100cm in length
Eggs: 70 um with thick shell
Dioctophyme renale-Diagnosis
Eggs in urine
Oslerus osleri-Common Name
Tracheal Worm
Oslerus osleri-Hosts
Dogs
Oslerus osleri-Identification
Adults: small, hair-like greyish nematode, 0.5-1.0cm, not recovered intact from tissues
L1 with kinked tail in feces or sputum
Oslerus osleri-Life Cycle
Direct. PPP = 10-18 wks.
L1 is infective stage
Adult female lays eggs with larvae→host coughs up into sputum and is swallowed→ excreted in feces→ next host ingests L1
Easy for mother to pass to puppies since she is constantly licking pups
Oslerus osleri-Site of Infection
Nodules in the trachea at bifurcation, adjacent bronchi or deeper in lungs
Oslerus osleri-Pathogenesis and Lesions
Small, soft, greyish, millet seed nodules
Heavy infection-greyish masses of many nodules
Oslerus osleri-Clinical Signs
Asymptomatic unless heavy infection.
Hyperpnea (increased rate of respiration)
Oslerus osleri-Diagnosis
Nodules detected with brochoscope
L1 in sputum, centrifugal floatation or Baermann technique
Oslerus osleri-Treatment and Prevention
Problem in kennels
Treat with benzimidazoles possibly
Aelurostrongylus abstrusus-Common Name
Cat lungworm
Aelurostrongylus abstrusus-Hosts
DH: Cats
IH: Snails and slugs
PH: Birds, rodents and frogs
Aelurostrongylus abstrusus-Identification
Adults: 1cm in length, slender and delicate so difficult to recover intact
L1 in feces with kink or S-shaped tail
Aelurostrongylus abstrusus-Life Cycle
Indirect. PPP = 6-12 wks.
L3 infective stage.
Adults lay eggs with L1 in lung parenchyma→eggs hatch→L1 coughed up and swallowed→ excreted in feces→L1 enter IH→ develop into L3→ cats ingest IH or PH→ L3 develop into adults in DH lungs
Aelurostrongylus abstrusus-Site of Infection
Lung parenchyma and bronchioles
Aelurostrongylus abstrusus-Pathogenesis and Lesions
Low pathogenicity, majority of infections found incidentally at necropsy
Aelurostrongylus abstrusus-Clinical Signs
Chronic mild cough
Aelurostrongylus abstrusus-Diagnosis
Fecal exam by smear, flotation or Baermann method to find L1 with kinked tail
Aelurostrongylus abstrusus-Treatment and Prevention
Levamisole and Ivermectin
Prevent access to IH and PH if possible
Dirofilaria immitis-Common Name
Heartworm
Dirofilaria immitis-Hosts
DH: Dogs and cats, can infect 30 other mammals
IH: Mosquitoes
*Zoonosis
Dirofilaria immitis-Identification
Adults: Long and slender, 20-30cm
Microfilariae (mff): L1 stage, 300 um long, tapered anterior end, straight tail, slow non-progressive movement in blood smears
Dirofilaria immitis-Life Cycle
Indirect. PPP = 6-9 mths.
L3 is infective stage
Adults females release mff (L1) into blood stream→can circulate for up to 3 yrs in host’s blood→taken up by mosquito→L1 develop into L3 in IH→L3 in salivary glands of mosquito→L3 inoculated (up to 12) into new host’s blood when mosquito feeds→L3 molts to L4 in 1-2 days→L4 migrates through subcutaneous tissues for 2-3 mths→L4 molts to L5→L5 enters vein→carried to pulmonary arteries→develop into sexually mature adult in 2-3 mths→release mff into blood
Dirofilaria immitis-Site of Infection
Adults found in pulmonary arteries of the caudal lung lobes
With heavy infection, found in right heart and the caudal vena cava
Dirofilaria immitis-Pathogenesis and Lesions
Endothelium is destroyed
Fluid leakage, thrombus formation
Tortuous arteries (thickening of arteries)
Increased resistance, right side of heart has to work harder
Post-caval syndrome→so many worms causing heart failure
Requires Wolbachia spp. to live and reproduce
Dirofilaria immitis-Clinical Signs
Dependent on animal’s activity
Most are asymptomatic.
Symptoms may include weight loss, anorexia, chronic non-productive cough, labored respiration, exercise intolerance, exertional dyspnea
Dirofilaria immitis-Diagnosis
mff in blood→appear 6-7 mths post infection
Antigen test: must have sexually mature adult females for a positive test
mff tests: complements antigen testing
Occult infection→infection with adults w/o mff
Radiography-characterizes severity of pulmonary lesions
Echocardiography
Dirofilaria immitis-Treatment and Prevention
Prophylaxis to prevent further infections→treat year round
Doxycycline to kill Wolbachia spp.
Kill mff to stop dog from being a source of infection
Manage clinical signs of moderate or severe lung disease and heart failure prior
Adulticide therapy-Melarsomine dihydrochloride→done at least 3 months after starting a preventative
Decrease activity
Acanthocheilonema (Dipetalonema) reconditum-Hosts
Dogs
Acanthocheilonema (Dipetalonema) reconditum-Identification
mff distinguished from D. immitis mff by progressive movement, few relative number, blunt head, buttonhook or curved tail
Acanthocheilonema (Dipetalonema) reconditum-Diagnosis
mff identification in blood
