Nematodes of Dogs & Cats

Toxocara sp.

Significance the most important parasites infection at birth death: first two weeks (lung migration) larval migration

Morphology male = 4-10 cm female = 5-18 cm

T. canis cervical alae: - long & narrow - semilanceolate

cervical alae: - broader - arrow head

Life cycle modes of transmission: T. canis transplacenta transcolostrum direct ingestion paratenic host

Direct life cycle 10-15 d tracheal migration prepatent period 4-5 weeks age < 3 mths

Indirect life cycle prepatent period 3-5 weeks (neonates) (age > 3 mths) 10-15 d somatic migration transplacenta transcolostrum paratenic hosts > 42 d gestation

Life cycle Toxocara cati: direct ingestion paratenic host no prenatal transmission

Effect on host adult: no clinical signs puppies: severely affected, pneumonia

signs: vomiting, emaciation, potbelly, obstruction, dull coats death: 2-3 weeks after birth

Diagnosis T. canis T. cati

Infective stage Ascarid egg

SEM differentiation large, coarse pitted surface small, fine pitted surface Uga et al., Vetrinary Parasitology 92(2000): 287-294

Treatment ivermectin dichlorvos fenbendazole febantel pyrantel piperazine

Saprophytic soil fungi Paecilomyces sp. Ovicidal activity of T. canis (Basualdo J.A., 2000)

Use of ivermectin during pregnancy 1) dose: 300 mcg/kg on day 0, 30, and 60 of gestation - reduce # worms by 90% - reduce # eggs by 99.8%

Use of ivermectin during pregnancy 2) dose: 300 mcg/kg on day 0, 30, 60 of gestation, 10 d post whelping - reduce # worms by 100% - no eggs were passed in environ. (Payne P.A., 1999)

Selamectin dose: 6 mg/kg (6-12 mg/kg) reduce # adults by 93.9-98.1% topical administration dose: 6 mg/kg (6-12 mg/kg) reduce # adults by 93.9-98.1% reduce # eggs by 90-95% (McTier T.L., 2000)

Control good sanitation regular deworming anthelmintics: 2, 4, 6 weeks of age

Public Health visceral larva migrans (T. canis): children: chronic granulomatous liver, lung, brain, eye ocular larva migrans choroidoretinitis

Toxascaris leonina (arrowhead worm)

head: lanceolate cervical alae male: up to 7 cm female: up to 10 cm

Life cycle transmission: direct ingestion paratenic host no larval migration prepatent period = 8-10 weeks

Effect on host puppy: potbelly, intermittent diarrhea, poor condition, intestinal obstruction

Diagnosis T. canis T. leonina

febentel + praziquantel Treatment piperazine dichlorvos pyrantel fenbendazole febentel + praziquantel

Ancylostoma caninum (Hookworm)

Ancylostoma caninum Geographic distribution temperate climates worldwide Significance very important causes deaths (all ages) causes heavy blood losses

Morphology worms: red or gray size: up to 1.6 cm mouth: 3 pairs of prominent teeth

Life cycle modes of infection: 1. eating (infective eggs) 2. skin penetration (larvae) tracheal migration

Life cycle modes of infection: intrauterine infection transcolostrum paratenic host prepatent period = 15-18 days

H O K W R M S A N C Y L O S T M

Larval penetration คัน! moist eczema & ulceration

effect on dog “pale mucous membrane”

effect on dog “severe blood loss”

effect on dog blood vessels rupture & hookworms feed on the released blood (0.25 ml/day)

Ancylostoma caninum

Clinical signs factors: dose, age, immune status dermatitis puppy pneumonia diarrhea: dark in color (blood & mucus)

Clinical signs severe blood loss: iron-deficiency anemia edema, weakness, weight loss poor coat condition

heavy infection: frequently fatal within 2 weeks of birth in puppies

Diagnosis clinical signs fecal examination: fresh direct smear simple floatation 60 x 40 microns ovoid, thin-shelled, morulate embryo

Treatment supportive care: blood transfusions, iron supplement anthelmintics: fenbendazole, ivermectin, tetrahydropyrimidine (pyrantel)

Ivermectin + pyrantel ivermectin = 6 mcg/kg pyrantel pamoate = 5 mg/kg 99.6 % reduction of adult hookworms (Nolan T.J. et. al, 1992)

Doramectin 1 mg/kg on d30 of gestation reduce somatic larvae in bitches and adult hookworms in bitches and puppies (Schnieder, T. et al, 1996)

Moxidectin 1 mg/kg on d55 of gestation (5-8 d before parturition): completely prevent lactogenic infections in puppies. (Epe, C., 1999)

Deworming program CDC recommendation: bitch: fenbendazole in the 3rd trimester (kill migrating larvae) pups: 2, 4, 6, and 8 weeks of age

Control feces elimination keep kennel-floor dry regular deworming treat bitch with ivermectin

Effect on man Adult Ancylostoma caninum excretory/secretory antigens causes hypersensitivity in man human eosinophilic enteritis

Cutaneous larval migration

Cutaneous larval migration

Trichuris vulpis (whipworms)

Morphology size: 4.5-7.5 cm. anterior part: 3/4 of body, long & slender

Life cycle location: caecum infection: direct ingestion of infective egg

T R I C H U R I S L I F E C Y C L E prepatent period = 11-12 weeks

Effect on host intestine: irritation of caecum & large intestine profuse diarrhea, loss of weight, unthriftiness anemia in heavy infection

Diagnosis 70-90 x 30-40 microns Lemon-shaped with bipolar plugs

Treatment mebendazole fenbendazole dichlorvos febantel avermectins are not as effective.

Spirocerca lupi (esophageal worm)

Definitive host dogs Intermediate host coprophagous beetles lizards, chickens, mice (paratenic host)

morphology: red, coiled nematode 3-8 cm long

beetles encyst larvae esophagus thoracic aorta prepatent period 5-6 mths coeliac artery gastroepiploic artery adults in nodule (L1) beetles encyst larvae (L3)

Effect on host larval migration: aorta haemorrhage granuloma, stenosis aneurysm, rupture

Effect on host adult: embedded in the walls of aorta, esophagus and stomach

Effect on host adult: nodules, tumor nodules: interfere with swallowing, respiration and circulation

signs: persistent vomiting, wt. loss, hemoptysis aneurysm burst causes sudden death “esophageal sarcoma” 10% of infected dogs

Diagnosis floatation method radiography endoscopy necropsy

Diagnosis egg: small, oblong in shape, thick-shelled, larva inside 30-38 x 11-15 microns

Treatment fenbendazole avermectins

Control isolate infected animals dispose of the vomit and feces keep dogs from eating beetles, paratenic hosts

Strongyloides stercoralis (threadworms)

Morphology parasitic stage: pathenogenetic female size: 2-9 mm. long filariform esophagus

Life cycle host: dogs, cats, men direct life cycle: free-living, parasitic prepatent period = 7 days

Life cycle modes of infection: skin penetration ingestion (rare) hyperinfection (mucosal migration) autoinfection (perianal area)

Significance reinfection: kennel situation causes severe disease only in young animals heavy infection: death in puppies

Effect on host skin: dermatitis

intestine: irritation, catarrhal inflammation, mucosal erosion, necrosis signs: diarrhea (blood), low appetite, weight loss, dehydration, weakness, death

lung migration: alveoli destruction, ecchymotic hemorrhage, pneumonia

Diagnosis fecal examination larvae, eggs containing larvae 40-50 microns

Treatment Dichlorvos Fenbendazole Control clean & dry floor

Gnathostoma spinigerum

G. spinigerum size: 1-3 cm. long head bulb: “ballonets” head & anterior part: spines

Life cycle prepatent period: 7 months 1st int. host: Cyclops 2nd int. host: fresh water fish, reptiles location: stomach

Gnathostoma spinigerum nodule in the gastric wall cats, dogs nodule in the gastric wall eggs (L1) fish, frog, snake (L3) man Cyclops (L2)

Effect on host Cutaneous larva migrans: cause intermittent, migratory, painful, priritus swelling

Effect on host visceral larva migrans: cough, hematuria, ocular involment eosinophilic meningtitsis myeloencephalitis

Pathogenesis larval migration: liver damage, mesentery, diaphragm, thoracic cavity adult: migrate in stomach wall cavity, pus, cyst

Diagnosis egg: rare in feces Treatment no specific drug (albendazole)

Physaloptera praeputialis

Morphology size: 1.5-4.8 cm long body: large, thick, stout nematodes egg: contain a larva when laid

Life cycle host: dogs, cats, other carnivores intermediate hosts: crickets, cockroaches, beetles prepatent period = 41-83 days

location: stomach, duodenum worldwide distribution

Effect on host adult irritation: firmly attach to the lining of the gastric mucosa bleeding, mucosa erosion digestion interference

Clinical signs loss of condition vomiting (possibly bloody, mucoid) anorexia

Diagnosis fecal examination (floatation) small, oblong eggs containing larvae 40-58 x 30-34 microns

Treatment anthelmintics dichlorvos, benzimidazoles, avermectins control pets’ eating habits