Exam 1 Flashcards
What drugs have the best activity and widest margin of safety against GI nematodes?
Pyrantel Pamoate Fenbendazole (FBZ) -Hookworms -Whipworms -Roundworms Plus Ingredient in Heartgard Plus -Ivermectin does not have significant efficacy against GI, unless ~200 ug/kg . Also, concern with MDR1 mutant dogs, young animals where BBB not fully developed. MDR1 good for treating parasites in other tissues and systems
What are some treatments and control drugs for parasitic infection in dogs and cats?
Prevention:
-Puppies dewormed at 2,4,6,8 weeks of age.
-Shorter than PPP or ERP
-Suppressive treatment
Drug choices:
-Pyrantel Pamoate (Strongyid) Fenbendazole (Panacur/Safeguard).
Prophylactic treatment:
-Interceptor: (Milbemycin) @ 4 wks of age for hookworms, roundworms, whipworms.
-HeartGard Plus (IVM + Pyrantel) @ 6 wks of age.
-Advantage Multi (Imidaclorip + Moxidectin) @ 7 wks of age.
Control of prenatal and Perinatal Parasitic Infections
Fenbendazole (FBZ)
-Daily treatment from 40th day of gestation through 14th day of lactation.
-Prevention of hookworm and roundworm
Ivermectin
-Single dose 4-9 days prior to whelping and 10 days post appear satisfactory, lactogenic Ancylostoma prevention
-Heroic tx @ day 20 and 42 for Toxocara canis in puppies
-Significant concern with MDR1 (multi-drug resistance genetic mutation)
What are some methods of disease and infection prevention?
- Remove feces from yard, play areas, sand boxes, etc
- Wash hands following pet contact
- Clean dogs promptly when they roll!
- Parasite control involves use of effective chemotherapy and attention to hygiene.
Ollulanus tricuspis
Feline stomach worm
-Small < 1mm Life cycle: Direct Infective Stage: Larvae in stomach becomes infective Transmission: ingestion of vomited larvae by susceptible host. Auto-infection PPP: Clinical signs: -Chronic gastritis -Induced vomiting -Auto-infection significant worm burden Dx: -Worms in vomitus Tx: FBZ (Panacur), clean up vomitus,
Physaloptera sp.
Canine Stomach Worm
-Stout: 13-48 mm
-Superficially resemble Ascarids
-Two lips
-Cuticle around anterior end
-Live in anterior portion of duodenum near gastric valve
Life cycle: Obligate indirect
I.H: mice, frogs
-Crickets, cock roaches, mice and frogs (paratenic hosts)
Infective Stage: Thick shelled, larvated ~ 50 um diameter. eggs passed in feces, ingested by Intermediate host
Clinical Signs:
-Chronic gastritis, anorexia, dark feces, weight loss, ulcers. Immature worms in vomitus of puppies
Tx: CATS
-Pyrantel repeat 2-3 weeks
-IVM repeat 2 weeks
Tx: Dogs
-FBZ once per day for 3 days.
-Pyrantel
-Ivermectin repeat 2 weeks
Spirocerca lupi
Canine esophageal worm
-Coiled, pinkish worm
-30- 80mm
-Superficially resembles Ascarids
-Three lips
-Occurs in fiberous nodules in the esophagus, stomach, aorta.
Life cycle: Obligate indirect life cycle
I.H: frogs, mice, lizards may serve as paratenic host
PPP: 5-6 mts
-Infective stage: eggs passed in feces. ~30x12 um. Resemble paper clip
Clinical signs:
-Dysphagia, vomiting, esophageal neoplasia, bleeding lesions may cause anemia.
-Aortic aneurysm, and rapture seen on necropsy
Tx:
-Milbemycin 7 and 28 days, and 6 mts
Strongyloides stercoralis Intestinal threadworm (dogs, humans)
-Small thread-like worms
-Small intestine
-Only females parasitic ~2.2 mm
-Parthenogenesis (lay fertilized eggs without males)
Life Cycle: Direct
-Homogonic: parthenogenic females
-Heterogonic: free living females and males
Transmission:
-Lactogenic
-Percutaneous
-Ingestion
-Auto-infection: accumulation of significant worm populations in short period of time.
Clinical signs:
-Coughing
-Verminous pneumonia
-Diarrhea
-Dehydration
-Death
Zoonotic Potential
Dx:
-1st Stage larvae: ~380 um
-Direct smear
-Larvated eggs ~50x35 um on fecal float
Tx:
IVM: repeat in 4 weeks
Nothing effective for tissue stages
Hygiene
Zoonotic potential
Trichuris vulpis
Canine Whipworm
-Small whip-like worms ~30-50mm
-Females always larger
-Tiny buccal capsule w/ long esophagus
Life Cycle: Direct
Infective stage: Larvated eggs in environment (3 weeks)
Larvae hatch and develops beneath intestinal lining. Migrate to large intestine.
PPP: 90 days post infection adults in large intestine.
Clinical Signs:
-Dysorexia (anorexia?)
-Weakness
-Weight loss
-Intermittent vomiting, diarrhea
-Fluid brown diarrhea w/ mucus (flecks of red blood) in severe infections
-Electrolyte imbalance
-Hyponatremia, hyperkalemia
-Decreased sodium/potassium ratio
-Pseudo-Addison’s disease
Dx:
-fecal flotation eggs ~90x40 um
Tx:
-FBZ (panacur)
-Febantel
-Milbemycine
-Moxidectin
Prevention:
-Remove feces daily
-Monthly suppressive treatment
Capillaria sp.
-Small worms with whip like anterior
-Resembles Trichuris but smaller
Hosts:
-Reptiles, birds, mammals, fish
Life Cycle:
-Simple direct
-Facultative indirect
-Obligate indirect with intermediate host
Clinical signs/importance:
-Capillaria puttori: Cats, mustelids Alimentary tract
-Capillaria boehmi: respiratory tract/sinuses
-Capillaria plica, Feliscati: urinary tract
Species of zoonotic significance:
-C. hepatica, C. philippinensis
Trichinella sp.
Trichina worm
-Small worms 1.4-1.6 mm
-Tiny buccal capsule w/ long esophagus approximately equal to rest of the body
Life Cycle:
-Direct
-Occurs in small intestine of a wide variety of mammals including humans
-Infective larvae encyst in tissue of D.H.
-Larvae rapidly develops into adults and mate within 2 days
Transmission:
Ingestion of encysted larvae from infected meat
Zoonotic disease of humans
-Most current infections from contaminated bear meat ingestion
Ascarids
Roundworms
General
-Dioecious, sexually dimorphic, females larger
-Occupy small intestine of vertebrate hosts. Humans, dogs, cats, livestock, reptiles
-Feed on host ingesta
-Blockage of intestinal lumen
-Inflammatory response of the host
-Development of infective stage in the environment
-
Toxocara canis
Ascaris
Roundworm
-Large stout worms 7-18 cm
-Mouth with three lips
-Buccal capsule
Life cycle: Direct basic
Infective stage: Larvated eggs passed in feces 2-3 weeks development in environment
-Tracheal migration
-Larvae enter the hepatic blood supply
PPP: Adults 4-5 weeks
Arrested development in somatic tissue
D.H: dog
P.H: rat
Transmission:
-Vertical
-In utero 42 days of gestation
-Lactogenic
-Mother with sequestered larvae pass infection up to 385 days to puppies
Facultative indirect: “bridge an ecologic gap” Rodents P.H. larvae encysts in tissue
Patent infections: puppies < 3 mts Clinical signs: -Hyper infection: immune naive animals -Mechanical damage from migration through the alveoli leading to pneumonia -Irritation in gut as worms mature -vomiting, anorexia, and diarrhea -Hypo-proteinemia, pot belly Dx: -Worms in feces/vomitus young puppies -Older puppies > 3mts Dull haircoat -Poor BCS -Emaciated -Eggs: 75-90 um diameter, albuminous coat, pitted shell Tx: -Pyrantel pamoate 2,4,6,8 -Monthly prophylactic for 1st year of life -ERP: 21 days -Interceptor (Milbemycin) @ 2wks -HeartGard Plus (IVM + Pyrantel) @ 6 wks -Advantage multi (Imidacloprid + Moxidectin) @ 7 wks Most zoonotic disease in Iceland Potential for dog pet as host or transport vector for larvated eggs
Toxocara cati
Ascarids
Roundworms
-Prominent cervical alae
-Projections or cuticle
Life cycle:
-Direct: Ingestion of larvated eggs passed in feces 42-49 days post infection. Arrive in alimentary tract via tracheal migration. Eggs hatch and migrate in hepatic blood supply
-Facultative indirect: adult cats eat infected paratenic host (infected meat larvae activated and travel to small intestine)
-Vertical transmission:
-No in utero infection
-Lactogenic when queen is acutely infected during late gestation
May be zoonotic threat
Clinical signs:
-Coughing, gagging, like chocking on a hair ball.
-Worms in feces/vomitus of infected host
Dx:
-Eggs: round pitted shell, sticky albuminous coat. ~60-70 um diameter.
Tx:
-Pyrantel pamoate suspension, no FDA approval
-Pyrantel/Praziquantel (Drontal) FDA approved
-Selemectin, Ivermectin, other drugs also effective
Toxocaris leonia
Ascarids
Roundworms
-Dogs and Cats similar to T. canis, and T. cati Life Cycle: Direct Infective stage: larvated eggs or ingestion of paratenic/intermediate host. -No tracheal migration -No in utero infection -No lactogenic transmission Minor zoonotic significance Clinical signs: -Worms in feces, vomitus Dx: -Eggs: round to slightly oval. Light translucent single cell embryo. 85-90 um diameter
Bylisascaris procyonis
Ascarids
Roundworms, Raccon
-Large stout worms
-Cervical alae inconspicous (vestigal)
-Worms much larger than T. canis, T. cati, but eggs are smaller
Life Cycle:
-Direct: ingestion of larvated eggs from contaminated latrines
-Facultative indirect: ingestion of paratenic/intermediate host.
PPP: 50-76 days post infection
-No tracheal migration
-No in utero transmission
-No lactogenic transmission
Intermediate Host:
-Aggressive somatic migration
-Continues to grow in size
-Neurotropic
Eggs ~ 65 um in diameter
Zoonotic Toxocariasis
Ingestion of infective eggs from fecally contaminated areas.
Ocular larval migrants
-Older children 7.5 yrs old
Males more often
10,000 cases per year
-Unilateral, strabismus, anterior leukoria, suspected retinoblastoma
-Large elevated white granuloma on retina or optic disk.
Symptoms:
-abdominal pain, headache, weakness, lethargy, fever, coughing, asthma, pneumonia.
-Low morbidity, low mortality
Prevention of zoonotic Toxocariasis
-Pyrantel pamoate 2,4,6,8, and monthly for 1st year of life.
-Most common heartworm drugs accomplish this
-Hygiene
The Hookworms
Ancylostoma caninum, A. tubaforme, A. braziliense, Uncinaria stenocephala.
Joseph Leidy
Voracious blood suckers
Ancylostoma caninum
Canine Hookworms
-Small worms 10-16 mm
-Large buccal cavity
-3 pairs of teeth
-Males with copulatory bursa
Life cycle: Direct
Infective stage:
-Larvae develops in environment 7-14 days after eggs are shed in feces
Transmission:
-Skin penetration
-Oral ingestion: older animals >12-15 wks
-Lactogenic routemost important
Tracheal migration to somatic tissues
-Arrested development of larvae
Adults in small intestine
-PPP: 17-21 days following infection
Lifespan: 12 to 18 months in absence of reinfection
Clinical signs:
Anemia in about 8 days post-infection
Peak blood loss between 15th and 18th day post infection Puppies
***Nursing puppies may pass eggs as early as 10-12 days after birth
Paratenic host: “bridge the ecologic gap”
Ancylostoma caninum types of clinical disease
- *Peracute in neonatal puppies
- Significant blood loss
- Microcytic, hypochromic anemia within hours to days (8 days)
- Pale mucus membranes (almost white)
- Diarrhea w/ black tarry stools, partially digested blood
- Naive immune status
- Deficient nutrition
- *Acute older puppies or even adults
- Cumulative process with prolonged exposure and progressive acquisition of additional worms
- Normochromic, normocytic anemia that becomes hypochromic, microcytic.
- *Chronic:
- Presence of infection without clinical signs
- PVC < 30%
- *Secondary compensated disease
- Older dogs primarily
- Malnourished animals
Ancylostoma caninum Dx
**Peracute disease
-Neonatal puppies showing profound anemia
-Tarry diarrhea
-PCV <20%
-Fecal exam may be negative
Dx:
-Eggs: thin shelled morulated ~ 60x40 um
-Symptoms, noticeable
Older animals >3-4 mts
-PVC <27% to <30%
-Low weight for age
-Poor hair coat
-Eggs in fecal exam
**Secondary De-compensated Disease
-Older animal >3 or 4 mts
-Clinical signs vary ADR
-Dermatitis in lower extremities/feet
-Underlying metabolic or metastatic disease
+TX of clinically ill animals:
**immediate antihelmitic treatment (single dose Pyrantel, suspension)
-Supportive care, blood transfusion, iron supplements, electrolytes
-Pyrantel is the drug of choice
-Fast acting
+Tx no clinical signs
-Pyrantel pamoate 2,4,6,8
-Fenbendazole
-Heartworm prophylaxis
***PPP: 21 days
Prevention of prenatal infection:
-40th day of gestation to 14th day of lactation
-IVM 4-9 days prior to whelping and 10 days post whelping
-Post treatment evaluation should be taken 7-10 days after
Ancylostoma tubaforme
Feline hookworm
-Eggs on fecal slightly smaller than caninum
Infection:
-Percutaneous route, Paratenic Host most important.
-Tracheal migration
-Adults in small intestine
Rodent plays a significant role
Ancylostoma braziliense (dog and cat)
Endemic to Southern US
-No vertical transmission
-Prefers warmer climate
Clinical significance is not clear
Uncinaria stenocephala (dog, cat, fox)
Primarily endemic in temperate climates -Cutting plates, no teeth Eggs: -70-90 x 40-50 um Primary route of transmission in sea lion and seals -Lactogenic Minor clinical significance in dogs Tx: -Milbemycine not effective -Ivermectin only 1/2 effective
Zoonotic Considerations
Cutaneous larval migrants L3 skin penetration Hypersensitivity from previous infections Visceral larval migrants -Loeffler's syndrome -Reach pulmonary circulation -Often self-limited Zoonotic potential justification for yearly fecal exams
