Exam 2 Flashcards
Which parasite is responsible for Nasal Acariasis?
pneumonyssoides caninum/nasal mites
What drugs can you use to treat nasal acariasis? Which ones are FDA approved?
Imidacloprid/moxidectin, milbemycin oxime, selamectin, ivermectin,
none are approved
Which parasite is responsible for nasal capillariasis?
Eucoleus boehmi
What is the diagnostic stage of E. boehmi? Describe its morphology.
Embryonated egg
Yellow-brown, bipolar plugs, asymmetrical poles, smooth walled, embryo does not fill egg completely, barrel shaped egg,
Higher plane of view may reveal pitted surface on one end of egg underneath the plug
What drugs can be used to treat E. boehmi? Which ones are FDA approved?
fenbendazole, ivermectin, imidacloprid/moxidectin, milbemycin oxime
None are FDA approved
What do you have to worry about when treating dogs for E. boehmi with ivermectin?
Ivermectin toxicity in predisposed breeds
Which parasite is known as the “Lungworm”
Eucoleus aerophilus
Describe the life cycle of Eucoleus aerophilus
Eggs are shed in feces, develop in environment to become larvated (infective), larvated eggs are ingested and larvae hatch and migrate to lungs, mature in fine bronchioles and alveoli, adults deposit eggs inside lungs and the eggs are coughed up and swallowed to be shed in feces
Which drugs can be used to treat Eucoleus aerophilus? which of these are FDA approved?
Dogs: Fenbendazole and ivermectin
Cats: moxidectin
NPA
What drug is effective against T. vulpis, E. boehmi, and E. aerophilus?
Moxidectin
Name where each of these parasites live in the D.H.
T. vulpis, E. boehmi, E. aerophilus
T. vulpis: colon and cecum
E. boehmi: nasal turbinates and sinuses
E. aerophilus: bronchi and trachea
How can you distinguish T. vulpis, E. boehmi, and E. aerophilus eggs from each other
T. vulpis: symmetrical bipolar plugs, smooth shell, embryo fills entire egg
E. boehmi: asymmetrical bipolar plugs, embryo does not fill entire egg, smooth shell
E. aerophilus: symmetrical/asymmetrical bipolar plugs, rough/striated shell, embryo fills entire egg,
You find a Capillaria egg in your cat’s feces, how can you determine if your cat is being parasitized by a feline capillaria or a rodent/bird capillaria
Confine cat for 3 days and recheck fecal for eggs. No eggs = cat was just passing capillaria eggs from ingesting an infected animal. Yes eggs = cat is being parasitized by feline capillaria
True/False: cats and dogs can be infected with Filaroides osleri
False, Filaroides osleri only infects dogs, coyotes, and wolves
What other parasite have we covered also forms nodules similar to Filaroides osleri?
Spirocerca lupi, forms esophageal nodules
What is unique about the larval stage of Filaroides osleri
Diagnostic and infective stage are the same (L1 larvae)
Where does development of all 5 stages (L1-Adult) of Filaroides osleri occur?
Lungs
What are the different ways a dog can get infected with Filaroides osleri?
Ingestion of L1 larvae (in feces), vomitus/saliva/stomach contents containing L1, bitch –> pups during cleaning
How can you diagnose a Filaroides osleri infection?
Sedimentation exam (look for L1 larvae) or endoscopy (look for nodules at tracheal bifurcation)
How can you differentiate Filaroides osleri larvae from S. Stercoralis larvae?
F. osleri larvae have “S” shaped tail with a slight kink
S. stercoralis have a straight tail and are recognized by prominent genital primordium
What drugs can be used to treat F. osleri infection, which ones are FDA approved?
Fenbendazole and ivermectin
NPA
How can you tell if F. osleri infection has been cleared?
- Disappearance of clinical signs
- resolution of nodules
- disappearance of larvae from feces
What is the domestic host for Aleurostrongylus abstrusus?
Cat
Describe the life cycle for A. abstrusus
Female worm deposits eggs in bronchioles and alveoli, L1 larvae hatch and move up airways via mucociliary action and are coughed up and swallowed to be shed in feces. Larvae molt to L3 in snail/slug I.H. which is ingested by a cat and migrate back to lungs
Is the severity of clinical signs correlated to degree of infection for A. abstrusus?
Yes
What diagnostic technique can you use to recover the diagnostic stage of A. abstrusus? Describe the morphology of the diagnostic stage
Baermann technique
L1 larvae, curled body with S-shaped tail that has a small spine, 350-390 um long
What drugs can you use A. abstrusus infections and which ones are FDA approved?
Emodepside/praziquantel, Imidacloprid/moxidectin, selamectin
none are approved for treating this specific worm, but these are all approved drugs for treating other parasites in cats
Which parasites are responsible for “Paragonimiasis”
lung flukes
Why is Paragonimus kellicotti only found east of the Rocky Mountains?
Its snail I.H. is only found east of the Rockies
What is the life cycle of P. kellicotti?
What is relatively unique about its lifecycle?
Eggs are coughed up and swallowed –> eggs are passed in feces –> miracidium hatches and penetrates snail (I.H. #1) –> cercariae leave snail to penetrate crayfish (I.H. #2) –> encyst as metacercariae –> ingested by D.H. –> excyst in the intestines –> penetrate abdominal cavity –> migrate to lungs and encyst to mature flukes (live inside cysts)
2 I.H.’s, paratenic host (rat) may ingest crayfish and have metacercariae encyst in tissues
What are your diagnostic options for Paragonimus kellicotti?
Sedimentation for egg recovery or radiographs for cyst and nodule detection in liver
What drugs are available to treat P. kellicotti?
Which ones are approved by FDA?
Fenbendazole, Ivermectin
NPA
Is Paragonimus kellicotti zoonotic?
Yes, radiographs look similar to tuberculosis, flukes can mature and reproduce in humans, treat humans with praziquantel
What natural definitive host serves as a reservoir for Dirofilaria immitis?
coyotes
What is the length of microfilaria? Diameter?
270-340 um long, 6-8 um wide
Detail the life cycle of Dirofilaria immitis
Females in pulmonary arteries deposit microfilariae into curculation, mosquito feeds on infected dog and ingests microfilariae in the process, microfilariae undergo change from L1 to L3 (infective stage) within 8-30+ days, L3’s migrate to salivary glands of mosquito, mosquito feeds on uninfected dog and deposits L3 larvae AROUND the bite wound, L3 migrate into opening made by bite wound and reside in SC tissue where they molt to L4 within 3-12 days post infection, L4 migrate through to SC tissues or muscles in thorax and molt to immature adults within 45-70 days post infection, immature adults enter circulation and are swept into pulmonary circulation within 70-120 days post infection, immature adults mature and mate and females produce microfilariae 6-7 months post infection
T/F: microfilariae = L1 larvae
T/F: L1 larvae are infective stage
T/F: Mosquitos do not actually deposit L3 larvae directly into the D.H.
False
False (L3 are infective stage)
True
Can you have a persistent heartworm infection in a cat population if there are no dogs/coyotes nearby?
No
Which stages of the D. immitis life cycle can be found in circulating vasculature?
Microfilaria, Adults
Which life stages of D. immitis can only be found within the mosquito?
L1, L2, L3
Where are the L4 larvae of D. immitis found?
in the SC tissues and thoracic (intercostal) muscles of the D.H.
What happens to placentally transmitted microfilariae?
When should you start adminsitering heartworm preventatives?
They will not mature past microfilariae stage (require mosquito I.H. in order to continue development)
As early as the label allows
What differences will there be in terms of L3 larvae inside the body of a dog who has lived outdoors in area with a high prevalence of heartworm disease vs. a dog that has lived indoors its entire life?
Outdoor dog will have built up immune system towards D. immitis and will kill most L3 larvae.
Indoor dog will not be able to fight off L3 infection much and will have a more severe infection in the long run
In most dogs, clinical signs of heartworm infection will not manifest until _______
the worms mature
T/F: Number of worms is more important than activity level of the infected dog in terms of severity and progression of disease
False, activity level may be more important
What are the pathological possibilities of adult heartworm burdens? (hint: 5 main outcomes)
1) Progressive pulmonary hypertension –> right ventricular hypertrophy
2) Obstruction of blood vessels and heart chambers and valves
3) inflammatory mediators induce immune complex glomerulonephritis
4) Caval Syndrome (sudden exposure to large number of worms –> accumulation of immature adults in posterior vena cava)
5) Wolbachia pipientis - gram (-) parasite of D. immitis that produces endotoxins
What is required for D. immitis to progress to L4 larva stage
Wolbachia pipientis symbiote
What pathology can you expect from microfilariae?
1) obstruction of fine capillaries
2) immunological response to death of microfilariae may form immune complexes within glomeruli and impair kidney function –> proteinuria
How does Caval Syndrome occur?
If a dog is fed on by large number of mosquitoes (within few days of each other) harboring many L3 larvae that that all mature in close proximity, leading to obstruction of right atrium, tricuspid valve, and posterior vena cava
What do D. immitis antigen tests look for?
Female worms (female uterine antigen)
What is the earliest age you should run a heartworm antigen test? (according to American Heartworm Society)
7 months
What are the ways in which you can get a false negative antigen test?
1) low worm burden may not be detected
2) Immature females (recent infections)
3) male only infections will show up as false negative
4) Not allowing test kit to warm to room temp
5) dogs/cats who have already been exposed previously may have antibodies in circulation that bind to antigen, making it unavailable to bind to antigen test
What does a negative test result tell you on an antigen test? If you want to make a reasonable assurance that the animal is truly free of adult heartworm infection, what can you do after getting a negative test result on an antigen test?
all a negative test says is that no antigen was detected which is not the same as no worms detected, or that there are even no antigens
You can conduct another test (separate, different test)
How can you get a false positive antigen test result?
1) well-type tests in which the wells were not properly washed
2) cross reaction with other antigens (from Spirocerca lupi infection)
3) other unknown antigens or test error
4) residual circulating antigen following elimination of adult worms (recent treatments)
When would be an optimal time to run an antigen test (for D. immitis) on a patient?
late afternoon due to nocturnal periodicity of microfilariae
What is the correlation between number of microfilariae and number of adult worms
Low
What parasite has microfilariae that can be confused with D. immitis microfilariae?
How can you differentiate the 2 microfilariae?
Acanthocheilonema sp.
Acanthocheilonema sp. :have blunt body anteriorly, may have button hook tail, generally thinner and shorter in body size than D. immitis. Produce few microfilariae, these are capable of moving across a glass slide
D. immitis: have tapered body anteriorly, straight tails, body size overall is larger than Acanthocheilonema sp., D. immitis microfilariae are 270-340 um long, do not move across glass slide
What does it mean if your patient has an occult infection of D. immitis?
Adults are present but there are no microfilariae
This can be due to having a prepatent infection (sexually immature worms), unisex infections, drug-induced reduction of microfilariae, immune-mediated clearance of microfilariae (animals who have had previous exposure and developed some immunity)
What are some scenarios in which you would want to conduct a microfilaria test in tandem with an antigen test?
Dogs with low number of female worms can be antigen negative but microfilaria positive
Dogs with immune complexes binding female antigen could be antigen neg. and microfilaria positive
Early developing infections in some dogs can be antigen negative and microfilaria positive
What kind of drugs are current heartworm preventatives?
macrocyclic lactones which are avermectins and milbemycins
avermectins to note: ivermectin, selamectin
milbemycins: milbemycin oxime and moxidectin
What are the dosages, routes of administration, and frequency for treating heartworms with ivermectin, milbemycin oxime, moxidectin, and selamectin?
Ivermectin @ 6.0 ug/kg, oral. monthly
Milbemycin oxime @ 0.5 mg/kg, oral, monthly
Moxidectin @ 0.17 mg/kg, injectable, 6 months
Moxidectin @ 2.5mg/kg, topical, monthly
Selamectin @ 6.0 mg/kg, topical, monthly
Which stage of the D. immitis life cycle is targeted by monthly preventatives?
L3 and L4 larvae in SC tissues
microfilariae - but this is not part of the preventive action
What are the 3 desired outcomes of treating a dog, with a macocyclic lactone, infected with heartworms?
prevent further infections, prevent maturation of (kill) L3 and L4 larvae that may be present, eliminate infected dog as a potential reservoir
administration of _______ @__mg/kg BID for _____ prior to treatment is to eliminate _____ from _______ before adulticide treatment
This will ______ the pathology associated with worm death
Doxycycline, 10, a month, Wolbachia, D. immitis, lessens
What is an important part of treatment in a heartworm positive dog that does not involve the use of drugs?
Exercise restriction (cage rest, sedation, walking on a leash) in order to reduce chance for pulmoanry embolism
What drug is an FDA approved adulticide for D. immitis?
What is the dosing regimen for this drug?
Melarsomine - deep I.M. injection
Split dosing into a 3 dose regimen
1st dose at 2.5 mg/kg then 1 month later give a 2nd dose 2.5 mg/kg then 24 hours later give 3rd dose at 2.5 mg/kg
When would a surgical approach be most appropriate for treating D. immitis infection? What other treatment is involved in this approach?
Use surgical approach in caval syndrome, Sx is followed by 2-3 dose course of melarsomine because it is likely that not all of the worms were removed during the surgery
When switching from 1 heartworm preventive to another, when should you test the patient for heartworms?
when the switch occurs, 6m after switch, 12m after switch, then annually
this way you can completely evaluate efficacy of new preventive
Cats are ______ but ______ hosts to D. immitis
resistant, susceptible
?/3 of D. immitis infections are single gender infections in cats.
1/3
How many adult worm(s) are needed to kill a cat?
just 1 is enough
For D. immitis in cats,
PPP=?
life span of adults =?
microfilaria are common/uncommon and numbers are high/low
Low/high mortality of immature adults as they first reach lungs
PPP = 7-8months
Life span = 2-3 yrs
Microfilaria are uncommon and numbers are low
high mortality
What is needed in the environment to have heartworms in cats?
nearby reservoir of infected dogs/coyotes for mosquitoes to feed on
What is HARD?
What happens in stage 1 of this in cats?
How may a cat present to you clinically if it has stage 1 HARD?
Heartworm Associated Respiratory Disease
75-100 days after infection: Immature adults arrive at caudal pulmonary arteries. Intense inflammatory response from lungs, type II cell hyperplasia and activation of pulmonary intravascular macrophage which results in occlusive medial hypertrophy of small pulmonary arterioles & bronchi, bronchioles, alveoli, and pulmonary arteries
asthma-like symptoms
True/False: a cat can have mild to severe life-threatening respiratory disease and have no mature heart worms
True
When does Stage 2 Hard occur?
Do the heartworms that survive the initial immunological reaction in the cat cause much pathology?
What happens when these adults die?
Can this intense immune reaction be stimulated from just a single worm dying?
1-3 years post infection
No
Intense immunological reaction in cat, lungs become extremely inflamed and PIM become key players in intense reaction, resulting in non-functioning lung and acute respiratory distress syndrome
Yes
What is responsible for the life-threatening event in HARD?
actue edema of lung leading to respiratory failure or heart failure?
lung failure
Where might you find adult heart worms in a cat on necropsy?
polumonary arteries, lobar arteries of the lungs, right ventricle & atrium, posterior vena cava
Is aberrant migration more common in cats or dogs?
Cats
Are single sex or multi sex worm infections more common in cats?
Why might this be?
single sex
Cats are not natural definitive host
How many adult worms are needed to cause sudden death in a cat (due to acute pulmonary infarction and lung injury)
1
What 2 serologic methods are available for HW testing?
Adult female uterine antigen test
Antibody directed against molting larvae
Why is antigen testing not very reliable in cats?
More common in cats to have male only infections, tend to have low worm burdens thus low female count, symptomatic immature infections, immune complexes bind antigen
What is the general rule of thumb on interpreting antigen tests for HW disease in cats?
Can trust a positive result, can not trust a negative result
Antibody testing:
what does this test detect?
How soon can you get a positive AB titer
How long does it take for L3 to molt to L4
What does a positive test result mean?
Does a positive Ab test indicate presence of adults?
detects antibodies produced in cat in response to early migration (molting) of L3/L4 larvae
1-3 months post infection
3-12 days
Exposure to infective larvae
No
Can AB positive, but heartworm negative cats (no adults at necropsy) have hypertrophy of pulmonary arterial walls?
Yes
Are radiographic signs to help diagnose heartworm disease more prominent in dogs or cats?
What about ultrasound?
Dogs
Cats
Most feline heartworm cases are/are not amicrofilaremic, thus ______ test will typically be postive/negative
are, Knott’s, negative
What ultrasonography finding is indicative of HW disease
presence of double-lined echodensity in main pulmonary artery
Why is treating/not treating adult heartworms in cats a lose-lose scenario?
treat: killing worms with adulticide all at once can cause acute complications
do not treat: waiting for cat to clear infection on own over several years and continue to suffer or risk of acute crisis in future
HW Dz:
Melarsomine Tx in cats is/is not recommended. Melarsomine in cats/dogs is more toxic
Typical treatment in cats is _______
is not
cats
supportive Tx (parenteral fluids, prednisolone, oxygen therapy, cage rest)
What prophylactic drugs are available for HW’s in cats?
Ivermectin, milbemycin oxime, moxidectin, selamectin
For these prophylactic drugs (for HW’s) for cats:
What are the dosages and route of administration for each drug?
Selamectin
Moxidectin
Ivermectin
Milbemycin oxime
Selamectin: 6mg/kg topically
Moxidectin: 1.0 mg/kg topical (2.5x lower than dose in dogs)
Ivermectin: 24 ug/kg oral (4x dose of dogs)
Milbemycin oxime: 2mg/kg oral (4x dose of dogs)
What is the vector for Babesia canis?
Rhipicephalus sanguineous (Brown Dog Tick)
What life stage of Babesia spp. is found within erythrocytes?
trophozoite stage ( feeding stage-piroplasms)
Generally, what distinction can be made from Babesia canis piroplasms and Babesia gibsoni piroplasms?
B. canis: larger (2.5 um), occur as paired trophozoites (piroplasms)
B. gibsoni: smaller (1.9x1.2 um) tend to appear as single piroplasms,
Describe the life cycle for Babesia canis vogeli, starting from piroplasms in the blood
Piroplasms and/or merozoites are taken up by tick when it feeds on infected dog –> piroplasms undergo gametogony –> sporozoites –> migrate to salivary glands/ovaries of the tick –> infect dog with sporozoites when tick feeds
Is the tick or the dog considered the intermediate host in Babesia canis vogeli? Why?
The dog
B/c Babesia undergo gametogony in the tick, infective stage is in the tick,
What happens when a Babesia merozoite stage is released from a destroyed RBC?
it invades other RBC’s or are taken up by a tick
T/F: with Babesia infections, you do not have to be worried about transplacental transmission to the puppies from the mother
False, transplacental transmission can occur
What modes of transmission can Babesia undergo inside the tick?
Transstadial: transmitted from life stage to life stage
Transovarian: babesia organisms transmitted from infected female tick through her eggs to the progeny
Which life stages are part of transstadial transmission in the tick?
larva-nymph-adult
What is the suspected mode of transmission of Babesia gibsoni?
inoculation from infected blood during dog fights
Transplacental transmission has been documented as well
When are Babesia canis vogeli cases seen in dogs
adults/puppies that are stressed