SAM I Heartworm Flashcards
Which dogs are more likely to be infected with heart worm? Outdoor or Indoor
Outdoor dogs are more likely to be infected
How long can microfilaria released by adult female heart worms circulate in the animal?
Up to 3 years
Intermediate host of heart worm
Mosquitoes
Which stage of heartworm is inoculated by the mosquitos ?
L3
After 2-3 months where are the L5s carried to in the animal?
Caudal pulmonary arteries
How long after initial infection with heart worms do they begin releasing microfilaria into the blood?
6-9 months
Does the amount of worms in the dog affect the severity of pathology of the disease ?
NO
What intracellular bacteria is harbored by D. Immitis and contributes to the pathogenesis of heartworm disease?
Wolbachia spp.
Signalment of Canine Heartworm Disease:
Age
Sex
Breed
Age:Over 6 months
Sex: Outdoor Males
Breed: Large Breed Dogs from Endemic Areas(Southeast)
Severity of disease is determined by _____________.
Pulmonary Blood Flow
Small number of worms in dogs that exercise regularly cause more severe pathology than a large number of worms in dogs that are sedentary.
Which side heart failure is seen in dogs with heartworm?
Right sided congestive heart failure
Main sign of right sided congestive heart failure.
As cites
Definitive diagnosis of canine heartworm
ID microfilaria in the blood with Knotts or DiFil Test
Gold Standard for diagnosing heartworm.
Antigen Assay
What is commonly seen in hematology?
Thrombocytopenia
When using ultrasound what can you see in the right heart with heavy infections ?
Parallel hyperechoic lines
Main signs that are seen in radiographs with canine heart worm.
Right ventricular enlargement, prominent pulmonary artery at 1 o’clock (INVERTED D), enlarged lobar arteries(pruned or truncated).
What diagnostic tool is useful to characterize the severity of the LUNG lesions.
Radiographs
What diagnostic tool is used to confirm severity of disease in the heart?
Ultrasound
Goals of canine heart worm therapy.
- Begin animal on prophylaxis to prevent further infections
- Manage signs of moderate or severe lung disease and heart failure
- Kill microfilaria to stop the dog from being a source of infection
- Adulticide therapy
Preventatives kill what stage and age of larvae?
L3 and L4 up to 1 month of age
What preventative kills juveniles over 4 months of age?
Melarsomine
What drug could you add to the prophylaxis treatment that should kill Wolbachia and results in less lung pathology following adulticide therapy?
Doxycycline
At what age should you start a dog on prophylaxis?
6-8 weeks of age
What needs to be done to improve owner compliance of prophylaxis ?
Administer year round in all areas
Breaks under __________ months of prophylaxis administration should be reintroduced asap and then test the animal 7 months after the beginning of lapse in treatment.
5-7 months
Over 5-7 months of break should be tested first and then put on prophylaxis.
Term used to describe if treatments are missed for 3-4 months and then given for a year, there is still protection.
Reach Back Effect
Daily treatment effective against L3, L4 and microfilaria.
Diethylcarbamzaine
Monthly treatment that kills L3/L4 and most adult worms over 2-3 years.
Ivermectin
This drug can safely be given to Collies at a prophylactic dose.
Ivermectin
What drug is combined with Ivermectin that helps in killing adult worms in 9 months and when given prior to melarsomine therapy can decrease lung pathology?
Doxycycline
What treatment is effective against L3/L4 and is highly effective against microfilaria?
Milbemycin
Interceptor/ Sentinel
Monthly topical used in dogs and cats and approved in heartworm positive dogs because it sucks at killing adults and microfilaria.
Selamectin aka Revolution
Only product registered as a microfilaricide.
Moxidectin aka Advantage Multi, Proheart
Heart worm is caused by _______, transmitted by mosquitos.
Dirofilaria immitis
Remember that aspirin does NOT work!
Don’t use it!!
Heart failure as a result of heart worm should be controlled with what 4 drugs for 2 weeks before beginning adulticide treatment.
- Furosemide
- Arterial vasodilators
- Low sodium diet
- Digoxin/ Pimobendan
Pretreatment with what 2 drugs may prevent reactions from occurring during microfilaria therapy.
- Benadryl
2. Dexmethasone
What drug given with Ivermectin can reduce the risk of the development of resistance?
Doxycycline
Worms that survive after adulticide therapy are usually what kind of worms?
Antigen producing females
Heartworm antigen test should be negative by _______ weeks post adulticide treatment.
16 weeks
Why isn’t Thiacetarsamide (Caparsolate) no longer used?
Because it causes kidney and liver toxicities.
Drug of choice for heart worm disease
Melarsomine.
Rarely causes kidney and liver toxicity.
Use graded kill method for those with severe disease.
What condition is an inevitable consequence of successful adulticide therapy?
Pulmonary Thromboembolism
How long should you put the animal on cage rest after heart worm treatment?
4-6 weeks
What heart worm medication is given monthly and has slow adulticide activity with kills occurring over a few years?
Ivermectin
Which treatment can be used in animals with a large number of worms and severe changes in pulmonary vasculature?
Surgical removal of adult worms with alligator forceps.
Condition that occurs when there are adult D. immits in the pulmonary arteries but no microfilariae (amicrofilaremic).
Occult Heartworm Disease
Occult Heartworm Disease results from:
- prepatent infections
- reproductively senile worms
- unisex infections
- immune responses of the host from killing the microfilariae or preventing their release from the females
Condition where there is a heavy burden of worms (>40) that are in the pulmonary arteries and the right atrium and caudal vena cava.
Post caval syndrome
Treatment for Post Caval Syndrome
Jugular venotomy and removal of worms with forceps or retrieval basket.
What species are incidental hosts for heart worm?
CATS
Occult infection are very rare or very common in cats?
VERY COMMON
Is heart therapy effective in cats?
NOOOO
