Heartworm Disease III- CardioRush
Anaphylaxis risk high
Why shouldn't you give high dose ivermectin to kill off microfilaria rapidly?
Progressive pulmonary pathology occurs during long kill period (30 months), very prolonged exercise restriction
Why would relying on the preventative dose of ivermectin for slow kill of adult worms be an unacceptable approach?
False (some dogs require sedation or analgesia, which is fine)
True or false: you should never give sedation or analgesia when administering melarsomine, it may interact with the adulticide therapy
Selamectin, moxidectin
What HW preventative drugs can be used in cats and are easier to use because they are topical?
Severe systemic disease, RCHF, pneumonitis
What animals must be stabilized before adulticide treatment?
Ivermectin, milbemycin, selamectin, moxidectin
What are some examples of macrocyclic lactones used for HWD prevention?
Pulmonary artery enlargement, bronchointerstitial pattern
What are some possible radiographic findings consistent with feline HWD?
Local pain, inflammation, malaise, GI signs, reversible paralysis or neuro signs, pulmonary edema idiosyncratically, renal or hepatic tox, PTE, death
What are some possible side effects of adulticide therapy?
Pleural effusion (echo free space outside the cardiac wall)
What are the arrows pointing to?
Lengthier exercise restriction, increased cost of extra dose, increased total arsenical dose
What are the cons of using the split dosing protocol for adulticide treatment?
Double line structure in PA or R heart, RV enlargement, septal flattening, effusions, evidence of PHT
What are the echo findings consistent with HWD?
Enlarged RV, pleural effusion
What are the findings on this echo?
Confirm diagnosis, give doxy 10mg/kg BID and monthly HW preventative for 1 month, give melarsomine after 2 months
What are the general recommendations for HW treatment?
Kill Wolbachia, eliminate MF, kill adult worms, minimize pulmonary parenchymal and arterial pathology, treat RCHF and PHT is present
What are the goals of HW treatment?
Exercise restriction, doxycycline, ivermectin, corticosteroids, anticoagulants, O2, phosphodiesterase inhibitors for PHT, RCHF therapy
What are the important ancillary therapies in HW treatment?
Cough, hemoptysis, fever, dyspnea, sudden death
What are the signs of PTE in dogs following adulticide treatment?
Correct dose, needle size for body weight, change needle between drawing and injecting, deep IM epaxial injection between L3-L5, firm pressure for 5 minutes at injection site
What aspects of giving melarsomine are extremely important to follow?
Heartgard, Triheart, iverhart
What brandname HW preventative have ivermectin as the main ingredient?
Trifexis, interceptor, sentinel
What brandname HW preventative have milbemycin oxime as the main ingredient?
Advantage multi, proheart 6
What brandname HW preventative have moxidectin as the main ingredient?
Revolution
What brandname HW preventative have selamectin as the main ingredient?
PHT increases RV pressure, flattens septum
What causes septal flattening on echo?
Severity of PHT, caval syndrome, cor pulmonale, parasite burden, concurrent heart disease
What characteristics are you checking for when performing an echo on a dog with HWD as supplemental diagnostic?
Asthma
What disease is often confused for feline HWD based on radiographs and signs?
Geriatric dogs with low or high worm burdens, dogs with severe systemic disease, dogs who have adverse reaction to melarsomine
What dogs are good candidates for the slow kill approach to HW treatment?
50mg/kg
What dose of ivermectin can be used extalabel to RAPIDLY kill microfilaria?
Doxycycline
What drug can be paired with ivermectin to expedite the slow kill process for microfilaria control?
Macrocyclic lactones
What drug class is the mainstay of HWD prevention?
Ishihara
What forceps are used for HW extraction?
Susceptibility gap
What is decreased by pretreating with macrocyclic lactones before adulticide treatment?
Doxycycline 10-20mg/kg/day
What is given in combination with preventative doses of ivermectin in the slow kill approach to HW treatment?
Arsenical compound
What is is melarsomine made of?
Jugular venotomy, sedation or anesthesia, local block
What is required to surgically extract HWs in caval syndrome?
HW
What is the arrow pointing to?
HWs
What is the arrow pointing to?
Controlled, staged killing, lungs have time to recover before 2 doses, kills 98% of worms
What is the benefit of the split dosing protocol for HW adulticide treatment?
Enlarged PA
What is the cursor pointing to?
Primary diagnostic tool to confirm diagnosis
What is the diagnostic importance of performing an echo in a cat to diagnose HWD?
Supplemental to serology
What is the diagnostic importance of performing an echo in a dog to diagnose HWD?
6-12mg/kg
What is the dose of ivermectin given for HW prevention?
Sterile, no larvae produced
What is the effects of macrocyclic lactones of the reproduction of adult female worms?
10-20% (more common than FeLV or FIV)
What is the feline infection rate of HW in endemic areas compared to that of dogs?
Septal flattening
What is the finding on echo?
Melarsomine
What is the mainstay of adulticide therapy for treatment of HW?
Corticosteroids
What is the mainstay of treatment is a cat symptomatic from HW infection?
Moxidectin/imidacloprid (Advantage multi)
What is the preventative of choice to use with doxycycline in the slow kill approach?
Kill L3 to L4 stage
What is the purpose of administering monthly HW preventative for 1-2 months before adulticide treatment?
Kill Wolbachia
What is the purpose of giving doxy for a month before adulticide treatment?
L3 and L4 target stages are around for more than a month, so when a single dose is missed, they can be killed with the next month dose
What is the reachback effect referring to in HW prevention?
Initial single injection following in 1-3 months by 2 doses 24 hours apart
What is the recommended adulticide therapy protocol?
Doxycycline and macrocyclic lactones
What is the recommended treatment for HW before adulticide is used?
Surgical extraction prior to melarsomine
What is the recommended treatment for dogs with caval syndrome?
Symptomatic dogs
What is the split dosing protocol required to treat?
Juvenile HW stage that isn't susceptible to either preventative or adulticide
What is the susceptibility gap in HW treatment?
Caval syndrome (when image plays, you can see the mass of worms moving between the RA and RV)
What is this finding?
L4, early L5
What life stage of HW is NOT susceptible to melarsomine?
L5, adults
What life stages does melarsomine target?
Moxidectin
What macrocyclic lactone is available as a 6 month slow release injectable?
96%
What percentage of adult worms were kills after doxy and Moxidectin/imidacloprid use for 10 months?
10-20%
What percentage of cats may die suddenly from HW infection?
HW test
What should you with a cat that presents with coughing before diagnosing it with asthma?
Caval syndrome (stage 4)
What stage of HWD can you NOT use adulticide treatment for in dogs?
L3, L4
What stage of the HW lifecycle is targeted by macrocyclic lactones?
Severe renal or hepatic disease
What underlying diseases should you use caution in when giving adulticide treatment?
Prevent transmission
Why is it important to eliminate microfilaria during HW treatment?
High die off increases risk of side effect, 10% may still remain
Why is the original dosing recommendation of 2 injections 24 hours apart no longer recommended?
Worm toxicity confined to L3 to L4 molt, had to give daily, could cause shock
Why isn't DEC used as a HW preventative anymore?
Rapidly microfilaricidal, may result in shock
Why isn't milbemycin oxime (interceptor, trifexis) recommended in microfilaremic dogs?
Very sensitive to antigen, high risk of death
Why should you not perform surgical extraction for caval syndrome in cats unless they are severely affected by the presence of the worm in the heart?
False (variable radiographic signs make it harder to diagnose)
True or false: Feline HWD presents consistently with the same radiographic findings
True
True or false: Melarsomine is safer and more effective than Na carparsolate, but there are still severe side effects
False (not all dogs are good candidates, some owners not interested)
True or false: in practice, adulticide is a good option for all HW positive dogs and most owners are on board for treatment
False (NOT protective)
True or false: indoor only status is protective against HW in cats, so no prevention is required
False (NEVER use any adulticide in a cat, it will kill them)
True or false: only certain adulticide treatments for HW can be used in cats
8 weeks
At what age should you start a HW preventative in dogs?
False (ALL animals get PTE accompanying worm die off, which is why we need to minimize risk)
True or false: only some animals get PTE as a result of worm death
True
True or false: rapidly microfilaricidal drugs, such as high dose ivermectin, should only be given to dogs that are known microfilaria negative
False (the low dose is safe for any dog or any breed)
True or false: the HW prevention dose of ivermectin is only safe in breeds without the MDR1 mutation
True
True or false: the HW prevention dose of ivermectin is safe for use in all dogs regardless of HW or microfilaria status, but the owner should monitor for the first 24 hours to look for signs of anaphylaxis
False (risk of inflammation is greater, so steroids are used)
True or false: the risk of hypercoagulability is greater than the risk of inflammation in HW, so corticosteroids are avoided
False (melarsomine is still considered the best option and slow kill is not recommended)
True or false: the slow kill approach to adulticide treatment of HW is the standard of care recommended by the AHS
False (required for symptomatic dogs, recommended for all dogs needing adulticide)
True or false: the split dosing protocol is only recommended for symptomatic dogs
False (it's really only dogs that we call caval syndrome, we don't always see the severe signs we see in caval syndrome with dogs)
True or false: we always call HWs in the R heart caval syndrome when in the cat
Exercise restriction, corticosteroids for pneumonitis
How can we minimize pulmonary parenchymal and arterial pathology in HW treatment?
Absolute cage rest for 6-8 weeks post treatment, tapering course of prednisone
How can we minimize risk associated with worm die off after adulticide treatment?
Allows time for juvenile to become susceptible as adults, no new juveniles develop
How does giving macrocyclic lactones for 2 months before adulticide treatment decrease the susceptibility gap?
6 months
How long after HW adulticide treatment should we administer another antigen test?
9-12 months
How long does the slow kill approach using ivermectin and doxycycline take to reduce the adult worm burden by 80-95%?
21 days
How soon is after starting slow kill treatment is doxy combined with Moxidectin/imidacloprid microfilaricidal?
Give 1 month before anticipated HW season, continue for 3 months after transmission ends
If an owner only wants to give HW preventative seasonally, how should you give it?
