Melarsomine is the only FDA-approved adulticide for heartworms, but myths and misunderstandings about treatment still exist. Test your knowledge when it comes to treating heartworm infestation.
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Melarsomine is the only FDA-approved adulticide for heartworms, but myths and misunderstandings about treatment still exist. Test your knowledge when it comes to treating heartworm infestation.
Which of the following is/are an FDA-approved heartworm adulticide(s) in dogs?
Melarsomine dihydrochloride
Moxidectin
Doxycycline
A & B
The correct answer is A. Melarsomine dihydrochloride is the only FDA-approved heartworm adulticide.1 Moxidectin is approved for the prevention of heartworm disease and in one product (Advantage Multi for Dogs) by treating circulating microfilariae.2 There are no FDA-approved doxycycline products for the prevention or treatment of heartworm disease in dogs.3
The correct answer is A. Melarsomine dihydrochloride is the only FDA-approved heartworm adulticide.1 Moxidectin is approved for the prevention of heartworm disease and in one product (Advantage Multi for Dogs) by treating circulating microfilariae.2 There are no FDA-approved doxycycline products for the prevention or treatment of heartworm disease in dogs.3
The correct answer is A. Melarsomine dihydrochloride is the only FDA-approved heartworm adulticide.1 Moxidectin is approved for the prevention of heartworm disease and in one product (Advantage Multi for Dogs) by treating circulating microfilariae.2 There are no FDA-approved doxycycline products for the prevention or treatment of heartworm disease in dogs.3
The correct answer is A. Melarsomine dihydrochloride is the only FDA-approved heartworm adulticide.1 Moxidectin is approved for the prevention of heartworm disease and in one product (Advantage Multi for Dogs) by treating circulating microfilariae.2 There are no FDA-approved doxycycline products for the prevention or treatment of heartworm disease in dogs.3
Which is NOT correct about administering melarsomine dihydrochloride?
Use a 23-gauge 1-inch needle in dogs weighing less than 22 lbs (10kg)
Use a 22-gauge 1.5-inch needle in dogs weighing more than 22 lbs (10kg)
Administer deep IM in the epaxial musculature between L3-L5
Administer subsequent injections ipsilaterally
The correct answer is D. According to the label, melarsomine dihydrochloride should be administered deep IM (never IV or SQ) between L3-L5 on alternating (contralateral) sides between injections. Use a 23-gauge 1-inch needle in dogs weighing less than 22 lbs (10 kg) and a 22-gauge 1.5-inch needle in dogs weighing more than 22 lbs (10 kg).4
The correct answer is D. According to the label, melarsomine dihydrochloride should be administered deep IM (never IV or SQ) between L3-L5 on alternating (contralateral) sides between injections. Use a 23-gauge 1-inch needle in dogs weighing less than 22 lbs (10 kg) and a 22-gauge 1.5-inch needle in dogs weighing more than 22 lbs (10 kg).4
The correct answer is D. According to the label, melarsomine dihydrochloride should be administered deep IM (never IV or SQ) between L3-L5 on alternating (contralateral) sides between injections. Use a 23-gauge 1-inch needle in dogs weighing less than 22 lbs (10 kg) and a 22-gauge 1.5-inch needle in dogs weighing more than 22 lbs (10 kg).4
The correct answer is D. According to the label, melarsomine dihydrochloride should be administered deep IM (never IV or SQ) between L3-L5 on alternating (contralateral) sides between injections. Use a 23-gauge 1-inch needle in dogs weighing less than 22 lbs (10 kg) and a 22-gauge 1.5-inch needle in dogs weighing more than 22 lbs (10 kg).4
Which does NOT add to the risk for pulmonary thromboembolism after adulticidal therapy for heartworms?
Strict exercise restriction
Heartworm burden
Degree of pulmonary arterial disease
Proximity to adulticidal therapy
The correct answer is A. According to the American Heartworm Society Guidelines, pulmonary thromboemboli are most commonly seen within 7 to 10 days after treatment with adulticidal therapy, but can be seen as late as 4 weeks after finishing treatment. A high heartworm burden and existing extensive arterial damage can increase the severity of thromboemboli. Strict exercise restriction is essential to help prevent thromboemboli, and a lack of compliance with exercise restriction puts pets more at risk.1
The correct answer is A. According to the American Heartworm Society Guidelines, pulmonary thromboemboli are most commonly seen within 7 to 10 days after treatment with adulticidal therapy, but can be seen as late as 4 weeks after finishing treatment. A high heartworm burden and existing extensive arterial damage can increase the severity of thromboemboli. Strict exercise restriction is essential to help prevent thromboemboli, and a lack of compliance with exercise restriction puts pets more at risk.1
The correct answer is A. According to the American Heartworm Society Guidelines, pulmonary thromboemboli are most commonly seen within 7 to 10 days after treatment with adulticidal therapy, but can be seen as late as 4 weeks after finishing treatment. A high heartworm burden and existing extensive arterial damage can increase the severity of thromboemboli. Strict exercise restriction is essential to help prevent thromboemboli, and a lack of compliance with exercise restriction puts pets more at risk.1
The correct answer is A. According to the American Heartworm Society Guidelines, pulmonary thromboemboli are most commonly seen within 7 to 10 days after treatment with adulticidal therapy, but can be seen as late as 4 weeks after finishing treatment. A high heartworm burden and existing extensive arterial damage can increase the severity of thromboemboli. Strict exercise restriction is essential to help prevent thromboemboli, and a lack of compliance with exercise restriction puts pets more at risk.1
How long has IMMITICIDE® (melarsomine dihydrochloride) been FDA-approved?
5-10 years
10-15 years
15-20 years
Over 20 years
The correct answer is D. IMMITICIDE® (melarsomine dihydrochloride) has been FDA-approved with a collection of safety data for over 20 years.5
The correct answer is D. IMMITICIDE® (melarsomine dihydrochloride) has been FDA-approved with a collection of safety data for over 20 years.5
The correct answer is D. IMMITICIDE® (melarsomine dihydrochloride) has been FDA-approved with a collection of safety data for over 20 years.5
The correct answer is D. IMMITICIDE® (melarsomine dihydrochloride) has been FDA-approved with a collection of safety data for over 20 years.5
Which of the following is/are NOT FDA-approved and NOT recommended by the American Heartworm Society for the treatment of adult heartworms?
Long-term macrocyclic lactones
Compounded medications
Herbal therapy
All of the above
The correct answer is D. The American Heartworm Society Guidelines highlight objections to all of the above alternative therapies. Long-term macrocyclic lactones expose patients to a potentially long period of progressive pathology and increase risk for the development of heartworm resistance to these medications. Compounded medications are not FDA-approved and in addition to potential legal concerns, toxicity with compounded arsenicals is a potential problem. There is no evidence supporting the use of any herbal therapy in the prevention or treatment of heartworms.1
The correct answer is D. The American Heartworm Society Guidelines highlight objections to all of the above alternative therapies. Long-term macrocyclic lactones expose patients to a potentially long period of progressive pathology and increase risk for the development of heartworm resistance to these medications. Compounded medications are not FDA-approved and in addition to potential legal concerns, toxicity with compounded arsenicals is a potential problem. There is no evidence supporting the use of any herbal therapy in the prevention or treatment of heartworms.1
The correct answer is D. The American Heartworm Society Guidelines highlight objections to all of the above alternative therapies. Long-term macrocyclic lactones expose patients to a potentially long period of progressive pathology and increase risk for the development of heartworm resistance to these medications. Compounded medications are not FDA-approved and in addition to potential legal concerns, toxicity with compounded arsenicals is a potential problem. There is no evidence supporting the use of any herbal therapy in the prevention or treatment of heartworms.1
The correct answer is D. The American Heartworm Society Guidelines highlight objections to all of the above alternative therapies. Long-term macrocyclic lactones expose patients to a potentially long period of progressive pathology and increase risk for the development of heartworm resistance to these medications. Compounded medications are not FDA-approved and in addition to potential legal concerns, toxicity with compounded arsenicals is a potential problem. There is no evidence supporting the use of any herbal therapy in the prevention or treatment of heartworms.1
Based on current research, which type of macrocyclic lactone appears potentially affected by heartworm resistance?
Topically administered products
Parenterally administered products
Orally administered products
All of the above
The correct answer is D. The American Heartworm Society’s resistance statement notes: “Every compound currently marketed in every form of administration (oral, topical, and parenteral) has been shown to be less than perfect in at least one study.” and “…the evidence indicates that resistance affects all macrocyclic lactones…” This highlights the importance of not contributing to the further development of heartworm resistance by inappropriate use of macrocyclic lactones.6
The correct answer is D. The American Heartworm Society’s resistance statement notes: “Every compound currently marketed in every form of administration (oral, topical, and parenteral) has been shown to be less than perfect in at least one study.” and “…the evidence indicates that resistance affects all macrocyclic lactones…” This highlights the importance of not contributing to the further development of heartworm resistance by inappropriate use of macrocyclic lactones.6
The correct answer is D. The American Heartworm Society’s resistance statement notes: “Every compound currently marketed in every form of administration (oral, topical, and parenteral) has been shown to be less than perfect in at least one study.” and “…the evidence indicates that resistance affects all macrocyclic lactones…” This highlights the importance of not contributing to the further development of heartworm resistance by inappropriate use of macrocyclic lactones.6
The correct answer is D. The American Heartworm Society’s resistance statement notes: “Every compound currently marketed in every form of administration (oral, topical, and parenteral) has been shown to be less than perfect in at least one study.” and “…the evidence indicates that resistance affects all macrocyclic lactones…” This highlights the importance of not contributing to the further development of heartworm resistance by inappropriate use of macrocyclic lactones.6
Once reconstituted with sterile water, IMMITICIDE® is stable as long as it is __________.
Used within 24 hours
Refrigerated
Kept from light
All of the above
The correct answer is D. According to the drug label, once IMMITICIDE® (melarsomide dihydrochloride) is reconstituted with sterile water, it is stable for 24 hours when refrigerated and kept from light. Before reconstituting, it will be stable when stored upright between 59°F-77°F (15°C-25°C) until it reaches the labeled expiration date.4
The correct answer is D. According to the drug label, once IMMITICIDE® (melarsomide dihydrochloride) is reconstituted with sterile water, it is stable for 24 hours when refrigerated and kept from light. Before reconstituting, it will be stable when stored upright between 59°F-77°F (15°C-25°C) until it reaches the labeled expiration date.4
The correct answer is D. According to the drug label, once IMMITICIDE® (melarsomide dihydrochloride) is reconstituted with sterile water, it is stable for 24 hours when refrigerated and kept from light. Before reconstituting, it will be stable when stored upright between 59°F-77°F (15°C-25°C) until it reaches the labeled expiration date.4
The correct answer is D. According to the drug label, once IMMITICIDE® (melarsomide dihydrochloride) is reconstituted with sterile water, it is stable for 24 hours when refrigerated and kept from light. Before reconstituting, it will be stable when stored upright between 59°F-77°F (15°C-25°C) until it reaches the labeled expiration date.4
One study suggested that what percent of shelter dogs in a high-risk area of the United States might have false negatives on a heartworm antigen test due to antigen blocking?
0%, these tests nearly never have false negatives
3.5%
7%
14%
The correct answer is C. A study in the southeast United States showed that about 7.1% of shelter dogs were antigen-negative but possibly microfilariae-positive. It is thought that antigen-antibody complexes can cause false-negative test results. Heat treatment of serum samples may help detect some of these false negatives; however, this technique is not yet recommended for routine heartworm testing. The American Heartworm Society recommends that all dogs be tested annually for microfilariae.1
The correct answer is C. A study in the southeast United States showed that about 7.1% of shelter dogs were antigen-negative but possibly microfilariae-positive. It is thought that antigen-antibody complexes can cause false-negative test results. Heat treatment of serum samples may help detect some of these false negatives; however, this technique is not yet recommended for routine heartworm testing. The American Heartworm Society recommends that all dogs be tested annually for microfilariae.1
The correct answer is C. A study in the southeast United States showed that about 7.1% of shelter dogs were antigen-negative but possibly microfilariae-positive. It is thought that antigen-antibody complexes can cause false-negative test results. Heat treatment of serum samples may help detect some of these false negatives; however, this technique is not yet recommended for routine heartworm testing. The American Heartworm Society recommends that all dogs be tested annually for microfilariae.1
The correct answer is C. A study in the southeast United States showed that about 7.1% of shelter dogs were antigen-negative but possibly microfilariae-positive. It is thought that antigen-antibody complexes can cause false-negative test results. Heat treatment of serum samples may help detect some of these false negatives; however, this technique is not yet recommended for routine heartworm testing. The American Heartworm Society recommends that all dogs be tested annually for microfilariae.1
According to the label, IMMITICIDE® (melarsomine dihydrochloride) has been given concurrently with which other classes of medications during clinical field trials without noted adverse drug interactions?
Anti-inflammatories
Antibiotics
Heartworm prophylactics
All of the above
The correct answer is D. Heartworm patients should be stabilized prior to adulticide therapy. Regardless, keeping these patients stable may require concurrent treatment while they receive a heartworm adulticide. Testing of IMMITICIDE® (melarsomine dihydrochloride) showed no significant adverse interactions when drugs commonly used to provide stabilizing and supportive care to dogs with heartworm disease.4
The correct answer is D. Heartworm patients should be stabilized prior to adulticide therapy. Regardless, keeping these patients stable may require concurrent treatment while they receive a heartworm adulticide. Testing of IMMITICIDE® (melarsomine dihydrochloride) showed no significant adverse interactions when drugs commonly used to provide stabilizing and supportive care to dogs with heartworm disease.4
The correct answer is D. Heartworm patients should be stabilized prior to adulticide therapy. Regardless, keeping these patients stable may require concurrent treatment while they receive a heartworm adulticide. Testing of IMMITICIDE® (melarsomine dihydrochloride) showed no significant adverse interactions when drugs commonly used to provide stabilizing and supportive care to dogs with heartworm disease.4
The correct answer is D. Heartworm patients should be stabilized prior to adulticide therapy. Regardless, keeping these patients stable may require concurrent treatment while they receive a heartworm adulticide. Testing of IMMITICIDE® (melarsomine dihydrochloride) showed no significant adverse interactions when drugs commonly used to provide stabilizing and supportive care to dogs with heartworm disease.4
IMMITICIDE® (melarsomine hydrochloride) is contraindicated in Class 4 heartworm patients—those with active caval syndrome—instead, surgery is the initial treatment of choice. Which is NOT a clinical sign of caval syndrome?
Jugular pulsations
Left untreated, a rapidly fatal course of disease
Sudden onset of severe lethargy
Methemoglobin & methemoglobinuria
The correct answer is D. Dogs that carry heavy heartworm burdens can become extremely sick when the heartworm burden becomes so heavy that the worms begin to obstruct the vena cava and closure of the tricuspid value. Blockage of this area can cause congestion of the liver, jugular pulsations, and a coarse tricuspid murmur. Dogs with caval syndrome are often presented with signs of sudden, severe weakness, pale gums, and difficulty breathing. The presence of heartworms can lead to red blood cell breakdown and result in hemoglobinemia and hemoglobinuria (but not the presence of methemoglobin).1
The correct answer is D. Dogs that carry heavy heartworm burdens can become extremely sick when the heartworm burden becomes so heavy that the worms begin to obstruct the vena cava and closure of the tricuspid value. Blockage of this area can cause congestion of the liver, jugular pulsations, and a coarse tricuspid murmur. Dogs with caval syndrome are often presented with signs of sudden, severe weakness, pale gums, and difficulty breathing. The presence of heartworms can lead to red blood cell breakdown and result in hemoglobinemia and hemoglobinuria (but not the presence of methemoglobin).1
The correct answer is D. Dogs that carry heavy heartworm burdens can become extremely sick when the heartworm burden becomes so heavy that the worms begin to obstruct the vena cava and closure of the tricuspid value. Blockage of this area can cause congestion of the liver, jugular pulsations, and a coarse tricuspid murmur. Dogs with caval syndrome are often presented with signs of sudden, severe weakness, pale gums, and difficulty breathing. The presence of heartworms can lead to red blood cell breakdown and result in hemoglobinemia and hemoglobinuria (but not the presence of methemoglobin).1
The correct answer is D. Dogs that carry heavy heartworm burdens can become extremely sick when the heartworm burden becomes so heavy that the worms begin to obstruct the vena cava and closure of the tricuspid value. Blockage of this area can cause congestion of the liver, jugular pulsations, and a coarse tricuspid murmur. Dogs with caval syndrome are often presented with signs of sudden, severe weakness, pale gums, and difficulty breathing. The presence of heartworms can lead to red blood cell breakdown and result in hemoglobinemia and hemoglobinuria (but not the presence of methemoglobin).1
Quiz: Treating Active Heartworm Infection
Final scoreIMPORTANT SAFETY INFORMATION: IMMITICIDE should not be used in dogs with very severe (Class 4) heartworm disease. IMMITICIDE should be administered by deep intramuscular injection in the lumbar (epaxial) muscles (L3–L5) only. Do not use in any other muscle group. Do not use intravenously. Care should be taken to avoid superficial injection or leakage. Serious adverse reactions may occur in any dog with heartworm disease due to the killing of heartworms in the pulmonary arteries. Reactions may include thromboembolism, dyspnea, coughing, depression, right side heart failure, and death. Dogs should be cage rested following treatment due to possible thromboembolic disease. Post-injection site reactions (eg, pain, swelling) were the most commonly reported adverse events. See full prescribing information for dosing and administration directions prior to each use of IMMITICIDE. For more information, please see full prescribing information.
References
1. American Heartworm Society. Current canine guidelines for the prevention, diagnosis, and management of heartworm (Dirofilaria immitis) infection in dogs. https://www.heartwormsociety.org/images/pdf/2018-AHS-Canine-Guidelines.pdf. Published 2018. Accessed April 2019.
2. Plumb DC. Moxidectin. Plumbs Veterinary Drugs. https://www.plumbsveterinarydrugs.com/#!/monograph/ukyFBaheMv. Accessed April 2019.
3. Plumb DC. Doxycycline. Plumb’s Veterinary Drugs. https://www.plumbsveterinarydrugs.com/#!/monograph/cqWG1Kqvh9. Accessed April 2019.
4. Immiticide Prescribing Information
5. Determination of Regulatory Review Period for Purposes of Patent Extension; IMMITICIDE. Fed Regist. 1996;61(53):11054-11055. https://www.govinfo.gov/content/pkg/FR-1996-03-18/html/96-6454.htm. Accessed April 2019.
6. American Heartworm Society. American Heartworm Society Resistance Statement. https://www.heartwormsociety.org/images/pdf/Resistance_statement_FINAL.pdf. Accessed April 2019.
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