AVMA Collections: Heartworm disease



Single-topic compilations of the information shaping our profession
 

 

 

March 2010

 
In this collection:
Summary:  Text | Audio 

Prevalence

Diagnosis

Treatment

Prevention

On the horizon

 
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Prevalence

 
 
Seroprevalence of Dirofilaria immitis, feline leukemia virus, and feline immunodeficiency virus infection among dogs and cats exported from the 2005 Gulf Coast hurricane disaster area Highlights:
•   Lack of veterinary care, abandonment linked
•   Plausible that rescued pets have more disease
•   Found prevelance same as in general population
Relocating to low prevalence areas a concern
View article   (PDF, 704 KB)
Julie K. Levy, Charlotte H. Edinboro, Carmen-Susan Glotfelty, Patricia A. Dingman, Aundria L. West, Kathy D. Kirkland-Cady
J Am Vet Med Assoc 2007;231:218-225. July 15, 2007.
 
Prevalence of naturally occurring Dirofilaria immitis infection among nondomestic cats housed in an area in which heartworms are endemic Highlights:
•   97 nondomestic cats in endemic area studied
•   76% had evidence of exposure to D immitis
•   Mature heartworms were found in 1 cat
Nondomestic cats in endemic areas at risk
Clarke Atkins, Anneke Moresco, Annette Litster
J Am Vet Med Assoc 2005;227:139?143. July 1, 2005.
 
Prevalence of heartworm infection in healthy cats in the lower peninsula of Michigan Highlights:
•   1,348 healthy, client-owned cats studied
•   Antibody tests did not detect >20% of infected cats
•   Geographic distribution paralleled that of dogs
In-clinic antibody tests have limited usefulness
Tina S. Kalkstein, Lana Kaiser, John B. Kaneene
J Am Vet Med Assoc 2000;217:857-861. September 15, 2000.
 
Prevalence of Dirofilaria immitis infection among shelter cats Highlights:
•   Adult D immitis were found in 2.5% of cats studied
•   Postmortem filter tests negative in infected cats
•   Postmortem blood positive for antibodies, antigen
Antigen titers may be higher owing to dying worms
Michael Hermesmeyer, Robyn K. Limberg-Child, Alice J. Murphy, Linda S. Mansfield
J Am Vet Med Assoc 2000;217:211-212. July 15, 2000.
 
 

Diagnosis



 
 
Heartworm infection in cats: 50 cases (1985-1997) Highlights:
•   50 cats with D immitis infection studied
•   Dyspnea, cough strongest indicators of disease
•   Indoor housing provides incomplete protection
Serologic tests were most useful for diagnosis
Clarke E. Atkins, Teresa C. DeFrancesco, Julie R. Coats, Jennifer A. Sidley, Bruce W. Keene
J Am Vet Med Assoc 2000;217:355-358. August 1, 2000.

Comparison of results of three commercial heartworm antigen test kits in dogs with low heartworm burdens Highlights:
•   Serum tested from dogs with, without heartworms
•   Ability of tests to detect low worm burdens differed
•   Sensitivity of the test kits ranged from 78 to 84%
All 3 tests yielded false results for some dogs
Clarke E. Atkins
J Am Vet Med Assoc 2003;222:1221-1223. May 1, 2003.
 
Performance of serologic tests used to detect heartworm infection in cats Highlights:
•   Serologic tests compared to necropsy findings
•   Adult D immitis found in 19 of 330 (5.8%) cats
•   Combined Ab, Ag test results were more sensitive
Cats may need more than antibody testing
Patti S. Snyder, Julie K. Levy, Marc E. Salute, Shawn P. Gorman, Paul S. Kubilis, Paul W. Smail, Linda L. George
J Am Vet Med Assoc 2000;216:693-700. March 1, 2000.
 
Use of echocardiography for the diagnosis of heartworm disease in cats: 43 cases (1985-1997) Highlights:
•   Echocardiography was compared to other tests
•   Sensitivity lower than serologic testing
•   Detected heartworms in 5 Ag-negative cats
Consider echocardiography in Ag-negative cats
Teresa C. DeFrancesco, Clarke E. Atkins, Matthew W. Miller, Kathryn M. Meurs, Bruce W. Keene
J Am Vet Med Assoc 2001;218:66-69. January 1, 2001.
 
Pulmonary arterial disease in cats seropositive for Dirofilaria immitis but lacking adult heartworms in the heart and lungs Highlights:
•   630 shelter cats in Florida studied
•   Pulmonary arterial wall thickness measured
•   Arterial lesions more likely in seropositive cats
Cats without adult worms may still be affected
Leanne E. Browne, Todd D. Carter, Julie K. Levy, Patti S. Snyder, Calvin M. Johnson
Am J Vet Res 2005;66:1544?1549. September 2005.
 
Reassessing the definition of heartworm infection in cats (Commentary) Highlights:
•   New definitions of disease in cats may be needed
•   Pulmonary disease found in cats without worms
•   Raises questions about definition of "exposure"
Suggests new classifications of infection for cats
Clarke E. Atkins
J Am Vet Med Assoc 2007;231:1338. November 1, 2007.
 
Scanning electron microscopy of vascular corrosion casts and histologic examination of pulmonary microvasculature in dogs with dirofilariosis Highlights:
•   Capillaries in lungs dilated
•   Aneurysms, edema seen in small arteries
•   Bronchial-pulmonary arterial anastomoses seen
Gives structural explanation for disease in dogs
Hiroyoshi Ninomiya, Yoshito Wakao
Am J Vet Res 2002:63:1538-1544. November 2002.
 
 

Treatment



 
 
Outcome of minimally invasive surgical treatment of heartworm caval syndrome in dogs: 42 cases (1999-2007) Highlights:
•   42 dogs with heartworm caval syndrome studied
•   21 underwent transvenous heartworm extraction
•   14 were discharged; 7 survived > 24 months
Good prognosis for dogs that survive to discharge
Christina M. Bové, Sonya G. Gordon, Ashley B. Saunders, Matthew W. Miller, Risa M. Roland, Sarah E. Achen, Lori T. Drourr, May M. Boggess
J Am Vet Med Assoc 2010;236:187-192. January 15, 2010.
 
Use of a nitinol gooseneck snare catheter for removal of adult Dirofilaria immitis in two cats Highlights:
•   Procedure performed on 2 cats with heart failure
•   Snare catheter introduced via jugular venotomy
•   In both cats, clinical signs resolved within 4 weeks
Snare catheter may be safe, effective technique
Merrilee T. Small, Clarke E. Atkins, Sonya G. Gordon, Adam J. Birkenheuer, Margaret A. Booth-Sayer, Bruce W. Keene, Yoko Fujii, Matthew W. Miller
J Am Vet Med Assoc 2008;233:1441-1445. November 1, 2008.
 
Neurologic complications after melarsomine dihydrochloride treatment for Dirofilaria immitis in three dogs Highlights:
•   Reports given for 3 dogs treated with same drug
•   Dogs developed neurologic signs after treatment
•   Severity of signs, prognosis may not correlate
Strictly follow manufacturer's recommendations
Bianca F. Hettlich, Kirk Ryan, Robert L. Bergman, Steven L. Marks, Barbara C. Lewis, Anne Bahr, Joan R. Coates, Joanne Mansell, Claudia L. Barton
J Am Vet Med Assoc 2003;223:1456-1461. November 15, 2003.
 
 

Prevention



 
 
Safety of moxidectin in avermectin-sensitive Collies Highlights:
•   Moxidectin given to 18 ivermectin-sensitive Collies
•   10-30x recommended heartworm dose used
•   No signs of toxicosis observed up to 1 month later
Wider margin of safety than ivermectin, milbemycin
Allan J. Paul, William J. Tranquilli, Douglas E. Hutchens
Am J Vet Res 2000;61:482-483. May 2000.
 
Activity of an injectable, sustained-release formulation of moxidectin administered prophylactically to mixed-breed dogs to prevent infection with Dirofilaria immitis Highlights:
•   Moxidectin SR given at 0.06, 0.17, 0.5 mg/kg
•   Dogs inoculated with L3 larvae 180 days later
•   No infection in dogs given 0.17, 0.5 mg/kg doses
Single dose of moxidectin protective for 180 days
James B. Lok, David H. Knight, G. T. Wang, Mary E. Doscher, Thomas J. Nolan, Mattie J. Hendrick, William Steber, Kathleen Heaney
Am J Vet Res 2001;62:1721-1726. November 2001.
 
Evaluation of a single injection of a sustained-release formulation of moxidectin for prevention of experimental heartworm infection after 12 months in dogs Highlights:
•   Treated dogs given single SC injection, 0.5 mg/kg
•   Dogs experimentally inoculated after 12 months
•   No dogs in treated group became infected
Could eliminate problem of poor compliance
Merete Holm-Martin, Rick Atwell
Am J Vet Res 2004;65:1596-1599. November 2004.
 
Impact of the owner-pet and client-veterinarian bond on the care that pets receive Highlights:
•   National study of pet owners conducted
•   Attachment to pets, not income, drove decisions
•   Communication key to client-veterinarian bond
Could increase heartworm compliance by 25%
Todd W. Lue, Debbie P. Pantenburg, Phillip M. Crawford
J Am Vet Med Assoc 2008;232:531-540. February 15, 2008.
 
 

On the horizon

 
 
Evaluation of a covered-rod silicone implant containing ivermectin for long-term prevention of heartworm infection in dogs Highlights:
•   Implants used in challenge studies, field studies
•   Concentration of 0.2 ng/mL was maintained
•   100% effective in treated dogs after 12 months
Could alleviate problems of poor compliance
Craig P. Cunningham, Jenaay M. Brown, Glenn A. Jacobson, Malcolm R. Brandon, Serge R. Martinod
Am J Vet Res 2006;67:1564-1569. September 2006.
 
Long-term delivery of ivermectin by use of poly(D,L-lactic-co-glycolic)acid microparticles in dogs Highlights:
•   24 dogs received ivermectin-PLGA formulations
•   Dogs infected with D immitis 121, 170 days later
•   No heartworms in treated dogs after 6 months
PLGA microparticles are promising delivery matrix
Steven L. Clark, Angela J. Crowley, Paul G. Schmidt, Ann R. Donoghue, Claude A. Piché
Am J Vet Res 2004;65:752-757. June 2004.