Recommendations for diagnosing, treating, and preventing heartworm disease - Veterinary Medicine
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Recommendations for diagnosing, treating, and preventing heartworm disease
With so many different preventives, treatment protocols, and tests, it is difficult to know what is most appropriate for your patients. Here's some help.


VETERINARY MEDICINE SUPPLEMENT


The role of Wolbachia species

Wolbachia species bacteria have an endosymbiotic relationship with D. immitis.42 This rickettsial organism reportedly plays a role in larval embryogenesis, fertility, and maturation of D. immitis.42 The bacteria are found in all the larval stages and are released in considerable amounts during worm molts, microfilariae production, and worm death.43 Researchers have shown that 25 days of tetracycline therapy inhibits Wolbachia species multiplication, thus inhibiting embryogenesis and the maturation of L3 larvae into adult heartworms.42 It has been hypothesized that treating heartworm-positive patients with a 25-day tetracycline course before the adulticide treatment may lessen patients' inflammatory responses to the dying worms. This is strictly hypothetical. Future studies are required to determine the true biology of the gram-negative, rickettsial, endosymbiotic Wolbachia species and its role in heartworm disease.

Kevin J. Christiansen, DVM
Meg M. Sleeper, VMD, DACVIM (cardiology)
Matthew J. Ryan Veterinary Hospital
School of Veterinary Medicine
University of Pennsylvania
Philadelphia, PA 19104-6010

REFERENCES

1. Orihel TC. Morphology of the larval stages of Dirofilaria immitis in dogs. J Parasitol 1961;47:251-262.

2. Rawlings CA, McCall JW, Lewis RE. The response of the canine's heart and lungs to Dirofilaria immitis. J Am Anim Hosp Assoc 1978;14:17-32.

3. Calvert CA, Rawlings CA, McCall JW. Canine heartworm disease. In: Fox PR, Sisson D, Moise SN, eds. Textbook of canine and feline cardiology: principles and clinical practice. Philadelphia, Pa: WB Saunders Co, 1999;702-721.

4. Lewis RE, Losonsky JM. Sex and age distribution of dogs with heartworm disease, in Proceedings. Heartworm Symp 1977;8-9.

5. Rawlings CA, Keith JC, Schaub RG. Development and resolution of pulmonary disease in heartworm infection: Illustrated review. J Am Anim Hosp Assoc 1981;17:711-720.

6. Schaub RG, Rawlings CA. Pulmonary vascular response during phases of canine heartworm disease: scanning electron microscopic study. Am J Vet Res 1980;41:1082-1089.

7. Vezzoni A, Genchi C. Reduction of post-adulticide thromboembolism complications with the low dose heparin therapy, in Proceedings. Heartworm Symp 1989;73-83.

8. Rawlings CA, Keith JC, Schaub RG, et al. Post adulticide treatment pulmonary disease and its modification with prednisolone and aspirin, in Proceedings. Heartworm Symp 1989;122-129.

9. Atkins CE. Pathophysiology of heartworm caval syndrome: recent advances, in Proceedings. Heartworm Symp 1989;27-31.

10. Ishihara K, Sasaki Y, Kitagawa H. Removal of canine heartworms using flexible alligator forceps, in Proceedings 1989;33.

11. Atkins CE. Comparison of results of three commercial heartworm antigen test kits in dogs with low heartworm burdens. J Am Vet Med Assoc 2003;222:1221-1223.

12. Atwell RB, Van Kan DM, Cottis LE, et al. The use of antigen test for diagnosis as an indicator of filarial numbers, and for assessing filarial mortality following thiacetarsamide therapy, in Proceedings. Heartworm Symp 1986;71-76.

13. Rawlings CA, Prestwood AK, Beck BB. Eosinophilia and basophilia in Dirofilaria immitis and Dipetalonema reconditum. J Am Anim Hosp Assoc 1980;16:699-704.

14. Losonsky JM, Thrall DE, Lewis RE. Thoracic radiographic abnormalities in 200 dogs with spontaneous heartworm infections. Vet Radiol 1983;24:120-123.


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