Heartworms | Pets & Parasites: The Pet Owner's Parasite Resource
Heartworms are common in dogs throughout the United States (cats can have them, too). They are among the most damaging parasites in dogs but they are. Does your dog have heartworms or Dirofilaria immitis? There is a long A symbiotic relationship is believed to exist between the heartworm and the bacteria. D. immitis produces both canine and feline cardiopulmonary dirofilariasis, whereas . ), and seem to have developed a symbiotic relationship with these and Canine cardiopulmonary dirofilariasis (heartworm disease) is a serious and.
In one study, Current and Potential Therapies The current therapy for canine heartworm disease is melarsomine dihydrochloride, an organoarsenic with an unknown mechanism of action that is effective in killing mature and immature adult D.
Although the safety of melarsomine is better than that of thiacetarsamide the organoarsenic previously used to treat heartworm disease in dogsadverse effects of therapy still occur.
Adverse effects associated with melarsomine administration include irritation and pain at the injection site, swelling, tenderness, and reluctance to move. Melarsomine therapy is currently not recommended in cats due to previous studies that indicated melarsomine was toxic to cats even at low doses. A protocol has not been established for the treatment of Wolbachia infection, but effects on the fertility of filarial nematodes and a reduction in the number of Wolbachia bacteria present have been reported in dogs and humans treated with doxycycline and tetracycline at doses recommended for rickettsial infections.
The complications of heartworm disease, such as congestive heart failure, glomerulonephritis, allergic pneumonitis, eosinophilic granulomatosis, pulmonary thromboembolization, and HARD in catscan be life threatening.
The treatment available for heartworm disease is not without risk in canine patients, and only supportive therapy is recommended in cats.
Research has proven that the Wolbachia bacteria present in D. Additionally, these bacteria have been found in the lungs and kidneys of heartworm-infected dogs. The emerging role of Wolbachia spp in the pathogenesis of heartworm disease offers the potential for novel therapies for this disease that may reduce the complications of heartworm infections as well as the adverse effects associated with treatment. In cats, antibiotic therapy has the potential to reduce clinical signs and the risk of acute death associated with heartworm disease.
Furthermore, the ability to detect Wolbachia antigens may lead to the development of new testing methods that may enhance the diagnostic sensitivity of heartworm testing in cats and dogs with a low worm burden. Although the role of Wolbachia spp in inflammation has been proven and chemotherapy with tetracycline, doxycycline, rifampin, or azithromycin reduces worm viability, to our knowledge, no studies have yet been performed establishing a protocol for antibiotic use in dogs and cats to eliminate, reduce, or sterilize Wolbachia bacteria.
One study of dogs that had been experimentally infected with D. Prospective studies are needed to evaluate whether adding antibiotics to standard heartworm therapy in naturally infected dogs and cats improves clinical outcome and survival.
The potential for adverse effects of therapy, including antibiotic resistance and gastrointestinal signs, must be considered when deciding whether to use antibiotics in dogs and cats with heartworm disease. Textbook of Veterinary Internal Medicine. J Feline Med Surg ;10 2: Textbook of Canine and Feline Cardiology. Heartworm disease in animals and humans. Heartworm infections in cats: Symbionticism and complex adaptive systems I: What is new in the Wolbachia spp. Antigenic role of the endosymbionts of filarial nematodes: IgG response against the Wolbachia spp.
Proc Biol Sci ; Specific IgG antibody response against antigens of Dirofilaria immitis and its Wolbachia spp. Immunological role of the endosymbionts of Dirofilaria immitis: Neutrophil accumulation around Onchocerca worms and chemotaxis of neutrophils are dependent on Wolbachia endobacteria. Immune response to and tissue localization of the Wolbachia spp.
Dog and Heartworm Relationship by Hermione Granger on Prezi
Vet Immunol Immunopathol ; Wolbachia bacteria in filarial immunity and disease. Parasite Immunol ;23 7: Bacterial endosymbionts of Onchocerca volvulus in the pathogenesis of posttreatment reactions. J Infect Dis ; 6: Most of the response elicited against Wolbachia surface protein in filarial nematode infection is due to the infective larval stage. J Infect Dis ; Antibody response against Dirofilaria immitis and the Wolbachia endosymbiont in naturally infected canine and human hosts [abstract].
Laboratory data are often normal. Eosinophilia and basophilia alone or together may occur in dirofilariasis. Eosinophilia is most often seen at the time that stage 5 young adult larvae arrive in the pulmonary arteries. Subsequently, eosinophil counts vary but are usually high in dogs with immune-mediated occult infections, especially if eosinophilic pneumonitis develops Hyperglobulinemia due to antigenic stimulation may be present in dogs and cats. Serum ALT and alkaline phosphatase are occasionally increased but do not correlate well with abnormal liver function, efficacy of adulticide treatment, or risk of drug toxicity.
Urinalysis may reveal proteinuria that can be quantitated by a urine protein: Occasionally, severe glomerulonephritis can lead to hypoalbuminemia and nephrotic syndrome. Dogs with hypoalbuminemia, secondary to glomerular disease, also lose antithrombin III and are at risk of thromboembolic disease.
Hemoglobinuria is associated with caval syndrome and occurs when RBCs are lysed in the circulation. In dogs, thoracic radiography provides the most information on disease severity and is a necessary screening tool to assess the clinical status of dogs with dirofilariasis, particularly when symptomatic.
High-risk infections are characterized by a large main pulmonary artery segment and dilated, tortuous caudal lobar pulmonary arteries. Right ventricular enlargement may also be seen and, along with enlarged pulmonary arteries, is indicative of pulmonary hypertension.
With pulmonary thromboembolism and pulmonary infiltrate with eosinophils pneumonitisill-defined parenchymal infiltrates surround the caudal lobar arteries, typically most severe in the right caudal lobe.
In cats, cardiac changes and pulmonary hypertension are less common. Patchy parenchymal infiltrates may also be present in cats with respiratory signs.
The main pulmonary artery segment usually is not visible because of its relatively midline location. In ferrets, the diagnosis is less readily made with thoracic radiographs, because only the right ventricle tends to be enlarged. However, the commercial antigen tests have detected HW antigen experimentally, as early as 5 mo after infection, and have been shown to be effective in clinical situations.
False-negative results may occur, especially in species that harbor lower worm burdens cats and ferrets. Furthermore, although microfilaria testing is only rarely helpful, adult worms can often be seen with echocardiography and nonselective angiography.
The extent of the preadulticide evaluation varies, depending on the clinical status of the dog, the likelihood of coexisting diseases that may affect the outcome of treatment, the owner's ability to restrict the dog's exercise, and cost considerations. Clinical laboratory data should be collected selectively to complement information obtained from a thorough history, physical examination, antigen test, and thoracic radiography.
Two important variables known to directly influence the probability of thromboembolic complications after adulticide treatment and the outcome of treatment are the extent of concurrent pulmonary vascular disease and the current worm burden.
Assessment of cardiopulmonary status is indispensable for evaluating a dog's prognosis. Pulmonary thromboembolic complications after adulticide treatment are most likely to occur in heavily infected dogs already exhibiting clinical and radiographic signs of severe pulmonary vascular disease, especially when severe pulmonary hypertension and CHF are present.
Before adulticide therapy, HW-infected dogs are assessed and rated for risk of postadulticide thromboembolism. Dogs can be categorized as follows: Dogs in the low-risk category would ideally fulfill the following conditions: The low-risk group would also include dogs having previously undergone adulticidal therapy but that remain antigen positive. Dogs with near-normal thoracic radiographs may develop severe thromboembolic disease, occurring most often when exercise is not restricted.
Symbiotic Relationship: Dog and Heartworm by brianna carpenter on Prezi
Dogs at high risk of thromboembolic complications include those with signs related to HW infection eg, coughing, dyspnea, ascitesabnormal thoracic radiographs, high level of circulating antigen, worms visualized by echocardiography, concurrent disease, and little or no possibility that the owners will restrict exercise. The only approved heartworm adulticide is melarsomine dihydrochloride, which is variably effective against mature adult and immature heartworms of both sexes, with male worms being more susceptible.
Melarsomine is given at 2. Pressure at the injection site is applied and maintained for 5 min to prevent drug migration. Approximately one-third of dogs will exhibit local pain, swelling, soreness with movement, or sterile abscessation at the injection site.
Local fibrosis is not uncommon and is the reason for targeting the belly of the epaxial musculature. In standard use, the procedure is repeated on the opposite side 24 hr later for dogs at low risk of treatment complications.
Using this protocol, a single injection of melarsomine is given, followed by two injections 24 hr apart, after an interval of at least 30 days. The American Heartworm Society recommends this three-dose alternative regimen, regardless of the stage of disease or risk category.
Exercise restriction is essential once treatment is started to minimize the risk of pulmonary thromboembolism due to dead and dying adult worms. After 2 mo, adulticidal injections melarsomine at 2. Daily corticosteroids, using a tapering dosage, may also be administered during this period to reduce pulmonary inflammatory lesions from dying worms and from melarsomine. Although exercise is minimized from the day of diagnosis, cage rest must be enforced from the day of each initial injection for 4—6 wk.
If the dog's condition allows, melarsomine injections are repeated in 1 mo 2 injections 24 hr apartwith the same regimen of prescribed exercise restriction.