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1.
Ticlopidine hydrochloride was evaluated for its effectiveness in inhibiting platelet aggregation and serotonin release in 5 laboratory Beagles before and after heartworm implantation with 7 adult Dirofilaria immitis, and after embolization with 7 dead heartworms to mimic what happens after heartworm adulticide treatment. Five other laboratory Beagles, similarly implanted and embolized with heartworms, were used as nonmedicated controls. During the heartworm-negative stage, the dosage of ticlopidine that inhibited adenosine diphosphate (ADP)-induced platelet aggregation in 5 dogs by at least 50% after 5 days of treatment was 62 mg/kg of body weight once a day. In the same dogs implanted with 7 adult heartworms 21 days previously, mean (+/- SD) ticlopidine dosage required to obtain similar results was 71 (+/- 13) mg/kg given once daily. During the 21 days after dead heartworms were implanted in heartworm-infected dogs, mean ticlopidine dosage was 108 (+/- 35) mg/kg (range, 62 to 150 mg/kg). Ticlopidine treatment was associated with increased platelet numbers in all 5 dogs during the heartworm-negative stage and in 4 of 5 dogs during the heartworm implantation and heartworm embolization stages. Mean platelet volume tended to decrease as platelet numbers increased. At necropsy, gross and histologic pulmonary lesions were less severe in ticlopidine-treated dogs than in nonmedicated control dogs.  相似文献   

2.
To determine the drug dose required to inhibit platelet reactivity by at least 50%, 2 drug regimens were evaluated in heartworm-negative, heartworm-infected, and heartworm-infected dogs embolized with dead heartworms. Aspirin, or a combination of aspirin and dipyridamole, were administered to 2 groups of Beagles (n = 5 each) for 5 to 9 days; a third group of 5 Beagles served as nontreated controls. For heartworm-negative dogs, mean (+/- SD) aspirin dosage that inhibited collagen-induced platelet reactivity by at least 50% was 6 (+/- 2) mg/kg of body weight given once daily. The aspirin/diphridamole combination dosage was 1 mg of each drug/kg given every 12 hours. All dogs (n = 15) were implanted with 7 adult heartworms each and remedicated (or not treated) beginning at 21 days after heartworm implantation. In heartworm-infected dogs, mean aspirin dosage required to inhibit collagen-induced platelet reactivity greater than or equal to 50% was 10 (+/- 6) mg/kg. Mean dosage of aspirin/dipyridamole combination was 1.6 +/- (0.5) mg of each drug/kg given every 12 hours. When platelet reactivity in response to collagen was determined to be inhibited by at least 50% in all medicated dogs, each dog (n = 15) was embolized with 7 dead adult heartworms to mimic heartworm adulticidal treatment. Platelet reactivity was monitored for 21 days after treatment, and drug dose was adjusted to maintain platelet inhibition by at least 50%. In embolized dogs, mean aspirin dosage was 17 (+/- 14) mg/kg given once daily. Mean dosage of the aspirin/dipyridamole combination was 2.8 (+/- 1.3) mg of each drug/kg given every 12 hours. All dogs (n = 15) were euthanatized 21 days after heartworm embolization. Each lung lobe was evaluated for severity of lesions and presence of organized or fibrinous thrombi. Lesion severity in the aspirin- and aspirin/dipyridamole-treated dogs was not significantly different from that in control dogs.  相似文献   

3.
The morphologic response of the pulmonary arteries and lungs in cats was studied after a five month heartworm infection produced by transplantation of four adult heartworms/cat. One group of seven heartworm infected cats was not treated, another group of seven cats was treated with 97.5 mg of aspirin given twice a week, and the third group of six cats was given aspirin at a sufficient dosage to block in vitro platelet aggregation throughout the study. A fourth group of eight noninfected cats served as controls. Five months after heartworm infection, the cats were euthanized and the lungs perfusion fixed for light microscopy and scanning electron microscopy of the pulmonary arterial surfaces. All cats in the three heartworm-infected groups had live heartworms and the typical pulmonary arterial changes of heartworm disease at necropsy. The arterial surfaces, as viewed with scanning electron microscopy, had villus proliferations that were more numerous and exuberant than similar infections in dogs. Mean percentage of arterial surface involvement with villus proliferation of the nontreated heartworm infected cats was 67.3%; the aspirin treated cats, 73.8%; and the adjusted aspirin treated cats, 75.9%. The villi were myointimal proliferations in the small and medium-sized arteries. The more elastic arteries had a predominance of fibromuscular proliferation. All heartworm infected cats had arterial muscular hypertrophy of the small arteries, in contrast to only three of eight of the nonheartworm infected cats. The caudal lobar arteries were frequently obstructed with either villus proliferation, thrombi, and/or dead heartworms. The muscular arteries had branches with marked dilation, a condition associated with pulmonary hypertension in man. However, only three cats, one in each group, had pulmonary hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

4.
OBJECTIVE: To determine prevalence of heartworm infection among healthy, client-owned cats in the lower peninsula of Michigan. DESIGN: Cross-sectional prevalence study. ANIMALS: 1,348 healthy cats examined at private veterinary practices throughout the lower peninsula of Michigan. PROCEDURE: Sera were tested by use of an ELISA-based antigen test kit to determine infection and 2 commercially available antibody detection kits to determine exposure. A questionnaire was used to collect data to assess risk factors associated with infection. RESULTS: 25 cats had positive results for heartworm antigen, yielding an observed prevalence of 1.9%. Neither antibody test was reliable or provided reproducible results, and neither yielded positive results for more than 20% of the antigen-positive heartworm-infected cats. Multivariate regression indicated that cats from southeastern Michigan and cats > or = 2 years old had a higher risk of infection. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that most (80%) heartworm-infected cats in the lower peninsula of Michigan were from the southeastern part of the state, a pattern that closely paralleled the prevalence of heartworm infection in dogs. Therefore, knowledge of the regional prevalence of heartworm infection in dogs may be useful in assessing the risk of infection in cats. Results also suggested that currently available in-clinic heartworm antibody detection kits have limited utility in the diagnosis of heartworm infection in cats.  相似文献   

5.
Heartworm infections were established in dogs by surgical transplantation of adult heartworms into the external jugular vein. The heartworms were obtained from donor dogs that had been infected with large numbers of infective larvae. This heartworm model standardized the infection with a known number of heartworms of a known age and sex. This paper presents the methods for obtaining heartworms from donor dogs, for selection of recipient dogs, and for transplantation of heartworms.  相似文献   

6.
OBJECTIVE: To compare results of 3 commercial heartworm antigen test kits performed on serum samples from dogs infected with low numbers of adult female heartworms. DESIGN: Blinded laboratory evaluation. Sample Population-Serum samples from dogs (n = 208) proven at necropsy to be infected with 1 to 4 adult female heartworms and from dogs (32) without heartworms. PROCEDURE: Samples were sequentially tested with each test kit, following the manufacturers' instructions, by licensed veterinary technicians in private practice who were not aware of infection status of the dogs. The order of test kit evaluations was randomly chosen. For each test kit, sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were evaluated. RESULTS: All tests yielded some false-negative results, and there were significant differences among tests in regard to ability to detect low heartworm burdens. Sensitivity of the test kits ranged from 78 to 84%. For all test kits, sensitivity increased as number of female heartworms increased. All 3 test kits had high specificity (97%). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that sensitivity of the 3 commercially available heartworm antigen test kits ranged from 78 to 84% when used to test serum samples from dogs with low heartworm burdens, and that sensitivity varied among test kits. For all 3 test kits, specificity was 97%. All 3 test kits yielded false-positive and false-negative results for some dogs with low heartworm burdens.  相似文献   

7.
OBJECTIVE: To evaluate use of covered-rod (CR) silicone implants containing ivermectin for long-term prevention of infection with Dirofilaria immitisin dogs. ANIMALS: 145 adult male and female dogs. PROCEDURES: Dogs received implants of different sizes, and ivermectin concentrations and serum ivermectin concentrations were monitored for 16, 57, and 56 weeks, respectively, in 3 preclinical dose selection studies. Ability of implants to prevent infection with D immitis was evaluated in 2 further studies; dogs were challenged with 50 infective third-stage larvae 52 weeks after implant administration and necropsied 145 days after challenge, and the total number of adult heartworms was counted. A field study was then undertaken in which client-owned dogs received an implant and plasma samples were collected at intervals until week 52 for ivermectin analysis and heartworm antigen determination. RESULTS: Use of the implants resulted in maintenance of an ivermectin concentration > or = 0.2 ng/mL for 12 months. In challenge studies, no treated dogs had adult heartworms, in contrast to untreated dogs, which all had adult heartworms at necropsy. In the field study, dogs treated with an implant had negative results of heartworm antigen testing for 12 months. CONCLUSIONS AND CLINICAL RELEVANCE: The CR silicone implant containing 7.3 mg of ivermectin was 100% effective in preventing experimental infection with D immitislarvae and resulted in negative results for heartworm antigen in a field trial. This product has the potential to alleviate poor owner compliance with monthly prevention regimens.  相似文献   

8.
Despite the ability to prevent heartworm disease, infection with Dirofilaria immitis continues to be a major problem for domestic dogs. To determine worm burden in heartworm-positive dogs from three county animal shelters in the state of Michigan in the United States and to assess the relationship between gross intimal proliferation and worm burden, necropsy was done on 176 heartworm-positive dogs. Adult heartworms were found in the heart and pulmonary artery of 170 of the 176 (96.6%) dogs examined. Mean worm burden was 14 +/- 13 (range 0-85). Fifty-nine percent of dogs had < or =10 heartworms. In contrast, 52% of dogs in a published report from the southern US (Florida) had worm burdens >10 [C.H. Courtney, Q.Y. Zeng, The structure of heartworm populations in dogs and cats in Florida, in: Proceedings of the American Heartworm Symposium, 1989]. These data suggest that mean worm burden in northern areas may be < or = that in warmer areas. Also, since diagnostic tests are less sensitive with lower worm burdens, diagnosis of heartworm infection in Michigan and other surrounding more northern states may be a greater challenge than in areas with higher worm burdens.  相似文献   

9.
Heartworms harboring in the pulmonary arteries migrated toward the right atrium following insertion of dead heartworms or heartworm-like silicone tubes, or intravenous injection of body fluid extract of a female heartworm. The migration occurred within 3 hr (early group) or 1 to 7 days (late group) after insertion of dead worms, 1 to 11 days after insertion of silicone tubes, and immediately after infusion of heartworm-body fluid. The cardiac output decreased to an unmeasurably low level, and the pulmonary arterial pressure was also reduced in the early group. Although the output decreased, the pulmonary arterial pressure and the total pulmonary resistance increased gradually in the late group. In dogs with heartworm migration, in which silicone tubes had been inserted, the changes in cardiopulmonary values were the same as those in dogs of the late group. In dogs to which the body fluid had been administered intravenously, the changes in cardiopulmonary values were well accord with those in the early group. The systemic blood pressure also fell immediately after the administration with the shock-like state. These results suggest that the death of a part of the heartworms may be closely associated with the migration of heartworms toward the right atrium through the pulmonary arterial embolism and/or shock-like reaction by heartworm body fluid.  相似文献   

10.
OBJECTIVE: To evaluate the efficacy of a single injection of a sustained-release formulation of moxidectin in preventing heartworm (Dirofilaria immitis) infection for 12 months in dogs. ANIMALS: 14 healthy dogs. PROCEDURE: Group A (nontreated control dogs; n = 6) received sterile vehicle administered SC, and group B (treated dogs; n = 6) received a sustained-release formulation of moxidectin administered SC. All dogs were housed in a heartworm-endemic area for 11.5 months, and heartworm antigen and modified Knott tests were performed monthly. All dogs (including 2 additional control dogs [group C]) were then inoculated with infective-stage larvae (L3) of D. immitis, and 4.5 months later, all dogs were euthanatized and post-mortem examinations were performed. Adult D. immitis were counted and measured, and their age was estimated. RESULTS: All dogs in groups A and C were infected with young (4- to 4.5-month old) adult male and female D. immitis. No dogs in group B were infected with heartworms. CONCLUSIONS AND. CLINICAL RELEVANCE: The age of heartworms recovered suggests that infection was the result of experimental inoculation and not natural exposure to mosquitoes during the 11.5-month period the dogs resided in a heartworm-endemic area. A single SC injection of a sustained-release formulation of moxidectin was effective in providing protection against heartworm infection after 12 months in dogs. This formulation is a convenient method of heartworm prophylaxis that could eliminate the problem of poor owner compliance.  相似文献   

11.
A combination of aspirin and prednisolone was used in an attempt to modify the pulmonary disease produced by thiacetarsamide treatment of heartworm-infected dogs. Results of 6 heartworm-infected dogs treated with prednisolone (1 mg/kg, daily for 4 weeks) and aspirin (10 mg/kg, daily for 4 weeks) after thiacetarsamide treatment were compared with previously published results of 3 groups of dogs (6 dogs/group). One of these 3 groups was a nontreated control group, another was treated with prednisolone, and the 3rd was treated with aspirin. All dogs, each with 9 adult heartworms transplanted, were treated with a 2-day, twice-a-day treatment of thiacetarsamide (1 mg/kg) 4 weeks after the transplant. Thoracic radiographs were taken before and at 1, 2, and 3 weeks after thiacetarsamide treatment to evaluate lung disease. Pulmonary arteriography was performed before and 3.5 weeks after thiacetarsamide treatment to evaluate pulmonary blood flow. After treatment, radiographs of the aspirin-prednisolone group were similar to radiographs of the prednisolone group, both with a marked attenuation of the parenchymal disease, as compared with the non-treated group. Addition of aspirin to prednisolone prevented the blood flow obstruction and intraluminal filling defects that were present in the groups not receiving aspirin. Sixteen of 54 transplanted heartworms survived thiacetarsamide treatment in both prednisolone-treated groups, in contrast to complete elimination of heartworms in the nontreated group. Aspirin may be considered for treatment of any heartworm-infected dog that does not have hemotypsis, but postthiacetarsamide use of prednisolone should be restricted to the dog that develops severe lung disease after the heartworms have been killed.  相似文献   

12.
Total serum creatine kinase (CK) and its isozyme activities were determined in dogs with dirofilariasis. Before heartworm removal, total CK and isozyme activities in dogs of the mild group were not different from those in dogs of the heartworm-free group. BB activity was higher in dogs of the hemoptysis group. Dogs of the ascites group displayed a mild increase in MM activity. In dogs of the caval syndrome (CS) group, total CK and MM activities were highest among the heartworm-free and heartworm-infected dogs, and MM isozyme accounted for most (75%) of total CK activity. MB and BB activities were also higher. However, there were no significant differences in CK activities between the surviving and non-surviving cases. In dogs with pulmonary heartworm disease (mild and ascites groups), MM activity correlated significantly with the number of heartworms (r = 0.45), hematocrit value (Ht, r = -0.40), serum alanine aminotransferase (ALT, r = 0.42) and lactate dehydrogenase (LDH, r = 0.46) activities, mean pulmonary arterial pressure (r = 0.64) and total pulmonary resistance (r = 0.50). In dogs with CS, MM activity did not correlate with any parameter, but BB activity correlated with the number of heartworms at the right atrium (r = 0.61), Ht (r = -0.53), ALT (r = 0.80), LDH (r = 0.73) and serum urea nitrogen (r = 0.47). At 1 week after heartworm removal, BB and MM activity decreased in dogs of the hemoptysis and ascites groups, respectively. In dogs of the CS group, total CK and MM isozyme activities decreased markedly (P less than 0.01) regardless of their prognosis.  相似文献   

13.
Kidneys of 16 beagles with experimentally induced heartworm (Dirofilaria immitis) infections and 4 heartworm-nai;ve dogs were studied by light and electron microscopy. The infections were induced either by subcutaneous injection of infective larvae or by the transplantation of adult parasites, and infection periods varied from 111 to 818 days and 365 to 923 days, respectively. One control group of heartworm-na?ve dogs and four groups of heartworm-infected dogs, which were divided according to the type and the length of infection, were used. In the infected dogs, thickening of the glomerular basement membrane (GBM), the presence of dense deposits in the GBM, and foot process effacement were the most frequent lesions observed. In some dogs, electron dense deposits were seen in the GBM and the mesangium and/or enlargement of the mesangial matrix could be characterized. The longer the infection period, the thicker the GBM and the more common the occurrence of foot process effacement. In general, these alterations were more evident in animals that had been infected for more than 1 year, had high microfilaremia, and had 14 or more parasites in the main pulmonary artery and its branches. The presence of dense deposits suggests that the pathogenesis of kidney disease in dirofilariasis is associated with deposits of immune complexes in the membrane. The finding of ultrastructural changes in dogs with early prepatent infections suggests that immature heartworms, as well as microfilariae and possibly adult worms, contribute to the glomerulonephropathy.  相似文献   

14.
Three hundred two dogs were tested with 4 serotests for heartworm antigen (AG) or antibody (AB) and with the Knott test. The 4 serotests evaluated were an enzyme-linked immunosorbent assay (ELISA) for adult heartworm-specific AB (AB-ELISA), a quantitative, indirect immunofluorescent assay (IFA) for adult heartworm-specific AB (AB-IFA), an IFA test for microfilaria (MF)-specific AB (MF-IFA), and an ELISA for adult heartworm AG (AG-ELISA). The presence of heartworms was ascertained in all dogs by necropsy examination. Of 302 dogs, 20 (6.6%) had heartworms in the heart at necropsy. Of infected dogs, 9 (45%) had occult infections. Test sensitivities were 75%, 95%, 70%, and 75% for the AB-ELISA, AB-IFA, MF-IFA, and AG-ELISA, respectively. Test specificities were 85% (AB-ELISA), 77% (AB-IFA), 87% (MF-IFA), and 99% (AG-ELISA). The best agreement between serotest results and necropsy findings was obtained with the AG-ELISA (97%). The 4 serotests detected 86% (AB-ELISA), 100% (AB-IFA), 67% (MF-IFA), and 78% (AG-ELISA) of the dogs with occult heartworm infection. A significant (P less than 0.05) association between intestinal parasitism and positive heartworm test results was found with only AB-IFA. Seemingly, the Knott test, or some other concentration method for detecting circulating MF should be the first heartworm test performed. If the examination for MF is negative, the dog has clinical signs, and radiographic findings are suggestive of occult heartworm infection, then a serotest for adult heartworm AG is recommended.  相似文献   

15.
Haematological studies in heartworm-infected dogs revealed low haemoglobin concentration, increased erythrocyte sedimentation rate and a marked increase in lymphocyte percentage. Biochemical analysis of serum of dogs infected with heartworm showed increases in serum total bilirubin, serum globulin, chloride, phosphorus, serum glutamic oxaloacetic transaminase and serum glutamic pyruvic transaminase values and a decrease in albumin content.  相似文献   

16.
An interaction between blood platelets and adult heartworms was examined in vitro. Surfaces of glutaraldehyde-fixed heartworms, which were taken from infected dogs washed, and incubated in platelet-rich plasma (PRP), were evaluated by scanning electron microscopy. Adherence of platelets to heartworms occurred only with PRP from infected dogs. Aggregation to epinephrine and adenosine diphosphate of PRP incubated with heartworms was monitored. Seemingly, platelet activation to heartworm membranes occurs in dogs with heartworm disease. The increased platelet reactivity was also observed in dogs with occult heartworm disease, indicating that the presence of circulating microfilaria was not important for this process. The ability to transfer the reactivity to heartworm-negative platelets by suspending them in heartworm-positive plasma indicated that this reactivity resided in the plasma. The processes leading to platelet activation may be responsible for the platelet-associated vascular disorders of canine heartworm disease.  相似文献   

17.
Cardiopulmonary biomarkers are biological parameters that can be objectively measured and quantified as indicators of pathogenic processes (heartworm disease) or as indicators of response to therapeutic intervention. To determine levels of cardiopulmonary biomarkers in canine dirofilariasis, measurements of cardiac troponin T, cardiac troponin I, myoglobin, and D-dimer concentrations were performed for dogs with and without evidence of adult heartworm infection. The results showed that levels of cardiac troponin T were undetectable in all dogs studied while levels of cardiac troponin I were higher in dogs infected with Dirofilaria immitis. In healthy dogs, levels of myoglobin and D-dimer were below detection limits of the instrument and were significantly higher in heartworm-infected dogs, notably in microfilaremic dogs. The results suggest the possibility of using troponin I and myoglobin as markers for cardiac damage and the D-dimer as a supportive tool for a diagnosis of pulmonary thromboembolism in dogs with cardiopulmonary dirofilariasis.  相似文献   

18.
OBJECTIVE: To determine the usefulness of echocardiography in the diagnosis of heartworm disease in cats and to compare this modality with other tests. DESIGN: Retrospective study. ANIMALS: 43 cats with heartworm infection that had echocardiographic examinations at 2 veterinary teaching hospitals between 1985 and 1997. Twenty-two of these 43 cats also underwent radiography of the thorax and heartworm antibody and heartworm antigen testing. PROCEDURE: Cats were determined to be infected with Dirofilaria immitis infection on the basis of 1 or more of the following findings: positive modified Knott or antigen test result, echocardiographic evidence of heartworm disease, or confirmation of the disease on postmortem examination. The percentage of echocardiographs in which heartworms were evident was compared with the percentage of radiographs in which pulmonary artery enlargement was evident and results of antigen or antibody tests in cats in which all tests were performed. RESULTS: Overall, heartworms were detectable by use of echocardiography in 17 of 43 cats, most often in the pulmonary arteries. In the 22 cats in which all tests were performed, antibody test results were positive in 18, antigen test results were positive in 12, and pulmonary artery enlargement was evident radiographically and heartworms were identifiable echocardiographically in 14. Heartworm infection was diagnosed exclusively by use of echocardiography in 5 cats in which the antigen test result was negative. CONCLUSIONS AND CLINICAL RELEVANCE: Although echocardiography was less sensitive than antigen testing, it was a useful adjunctive test in cats that had negative antigen test results in which there was a suspicion of heartworm disease. The pulmonary arteries should be evaluated carefully to increase the likelihood of detection of heartworms echocardiographically.  相似文献   

19.
Adult heartworms were surgically removed from 4 infected dogs by use of intracardiac techniques during cardiopulmonary bypass. The number of worms removed ranged from 12 to 14 per dog. Observation for 9 months after surgery gave no clinical evidence of active adult heartworm infection, in spite of the consistent finding of circulating microfilariae during the follow-up period. There were no significant early or late postoperative complications. Results of postoperative hematologic and biochemical studies were unremarkable. At necropsy (following euthanasia, 9 months after surgery) the heart and pulmonary arteries of all dogs were free of adult heartworms; pathologic changes attributable to residual infection were not found.  相似文献   

20.
The arrhythmogenic dose of epinephrine (ADE) was determined in heartworm-infected and noninfected (control) dogs during thiamylal-induced and halothane-maintained anesthesia to assess the myocardial sensitization. The ADE in heartworm-infected dogs (2.42 +/- 0.26 micrograms/kg of body weight) was significantly lower than that for the controls (3.36 +/- 0.29 micrograms/kg). After 2 weeks, ADE was determined again in these dogs after atropine treatment. Atropine treatment lowered the ADE to 1.76 +/- 0.33 micrograms/kg and 1.77 +/- 0.19 micrograms/kg in heartworm-positive and -negative dogs, respectively. After 2 weeks more, the ADE was determined after administration of prazosin, an alpha 1-antagonist. Only 2 of 6 controls and 3 of 6 heartworm-positive dogs had arrhythmias after a threefold increase of ADE. The mean ADE in the dogs that responded to treatment were 7.4 micrograms/kg and 7.2 micrograms/kg for heartworm-positive and -negative dogs, respectively. The finding of this study indicated that ADE in heartworm-infected dogs were lower than those in the control dogs, which makes the heartworm-infected dogs more vulnerable to arrhythmia during anesthesia. Atropine did not protect the dogs of either group. However, prazosin protected the dogs of both groups by significantly increasing the threshold of the ADE. On the basis of our findings, to reduce the risk of arrhythmia, we suggest that routine screening of dogs for heartworm infection be done before anesthetics are used.  相似文献   

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