Survey of gastrointestinal parasitic infections in quarantined dogs in Taiwan

Intestinal helminth and protozoan infection in the quarantined dogs in Taiwan were examined using fecal examination between January to December, 2004. Of the 376 dogs imported from 11 countries, 63 (16.8%) were found to be infected with at least one species of intestinal parasite. The parasites detected were oocysts of Isospora canis and eggs of Toxocara canis, Trichuris vulpis and hookworms. Of the 63 infected dogs, 11 were found to have a mixed infection of two different species of parasites. This paper illustrates that parasites are transmitted from one country to another through the transport of animals. Moreover, there is also a possibility of parasitic infection among quarantined dogs as well as the zoonotic potential for quarantine officers during the quarantine period.     

Geographical information systems as a tool in the control of heartworm infections in dogs and cats

Geospatial tools (e.g., geographical information systems, remote sensing, global positioning systems, and virtual globes) are very useful for the simultaneous visualization of health data with environmental data, which holds promise to understand environmental-health linkages and to generate new hypotheses to be tested in future research. Current epidemiological studies clearly show that the distribution patterns of vector-borne infections are changing; for example, in Europe, heartworm infection and subcutaneous dirofilariosis are spreading throughout areas that previously had little to no incidence of heartworm. In view of the changes of the distribution patterns of Dirofilaria immitis and Dirofilaria repens, geospatial tools are now more useful for mapping (including territorial sampling), monitoring, ecological analysis, risk assessment, forecasting (including the choose of the timing of treatment), early warning, and surveillance of both heartworm and subcutaneous dirofilariosis. All these issues have control of these infections as the ultimate goal.     

Efficacy of long-term monthly administration of ivermectin on the progress of naturally acquired heartworm infections in dogs

This study was designed to evaluate the efficacy of prolonged monthly ivermectin treatment against Dirofilaria immitis in client-owned dogs with naturally acquired infections and to clinically monitor the animal's response to the slow killing of heartworms, with death of the worms distributed over a period of up to 2 years. A total of 17 male and female dogs of different breeds and ages were used. Prior to treatment, all of the dogs tested positive for heartworm antigen (Ag) and all but two had microfilariae (mf). The dogs were randomly allocated to one group of seven dogs which received a commercial formulation of ivermectin (minimum, 6 mcg IVM/kg) plus pyrantel (minimum, 5 mg PP/kg) (Heartgard Plus Chewables, Merial, Ltd.), another group of seven dogs which received a commercial formulation of IVM (min, 6 mcg/kg) (Heartgard Chewables, Merial Ltd.), and a group of three dogs which served as an untreated controls. All dogs were evaluated prior to initiation of treatment and thereafter at 3- to 5-month-intervals for mf, Ag, and radiographic and echocardiographic findings. All of the 17 dogs, with the exception of two dogs in the IVM group, had circulating mf of D. immitis prior to the 1st monthly dose, and a few also had mf of Dirofilaria repens. After 4 monthly doses, only one dog in the IVM/PP group and two dogs in the IVM group had a patent heartworm infection, and no heartworm mf were seen in the 14 treated dogs thereafter. After 10 monthly doses, the number of Ag-positive dogs in both of the treated groups decreased gradually. Efficacy, based on the reduction in number of Ag-positive dogs, was similar for the IVM/PP and IVM groups, with overall efficacy scores for the 14 dogs of 21, 21, 43, and 71% after 10, 14, 19, and 24 monthly doses, respectively. Two of the seven dogs treated with IVM/PP, one of the seven treated with IVM, and two of the three untreated controls showed echocardiographic evidence of a parasitic burden prior to treatment, and all of these scores had decreased by the end of the study. Only one dog (IVM/PP group) had a cardiovascular pattern of heartworm disease by echocardiography prior to treatment, but this dog's score increased to two and the scores of two additional dogs increased from zero to two (IVM group) or three (IVM/PP group) by the end of the study. Only 1 (IVM/PP group) of the 17 dogs showed a pulmonary pattern of heartworm disease by radiography prior to treatment, but this dog's score increased to three by the end of the study. The radiographic scores of two additional dogs in the treated groups increased from zero to three (IVM/PP) or two (IVM) by the end of the study. Thus, monthly administration of IVM to dogs with clinical, radiographic or echocardiographic evidence of heartworm disease is ill-advised and such treatment of even the asymptomatic dog should be done only with much caution and frequent monitoring by the veterinarian.     

圈养野生杂食动物肠道寄生虫感染情况调查

为了解福州动物园杂食动物寄生虫感染情况,采集8种杂食动物粪样20份,经麦克马斯特漂浮法检验发现3种杂食动物感染寄生虫种类8种,分别是棕熊感染线虫、蛔虫2种寄生虫;小熊猫感染贝蛔虫、类圆线虫和短膜壳绦虫3种寄生虫;豪猪感染蛲虫、鞭虫和球虫3种寄生虫。杂食动物寄生虫总感染率为37.5%(3/8),感染强度最高者为小熊猫贝蛔虫卵,高达12 210个/g。福州动物园杂食动物大多成群饲养,感染寄生虫的动物多属于寄生虫混合感染,驱虫工作难度大。     

Distinctive peripheral lymph node hyperplasia of young cats

Peripheral lymph node enlargement was found in 14 of a series of 132 feline lymph node biopsy specimens. Six of nine cats tested had antibodies for feline leukemia virus (FeLV). Half of the cats were clinically normal while the remainder had fever, lethargy, anorexia, and hepatosplenomegaly. There was severe distortion of lymph nodal architecture with variable loss of discernible follicles and sinuses. Histiocytes, lymphocytes, immunoblasts, and plasma cells were present in expanded paracortical regions which encroached on, and occasionally effaced, lymphoid follicles. Postcapillary venules were numerous and prominent throughout the paracortex. The lymphadenopathy was most commonly transient (86% of cases) with subsequent development of lymphoma in one cat. Lymph nodes from seven kittens with experimental FeLV infection were compared with spontaneously enlarged lymph nodes; four of seven had B and T lymphocyte hyperplasia with normal nodal architecture. Three had partial loss of nodal architecture as a result of expanded paracortical regions populated largely by histiocytes and lymphocytes. Proliferation of postcapillary venules was not prominent in nodes from FeLV-infected cats. The cause of spontaneous lymph node hyperplasia of young cats was not determined. However, the similarity of lesions to those of kittens with experimental FeLV infection and the association with FeLV by serologic tests in six of nine cats suggest that this retrovirus may be involved in the pathogenesis of the lesion.     

Comparison of heartworm antigen test kit performance in dogs having low heartworm burdens

Sensitivity and specificity of four in-clinic heartworm antigen test kits, AbboScreen (Abbott Laboratories), Snap PF (IDEXX Laboratories), Solo Step (HESKA Corporation), Witness (Synbiotics Corporation) and two heartworm antigen microwell plate assays, DiroCHEK (Synbiotics) and PetChek PF (IDEXX) were compared in a blinded study using serum or plasma drawn from 237 random source dogs, including 140 with necropsy-confirmed, low worm burden infections (minimum 1 worm, maximum 10, mean 2.3, median 3) and 97 confirmed heartworm-free at necropsy. In general, microwell format tests were more sensitive than membrane format tests and tests using ELISA technology were more sensitive than tests using lateral flow immunochromatographic technology. Percent sensitivity and specificity, respectively, were PetChek PF 76 and 97, DiroCHEK 71 and 94, SNAP PF 67 and 98, Solo Step 60 and 98, and AbboScreen 52 and 96. The Witness test protocol was changed by the manufacturer midway through the study, and the newer version of this test kit arrived containing a package insert alerting the user to a change in procedure, which purportedly resulted in improved sensitivity. PetChek was significantly more sensitive than all other tests except DiroCHEK and the new version of Witness. DiroCHEK was significantly more sensitive than all tests except PetCheck, SNAP and the new version of Witness. Snap was more sensitive than AbboScreen and the old version of Witness. Differences in specificity were not significant (P>0.05).     

A survey of heartworm in dogs in Australia

A survey conducted throughout Australia indicated that Dirofilaria immitis was far more widespread than previously described. It was prevalent throughout Queensland and New South Wales, including the western regions and was increasing in incidence. Confusion exists as to which diagnostic tests to use and the methods of treatment are extremely variable.     

Immunophenotypic comparison of blood and lymph node from dogs with lymphoma

Peripheral blood and lymph node tissue from 12 dogs with lymphoma was immunophenotyped. Additionally, the bone marrow was immunophenotyped in 6 dogs. The lymphomas were characterized as B-cell in 11 dogs and T-cell in 1 dog. Immunophenotypic patterns in the peripheral blood and bone marrow were variable. The trend in dogs with B-cell lymphoma was normal to increased percentage of IgG-positive cells, decreased percentage of pan-T-positive cells, decreased percentage of CD4-positive cells, and decreased CD4/CD8 ratio. Simultaneous immunophenotyping of lymph node, blood and bone marrow cannot be recommended routinely without further studies to document its value as an independent prognostic indicator. However, it is potentially useful for tumor staging and monitoring remission, especially in lymphoma patients with a leukemic phase.     

Role of histamine in heartworm extract-induced shock in dogs

OBJECTIVE: To determine whether heartworm (HW) extract-induced shock in dogs is consistent with anaphylactic shock by examining the role of histamine. ANIMALS: 6 mixed-breed dogs (3 without and 3 with HW infections) and 4 specific pathogen-free (SPF) Beagles. PROCEDURE: Four experiments were performed as follows: 1) 6 mixed-breed dogs were treated IV with 2 ml of HW extract, and plasma histamine concentrations were determined; 2) 4 SPF dogs were treated IV with 2 ml of HW extract and examined for shock; 3) sera from 6 dogs of experiment 1 and from 4 SPF dogs of experiment 2 that were obtained before HW extract treatment were tested for heterologous passive cutaneous anaphylaxis (PCA), using rabbits during a sensitization period of 48 to 72 hours; and 4) mast cell degranulation by HW extract was tested, using rat mesentery and canine cultured mast cells. RESULTS: Experiment 1: 6 dogs developed shock, and plasma histamine concentrations increased significantly from 0.3 +/- 0.2 (mean +/- SD) ng/ml before HW extract treatment to 44.6 +/- 68.9 ng/ml at the onset of shock; experiment 2: all SPF dogs developed shock and had an increase in plasma histamine concentrations; experiment 3: sera from mixed-breed dogs without HW infection and from SPF dogs had negative PCA reactions; experiment 4: HW extract degranulated rat mesentery mast cells and released histamine directly from canine mast cells. CONCLUSIONS AND CLINICAL RELEVANCE: Results of our study indicate that an unknown mast cell-degranulating substances contained in HW extract may degranulate mast cells directly, consequently releasing histamine that may participate in the onset of shock in HW extract-induced shock in dogs.     

The most important parasitic intestinal infections in calves and their role in diarrheal diseases

Various stock breeding herds in the USSR were examined for the presence of endoparasites. Coccidia of Cryptosporidium genus occurred in calves at the age of 3 to 4 days to one month, individually in older calves, too. Coccidia C. parvum infected the animals aged 14-15 days most frequently. Coccidia of Eimeria genus and intestinal round worm Strongyloides papilosus were registered sporadically in calves aged 13-15 days; most frequently they occurred in calves aged 1-2 months and older. Of the total number of the examined calves (aged 20 days), which were infected by Cryptosporidium, 77.7 resp. 89.8% were diarrhoeic. In cases of polyinfections with various species of coccidia of the Eimeria genus and S. papillosus, diarrhoea was recorded in 31.2% of one- to two-month-old calves. In cases of monoinfection with coccidia of the Eimeria genus diarrhoea was recorded in 15.8% of the calves, and in cases of infection with the intestinal worm S. Papillosus in 9.1% of the calves.     

Comparison of results of three commercial heartworm antigen test kits in dogs with low heartworm burdens

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.