Animal shelters: Managing heartworms in resource-scarce environments

Polak, Katherine; Smith‐Blackmore, Martha

doi:10.1016/j.vetpar.2014.03.023

Cited by 14 publications

(8 citation statements)

References 12 publications

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“…The diagnosis and management of canine heartworm disease is a growing concern for shelter veterinarians nationwide [ 1 – 4 ]. A recent survey of shelter veterinarians indicated that the majority of shelter practitioners rely exclusively on point-of-care antigen testing for the diagnosis of Dirofilaria immitis in shelter dogs [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

Impact of heat treatment on Dirofilaria immitis antigen detection in shelter dogs

et al. 2017

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BackgroundThe diagnosis and management of canine heartworm disease is a growing concern for shelter veterinarians. Although the accuracy of commercial antigen test kits has been widely studied, recent reports have renewed interest in antigen blocking as a causative factor for false “no antigen detected” results. The objectives of this study were to determine the prevalence of false “no antigen detected” results in adult dogs entering shelters in northern, southern, and western regions of the country and to identify historical and clinical risk factors for such results.MethodsSerum samples were evaluated for Dirofilaria immitis antigen using a commercially available point-of-care ELISA; samples in which no antigen was detected underwent a heat treatment protocol and repeat antigen testing. Whole blood samples underwent Knott testing to identify the presence of microfilariae. Historical and clinical findings were analyzed using exact logistic regression.ResultsA total of 616 samples were analyzed. Overall prevalence of positive antigen test results (prior to heat treatment) was 7.3% and frequency of false “no antigen detected” results due to antigen blocking (ie, samples with no antigen detected prior to heat treatment and positive after heat treatment) was 5.2%. Among dogs that had no detectable antigen on the initial tests, dogs that had microfilariae detected via modified Knott testing (OR = 32.30, p-value = 0.013) and dogs that previously received a heartworm preventive (OR = 3.81, p-value = 0.016) had greater odds of antigen blocking than dogs without these factors. Among dogs that were heartworm positive, those without microfilariae detected had greater odds of antigen blocking than dogs with this factor (OR = 11.84, p-value = 0.0005). Geographic region of origin was significantly associated with occurrence of antigen blocking (p = 0.0036); however, blocking occurred in all regions sizably contributing to heartworm diagnoses. Of the 74 dogs found to be infected with heartworms in this study, 39.2% (29) had no detectable antigen prior to heat treatment.ConclusionsHeat treatment of serum samples should be considered to improve diagnostic test accuracy, particularly in dogs that reportedly received a heartworm preventive prior to antigen testing regardless of region of origin.Electronic supplementary materialThe online version of this article (10.1186/s13071-017-2443-7) contains supplementary material, which is available to authorized users.

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Section: Introductionmentioning

confidence: 99%

Impact of heat treatment on Dirofilaria immitis antigen detection in shelter dogs

et al. 2017

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“…Annual disease incidence, as reported by IDEXX and Antech, averages greater than 100,000 new cases annually. Annual data likely represent the true annual incidence of heartworm infection in domestic dogs: when diagnosed with heartworm, most dogs are either treated, or in some cases euthanized, due to poor outcome or financial constraints [ 34 ]. While fulminant infection with D. immitis may be due to lack of owner compliance in use of preventatives, it also may be due to misunderstanding the disease risk; mosquito vectors are known to be dynamic in their range and survival under changing climatic conditions.…”

Section: Discussionmentioning

confidence: 99%

Forecasting United States heartworm Dirofilaria immitis prevalence in dogs

et al. 2016

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BackgroundThis paper forecasts next year’s canine heartworm prevalence in the United States from 16 climate, geographic and societal factors. The forecast’s construction and an assessment of its performance are described.MethodsThe forecast is based on a spatial-temporal conditional autoregressive model fitted to over 31 million antigen heartworm tests conducted in the 48 contiguous United States during 2011–2015. The forecast uses county-level data on 16 predictive factors, including temperature, precipitation, median household income, local forest and surface water coverage, and presence/absence of eight mosquito species. Non-static factors are extrapolated into the forthcoming year with various statistical methods. The fitted model and factor extrapolations are used to estimate next year’s regional prevalence.ResultsThe correlation between the observed and model-estimated county-by-county heartworm prevalence for the 5-year period 2011–2015 is 0.727, demonstrating reasonable model accuracy. The correlation between 2015 observed and forecasted county-by-county heartworm prevalence is 0.940, demonstrating significant skill and showing that heartworm prevalence can be forecasted reasonably accurately.ConclusionsThe forecast presented herein can a priori alert veterinarians to areas expected to see higher than normal heartworm activity. The proposed methods may prove useful for forecasting other diseases.

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“…59,60 Unfortunately, awareness of the importance of feline HWD prevention seems to be low; and/or prophylaxis is often neglected, especially in cat shelters, for economic reasons. 22,61,62 Adequate preventive treatment covering the whole of the transmission season is crucial for effective prevention, and a year-round approach is often the best option because of climatic differences in humidity levels having a great impact on the risk of exposure for susceptible hosts, as discussed earlier. 16 Five preventive drugs are currently available for cats and are given monthly orally or topically as spot-ons (Table 1).…”

Section: Preventionmentioning

confidence: 99%

Section: Preventionmentioning

confidence: 99%

Dirofilarioses in cats: European guidelines from the ABCD on prevention and management

Pennisi

Tasker

Hartmann

et al. 2020

Journal of Feline Medicine and Surgery

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Overview: Dirofilaria immitis and Dirofilaria repens are the most important filarial worms, causing heartworm disease and subcutaneous dirofilariosis, respectively. D repens is currently considered an emerging zoonotic agent in Europe. Life cycle and infection: Filarial worms infect mainly dogs, but also cats, ferrets, wild carnivores and humans. The life cycle involves an intermediate mosquito host. Compared with dogs, cats are imperfect hosts for dirofilarial worms. After inoculation, only a low number of L3 larvae develop to the adult stage in a small percentage of cats. Heartworm disease in cats may be associated with severe pulmonary thromboembolism and an eosinophilic inflammatory response in the lungs, potentially leading to sudden death. Otherwise self-cure occurs in most cases after 18–48 months. Subcutaneous dirofilariosis may present as subcutaneous nodules or dermatitis. Diagnosis and treatment: Diagnosis in cats is more difficult compared with dogs and needs a multistep approach (antigen and antibody tests, as well as diagnostic imaging). Cats with acute heartworm disease require stabilisation within an intensive care unit. Cats with respiratory signs or suggestive radiographic changes should receive prednisolone and follow-up with a similar multistep approach. Adulticidal therapy is not safe in cats. Prevention: In endemic areas cats should receive year-round chemoprophylaxis from 2 months of age.

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Animal shelters: Managing heartworms in resource-scarce environments

Cited by 14 publications

References 12 publications

Impact of heat treatment on Dirofilaria immitis antigen detection in shelter dogs

Impact of heat treatment on Dirofilaria immitis antigen detection in shelter dogs

Forecasting United States heartworm Dirofilaria immitis prevalence in dogs

Dirofilarioses in cats: European guidelines from the ABCD on prevention and management

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