Chapter 7: Feline Heartworm Disease: It's More Common Than You Think 2 CE Hours
Expiration Date : May 4, 2027 Learning outcome
Feline heartworm disease is a significant risk to the health of cats throughout the United States. Although Dirofilaria immitis has traditionally been regarded as a parasite of dogs, recent research has demonstrated that feline infections are far more common than veterinarians once thought. These infections often remain undiagnosed, however, given the wide variation in clinical signs Learning objectives After completing this course, the learner will be able to: Describe the current range of feline heartworm disease, discussing changes in range that have occurred as a result of urbanization and climate change. Identify whether or not a cat is at risk of feline heartworm disease. Explain the pathophysiology and clinical signs of heartworm- associated respiratory disease in cats. Compare the incidence of feline heartworm disease to other well-known feline infectious diseases, such as feline leukemia and feline immunodeficiency virus. Course overview Although heartworm disease is widely regarded as a disease that primarily affects dogs, feline heartworm disease is a significant clinical entity as well. Cats are infected with heartworm disease in the same manner as a dog: through a mosquito bite. Once in the cat, the heartworm experiences a relatively similar life cycle to what is experienced in dogs, with several changes in the length and duration of different life stages. Infection with larval and immature adult heartworms causes significant pulmonary inflammation in cats; this is in contrast to dogs, which primarily demonstrate clinical signs in association with mature
of feline heartworm disease and the challenges of obtaining an accurate diagnosis with currently available diagnostic tests. If feline heartworm infection is detected or suspected based on tests, treatment is similarly challenging. There is no single “best” treatment for heartworm disease in cats; most cases are treated symptomatically, with a guarded prognosis. Compare and contrast the diagnostic tests currently available for feline heartworm disease, including heartworm antigen tests, heartworm antibody tests, microfilaria tests, and imaging modalities. Convince clients of the importance of feline heartworm disease and the need for consistent, year-round, monthly heartworm prevention. Design a monitoring protocol for a cat with asymptomatic heartworm disease. Create a treatment protocol for a cat with clinical signs of heartworm-associated respiratory disease. adult heartworm infection. Additionally, cats experience much lower adult heartworm burdens than dogs, if the heartworms even survive to adulthood. Low worm burdens complicate the diagnosis of feline heartworm disease; in many cases, multiple tests are required to arrive at and confirm a diagnosis. Finally, feline heartworms differ from canine heartworms in treatment. While melarsomine is an effective and relatively safe treatment in dogs, there is no similar treatment available in cats. Therefore, most cases of feline heartworm disease are managed symptomatically with a more variable prognosis.
EPIDEMIOLOGY
Dirofilaria immitis is a nematode parasite that can affect domestic dogs, domestic cats, and ferrets. Dirofilaria immitis is also capable of infecting a number of wildlife species, including wolves, foxes, and coyotes. The parasite can be spread by a wide variety of mosquito species, although the exact species capable of transmission within the United States are currently unknown. Heartworm geography Traditionally, heartworm disease has been regarded as a disease that is confined to warm-weather areas. In the United States, for example, heartworm disease was regarded as a disease affecting the southern states; in Europe, heartworm disease was primarily a concern in Italy and other southern countries (American Heartworm Society, 2016). In recent years, however, veterinarians have started to notice significant changes in which other regions of the world are capable of sustained heartworm transmission. Climate change and the increased frequency of long-distance pet travel are now beginning to lead to changes in the distribution of heartworm disease, introducing heartworm infections in areas and climates where they had not previously been seen. This spread in the distribution of heartworm disease is increasing the risk that heartworm disease presents to our feline patients (American Heartworm Society, 2016). In addition to the effects of climate change and increasing long- distance travel, the development of previously natural areas is
In general, dogs are considered to be the primary host for Dirofilaria immitis infections. Cats are considered to be susceptible to infection but, for a number of reasons, they are not regarded as an ideal host for the parasite (ESDA, 2017). Unlike dogs, infected cats tend to develop low worm burdens and experience a shortened life cycle of adult heartworms, making them a poor candidate for disease transmission. also contributing to changes in the distribution of heartworm disease. Development not only places more humans and their pets in close proximity to natural areas (which may harbor more mosquitoes) but can also significantly alter key aspects of local ecology. These changes in the local environment can contribute to alterations in local mosquito populations, thus leading to changes to the prevalence of Dirofilaria immitis . One example of how human infrastructure can influence mosquito populations is seen in the western United States. Historically, much of the western U.S. did not have adequate moisture or standing water to sustain a significant local mosquito population. Now, with the rise of irrigation and landscaping in business and residential areas, local conditions have changed. This has led to an increase in the population of a number of mosquito species, some of which are capable of heartworm transmission (American Heartworm Society, 2014). Urban areas also have other characteristics that might contribute to the success of local mosquito populations. Urban
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Book Code: VFL1524
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