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Heartworm is a parasitic roundworm (Dirofilaria immitis) that is spread from host to host through the bites of mosquitoes. The heartworm affects dogs, cats, wolves, coyotes, foxes, and some other animals, such as ferrets, sea lions, and even humans. The parasitic worm is called a "heartworm" because the parasite, in the final reproductive stage of its life cycle, resides in the heart of its host where it can stay for many years and may kill its host through congestive failure of the heart. Mites parasitising a harvestman Parasitism is one version of symbiosis (living together), a phenomenon in which two organisms which are phylogenetically unrelated co-exist over a prolonged period of time, usually the lifetime of one of the individuals. ...
Classes Adenophorea Subclass Enoplia Subclass Chromadoria Secernentea Subclass Rhabditia Subclass Spiruria Subclass Diplogasteria The roundworms or nematodes (Phylum Nematoda from Gr. ...
This article or section does not cite its references or sources. ...
Trinomial name Canis lupus familiaris The dog is a mammal in the order Carnivora. ...
Trinomial name Felis silvestris catus (Linnaeus, 1758) The cat (or domestic cat, house cat) is a small carnivorous mammal. ...
Wolf Wolf Man Mount Wolf Wolf Prizes Wolf Spider Wolf 424 Wolf 359 Wolf Point Wolf-herring Frank Wolf Friedrich Wolf Friedrich August Wolf Hugo Wolf Johannes Wolf Julius Wolf Max Franz Joseph Cornelius Wolf Maximilian Wolf Rudolf Wolf Thomas Wolf As Name Wolf Breidenbach Wolf Hirshorn Other The call...
Binomial name Canis latrans Say, 1823 The coyote (Canis latrans, meaning barking dog) also prairie wolf [2]) is a member of the Canidae (dog) family and a relative of the domestic dog. ...
A fox is a member of any of 27 species of small omnivorous canids. ...
Trinomial name Mustela putorius furo (Linnaeus, 1758) In general use, a ferret is a domestic ferret (Mustela putorius furo). ...
Genera Eumetopias Zalophus Otaria Neophoca Phocarctos Hundreds of California Sea Lions sunbathing on Pier 39 in San Francisco. ...
Trinomial name Homo sapiens sapiens Linnaeus, 1758 Humans, or human beings, are bipedal primates belonging to the mammalian species Homo sapiens (Latin for wise man or knowing man) under the family Hominidae (the great apes). ...
A life cycle is a period involving one generation of an organism through means of reproduction, whether through asexual reproduction or sexual reproduction. ...
The heart and lungs, from an older edition of Grays Anatomy. ...
Congestive heart failure (CHF), also called congestive cardiac failure (CCF) or just heart failure, is a condition that can result from any structural or functional cardiac disorder that impairs the ability of the heart to fill with or pump a sufficient amount of blood throughout the body. ...
 Canine heart infested with heartworm Image File history File linksMetadata Download high-resolution version (2592x1944, 2067 KB) A German Shepherd Dog heart infected with heartworm. ...
Image File history File linksMetadata Download high-resolution version (2592x1944, 2067 KB) A German Shepherd Dog heart infected with heartworm. ...
History of the disease
Heartworm was first discovered in dogs over a century ago and documented in cats by the 1920s. Since then, diagnostic tests and treatments for heartworm as well as preventative measures have been developed. Heartworm infestation may be extremely serious for the infected host; infected dogs that go untreated can die and even treated dogs must go through a long period of uncomfortable treatment (sometimes requiring surgery) to kill the worms and remove them from the body. The best defense against heartworm is the use of prophylactic treatment given regularly during the mosquito season. The 1920s was a decade sometimes referred to as the Jazz Age or the Roaring Twenties, usually applied to America. ...
This page is a candidate to be moved to Wiktionary. ...
A cardiothoracic surgeon performs a mitral valve replacement at the Fitzsimons Army Medical Center. ...
This page is a candidate to be moved to Wiktionary. ...
A course of heartworm prevention begins with a blood test to see if the parasite is present. If the dog is parasite free, a prophylactic medication can be used to prevent heartworm infection. A positive test result, on the other hand, usually requires treatment to eradicate the worms. Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ...
Heartworm in North America Although at one time confined to more southern climates, heartworm has now spread to nearly all climates where its vector, the mosquito, is found. Transmission of the parasite from dog to dog occurs in all of the United States (except Alaska) and the warmer regions of Canada. The highest infection rates in North America occur in dogs within 150 miles of the Atlantic and Gulf coasts and along the Mississippi River and its major tributaries. However, high rates of infections are found in any area with large mosquito populations. Traditionally in medicine, a vector is an organism that does not cause disease itself but which spreads infection by conveying pathogens from one host to another. ...
Official language(s) English Capital Juneau Largest city Anchorage Area Ranked 1st - Total 663,267 sq mi (1,717,855 km²) - Width 808 miles (1,300 km) - Length 1,479 miles (2,380 km) - % water 13. ...
World map showing North America A satellite composite image of North America. ...
Look up Atlantic Ocean in Wiktionary, the free dictionary. ...
Gulf of Mexico in 3D perspective. ...
The Mississippi River, derived from the old Ojibwe word misi-ziibi meaning great river (gichi-ziibi big river at its headwaters), is the second-longest river in the United States; the longest is the Missouri River, which flows into the Mississippi. ...
The parasite
 Microfilaria (as seen through a 40X microscope) Heartworms go through several life stages before they become adults infesting the heart of the host animal. The worms require the mosquito as an intermediate stage in order to complete their life cycle and so at least two animal hosts other than the mosquito are required for the heartworm to reproduce. A mosquito ingests heartworm larvae, called microfilariae, from an infected host. The mosquito then transfers the larvae to another uninfected host when next it feeds. The microfilariae then go through several changes to reach adult form, eventually traveling to the right side of the heart to reproduce. Reproduction results in the dispersal of microfilariae into the bloodstream where ingestion by another feeding mosquito spreads the microfilariae to another host. Image File history File linksMetadata Download high resolution version (2592x1944, 1933 KB) Summary Picture of a heartworm (Dirofilaria immitis) microfilaria taken through a microscope at 40x. ...
Image File history File linksMetadata Download high resolution version (2592x1944, 1933 KB) Summary Picture of a heartworm (Dirofilaria immitis) microfilaria taken through a microscope at 40x. ...
Larvae are the plural of larva, juvenile form of animals with indirect development. ...
Reproduction is the creation of one thing as a copy of, product of, or replacement for a similar thing, e. ...
At this stage, the host dog will likely be asymptomatic. Once the infestation reaches a certain concentration in the lungs, the now adult worms migrate from the pulmonary artery to the right side of the heart and begin to reproduce in earnest, filling the blood with microfilariae. At this point the host will begin to show symptoms of infestation. These symptoms can manifest earlier or increase in severity depending on the activity level of the animals as infestation reduces cardio-pulmonary capacity. Very active animals may experience symptoms at lower heartworm concentrations and have more severe symptoms than less active animals. In medicine, a disease is asymptomatic when it is at a stage where the patient does not experience symptoms. ...
The pulmonary arteries carry blood from the heart to the lungs. ...
The heart and lungs, from an older edition of Grays Anatomy. ...
The lungs flank the heart and great vessels in the chest cavity. ...
Heartworms can reach up to 12 inches in length and can remain in the host's heart for several years.
Course of infestation The period between the initial infection when the dog is bitten by a mosquito and the maturation of the worms into adults living in the heart takes some 6.5 to 7 months in dogs and is known as the prepatent period.
Heartworms bear live young, known as microfilariae, producing thousands of them every day. The microfilariae then circulate in the bloodstream for as long as two years, waiting for the next stage in their life cycle in the gut of a bloodsucking mosquito. When ingested by a mosquito, the microfilariae undergo a series of molts to the infective, or third, larval stage and then migrate to the head of the mosquito, where they wait to infect another host. These changes can occur in as little as two weeks and as long as six weeks, depending on the warmth of the climate, and generally cease entirely at ambient temperatures below 14° Celsius (57° Fahrenheit). Ecdysis is the molting of the cuticula in arthropods and related groups (Ecdysozoa). ...
After infection, the third stage larval heartworms deposited by the mosquito grow for a week or two and molt to the fourth larval stage under the skin at the site of the mosquito bite. Then they migrate to the muscles of the chest and abdomen and, some 45 to 60 days after infection, molt to the fifth stage (immature adult). Between 75 and 120 days after infection these immature heartworms then enter the bloodstream and are carried through the heart to lodge in the arteries of the lungs. Over the next 3 to 4 months they increase greatly in size, growing backwards until they fill the right atrium and ventricle of the heart. By approximately 6.5 to 7 months after infection the adult worms have mated and the females begin producing microfilariae. It has been suggested that this article or section be merged into Muscular system. ...
Chest of a human male The chest is a part of the anatomy of humans and various other animals. ...
The abdomen is a part of the body. ...
In Anatomy, atrium refers to a structure of the heart. ...
In the heart, a ventricle is a heart chamber which collects blood from an atrium (another heart chamber that is smaller than ventricle) and pumps it out of the heart. ...
Symptoms of infestation Dogs show no indication of heartworm infestation during the 6 month long prepatent period prior to the worms' maturation, and current diagnostic tests for the presence of microfilariae or antigens cannot detect prepatent infections. Rarely, migrating heartworm larvae get "lost" and end up in unusual sites such as the eye, brain, or an artery in the leg, which results in unusual symptoms such as blindness, seizures and lameness. An antigen is a substance that stimulates an immune response, especially the production of antibodies. ...
This article is about the medical term, epileptic seizure, as distinct from psychogenic non-epileptic seizure. ...
Lame means moving with pain or difficulty. ...
Many dogs will show little or no sign of infection even after the heartworms have matured. To some degree these dogs may be described as seeming to age slightly faster than normal as the worms slowly damage the lungs, kidneys and liver. These animals usually have a light infection and live a fairly sedentary lifestyle. However, active dogs and those with heavier infections will quickly show the classic symptoms of heartworm disease. Early symptoms include a cough, especially on exercise, and early exhaustion upon exercise. More advanced cases progress to severe weight loss, fainting, coughing up blood, and, finally, congestive heart failure. The kidneys are bean-shaped excretory organs in vertebrates. ...
The liver is an organ in some animals, including mammals (and therefore humans), birds, and reptiles. ...
The term Faint redirects here. ...
Epidemiology Heartworm is present on every continent except Antarctica, where the mosquito vector is noticeably absent. The presence of heartworm in a geographic region is dependent on the following factors: - susceptibility of host population
- stability of the disease reservoir
- population stability of vector species
- proper climate conditions
Dogs are considered the definitive susceptible host for the parasite. Untreated dogs also provide a stable disease reservoir. (Cats, on the other hand, are considered a resistant host and a poor disease reservoir. However, cats are more difficult to treat and so prevention is even more critical with felines.) Mosquitoes of several different species are the vectors. Development of the microfilariae in the mosquito ideally requires a temperature at or above 80° Fahrenheit for about two weeks. No larval development takes place in the mosquito below 57° F.
Testing Heartworms can be detected by blood test. The filtration test finds microfilariae in the blood; the occult tests (antigen and antibody) are used to detect adult worms. Many veterinarians prefer to do both tests, since the absence of microfilariae in the blood does not necessarily mean that there are no adult worms in the heart. Both tests are done with a single blood draw, preferably in the early spring before daily temperatures warm above 57° F. Blood tests are laboratory tests done on blood to gain an appreciation of disease states and the function of organs. ...
An antigen is a substance that stimulates an immune response, especially the production of antibodies. ...
Schematic of antibody binding to an antigen An antibody or immunoglobulin is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects like bacteria and viruses. ...
Look up veterinarian in Wiktionary, the free dictionary. ...
X-ray radiographs and, to a lesser extent, ultrasound can also detect the presence of adult heartworms in the heart and lungs. X-rays also can provide a good estimate of the amount of lung damage caused by the presence of heartworms. In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz...
A fetus in its mothers womb, viewed in a sonogram (brightness scan) A fetus, aged 29 weeks, in a 3D ultrasound Ultrasound is sound with a frequency greater than the upper limit of human hearing, this limit being approximately 20 kilohertz (20,000 hertz). ...
Treatment If either a blood test or the onset of symptoms betray the presence of heartworms, treatment is indicated. Treatment is highly efficacious if the disease is diagnosed early in the disease process. Before the worms can be treated, however, the dog must be evaluated for good heart, liver, and kidney function to ensure the animal can survive the treatment. Any insufficiencies in these organs must be dealt with first, before treatment, as the eradication process can be taxing on organ function. Usually the adult worms are killed with an arsenic-based compound. The currently recommended compound, Melarsomine dihydrochloride, is marketed under the brand name Immiticide. It has a greater efficacy and fewer side effects than previous formulation (Thiacetarsamide sodium, sold as Caparsolate) which makes it a safer alternative for dogs with late-stage infestations. General Name, Symbol, Number arsenic, As, 33 Chemical series metalloids Group, Period, Block 15, 4, p Appearance metallic gray Atomic mass 74. ...
After treatment, the dog must rest (restricted exercise) for several weeks so as to give its body sufficient time to absorb the dead worms without ill effect. Otherwise, when the dog is under exertion, dead worms may break loose and travel to the lungs, potentially causing respiratory failure and death. According to the American Heartworm Society, use of aspirin in dogs infected with heartworms is no longer recommended due to a lack of evidence of clinical benefit, and may be contraindicated. It had previously been recommended for its effects on platelet adhesion and reduction of vascular damage caused by the heartworms. Respiratory failure is a medical term for inadequate gas exchange by the respiratory system. ...
Aspirin or acetylsalicylic acid (acetosal) is a drug in the family of salicylates, often used as an analgesic (against minor pains and aches), antipyretic (against fever), and anti-inflammatory. ...
The course of treatment is not completed until several weeks later when the microfilariae are dealt with in a separate course of treatment. Once heartworm tests come back negative, the treatment is considered a success.
Surgical removal of the adult heartworms is also a treatment that may be indicated, especially in advanced cases with substantial heart involvement.
Long term monthly administration of ivermectin (but apparently not moxidectin, milbemycin or selamectin) year round for at least three years at the dose normally used for heartworm prevention (see "Prevention") also removes most adult heartworms from most dogs. However, this is not the treatment of choice for removal of adult heartworms for two reasons. First, not all dogs are completely cleared of heartworms by this treatment. More importantly, adult heartworms do not begin to die until some 18 months of treatment have elapsed, which is not acceptable under most circumstances. This treatment is normally reserved for dogs that are not likely to tolerate treatment with the harsher, but more effective, melarsomine or instances where the owner cannot afford the more expensive melarsomine treatment. Ivermectin is an anti-parasite medication and is effective against most common intestinal worms (except tapeworms), most mites, and some lice. ...
Moxidectin is a parasiticide. ...
Selamectin is the active ingredient in Revolution, a topical insecticide and antihelminthic used on dogs and cats. ...
Heartworm is a parasitic roundworm (Dirofilaria immitis) that is spread from host to host through the bites of mosquitoes. ...
From time to time various "homeopathic," "natural" or "organic" products are touted as cures or preventives for heartworm disease. However, such products have never been proven effective by rigorous scientific methods, and the claims should be viewed with skepticism. Homeopathy (also spelled homœopathy or homoeopathy), from the Greek words homoios (similar) and pathos (suffering), is a controversial system of alternative medicine involving the use of remedies without chemically active ingredients. ...
An organic product is one which is certified organic. ...
Prevention Prevention of heartworm infection can be obtained through a number of veterinary drugs. Most popular are ivermectin (sold under the brand name Heartgard), milbemycin (Interceptor) and moxidectin (ProHeart) administered as pills or chewable tablets. These drugs are given monthly during the local mosquito season. Moxidectin is also available in a six-month sustained release injection, Proheart 6, administered by veterinarians, but the injectable form of Moxidectin was taken off the market in the United States due to safety concerns. ProHeart 6 remains on the market in many other countries including Canada and Japan and is used with great success. Its sister product, ProHeart SR-12 is used extensively in Australia and Asia as a 12 month injectable preventative. Selamectin (Revolution), on the other hand, is a topical preventive that is likewise administered monthly. Some of these drugs also kill other parasites, including intestinal worms. In addition, Selamectin controls fleas, ticks, and mites. Ivermectin is an anti-parasite medication and is effective against most common intestinal worms (except tapeworms), most mites, and some lice. ...
This article belongs in one or more categories. ...
Selamectin is the active ingredient in Revolution, a topical insecticide and antihelminthic used on dogs and cats. ...
Families Tungidae – sticktight and chigoe fleas (chiggers) Pulicidae – common fleas Coptopsyllidae Vermipsyllidae – carnivore fleas Rhopalopsyllidae – marsupial fleas Hypsophthalmidae Stephanocircidae Pygiopsyllidae Hystrichopsyllidae – rat and mouse fleas Leptopsyllidae – bird and rabbit fleas Ischnopsyllidae – bat fleas Ceratophyllidae Amphipsyllidae Malacopsyllidae Dolichopsyllidae – rodent fleas Ctenopsyllidae Flea is the common name for any of the small...
Families Ixodidae - Hard ticks Argasidae - Soft ticks Nuttalliellidae Wikispecies has information related to: Ixodoidea Tick is the common name for the small arachnids that, along with mites, constitute the order Acarina. ...
Families Tetranychidae - Spider mites Eriophyidae - Gall mites Sarcoptidae - Sarcoptic Mange mites The mites and ticks, order Acarina or Acari, belong to the Arachnida and are among the most diverse and successful of all the invertebrate groups, although some way behind the insects. ...
Preventative drugs are highly effective, and when regularly administered will protect more than 99 percent of dogs from infection. Most failures of protection result from irregular and infrequent administration of the drug. However, the monthly preventives all have a reasonable margin for error in their administration such that if a single month's dose is accidentally missed, adequate protection is usually provided so long as the next two monthly doses are administered on schedule.
Cats may be treated with ivermectin (Heartgard for Cats), milbemycin (Interceptor), or the topical selamectin (Revolution for Cats).
Monthly heartworm prevention should be administered beginning within a month of the onset of the local mosquito season and continued for a month after the cessation of local mosquito activity. In warm climates, such as the warm temperate climate along the immediate Gulf coast of the United States and in tropical and subtropical regions, heartworm prevention must be administered year round. Some authorities recommend year round administration even in colder climates on the theory that mosquito activity may occur during the occasional unseasonable warm spell, but others argue that computer models indicate heartworm transmission is highly unlikely under such circumstances.
Human health considerations The dog heartworm is a negligible public health risk, because it is unusual for humans to become infected. Additionally, human infections usually are of little or no consequence, although rarely an infected human may show signs of respiratory disease. In most cases, however, the heartworm dies shortly after arriving in the human lung, and a nodule, known as a granuloma, forms around the dead worm as it is being killed and absorbed. If an infected person happens to have a chest X-ray at that time, the granuloma may resemble lung cancer on the X-ray and require a biopsy to rule out the life threatening condition. This may well be the most significant medical consequence of human infection by the dog heartworm. H&E section of non-caseasting granuloma seen in the colon of a patient with Crohns disease In medicine (anatomical pathology), a granuloma is a group of epithelioid macrophages surrounded by a lymphocyte cuff. ...
Lung cancer is a cancer of the lungs characterized by the presence of malignant tumours. ...
A biopsy (in Greek: bios = life and opsy = look/appearance) is a medical test involving the removal of cells or tissues for examination. ...
At one time it was thought that the dog heartworm infected the human eye, with most cases reported from the southeastern United States. However, these cases are now known to be caused by a closely-related parasite of raccoons, Dirofilaria tenuis. Several hundred cases of subcutaneous (under the skin) infections in humans have been reported in Europe, but these are almost always caused by another closely-related parasite, Dirofilaria repens, rather than the dog heartworm. This article or section does not cite its references or sources. ...
The subcutis is the layer of tissue directly underlying the cutis. ...
Resources and external links
Heartworm Society - American Heartworm Society Founded in 1974, the American Heartworm Society is internationally recognized as the definitive authority with respect to heartworm disease in dogs and cats.
American Heartworm Society information for pet owners: - Quick Review of Heartworm Disease
- Frequently Asked Questions
- Heartworm Disease in Dogs
- Heartworm Disease in Cats
American Heartworm Society information for veterinarians. (Every three years the American Heartworm Society holds an international symposium. Following each triennial symposium, the Society updates its guidelines for veterinarians to incorporate any new discoveries. The following guidelines are widely considered "best practices" and should be closely followed by veterinarians in dealing with this parasite.) - Guidelines for the Diagnosis, Prevention and Management of Heartworm (Dirofilaria immitis) Infection in Dogs
- Guidelines for the Diagnosis, Prevention and Management of Heartworm (Dirofilaria immitis) Infection in Cats
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