Worms in Dogs

There are several different types of worms that can affect dogs, from the common roundworm to the more rare varieties such as lungworm and heartworm. This year (2012), mainly due to the very wet months early in the year, there has been a massive increase in the number of slugs and snails around, so that lung worm is becoming an increasing risk but is little known and so is often unrecognised.

worms in dogs The WebMD page on worms in dogs

Lung Worm

Lung worm used to be very rare in the U.K. and the only places of risk that were given were the wildest and least inhabited areas such as moorland. Now it seems to be getting more and more common but is still often unrecognised.

Lungworm is an infection of the lower respiratory tract, which refers to the portions of the respiratory system from the trachea to the lungs. Thus, the trachea (wind pipe) the two bronchial tubes (one to each lung), the bronchioles, and the lungs. The bronchioles are the first passageways by which the air passes through the nose or mouth to the air sacs of the lungs in which branches no longer contain cartilage or glands in their submucosa. They are branches of the bronchi. The bronchioles terminate by entering the circular sacs called alveoli.

Some sources include the larynx as part of the lower respiratory tract, whereas others include it in the upper respiratory tract (which also comprises the nasal cavity (nose) and the pharynx). Between them, the upper and lower respiratory tracts make up the whole respiratory system. Lower respiratory tract infections can be the cause of several serious illnesses, including pneumonia.

Lungworm can be caused in many species by any of several parasitic nematodes, including Angiostrongylus vasorum (French Heartworm) and Oslerus osleri, Filaroides hirthi and Crenosoma vulpis which affect dogs, and these are carried by slugs and snails, which are known as intermediate hosts. A dog does not have to actually eat these common garden pests but can pick up the lungworm eggs from the trails of slugs and snails when rummaging through undergrowth, eating grass, drinking from puddles or outdoor water bowls, or from playing outside with toys, especially toys that have been left outside for any length of time.

The general life cycle of a lungworm begins with an ingestion of infected larvae. The infected larvae then penetrate the intestinal wall where larvae migrate into the lungs through the bloodstream. The infected larvae reside in the lungs until the development into adult larvae. The eggs of the adult larvae hatch thus producing lungworm. These eggs that reside in the lungs are coughed up and then ingested back into the stomach and then into faeces.

The lungworm larvae then grow inside the dog and adult lungworms move through their body to live in their heart and blood vessels. This can cause heart problems, breathing problems and pneumonia. After about 28 days the worms start to produce their own larvae which can lead to serious problems. It can cause haemorrhages in the lungs, liver, intestine, eyes and spinal cord but also pretty much anywhere in the body. If left untreated, it can be fatal in severe cases. Young dogs seem to be more prone to the disorder but that might be only that they are more likely than older dogs to be rooting about in undergrowth, eating those odd looking creatures crawling about, playing with things that are coated with slug and snail slime, and drinking from puddles.

Symptoms in an infected dog can include coughing, panting, reluctance to exercise, tiring easily, fits (seizures), vomiting, diarrhoea, depression, weightloss, persistent bleeding such as nose bleeds or even minor wounds continuing to bleed, bleeding into the eye, anaemia, incoordination, inability to walk. Many of these symptoms occur in other disorders such as laryngeal paralysis, which see.

Lungworm is not affected by normal worming treatment but requires a specific lungworm treatment and control programme.


petmd The Pet MD page on Lungworms in Dogs
Wikipedia The Wikipedia page on lungworm
dfordog The dfordog.co.uk article - Be Lungworm Aware
Official Lungworm Site Be Lungworm Aware - the lungworm official website
Chipping Norton Veterinary Hospital Chipping Norton Veterinary Hospital download on lungworm (Microsoft Word document)

Heart Worm

This is still quite rare in the U.K., as it is carried by mosquitoes and so is more common in hot countries. It is a parasitic roundworm known as a filaria, a small thread-like worm and, although it is called heart worm, the adults actually reside mainly in the pulmonary arterial system (lung arteries) causing damage to the lung vessels and tissues, although in heavy infestations adult worms may migrate to the right side of the heart and the great veins.

Heartworms go through several life stages before they become adults infecting the pulmonary artery of the host animal. The worms require the mosquito as an intermediate stage to complete their life cycles and their rate of development within the mosquito is temperature-dependent, so infection is limited to hot weather. Once a dog is bitten by an infected mosquito it takes six to seven months for the maturation of the worms into adults to occur.

After infection, the third-stage larval heartworms deposited by the mosquito grow for a week or two and moult to the fourth larval stage under the skin at the site of the mosquito bite. They then migrate to the muscles of the chest and abdomen, and 45 to 60 days after infection, moult 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 reside in the pulmonary artery. Over the next three to four months, they increase greatly in size. The female adult worm is about 30 cm in length, and the male is sbout 23 cm, with a coiled tail. By seven months after infection, the adult worms have mated and the females begin giving birth to live young, called microfilariae. These then circulate through the bloodstream - which can be for as long as two years - waiting to be taken up by a mosquito, after which they go through several stages of moult until they migrate to the salivary glands of the mosquito and await being able to infect another host.

Normally dogs show no signs of infestation until the worms have matured and congregate in the pulmonary arteries. Early signs of infestation include a cough, especially when exercising, and early exhaustion from exercise. In the most advanced cases, where many adult worms have built up in the heart without treatment, signs progress to severe weight loss, fainting, coughing up blood and, finally, to congestive heart failure. Occasionally migrating heart worms get lost and end up somewhere such as in an artery in a leg, or in an eye, or the brain, causing unusual symptoms such as lameness, blindness, or fitting.


WebMD The WebMD Healthy Pets page on heartworm
Heartworm Society The American Heartworm Society website
FDA The FDA (US Food & Drug Administration) page on Heartworm Disease in Dogs
Wikipedia The Wikipedia page on heartworm
about.com The About.com page on Heartworm Disease in Dogs


Blastomycosis is a systemic fungal infection caused by Blastomyces dermatitidis, which is prevalent in swampy areas, lakes, and on river banks, but also in areas where there is decaying organic matter, such as woodlands, forests, and farmland, mainly in North America and Canada, although it does appear to be spreading internationally.

The fungus releases airborne spores that can be inhaled by humans and animals or even be taken in through the skin. Once inhaled the spores travel through the lungs and become large, yeast-like organisms that multiply within the lungs and other bodily tissue. It can cause significant pulmonary disease and can also travel to other areas of the body such as the eyes, the skin, and joints.

Symptoms of infection can include loss of appetite, weightloss, fever, depression, coughing, wheezing, inflammation of and discharge from the eyes, and pus-filled skin lesions. More severe symptoms can also occur, such as seizures, sudden blindness, lameness, enlarged lymph nodes, and inflammation of the testicles.

Because it's a fungal infection, antibiotics have no effect and anti-fungal drugs have to be given, although these can have serious side effects. The safest one to give seems to be Itraconazole, but it is a human drug and very expensive and has to be given for a long time. There is a herbal remedy - Fungus Free Plus [http://www.fungusfreeplus.com/] which might be an alternative. Virgin coconut oil added to the food could help as a preventative, as it is anti-fungal, and could also be used as a treatment on lesions caused by Blastomycosis.


healthy pets Article on Blastomycosis by Dr. Karen Becker on the Healthy Pets page presented by mercola.com
dogheirs Article on Blastomycosis in Dogs on the DogHeirs website
.dvm360 Article on Canine Blastomycosis on the .dvm360.com website

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Upated 8/14/2015