What is Heartworm Disease?


Heartworm disease is the result of an infection of the parasitic worm – Dirofilaria immitis.  Animals contract this heartworm after a bite from infected mosquito.  Besides infecting our pets it also infects wild dogs such as foxes and wolves,  and sea lions and seals, and on occasion us.

Worm life cycle:  To understand how to prevent this debilitating condition in your dog let’s take a look at the life cycle of the worm.  The life cycle of the worm begins when the mosquito that bites the dog injects a small bit of saliva and previous blood meal into the dogs skin.  This injection by the mosquito contains anticoagulant compounds which reduce blood clotting in the area of the mosquito is feeding from, this injection from the mosquito may also contain microfilaria -larvae- from a previous blood meal.

The injected larvae grow in the dogs skin for up to 2 weeks before they migrate to the dogs heart.  After about two months the small worms have completed their journey from the skin of the dog to its pulmonary artery where they take up residence, then over the next three months, they continue their growth into adult worms.  Adult female worms can grow up to 12 inches in Length.  They continue to grow and breed and increase in numbers.  The offspring that they produce are known as microfilaria, these then migrate into the bloodstream and circulate throughout the body.

Microfilaria can live up to two years in your dog’s blood stream waiting for the next mosquito to bite the dog and transfer them to the next host.  Adult heartworms can live 3 to 6 years in your dog’s body.

All dogs are at risk of catching heartworm disease, but dogs living in warmer climates are more prone to the disease where is dogs and cooler climates and less susceptible to mosquito bites.

Symptoms:  How disease symptoms make themselves apparent is by coughing and wheezing, an intolerance to exercise, loss of appetite, though some dogs just show a general decline in conditioning. Heartworm disease initially causes damage to the tissues of the heart but over time the worms can make their way to the lungs, this stage of the infection causes the classic wheezing and the coughing up of blood. If the growth of these worms is left unchecked they will continue to migrate through the body making their way to the liver. At this point it takes a massive toll on the doge immune system, and death is certain if the disease remains untreated.

States most at risk:  States in America most at risk of heartworm in order from most reported cases are Mississippi, Louisiana, Arkansas, Texas and Tennessee South Carolina, Georgia, North Carolina, Alabama and Florida. Among the top ten, only Alabama, Louisiana and Texas saw a decrease in reported infection rates, while the other seven saw an increase since the AHS began tracking incidence data in 2001.

Treatment is available for infected dogs, it is expensive and it will kill the worm, the issue being though the dead worms will leave the organs and enter the bloodstream, where they then start to breakdown, this causes a massive toxic shock to the dog and death again is a very real possibility. Clearly prevention is better than cure.

So we understand, pets are our companions, our best buddies. But as living beings, they like us get sick sometimes, and like us they need medications. It is up to us, as responsible owners to give it to them. Most of the time we have a good idea what the need in the way of prevention. But when our pets are ill, we definitely need a vet prescription. In the case of some prevention medications it is also necessary to prove clear before we administer them. However, if your certain your pet has previously tested clear buying pet meds without a vet prescription is okay if you're buying name brand products from a reliable website. 

When should you see a vet and when is it ok to save some money and buy directly buy pet meds over the counter?