Common Disease Name:
Heartworm Disease
Medical Term for Disease:
Dirofilaria Immitis infection
Species Affected by Disease:
Age Animal Usually Affected:
Most affected animals are 3-8 years old.
Commonly Affected Breeds:
All dogs in regions with endemic heartworm disease. Medium- to large-breed dogs that spend a lot of time outdoors.
Sex Usually Affected:
None
Disease Symptoms:
No symptoms are seen in dogs with
mild infection and in some with moderately severe infection. Coughing can be the
first symptom noticed, as well as 
weight loss, intolerance of
exercise, loss of appetite. With worsening infection may see labored
breathing, rapid heart rates and a pendulous abdomen, and dog may faint or
collapse when stressed. Severe and fatal cases
cough up bloody foam.
Method(s) of Diagnosis:
Highly specific and sensitive serologic tests which identify adult D. Immitis antigen are widely available. Common Disease Name it the SNAP heartworm test. There are other tests which can detect heartworms as well.
Disease Causes:
Infection with Derm Immitis. The mosquito carried the infective phase from a dog with heartworm disease to your dog once bitten, the larva is injected into your dog, and there it migrates for about 6 months through the tissues until it reached the right side of the heart. There it grows into a long thin worm. These worms reproduce and after time, there are hundreds in your dog's heart and the enlarge blood vessels from the heart to the lungs. The heart eventually gives out due to the stress of trying to pump blood when it is full of worms.
Treatment:
The extent of the disease must be assessed before considering treatment. Physical assessment plus chest radiographs and lab work will help classify the extent of infection. This will dictate if dog can be treated and what his chances of survival might be. Right congestive heart failure and/or respiratory failure must be stabilized before treatment in severely infected dogs. These dogs may not be able to undergo the standard adulticide treatment, and an alternative treatment plan may be suggested. An adulticide is administered to kill the worms in the heart. The dog cannot have any exercise for several weeks following this treatment or risk a potentially fatal embolism of dead worms to the lungs. This treatment is followed up 4-6 weeks after adulticide later by a microfilaricide to kill larvae. Another microfilaria check should be done in 3-4 weeks to make sure there are no adults still in the heart. Alternately, a SNAP test can be preformed 3-4 months after treatment to detect adult worm antigens in the blood stream. After microfilaria treatment, the dog is placed preferably on a monthly preventative which kills any larva he may have been exposed to the previous month. Some people prefer a daily heartworm preventive, but this risks infection if a day is missed and your dogs is exposed to a mosquito carrying the disease. Dogs in liver or kidney failure cannot be treated with an adulticide. Surgical removal of the worms from the right heart and pulmonary artery via jugular vein is an option.
Prognosis:
Good prognosis for
animals with mild to moderate infection. Postadulticide respiratory
complications are likely in dogs with moderate to severe infection. Re-infection
can occur unless appropriate preventive is administered monthly. Prognosis is
grave if dog is showing signs of congestive heart failure, liver or kidney
failure.
Complications:
Killing a large number of worms at one time can lead to anaphylactic shock. Disease can be fatal if left untreated.
Prevention:
Monthly heartworm preventative.
Medicines Used for Treatment of Disease:
Immiticide to treat adult heartworms; preventive to kill larval stages; various treatments for congestive heart or respiratory failure.
Helpful Products:
Monthly preventives such as Sentinel, Heart Guard, Revolution, Interceptor and many more on the market. Daily preventives containing diethylcarbamazine will work as well, however, do not miss a dose. Do not give ivermetin to a heartworm positive dog as it may cause a severe reaction.
