Heartworm Disease
Our Heartworm Disease Treatment and Education Form
What Is It?
Canine heartworm disease is a serious and fatal disease of dogs. Long white worms, technically known as Dirofilaria immitis, are the cause. Adult worms, which reach a length of 6 to 14 inches, live in the right side of the heart in the adjacent large blood vessels. A dog may have several hundred of them in its system, although the number is usually much less. Occasionally canine heartworms are found in other animals such as foxes, skunks, horses, and cats.
What Does It Do?
Large accumulations of adult worms impair circulation of the blood, which can result in serious damage to a dog's heart, lungs, liver, and kidneys. The important thing for dog owners to remember is that a great deal of damage can occur before any outward signs of heartworm disease are noticed. Although a dog can lead a nearly normal, healthy life with a few heartworms in its system, in advanced stages the disease may cause its victim to have difficulty breathing, cough, tire easily, become listless, lose weight or faint. If not detected and controlled with proper treatment, the disease can lead to congestive heart failure and death.
How Does a Dog Get Heartworms?
Heartworm infection is spread by mosquitoes. When a mosquito "bites" an infected dog, it takes up blood which may contain microscopic immature forms of heartworms called microfilariae. The microfilariae incubate in the mosquito for about one week, during which they become infective larvae. Then, when the mosquito bites another dog, the infective larvae are passed into the second dog, infecting it. The infective larvae migrate through the tissues of the body for about three months, then enter the heart where they reach adult size in another three months. The mosquito is the only natural agent of transmission for canine heartworms. As you might expect, heartworm infection is more common in areas where mosquitoes are numerous.
How Is It Detected?
The only way to detect heartworm disease is a blood test. A veterinarian, using relatively simple diagnostic procedures, can usually detect the tiny heartworm microfilariae in an infected dog's blood. But occasionally, an infected dog will have adult heartworms but no microfilariae. In such cases an X-ray examination and other laboratory tests are needed to confirm heartworm infection.
Can Infected Dogs Be Treated?
Most dogs can be successfully treated for heartworms if the disease is detected early. The adult worms are killed with an organic arsenical drug given through a series of carefully administered injections. A few days after treatment, the worms die and are carried by the bloodstream to the lungs where they lodge in small blood vessels. There they decompose and are absorbed by the body over a period of several months. There is always some risk involved in treating a dog with heartworms. However, fatalities resulting from treatment are rare among dogs that are otherwise in good general health. The patient should be given a thorough physical and laboratory examination prior to treatment, and any other problems that might cause complications should be corrected before heartworm treatment begins. Following treatment, complete rest is needed to prevent lung damage from the dead and decomposed worms. Excitement and exercise should be avoided for at least a month, followed by gradual return to normal activity. After all adult heartworms are eliminated, another drug must be given to rid the bloodstream of microfilariae, which are not affected by the drug used to kill adult heartworms.
Can It Be Prevented?
YES - Heartworm disease may be effectively prevented by a 30-day one pill taken orally ("Heartgard"). Heartworm disease is very preventable but very difficult and dangerous to treat. Prevention is the answer. If you have any questions about heartworm disease or preventative care, please call us at 713.468.1676.