HEARTWORM DISEASE   
          and YOUR PET 

            What you need to know....

• How big is my pet's risk for heartworm infection?      answer: The North Texas area has a high mosquito population.  Mosquitoes are currently mature and active (May 2009)   Animals are vulnerable to heartworm disease right now.  Also, owners may travel with their pets into heartworm-endemic areas, even if they currently live in an area with low heartworm incidence.  Heartworm disease is spreading to new regions of the country every year.  Uncared-for dogs and cats and certain wildlife species can be carriers of heartworms.  Mosquitos blown great distances by wind, and the movement of infected pets to different geographic locations all contribute to the increase and spread of heartworm disease to areas that may have previously been considered heartworm-free.  The best way for safe prevention of heartworm infection is to administer a year-round heartworm preventative as directed by your veterinarian.
  
• How is heartworm disease transmitted from one pet to another?     answer:  Adult female heartworms living in an infected dog, cat or other host release their young called microfilaria, into the bloodstream of the host animal.  Mosquitoes become infected by the microfilaria while taking a blood meal from these infected animals.  During the next 10 to 14 days, microfilaria mature to the infective larval stage within the mosquito.  When the mosquito then bites another dog, cat or susceptible animal, the infective larvae exit the mosquito's mouth parts and are deposited into the animal's skln through the fresh bite wound.  Inside the new host, it takes a little more than six months for the infective larvae to mature into adult heartworms.  Once mature, heartworms may live up to  five to seven years, and because of their longevity, each mosquito season can lead to an increasing number of worms in our pets.
   
• What physical signs could my pet have?     answer:  Heartworms may accumulate over years, or quickly when conditions allow exposure to high numbers of mosquitoes carrying infective heartworm larvae.  Clinical signs of disease may not be easily recognized in pets recently infected or those with low numbers of heartworms, but damage is being done!  Dogs heavily infected or those with chronic disease often show prominent clinical signs including: mild persistent cough, reluctance to exercise, fatigue afer moderate activity, decreased appetite and weigh loss.  In cats, symptoms include: vomiting, coughing and unexplained sudden death.  As disease progresses, pets may develop heart failure.  Pets infected with large numbers of heartworms can develop a sudden blockage of blood flow within the heart, leading to a life threatening form of cardiovascular collapse called "caval syndrome."  Signs include sudden onset of labored breathing, pale gums and dark bloody or "coffee-colored" urine.  Without prompt surgical removal of the heartworm blockage, few pets survive.
   
• Cats get heartworms too??      answer:  YES, cats get heartworm infection also.  While often overlooked, HW disease is increasing in our pet population, including cats.  Please see clinical symptoms for cats in the question/answer above.  Remember, since there is no approved treatment for heartworm infection in cats, prevention is critical.  Your cat should be tested prior to starting a preventative, and be tested annually thereafter.
   
• My vet suggested a Heartworm Test... how does this test work?      answer:  Two common types of test exist for diagnosing heartworm infection in dogs.  Because adult heartworms release their young (microfilaria) directly into a dog's bloodstream, a relatively simple blood filter test can identify them.  A positive test tells us adult worms are present.  Positive means positive.  Unfortunately, 15-20% of heartworm-positive dogs will not have microfilaria circulating in their bloodstream and a negative test will sometimes be falsely negative.  The most accurate test for detecting HW infection in dogs is the antigen test.  This test looks for the presence of small proteins released by adult female heartworms into the dog's bloodstream.  A positive test tells us mature female worms are present.  While false negative results are uncommon, they can occur if a pet has a "male-only" infection (since the test detects antigen from females), if one or two worms are present, or if the female worms are immature.  It takes 5-7 months frm the time a dog is bitten by infected mosquitos until a blood test can accurately detect the presence of adult worms. 
   
• My dog tested positive for heartworms... what does this mean?   answer:  A positive microfilaria or antigen test indicates that your dog has adult heartworms in the heart and arteries of the lungs. (please see photo above... those are heartworms coming from the heart and artery).  Even if your dog is not showing any symptoms, there may already be damage to the heart, blood vessels and lungs.  If not treated, this can lead to serious, even life-threatening disease. If treatment is started before symptoms are obvious, the chances are very good that your dog will not have any significant complications following treatment.
   
• How do heartworm preventatives work?    answer:  There are several very effective once-a-month heartworm preventatives available, some are chewable tablets and others are topically applied solutions.  An important note to keep in mind is that monthly medications are quickly eliminated from a pet's system and do not continue to work for 30 days.  Instead, they work "bakcwars" to eliminate the larvae the pet acquired the previous 30 days, in essence, we are "de-worming" our pets each month.  This is important to understanding that preventative MUST be given monthly, as heartworms must be killed at a critical stage of their development toward adulthood.  If too much time passes between doses of preventative, the heartworms mature to a stage not vulnerable to the preventative.   GIVE YOUR PETS HEARTWORM PREVENTATIVE MONTHLY!!!
   
• My cat/dog never goes outside.. do I need to give preventative?    answer: YES!!  How many times have ou been bitten by mosquitoes inside your home?  Mosquitoes come inside, so inside only pets are also vulnerable.  It only takes one bit!  Heartworm preventative should be given year-round to ALL your pets.
   
• I have missed two months (or more) of heartworm prevention... should I worry?      answer:  YES, you should worry, but more importantly, you need to cconsult your veterinarian and immediately start your pet back on monthly preventative (following your vet's express direction) and re-test in 6 months.  The reason for testing in six months is that heartworms must be approximately 6 months old before the infection can be diagnosed.  Don't beat yourself up... but let your "worry" spur you to action in safeguarding your pet. 
   
• Why do dogs need to be blood tested before starting heartworm medication?      answer:  Before starting a preventative program, all dogs should be tested for heartworms.  Giving preventatives to dogs that have adult heartworm infection can be harmful or even fatal to the pet.
   
• How often shuld I have my dog tested for heartworm infection?     answer:  Annual testing is recommended for several important reasons.  First, many of us do not take our own medications as directed, let alone medicate our pets.  We're busy; we forget; we miss a dose here and there.  Second, even if you never miss a dose there is nothing to prevent your dog from eating some grass and vomiting up the medication you just gave.  Your pet would be without protection for an entire month.  Third, if you pet accidently became infected with heartworms, your veterinarian needs to detect it as soon as possible before the irreversible heart and lung damage occur.  Early detection and treatment are always best.  Also, some heartworm tests now come combined with tests that monitor other significant diseases (Lyme disease, Ehrlichiosis and Anaplasmosis). With annual testing, you know your pet is heartworm free and not infected with these serious tick-borne diseases, some of which could affect family members.  The tests are quick and accurate and make sure your pet is free from infection.  Annual testing provides peace of mind in knowing that your pet is free of heartworms, and should your pet be infected, it assures you of early diagnosis.  Finally, some companies who manufacture HW preventatives  may pay for HW treatment, should your pet become HW positive, IF it can be shown that you puchased  appropriate weight heartworm preventative from your veterinarian *** and gave in a timely manner; and have had your pet heart-worm tested.   ***IMPORTANT NOTE:  Companies will NOT honor purchase of HW preventatives through on-line pharmacies, but only through a licensed veterinarian.  This is one of the specific reasons Parkside Animal Hospital will not authorize medications/prescriptions through on-line pharmacies.  Please see our statement on the ABOUT US tab.. INTERNET PHARMACY section.
   
• Is a puppy born with immunity to heartworm disease?       answer:  No, even nursing puppies are at risk for heartworm infection.  Puppies of any age exposed to mosquitoes carring infective larvae can become heartworm-infected, so it is important to begin prevention early.  Puppies can be started on HW preventative as early as four to eight weeks of age, depending on the label recommendations of the preventative.
   
• I heard that certain heartworm prevention medications will also protect against intestinal parasites.  Is this true?    answer:  Certain heartworm preventive products are also effective in removing specific intestinal (and external) parasites and are laabeled for such uses.  The either contain a single active ingredient that is effective against several parasites including developing heartworm or a combination of ingredients to achieve control of many different parasites.  Such products have been tested and meet the same safety requirements as the heartworm prevention-only products.
   
• How often should I have my cat tested for heartworms?  answer: Heartworm infection in cats is easily overlooked and harder to detect than in dogs.   Your cat should be tested prior to starting a preventive, and annually thereafter.  Remember, since there is no approved treatment for heartworm infection in cats, prevention is critical.
  
• What are the signs of heartworm disease in cats?   answer:  Signs of heartworm disease in cats can be very subtle and misleading.  Signs may include coughing, asthma-like attacks, intermittent vomiting, lack of appetite, or weight loss.  Occasionally ataxia (difficulty walking), seizures, fluid accumulation in the abdomen (ascites) and syncope (fainting) have been reported as well.  Unfortunately, the first sign in some cases is sudden collapse of the cat, or sudden death.
  
• My cat goes outside daily.  Should I put her on heartworm preventive medication?  answer:  The prevalence of feline heartworm infection parrallels that found in the local dog population.  If heartworms are found in dogs in your area (and the incidence of HW disease has risen dramatically in the DFW metropolitan area over the last few years), cats are also at risk and should be placed on preventive medication.  the products that prevent heartworm disease also remove intestinal parasites that are potentially contagious to family members.  Intestinal parasites are a year-round problema and require year-round treatment and prevention.
   
• My cat never goes outside.  Should I put her on heartworm preventive medication?   answer:  Whether living indoors or outdoors, cats can be exposed to mosquitoes carrying heartworm disease.  While the outdoor cat is more likely to be bitten by a higher number of mosquitoes, mosquitoes do get into our homes and are capable of biting our indoor pets.  It is important to realize that a single heartworm can cause severe consequences.  Multiple studies have reported a significant number of heartworm infections in cats living exclusively indoors.  If heartworms are found in dogs in your area, cats are also at risk and should abe placed on preventive medication.