Heartworm Disease in Dogs

WHAT IS HEARTWORM DISEASE?

Canine heartworm disease develops when a dog is bitten by a mosquito carrying microscopic heartworm larvae (juvenile worms) of a parasite called Dirofilaria immitis. As a mosquito feeds, these microscopic larvae are deposited on the  dog and quickly penetrate the skin to begin their migration into the dog’s bloodstream. Adult heartworms can grow 10 to 12 inches in length and make their home in the right side of the heart and pulmonary (lung) arteries,  often causing lung disease and heart failure.

Adult heartworms can grow 10 to 12 inches in length.

Heartworm Disease in Dogs heartworms HeartwormAlthough easy to prevent, heartworm disease continues to be a major health problem for dogs living in the United States and throughout the temperate and tropical regions of the world.

SIGNS OF HEARTWORM DISEASE

Since some dogs can be infected for many years before symptoms develop, heartworm disease in dogs may not be obvious. But, as heartworms slowly cause damage to the pulmonary arteries of the lungs, signs of disease may include a mild persistent cough, reluctance to exercise, fatigue after moderate activity, decreased appetite, and weight loss. Eventually, as blood flow through the diseased lungs becomes more restricted, some dogs can develop heart failure. This is commonly recognized by a buildup of fluid in the abdomen and the appearance of a “swollen belly.”

Although less common, a large number of heartworms can lead to a sudden obstruction of blood flow through the heart and lungs. This blockage often becomes a life-threatening form of cardiovascular collapse and is referred to as “caval syndrome.” Symptoms of caval syndrome often include a sudden onset of labored breathing, pale gums, dark red or “coffee-colored” urine, and an inability or unwillingness to move. Without prompt surgical removal of the heartworm blockage, few dogs suffering from caval syndrome survive.

DETECTING HEARTWORM INFECTION

Numerous blood tests are available for detecting heartworm infections in dogs, and your veterinarian will perform the test most appropriate for your dog. Keep in mind that no diagnostic test can accurately detect all heartworm infections. Tests cannot consistently detect infection until heartworms are at least seven months old. Moreover, tests are unable to detect infections if only male worms are present or if there are only one or two female worms. At times, your veterinarian may recommend the use of X-ray or ultrasound imaging to help in the diagnosis of heartworm disease. They may also repeat the blood test at suggested intervals.

WHO SHOULD BE TESTED?

Annual testing is recommended for monitoring the success of any heartworm prevention program. Sometimes, individual risk factors, clinical signs, preventive changes and testing limitations might warrant more frequent testing.

The frequency of testing should be discussed with your veterinarian, but all dogs more than six months of age should be tested for heartworms prior to initiating a preventive program. At a minimum, retesting is recommended six months following initiation of preventive or any lapse in administration, and annually thereafter.

TREATMENT

There are several things to consider once a dog is diagnosed with heartworm disease. Without treatment, heartworm disease will worsen and may lead to more serious illness. Unless medical reasons identify a dog as a poor candidate, heartworm-positive dogs should be treated. However, treating dogs for heartworms can also lead to serious health concerns, as these dead parasites may cause further injury to the lungs and pulmonary arteries.

A thorough physical examination, radiographs, and blood and urine tests may be needed prior to treatment to assess your dog’s level of risk. To reduce complications, your veterinarian will educate you in great detail before beginning treatment.

While the heartworm medication melarsamine hydrochloride is extremely effective in eliminating adult worms, some dogs will not be completely cleared with a single course of treatment. Testing is recommended six months after treatment to ensure all heartworms were killed. If tests are positive, additional adulticidal treatment may be indicated.

PREVENTION

Heartworm preventives are effective when given properly and on a timely schedule. It is important to note that these medications are quickly eliminated from a dog’s body shortly after they are given and do not continue to protect dogs from future infection. Instead, they eliminate infections acquired since the last dose.

All approved heartworm preventives are highly effective, safe, easy to use, relatively inexpensive, and often provide treatment for additional parasites. Prevention is always more safe and affordable than treating dogs with adult heartworm infections.

Please remember, it is your responsibility to faithfully maintain the program you have selected in consultation with your veterinarian. The best way to eliminate the risk of heartworm infection in your dog is to institute a year-round prevention program.

Be certain to have all pets tested prior to initiating or restarting any heartworm prevention program, as administration of some preventives can cause life-threatening reactions when given to heartworm-infected pets.

HEARTWORM LIFE CYCLE

Heartworm Disease in Dogs heartwormcycle HeartwormWhen a dog or other suitable host has a mature heartworm infection, female worms release their young (microfilariae) directly into the animal’s bloodstream. When a susceptible mosquito bites an animal with microfilariae in the blood, it ingests the microfilariae along with the blood. Over the following 10 to 14 days, these microfilariae develop and mature into infective larvae inside the mosquito. When the mosquito bites another dog, the larvae are left behind to enter the fresh wound.

In six to seven months, these microscopic larvae grow to a foot long during their migration to the heart and lung arteries. The larvae also become sexually mature and produce microfilariae of their own, which are available in the dog’s blood to other mosquitoes.

Because heartworms may live for five to seven years in the dog, each mosquito season can lead to an ever-increasing number of worms in unprotected dogs. Microfilariae cannot develop into adult heartworms in our dogs without first developing into the infective stage within a mosquito.

A MESSAGE TO TAKE TO HEART

While the risk of infection in dogs varies from one region of the country to another and even from one community to another, one fact remains: heartworm disease is a threat to unprotected dogs in every state except Alaska. Unprotected dogs, foxes, coyotes, and wolves act as reservoirs, or sources, for the spread of this serious disease. The relocation of dogs, as with humanitarian efforts following natural disasters, can introduce heartworm disease to non endemic parts of the country. Alternately, unprotected dogs traveling with owners to high-incidence areas will be at risk for exposure. Since heartworm disease is a complicated illness, the best approach is prevention.

This article highlights many general aspects of heartworm disease but cannot address every detail. Comprehensive guidelines have been prepared to assist you and your veterinarian in providing the most up-to-date heartworm information. Please visit the website of the American Heartworm Society (www.heartwormsociety.org) for more in-depth information regarding prevention, diagnosis, and treatment of heartworm disease.

 

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You assessed your cat's body condition score (BCS) to be to be 3 out of 9.

What does this mean? The BCS is an assessment of your cat’s general body composition, including muscle and fat. While a score of 4 to 5 is ideal, a BCS of 3 indicates that your cat is thin.

What to do next: While thin cats are generally at lower risk for serious health issues compared to overweight cats, being underweight can lead to decreased muscle mass, malnutrition, and a weakened immune system. Unless there is an underlying reason for your cat’s thinness, the situation can often be improved with simple lifestyle adjustments, such as:

  • Offering a palatable diet recommended by your veterinarian
  • Feeding small, frequent meals
  • Stimulating the appetite by warming the food or introducing toppers
  • Minimizing stress
  • Weighing your cat monthly
  • Re-checking your cat's BCS at home
  • Staying alert to other health changes (especially continued weight loss and appetite loss)

Your cat's BCS provides valuable insights into their overall health and helps us spot potential issues early. While a BCS of 3 isn’t an immediate cause for concern, it’s a sign that small adjustments to their feeding and care routine could have a positive impact on their health.

Questions? We can help. Let’s work together to score a win for your cat's health.

You assessed your cat's body condition score (BCS) to be to be 6 out of 9.

What does this mean? The BCS is an assessment of your cat’s general body composition, including muscle and fat. While a score of 4 to 5 is ideal, a BCS of 6 indicates that your cat is borderline overweight.

What to do next: Simple daily actions can help prevent your cat from becoming overweight. Even a few extra ounces or pounds can significantly impact their health, increasing the risk of serious conditions like diabetes, arthritis, and kidney disease.

Restore your cat's future health by:

  • Feeding portioned meals (Your veterinarian can assist you with how much to feed)
  • Reducing stress by minimizing household changes and maintaining a routine
  • Decreasing boredom with interactive toys, social interaction, and cat furniture
  • Separating pets during meal time (Consider a microchip-linked feeder for multi-cat households)
  • Weighing them monthly
  • Re-checking your cat's BCS at home

Your cat's BCS is like a warning light for their future health. Taking proactive steps to address your cat’s weight can minimize future complications and help ensure they stay fit, agile, and healthy.

Curious about other ways to improve your cat’s BCS and overall well-being? Get in touch. Let’s work together to score a win for their health.

You assessed your dog's body condition score (BCS) to be to be 4-5 out of 9.

What does this mean? The BCS is an assessment of general body composition, including muscle and fat. On a scale of 1 to 9, with 1 being very thin and 9 being obese, your dog's score means they are at their ideal weight for optimal health and well-being!

What to do next: First, give your dog a scratch behind the ears to celebrate your success! Your commitment to their preventive health—regular vet visits, balanced nutrition, and consistent exercise—is truly paying off. But don’t relax just yet—maintaining a healthy BCS takes ongoing effort throughout your dog's life, including:

  • Feeding portioned meals
  • Avoiding high-calorie treats, diets, and people food
  • Staying active with regular exercise
  • Re-checking your pet’s BCS monthly at home
  • Staying on top of routine care (exams, screening tests) to ensure early detection of health changes

Just like your dog's vital signs, their BCS gives valuable insight into their overall health. Right now, we like what we see—and feel! But remember, supporting your dog's lifelong health is a team effort. By continuing the great work you’re doing and partnering with us, we can help ensure they stay healthy for years to come.

You assessed your cat's body condition score (BCS) to be to be 7-8 out of 9.

What does this mean? The BCS is an assessment of your cat’s general body composition, including muscle and fat. While a score of 4 to 5 is ideal, a BCS of 7-8 indicates that your cat is overweight.

What to do next: Weight issues are a common cause of many feline health problems, some of which can shorten a cat's life. Fortunately, with your dedication and our support, your cat can achieve better health, mobility, and an ideal body weight.

Rather than asking your cat to participate in daily exercise, feline weight loss emphasizes targeted nutrition and stress reduction to help them shed those unwanted pounds. This entails:

  • Offering a palatable weight-management diet recommended by your veterinarian
  • Feeding portioned meals (Your veterinarian can assist you with how much to feed)
  • Using a microchip-linked feeder for multi-cat households to ensure each cat consumes their veterinarian-recommended portion
  • Minimizing stress by maintaining a stable routine
  • Decreasing boredom through positive interactions such as interactive toys, food puzzles, cat-friendly furniture, and social bonding
  • Promoting movement with motion-activated food toys and puzzles
  • Weighing them monthly
  • Re-checking their BCS at home

Overweight cats not only face long-term health risks but can also suffer from discomfort and emotional stress. Intentional, veterinary-supervised changes can help ensure your cat’s fitness, comfort, and overall well-being for years to come. Let’s work together to score a win for your cat's health.

You assessed your dog's body condition score (BCS) to be to be 3 out of 9.

What does this mean? The BCS is an assessment of general body composition, including muscle and fat. While a score of 4 to 5 is ideal, a BCS of 3 indicates that your dog is thin.

What to do next: Although a lean body condition is healthier than being overweight, thinness can indicate muscle loss, health changes, or a lack of appropriate nutrition. Here are a few ways to help your dog reach their optimal weight and health:

  • Follow any recommendations given by your vet (these are personalized for your dog's unique needs)
  • Gradually transition your dog to a calorie-dense diet
  • Weigh them monthly
  • Re-check their BCS at home
  • Provide regular moderate exercise to build healthy muscle
  • Monitor them for other health changes (appetite loss, vomiting, unusual stools, fatigue, etc.)

Just like your dog's vital signs, their BCS gives valuable insight into their overall health and can help identify potential issues early. While a BCS of 3 isn't a serious concern, it suggests that your dog may benefit from adjustments to their diet and exercise routine. Please continue to monitor your dog for any other health changes—including difficulty gaining weight—as these could indicate the need for further evaluation. Let’s work together to help your dog achieve better health, so you can make the most of every moment together.

Now that’s a perfect score.

You assessed your dog's body condition score (BCS) to be to be 9 out of 9.

What does this mean? The BCS is an assessment of general body composition, including muscle and fat. While a score of 4 to 5 is ideal, a BCS of 9 indicates that your dog is obese (weighing 20% or more above their ideal weight).

What to do next: Dogs with obesity are in significant danger of many life-altering health conditions, including arthritis, cardiovascular problems, kidney disease, and cancer. Reducing your dog's weight and improving their body condition is critical to restoring their comfort, mobility, health, and longevity.

Take action today to protect your dog's  health by:

  • Following any veterinarian’s recommendations (these are personalized to your dog's unique needs)
  • Using a measuring cup to portion meals
  • Removing uneaten food after 20 minutes
  • Limiting treats to low-calorie fruits or vegetables
  • Exercising daily for at least 30 minutes (leash walks are a great way to start)
  • Weigh them  monthly
  • Re-check their BCS at home

Just like your dog's vital signs, their BCS gives valuable insight into their overall health. In your dog's case, it’s a signal for immediate action.

By following the steps above and your veterinarian’s recommendations, getting your dog back to a healthy weight is possible, but it will take time and effort. That’s why we’re here to help you every step of the way.

Let’s work together to score a WIN for Sydney’s health.

You assessed your cat's body condition score (BCS) to be 1–2 out of 9.

What does this mean? The BCS is an assessment of your cat’s general body composition, including muscle and fat. While a score of 4 to 5 is ideal, a BCS of 1 to 2 indicates that your cat is very thin, at least 20% below their ideal weight. This may be caused by poor nutrition or an underlying illness.

What to do next: Since a BCS of 1 to 2 can indicate potential health concerns, your cat's veterinarian may suggest blood work or other tests.

In addition to following any plan outlined by your cat's veterinarian, the following steps may help them achieve their ideal weight and BCS:

  • Offering a palatable diet recommended by your veterinarian
  • Feeding small, frequent meals
  • Warming the food or introducing toppers
  • Feeding pets separately
  • Minimizing stress
  • Weighing them  monthly
  • Re-checking their BCS at home
  • Watching for other concerning signs, such as loss of appetite, vomiting, or changes in litter box habits, as these may require prompt veterinary care.

Just like your cat's vital signs, their BCS offers important insight into their overall health. While a BCS of 1 to 2 can be concerning, we’ll work together to help your cat safely achieve their optimal weight and vitality.

You assessed your dog's body condition score (BCS) to be to be 6 out of 9.

What does this mean? The BCS is an assessment of general body composition, including muscle and fat. While a score of 4 to 5 is ideal, a BCS of 6 indicates that your dog is borderline overweight.

What to do next: With just a few pounds separating your dog from being overweight, a BCS of 6 is a clear call to action! Excess weight can increase their risk for serious health problems, such as arthritis, heart disease, and even cancer, and studies have shown that it can shorten their lifespan.

Here are a few ways to help Gigi reach their ideal weight:

  • Follow any recommendations given by your veterinarian (these are personalized for your dog's unique needs!)
  • Use a measuring cup to portion meals
  • Don’t leave food out all day
  • Weigh them monthly
  • Re-check their BCS at home
  • Provide regular moderate exercise to build healthy muscle

Just like your dog's vital signs, their BCS gives valuable insight into their overall health and and can help identify potential issues early. While a BCS of 6 isn't dangerous, it does raise their risk for many life-altering conditions and signals a need for change.

Let’s work together to help your dog achieve a better BCS and overall wellness, so you can make the most of every moment together.

Now that’s a perfect score!

You assessed your dog's body condition score (BCS) to be to be 7-8 out of 9.

What does this mean? The BCS is an assessment of general body composition, including muscle and fat. While a score of 4 to 5 is ideal, a BCS of 7 to 8 indicates that your dog is overweight.

What to do next: Your dog's weight is putting them at an increased risk for many serious conditions, including arthritis, diabetes, cancer, and heart disease. Overweight dogs are also clinically shown to have a shorter lifespan and a reduced quality of life.

Thankfully, it’s not too late to get back on track! Here are some simple steps to help your dog achieve a better BCS and a healthier life:

Here are a few ways to help them reach their ideal weight:

  • Reduce meal portions by 10% to 20%
  • Use a measuring cup for accuracy
  • Switch to a weight management diet
  • Swap treats for low-calorie fruits and veggies
  • Increase daily walks and playtime
  • Use a food-dispensing toy instead of a bowl to encourage movement
  • Weigh them monthly
  • Re-check their BCS at home

Just like your dog's vital signs, their BCS gives valuable insight into their overall health and quality of life. The actions you take in the days, weeks, and months ahead can help them slim down, restore their well-being, and allow you both to make the most of every moment together.

Let’s work together to score a WIN for your dog's health and happiness.

Now that’s a perfect score!

You assessed their body condition score (BCS) to be to be 9 out of 9.

What does this mean? The BCS is an assessment of your cat’s general body composition, including muscle and fat. While a score of 4 to 5 is ideal, a BCS of 9 indicates that your cat is obese (20% or more over their ideal body weight).

What to do next: Cats with obesity are in a health crisis. Excess weight strains their joints, leading to painful and decreased mobility. In addition, abundant fat tissue increases their risk for life-altering diseases like diabetes, arthritis, kidney disease, heart disease, and cancer.

Let their BCS be a turning point in their health.

With simple lifestyle changes and guided support from our team, we can restore your cat's quality of life and help them lose those unnecessary pounds.

We’ll focus on nutrition and stress reduction to create positive results. This includes:

  • Offering a palatable weight-management diet recommended by your veterinarian
  • Feeding portioned meals (Your veterinarian can assist you with how much to feed)
  • Using a microchip-linked feeder for multi-cat households to ensure each cat consumes their veterinarian-recommended portion
  • Minimizing stress in your cat’s environment
  • Decreasing boredom through positive interactions (interactive toys, food puzzles, cat-friendly furniture, and social bonding)
  • Encouraging healthy movement and exploration (motion-activated toys, food puzzles, ramps to perches, scratching posts, cat tunnels)
  • Weighing them monthly
  • Re-checking their BCS at home

Your cat’s body condition is a key factor in their health and longevity. Together, we can score a victory by helping them lose weight and reclaim their health, happiness, and mobility.

You assessed your cat's body condition score (BCS) to be 4-5 out of 9.

What does this mean? The BCS is an assessment of your cat’s general body composition, including muscle and fat. On a scale of 1–9, with 1 being very thin and 9 being obese, this score means they are at their ideal weight for optimal health and well-being!

What to do next: First, give your cat a head bump or a scratch to celebrate your success! Your dedication to their overall health—through regular vet visits, balanced and portion-controlled nutrition, a low-stress environment, and plenty of physical and mental activity—is truly paying off.

But don’t relax just yet—maintaining your cat’s healthy BCS will take ongoing effort throughout their lifetime. Keep up the good work by:

  • Minimizing stress
  • Creating a mentally and physically stimulating environment
  • Satisfying your cat’s social needs with one-on-one time
  • Encouraging movement with interactive toys, perches, and furniture
  • Feeding measured portions of a veterinarian-recommended, high quality, palatable diet
  • Checking your cat’s BCS monthly at home
  • Staying on top of routine veterinary care

Just like your cat's vital signs, their BCS gives us valuable insight into their overall health. Right now, we like what we see—and feel! But remember, supporting your cat's lifelong health is a team effort. By continuing the great work you’re doing and partnering with us, we can help ensure they stay healthy for years to come.

You assessed your dog's body condition score (BCS) to be 1–2 out of 9.

What does this mean? The BCS is an assessment of general body composition, including muscle and fat. While a score of 4 to 5 is ideal, BCS of 1 to 2 indicates that your dog is very thin, at least 20% below their ideal weight. This may be caused by poor nutrition or an underlying illness.

What to do next: Since a BCS of 1 to 2 can indicate potential health concerns, your dog's veterinarian may suggest  blood work or other tests.

If no issues are found, the following steps may help your dog achieve their ideal weight and BCS:

  • Gradually transitioning them to a calorie-dense diet
  • Feeding more frequent meals
  • Weighing them monthly
  • Re-checking their BCS at home
  • Providing regular moderate exercise to build healthy muscle
  • Monitoring them for other health changes (appetite loss, vomiting, unusual stools, fatigue, etc.)

Just like your dog's vital signs, their BCS offers important insight into their overall health and can serve as an early warning that something may be wrong. While a BCS of 1 to 2 can be concerning, please know that your pet's well-being is our top priority. Let’s work together to help your pet pal achieve better health, so you can make the most of every moment together.