Parasites do not always cause external symptoms, making
and monthly preventative measures imperative.
Common Heartworm FAQs
What is heartworm disease?
Heartworm disease is a very serious and potentially fatal disease in pets. It is caused by mature heartworms, up to one foot in length, dwelling in the heart, lungs, and associated blood vessels. Once they lodge at these indicated sites, the parasites begin to reproduce. A dog can have as many as 250 worms living within its systems.
These heartworms cause lung disease, heart failure, and damage to other organs within the body. Although these nematodes are often referred to as dog heartworm, they also can affect cats, ferrets, and other mammal species.
How is heartworm disease spread?
The short answer is mosquitoes. Not all mosquitoes carry heartworm, but once a mosquito has bitten a heartworm positive animal, it can spread to the next animal that it feeds on.
The infestation begins when a mosquito harboring heartworm larvae bites a dog. In the process, the larvae are released into the dog under the skin or tiny blood vessels, while the mosquito feeds on the dog’s blood. These larvae mature in stages, leading to their migration towards the heart, where the adult heartworms take up residence.
If there are enough heartworms in the heart, they will begin to obstruct the vessels. A dog’s heart obstructed in this way will need to pump harder and harder to overcome the new resistance against blood flow. In time, this will result in heart failure.
Heartworms can damage the heart, lungs, and major blood vessels. They can cause inflammation of lung tissue, known as pneumonitis. While its lungs are inflamed, both the dog’s ability to breathe and exchange oxygen normally is impaired. Pneumonia and heart failure can cause the dog to cough, so annual testing for heartworms is critical to achieving early intervention.
The good news is that our pets don’t directly spread heartworms to one another. However, if one of your pets has heartworms, it could be a carrier and potential source of infection to other pets in the house. That said, it’s important to have all pets tested and covered by routine care.
Are dogs and cats both susceptible to heartworm disease?
Yes, both cats and dogs can be infected by heartworm.
What are the signs of heartworm in dogs?
In the early stages, many dogs may have no symptoms. However, the longer the infection persists, the more likely you’ll see your pup develop symptoms. Here are some of those symptoms:
- Mild cough
- Reluctance to exercise
- Fatigue after moderate activity
- Decreased appetite
- Weight loss
How Do They Affect My Dog?
The worms inside your dog damage the blood vessels surrounding your dog’s heart and causing high blood pressure. Additionally, damage to your dog’s heart may result in enlargement of the heart, which can lead to Congestive Heart Failure. In some cases, migrant worms may also damage a dog’s liver and kidneys. Additionally, heartworms have obligate bacteria inside of them, which can cause serious allergic reactions in dogs when the heartworms are damaged or destroyed.
What are the signs of heartworm in cats?
Heartworms are not as well adapted to cats’ bodies, so heartworm infestation is less prevalent among them. However, they can also become infected by the bite of a carrier mosquito. Often, heartworms will be unable to reach maturity in cats, but this does not mean it is impossible for them to do so.
If heartworms do mature in cats, they will often take up residence in both the cat’s heart and lungs. Generally, heartworm infestation symptoms in a cat will manifest differently than the case with a dog. The nebulous nature of this difference makes a diagnosis in cats particularly difficult. Worse, one of the most common signs of heartworm infestation in cats is sudden death.
Furthermore, even if a diagnosis of the infection is achieved, there are currently no treatments available for cats that can kill the worms without a great risk of killing the cat. The best we can do then is to provide relief that addresses whatever symptoms occur. Fortunately, there are safe means of heartworm prevention for cats.
Much like with dogs, symptoms for heartworm in cats can be severe or nearly noticeable. Here are a few things to watch for:
- Asthma attacks
- Lack of appetite
- Weight loss
How is heartworm disease diagnosed?
Heartworm disease can be detected with a tiny blood sample from your dog using a testing kit readily available at most veterinary hospitals. The test usually takes about 8 minutes to get a result. When a positive test result is identified, additional tests are required to confirm the diagnosis. It is important to note that heartworm testing can rarely have false-negative results and will only detect heartworm disease at least 5-7 months after the initial infecting mosquito bite. False negatives can occur in 3 conditions:
- Just a few worms are present inside your dog.
- Only juvenile-stage worms are present (the test detects the presence of adult worms only)
- All-male worm infection (the test detects female adult worms).
For this reason, dogs who miss at least 2 consecutive months of heartworm prevention, are at higher risk of acquiring the disease, or have unknown prevention status (rescues, recent shelter adoptions) should be re-tested 7 months after the last possible infectious bite from a mosquito. Yearly screening is also strongly recommended for all dogs, even for pets who are on heartworm prevention regularly.
HOW IS HEARTWORM TREATED?
Multiple X-rays and blood work to test the dog’s general health must be performed to assess if the patient is healthy enough to withstand the treatment.
Treatment consists of two to three injections of Immiticide (an arsenic-based medication) spaced out over several months. Each injection requires 12 hours of hospitalization and monitoring to ensure the pet does not have any complications from treatment. Your dog will need to remain calm and rested for 4-6 weeks after each injection to reduce the chances of a pulmonary embolism. It is much easier, safer, more comfortable, and less expensive to prevent heartworms compared to treating them. There are cases where the heartworm treatment is fatal.
A dog may live for months or even years infested with heartworms, but they are always fatal without treatment. Additionally, if the dog does receive treatment, the damage already done at the time of treatment will remain. The quality and quantity of life after treatment depends upon the number of worms present and the damage they have already caused at the time of treatment.
If the number of heartworms is few, and the damage they have caused is minor, then a dog can live for a normal lifespan and be less impacted by treatment. On the other hand, dogs with more extensive pre-treatment damage may need medication for the rest of their lives.
How can pet owners protect our dogs and cats from heartworm?
The short answer: PREVENTION! PREVENTION! PREVENTION!
There are a few things that you can do to keep mosquitoes away from your pets, such as using screens or keeping windows and doors closed or limiting any stagnant water. The most effective option is keeping up to date on preventative.
In preventing heartworm in your dog, be proactive. Make monthly heartworm chewable medication part of your pet care regime. Your pet should be tested annually for heartworm during routine visits. The test requires a small sample of blood to be drawn from your pet. This sample is then tested to detect the presence of the heartworm proteins. Even though heartworm preventative medications are very effective, dogs can still be infected.
Are humans susceptible to heartworm disease?
No, heartworms do not have the ability to live in humans. People can still be infected with heartworm through the bite of an infected mosquito, but the parasite is not able to survive in the human bloodstream.
Common Flea & Tick FAQs
What problems do fleas and ticks cause?
Fleas and ticks can cause many medical problems, ranging from anemia due to blood loss from multiple bites, to severe skin problems on animals allergic to fleas, to the various illnesses transmitted by these vectors of disease. Because of their importance in causing these problems, fleas and ticks should be addressed when found on our companion animals.
A flea infestation can even mask other diseases—meaning the causes of anemia, fatigue, or itching may go unexamined while there is a flea infestation. Generally, the longer your vet cannot define the source of a problem, the more severe a problem becomes before your pet is started on appropriate treatment. Please keep your pet on flea prevention all year to prevent infestations.
In particular, kittens are very sensitive to becoming anemic from flea bites, particularly when a large amount of fleas are present. Fleas can also cause a syndrome in cats, referred to as Eosinophilic Granuloma Disease. This complex causes plaques, granulomas, and oral ulcers, particularly on their lips. In these cases, the reaction patterns seen represent an allergic reaction, particularly to flea saliva.
Fleas may also carry bacteria called Haemobartonella or Hemotrophic Mycoplasmosis. Infection with this bacteria can cause anemia, depression, weight loss, and other clinical signs. Fleas also carry tapeworms, which can be caught when your pet grooms themselves, ingesting a flea. Tapeworm segments may be noted in your pet’s feces and tend to look like “white rice.”
Our climate provides an ideal environment for fleas. Ticks are a more sporadic problem, depending on the density of wooded areas, but are nevertheless very common in Pennsylvania. Generally, most dogs and cats will develop some degree of flea and tick infestation if preventive products are not employed.
What is the best Flea and Tick prevention method?
Contemporary flea prevention methods differ significantly from those of the past and are more streamlined and effective. Gone are the days of sprays, flea collars, and flea shampoos, which seldom help control fleas. Instead, we now use once-a-month products which quickly and fully exterminate the adult fleas on your pet.
Topical liquids applied to the skin on the back of your pet’s neck also contain egg inhibitors to stop potential future infestations. Chewable medication for dogs ends the struggle of applying topical treatments and is just as effective in killing fleas and ticks quickly, as well as preventing new infestations.
Many such products are available on the market, but we recommend you buy from your veterinarian to ensure the product is safe for your pet. Stores are full of cheap but often unsafe products. Most over-counter flea control topical liquids are simply a topical form of old pesticides.
Some animals have no adverse reaction to these pesticides, but it is not uncommon to have a sensitivity to the toxins in them. Additionally, a great number of flea control products are toxic to cats, but, despite them being clearly labeled for dog use only, wind up sending cats to the hospital. In some cases, merely being in the same house as these cat-toxic products is enough to get your cat sick.
What diseases do ticks carry?
Ticks in this area come in multiple types, and each one tends to carry a particular disease. For instance, the Deer Tick is infamous in Southeastern Pennsylvania as a vector of Lyme Disease. However, many other kinds of tick-borne diseases can make your pet sick, and in some cases, are even lethal.
Ehrlichia, Anaplasmosis, and Rocky Mountain Spotted Fever are all threats in this area and can all cause your pet’s health to take a turn for the worse. Though we can diagnose and treat these diseases, it is far preferable to prevent them. The best way to do so is to be sure your pet is on monthly tick prevention.
What is Lyme Disease?
Lyme disease is the most common tick-transmitted disease worldwide, and it frequently occurs in our area. This illness is caused by a spiral-shaped bacterium called Borrelia burgdorferi that is carried inside the tick and is transferred through the bite of this insect to other living organisms. When the bacterium has entered the bloodstream, it will then travel to different parts of the body, causing bodily harm to certain organs such as the joints. Transmission occurs after a tick has been attached for at least 48 hours. The disease is uncommon in cats.
Although humans have a visual aid to help indicate possible infection with Lyme Disease, it is a little trickier to identify it in our canine companions. Approximately 5-10% of dogs that have become infected show symptoms that they contracted the disease, making it extremely difficult as a pet owner to distinguish this infection. The most common physical symptom that pet owners can notice on their dogs is a developed lameness in their dog’s legs due to joint inflammation.
The black-legged tick, also known as the “deer tick,” serves as the carrier for Lyme disease. The insect itself does not have the disease biologically composed within its system; it only acts as the middleman in carrying disease from organism to organism through its bite.
What are symptoms of Lyme Disease in dogs?
Lameness is the most common physical symptom developed by dogs that have become infected with Lyme disease. This lameness can last from as little as three to four days. However, due to the disease’s prevalent nature, it can recur days or weeks later in the same or other legs.
In some cases, Lyme disease sometimes leads to glomerulonephritis inflammation (inflammation of the kidneys) accompanied by a deficit in the organ’s primary function—to filter blood. When this type of damage takes way, kidney failure can follow shortly after. Physical symptoms can become obvious for dogs experiencing kidney failure, for they will vomit, lack of appetite, urinate more, and have excessive thirst alongside weight loss.
Other symptoms include:
• A stiffness in gait
• Difficulty breathing
• Sensitivity to touch
• Lack of Appetite
• Swollen lymph nodes
At World of Animals Veterinary Hospitals, we recommend all dogs be tested annually for Lyme Disease. This is a simple blood test—requiring only a few drops—and can be done while you wait at our office; results are ready in 10 minutes.
How do I prevent Lyme Disease?
Using monthly flea & tick prevention all year long can help to kill ticks and fleas before they transmit disease. These medications are designed to kill pests and are not meant to prevent disease, so for the best prevention, ask your veterinarian about a Lyme Disease Vaccination for Your Dogs. The vaccine is given twice the first year (3-4 weeks apart); after that, annual vaccination is needed to maintain your dogs’ immunity. The vaccine is recommended for any dog that spends time in a grassy yard, walks in the park, or goes to wooded or sandy areas.
Even if your dog has been vaccinated for Lyme disease and is on a monthly preventative, always check for ticks after being in a grassy, wooded, or sandy area. Places ticks can more easily hide and evade detection are between the toes and in or around the ears of a dog. If you find a tick on your dog, be sure to call the office right away to schedule an appointment for an examination with our Veterinary Hospital.