Important Updates in Feline Heartworm Disease
What is heartworm disease?
Heartworms are parasites that are transmitted to cats from infected mosquitoes. The mosquito bites the cat and deposits microscopic heartworm larva into the bite site. These larvae live under the skin for 2 months, then mature and travel to the heart and arteries in the lungs, causing damage there over time. Most cats only have 1-3 heartworms when infected, but this small number can cause devastating disease. An important point to remember, too, is that heartworm disease is just as prevalent in cats in Texas as it is in dogs!
What are the signs of heartworm disease in my cat?
Many cats with heartworms do not show any signs at all when the worms are alive. This is because the heartworms decrease the body's natural defenses and the cat's immune system does not recognize the heartworm as causing a problem. Some common signs in cats with symptomatic heartworm disease include:
How is heartworm disease diagnosed in cats?
Diagnosing heartworm disease in cats is very difficult. The main test we use in dogs is the heartworm antigen test, which detects proteins circulating in the dog's blood that come from the adult female heartworms. Unfortunately, there needs to be at least a couple of female worms present for this test to be consistently positive. In cats, there is usually only one or two heartworms, and cats tend to have a higher percentage of male heartworm infections. This makes the heartworm antigen test not very useful in cats, and this test may have to be repeated several times before a positive result is seen. A large number of heartworms in cats also do not make it to the adult stage, dying off as larval heartworms and causing the same severe symptoms as adult heartworms, but they also do not cause a positive result on the antigen test.
Another blood test we have available is a heartworm antibody test. If a cat is positive on the antibody test, this means the cat has been exposed and infected at some point with heartworms. Antibodies to heartworms go away over time, though, so this test can become negative even if the cat has previously had heartworms.
Chest x-rays are a good way to see the clinical effects of heartworm disease in cats. A veterinarian can see inflammation in the areas of the lungs where the heartworms live. Even if the heartworm tests are negative, signs of heartworm disease on an x-ray can give a presumed diagnosis of heartworms.
The bottom line is that there is no good way to diagnose heartworm disease in cats, although several tests can make a veterinarian suspicious enough of this disease to treat it symptomatically and look for a positive response.
What are the treatment options for cats with heartworm disease?
Unfortunately, no good treatment exists for heartworm disease in cats. The medication we can give to dogs to kill the adult heartworms is too dangerous for cats. We can treat the inflammation and respiratory disease that the heartworms cause, though, with medications such as steroids and oxygen in critical cases. The severe episodes of respiratory distress can be life threatening though and treatment may not help once your cat develops symptoms of heartworm disease. There is ALWAYS a risk of sudden death due to breathing difficulties when cats have heartworms. This is the reason that heartworm prevention is so important!
Preventing heartworm disease in your cat
Since there is no good way to treat heartworms once cats become infected, and since diagnosing heartworms in cats is a challenge, the best option is to keep your cat on life-long heartworm prevention. Several options are available, both in pill and topical liquid form. Most of these heartworm preventatives also kill intestinal parasites, and there are forms that include flea and tick prevention as well. This medication is used once a month for the cat's entire life, and if used correctly and consistently should prevent heartworm disease in your cat.
Remember: in Texas we have mosquitoes year-round, so it is important to keep your cats on heartworm prevention even during the winter months!
Heartworms are parasites that are transmitted to cats from infected mosquitoes. The mosquito bites the cat and deposits microscopic heartworm larva into the bite site. These larvae live under the skin for 2 months, then mature and travel to the heart and arteries in the lungs, causing damage there over time. Most cats only have 1-3 heartworms when infected, but this small number can cause devastating disease. An important point to remember, too, is that heartworm disease is just as prevalent in cats in Texas as it is in dogs!
What are the signs of heartworm disease in my cat?
Many cats with heartworms do not show any signs at all when the worms are alive. This is because the heartworms decrease the body's natural defenses and the cat's immune system does not recognize the heartworm as causing a problem. Some common signs in cats with symptomatic heartworm disease include:
- Coughing, difficulty breathing, rapid breathing
- Fainting, collapse
- Vomiting
- Sudden death
How is heartworm disease diagnosed in cats?
Diagnosing heartworm disease in cats is very difficult. The main test we use in dogs is the heartworm antigen test, which detects proteins circulating in the dog's blood that come from the adult female heartworms. Unfortunately, there needs to be at least a couple of female worms present for this test to be consistently positive. In cats, there is usually only one or two heartworms, and cats tend to have a higher percentage of male heartworm infections. This makes the heartworm antigen test not very useful in cats, and this test may have to be repeated several times before a positive result is seen. A large number of heartworms in cats also do not make it to the adult stage, dying off as larval heartworms and causing the same severe symptoms as adult heartworms, but they also do not cause a positive result on the antigen test.
Another blood test we have available is a heartworm antibody test. If a cat is positive on the antibody test, this means the cat has been exposed and infected at some point with heartworms. Antibodies to heartworms go away over time, though, so this test can become negative even if the cat has previously had heartworms.
Chest x-rays are a good way to see the clinical effects of heartworm disease in cats. A veterinarian can see inflammation in the areas of the lungs where the heartworms live. Even if the heartworm tests are negative, signs of heartworm disease on an x-ray can give a presumed diagnosis of heartworms.
The bottom line is that there is no good way to diagnose heartworm disease in cats, although several tests can make a veterinarian suspicious enough of this disease to treat it symptomatically and look for a positive response.
What are the treatment options for cats with heartworm disease?
Unfortunately, no good treatment exists for heartworm disease in cats. The medication we can give to dogs to kill the adult heartworms is too dangerous for cats. We can treat the inflammation and respiratory disease that the heartworms cause, though, with medications such as steroids and oxygen in critical cases. The severe episodes of respiratory distress can be life threatening though and treatment may not help once your cat develops symptoms of heartworm disease. There is ALWAYS a risk of sudden death due to breathing difficulties when cats have heartworms. This is the reason that heartworm prevention is so important!
Preventing heartworm disease in your cat
Since there is no good way to treat heartworms once cats become infected, and since diagnosing heartworms in cats is a challenge, the best option is to keep your cat on life-long heartworm prevention. Several options are available, both in pill and topical liquid form. Most of these heartworm preventatives also kill intestinal parasites, and there are forms that include flea and tick prevention as well. This medication is used once a month for the cat's entire life, and if used correctly and consistently should prevent heartworm disease in your cat.
Remember: in Texas we have mosquitoes year-round, so it is important to keep your cats on heartworm prevention even during the winter months!