Friends of the Riney Canine Health Center,
Thank you for joining our pack! I’m Brian Collins, an extension associate for the Cornell Richard P. Riney Canine Health Center, and I’m pleased to share this month’s “From the Vet’s Desk” monthly health tip with our members.
March is here and I am so excited for the first day of spring on the 20th! March also has other very notable days including National K9 Veterans Day on the 13th which is also the day in 1942 when the U.S. Army K9 Corps first began. And we can’t forget about National Puppy Day on March 23rd, which was founded in 2006. You don’t have to go out and adopt a puppy (or 2) to celebrate it, but I would fully support you if you did!
And just around the corner, April is National Heartworm Awareness Month, so I wanted to devote this month’s health tip to understanding heartworm disease and how you can protect your beloved dogs.
Heartworm disease is a serious and potentially fatal condition that affects dogs worldwide. In the US, it has been diagnosed in every state, but the majority of cases are found in the southeastern part of the country and in the Mississippi River Valley. It is estimated that at least a million dogs at any one time in the US may be infected with this parasitic worm (scientific name: Dirofilaria immitis). Case numbers seem to be on the rise and are more widely distributed. In part, this may be related to climate change and to the relocation of dogs around the country as part of adoption efforts.
We all know how even a single mosquito can ruin a good night’s sleep for us, but – even worse – immature heartworms are spread when mosquitoes bite an infected dog (or fox, wolf, or coyote) and later bite and transmit the worms to another dog. It’s also useful to know that heartworm can also be transmitted to cats, ferrets, and rarely people – which makes mosquito control and avoidance important. You may live in a temperate area of the country where mosquitos are active year-round. In other areas, we get a reprieve until temperatures rise above 50 degrees.
Once inside the dog, the worms mature, reproduce, and take up residence in the heart and pulmonary arteries. Rarely, they can be found in other parts of the body, including the eyes, nervous system, abdomen, or skin. Growing up to one foot in length and living up to seven years, they can result in significant illness if not diagnosed and treated early in the course of the disease.
Initially, heartworms will go undetected, but as the worms mature, clinical signs may be observed; they may include coughing, labored breathing, lethargy, and weight loss – all as a result of heart failure, kidney disease, and adverse effects on red blood cells. Treatment of adult heartworm infections in dogs with or without symptoms is complicated, carries significant risks, and requires weeks of strict rest.
Fortunately, there are medications that can prevent dogs from developing heartworm disease. Many of you are probably already giving your dog one of these products – but how do they work? Heartworm preventives don’t actually prevent your dog from being bitten by mosquitos or even being infected with immature heartworms. However, when given on time each month, they kill early stages of the worms and prevent them from developing into adult worms which cause the majority of the problems.
These medications are available in oral (chewable) forms or topical liquids that are given monthly. There is even an injectable form that your veterinarian can administer every 6 to 12 months. These products are highly effective at controlling heartworm and are cost-effective in that it is much less expensive to treat your dog regularly than to treat an adult heartworm infection – as well as the peace of mind knowing that your dog is protected. An added benefit is that most of the drugs that kill immature heartworms are also effective at controlling gastrointestinal parasites that can cause problems for your dog and even for the human members of your family.
Year-round administration of a heartworm preventive is recommended – even in colder climates (I’m always surprised to find a mosquito in my house in January when the ground is covered with snow!). Annual heartworm testing (a small blood sample) and testing before starting a preventive regimen are also advised, as no product is 100% effective, and early detection can improve treatment outcomes and reduce complications. An interesting fact is that it takes 6-7 months from when a dog is bitten by a heartworm-infected mosquito for routine blood tests to detect it.
If your dog is not currently on a heartworm preventive or if you’ve missed some doses – please talk to your veterinarian about their recommendations. Some products also include protection against fleas and ticks – another bonus! Your veterinarian can help you choose the regimen that best suits you and your dog.
As always, thank you for being a Riney Canine Health Center member. We look forward to catching up with you next month!
Dr. Brian Collins, D.V.M. ‘94
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