Does Your Senior Dog Need Natural Heartworm Prevention? May 6, 2017 14:37

It’s a scary thing if your pet is infected with the heartworm disease. It’s even scarier if your dog is a senior.

In an infected dog, the presence of these parasites can lead to lung disease and heart failure. While there are treatments available, the process is arduous, costly, and can negatively affect the health of a dog. Senior dogs have an already compromised immune system so it’s possible the treatment could kill them if the heartworm infestation doesn’t first.

What is Heartworm Disease?

Heartworm disease is transmitted through the bite of an infected female mosquito. Mosquitoes become hosts of the heartworm larvae after biting an infected dog, coyote, or fox. The larvae mature in the salivary glands of the mosquito and are then transferred to your dog if bitten.

These larvae grow inside of your dog’s body and, when they become adult worms, can travel through the bloodstream and end up in the heart and lungs. Once they arrive there, they can mate and produce thousands of the tiny microfilariae which cause severe health complications.  

Initially, a dog infected with heartworms will show no symptoms. It can take 5-7 months for the heartworms to grow to sufficient size and number to affect your dog’s health. As the worms grow and start to fill the lungs and heart, a dog may experience these symptoms:

  • Coughing
  • Fatigue after exercise
  • Reluctance to exercise
  • Difficulty breathing
  • Coughing up blood
  • Rapid weight loss
  • Heart failure

For more, read 7 Warning Signs That Your Dog Has Heartworms.

What is the Risk Where I Live?

Talk to enough veterinarians and you will find out that there has been at least one case of heartworm reported in most populated areas of Canada and the US. However, just because heartworm CAN be present in any area doesn’t mean there is a significant risk.

Mosquitoes must be able to support a heartworm larvae incubation period long enough that they’re capable of transmitting them to your dog. This is primarily determined by temperature. You can read the Literature Review by Banfield Pet Hospital but, basically, the temperatures have to be above 26⁰C (79⁰F) for 10-14 days after ingestion for the mosquito to be infectious. If the temperature drops below 14⁰C (57⁰F) during that time period, larval development ceases.

As you can imagine, the incidence of heartworm is lower in geographic areas with colder climates. In Canada and the northwestern United States, temperatures rarely reach 26⁰C (79⁰F) for periods of more than a few days at a time. This means the chances of a mosquito in those areas being able to transmit the heartworm disease is low. It can vary by sub-region though so I would definitely talk to your vet about the risk in your area.

It is important to note that reported heartworm cases are increasing in areas where it was previously considered very rare. The Ontario Veterinary College published a paper in 2010 which showed that the estimated prevalence of heartworm in Canada increased by nearly 60% since the last study of its kind in 2002. (source The source of this increase isn’t known for sure but it could be related to 1) rescue dogs being imported from areas where heartworm is prevalent and 2) Climate change potentially causing the weather to be warmer for longer periods, allowing the right conditions for the larvae to incubate inside of a mosquito.

How Can I Help Prevent Heartworm in My Dog?

Unfortunately, there’s no way to tell if a mosquito is infected. It’s important to determine the risk factor for your senior dog by taking into account the known risk of heartworm in your area, how often you and your dog travel to areas where heartworm is prevalent, and the potential ability of your dog to endure treatment.

Many pet owners would rather be safe than sorry. There are treatments available for heartworm but many of them have potential side effects. Also, they may be stronger than needed for a dog that is at low risk of contracting heartworm. If your dog’s risk of contracting the disease is low, but you want reduce the risk even further, I suggest using natural products to prevent mosquito bites.

These are the natural mosquito bite preventatives that I recommend:

  • PetzLife TickZ - This herbal repellent helps to repel mosquitoes and other biting insects. It doesn’t contain any chemical insecticides and is great for dogs with allergies. Simply add it to your dog’s to food for months of protection.
  • NEEM shampoo - Neem oil, from the bark of a tree in India, both kills and repels fleas and ticks. It also leaves an odor that will continue to repel unwanted pests. Treat weekly or more often for effective flea and tick control for dogs and to catch all insects in their various stages of development.
  • PetzLife Complete Coat Insect and Parasite Repellent - PetzLife “Complete Coat” is formulated as a topical formula to keep your dogs coat healthy and, more importantly, to ward off insects and parasites of all types. It is all-natural and contains NO pesticides. It contains extracts of Quassia bark, which has been used for years as a natural insecticide for organic farming. The Rain-Tree Tropical Plant Database ( lists the curative properties of Amargo as: kills parasites, kills lice, kills insects, kills larva, and treats malaria.

As with any risk to your pet, it’s important to be educate yourself about it and understand your options.

Are you aware of any heartworm cases where you live?