Recently, there have been increasing reports of a shortage of the heartworm killing drug called Immiticide. This arsenic derivative has been increasingly used in veterinary medicine as an alternative to the older arsenic compound. While Immiticide has many advantages to its predecessor in terms of safety and efficacy, I have still seen many pets suffer from complications, including secondary clots and organ failure.
When a pet is diagnosed with heartworms, there is often also an expensive workup to include blood work, urine analysis, and x-rays. Many pets are started on the antibiotic Doxycycline to cut down on airway inflammation, as well as kill the Wolbachia parasite that often accompanies heartworm infection. The costs can often run up to several hundred dollars. It is certainly far better to prevent heartworm infection by using tried and tested monthly oral preventatives such as Heartgard and Interceptor. Certain topical medications such as prescription Revolution may also be used for heartworm prevention.
If your pet is diagnosed with heartworms, it is still possible to put your pet on monthly preventative medication while under the supervision of a veterinarian. Many pets will convert to heartworm negative status after 1-2 years of continuous heartworm medication. Annual heartworm testing is recommended at your veterinary office before prescriptions can be refilled.
With the summer temperatures and humidity comes the increase of flea and tick populations which can also increase your pet’s risk of heartworm disease. With that said, it’s always best to take a proactive approach, especially when potentially fatal diseases such as heartworm disease are at risk.
Heartworm disease is treatable; however, it is much better to protect your pet as opposed to treating an illness such as heartworm disease if your pet were to become infected. Treatment can take a toll on your pet’s respiratory system, and is also very expensive in relation to the cost of a monthly heartworm preventative.
One of the more economical prescription alternatives to Heartgard or Interceptor is Iverhart Max. Iverhart Max is an excellent broad spectrum internal parasite preventative that focuses not only heartworms, but hookworms, roundworms, and tapeworms. The benefit of additional worm protection comes from the ingredients pyrantel and praziquantel in this product.
When I have prescribed Iverhart Max to clients, there haven’t been any concerns with this product, and side effects are rare, mostly resolving around mild digestive upset and in more rare cases seizures.
When given monthly both heartworm control and flea control are implemented. However, by itself Sentinel does not kill adult fleas or repel fleas so it is usually good to use this product with another one that either kills adult fleas or breaks the flea life cycle such as Capstar or topical Advantage II.
Side effects are rare and may include digestive upset and less commonly neurological reactions. The only concerns clients have had with this product has been the need to incorporate other measures of external parasite control for fleas, ticks, lice and/or flies. However, its convenience and ease of use makes Sentinel a popular choice for flea and heartworm control for many satisfied clients over the years.
Which heartworm preventative do you use on your pet? Are there any concerns you’ve had in using a heartworm preventative?
Did you know April is National Heartworm Month? Organizations such as the American Heartworm Society want to help educate pet owners on the importance of protecting pets against these potentially fatal parasites – especially since heartworm disease is highly preventable with the use of medications like Heartgard Plus, Revolution, and Interceptor. Often times pet owners will ask why heartworm prevention is so important. The following points are among the most important reasons to give your pet a monthly heartworm preventative:
- Heartworm disease is preventable.
- Heartworm disease has been documented in all 50 states throughout the year.
- Heartworm infection can cause varying degrees of heart and lung pathology in dogs and cats.
- This disease can lead to various symptoms from exercise intolerance, coughing, possible heart failure, vomiting, lethargy, abdominal distention, and in some cases sudden death.
It is for these reasons and more that the American Veterinary Heartworm Society recommends year-round heartworm preventative medication for dogs and cats. My favorite monthly heartworm preventatives include Interceptor and Heartgard Plus, which not only prevent heartworms, but prevent and control intestinal worms as well. Although these pet medications are available at 1-800-PetMeds they do require a prescription from your veterinarian due to the blood testing involved, which is to ensure your pet does not already have heartworms.
In the prior blog I addressed the question about what an animal guardian should do if they miss a dose of heartworm pet medicine. As mentioned, simply resuming monthly administration is the answer in most cases. The reason why animal guardians should not just pick and choose their own schedule of monthly heartworm medication administration is that it is hard to predict when heartworm transmission season ends or begins in many areas of the country.
With the recent tendency to global warming, heartworm-carrying mosquitoes have been seen even in colder months in some areas. Also many animal guardians will forget to start up heartworm preventative medication, if left to decide on their own, as well as the fact that irregular use of many medicines such as prescribed antibiotics and/or parasitic medication may be associated with the development of resistant strains of parasites, which is a recent concern even with heartworm medication that is currently being looked at more closely.
Also most of the monthly oral heartworm medicines like Interceptor or Heartgard helps control and prevent other parasites such as intestinal worms, which can occur any time of year in most areas of the country.
Whenever parasitical products are used in killing or preventing parasites, whether they are for insects, cockroaches, fleas and ticks, mosquitoes and heartworms, there is always the possibility of resistance developing in the parasites over time if the same heartworm medications are continually used over many years. That is why many exterminators rotate use of their products in the home to avoid this possibility.
In veterinary medicine, there has been recent concern amongst many veterinarians and clients that resistance to current heartworm products may be currently developing. However, according to the American Heartworm Society and the Companion Animal Parasite Council, current strategies of recommending year round monthly heartworm prevention must still be implemented until further research and conclusions can be reached regarding the possibility of emerging resistant heartworms.
At the present time, the issue of heartworm resistance may be related to client compliance, and/or be limited to certain geographic locations in the country. Current products on the market are still believed to be highly efficacious, as well as the use of effective heartworm testing and treatment programs still make up the cornerstone of controlling and preventing heartworm infection. It will be interesting to see the emerging research and conclusions in the coming months and years on the potential issue of heartworm resistance and strategies used to avoid this possibility.
One of the more recent developments that have frustrated both veterinarians and animal guardians alike is the removal of the non-flavored Heartgard tablet. While in the vast majority of cases this is not an issue, as most pets love the Heartgard chewable tablet, some pets may have a chronic skin issue and need to eliminate common flavors and meats from the diet, like beef (the flavoring used in the Heartgard chewable tab). As a result, this forces animal guardians to use a topical means of heartworm prevention like Revolution. Hopefully with enough marketing pressure by vets and animal guardians alike, the non-chewable form will be back soon.
Another common question I get from guardians is what to do if they miss a dose of Heartgard. Generally speaking, it is okay to start up the preventative right away if a dose is missed. In fact, in most circumstances, Heartgard lasts for at least 45 days in preventing heartworms, so there is usually no need to worry or retest before redosing. Simply resume the normal once monthly schedule.
Another hot topic in recent years is whether Heartgard can be used to treat heartworms rather than the expensive series of injections given at the vet office to heartworm-positive dogs. While it is usually preferable in most cases to treat a heartworm positive dog with the approved injectable medication Immiticide at the local vet, another alternative in pets that are at risk for treatment reactions or for those clients who can’t afford the Immiticide treatment protocols, I recommend using Heartgard monthly for at least 1-2 years.
Because many heartworm positive dogs are also positive for another parasite called Wolbachia, a 3-4 week course of Doxycycline is often used at the same time. I have seen many cases eventually turn heartworm-negative when Heartgard is used this way continuously year round. Obviously if a pet has advanced signs of heartworm disease, such as heart failure, abdominal fluid retention, etc., it is best to use the approved Immiticide for treatment in most cases.
Lastly, I’m also frequently asked about side effects or risks associated with Heartgard. While the drug company claims the amount of Ivermectin is too small to cause a reaction in sensitive breeds, like Collies and related breeds, I will usually prefer to use monthly Interceptor. Although rare digestive or neurological reactions can occur with any heartworm preventative medication, I haven’t found Heartgard to be more of a risk to give certain breeds that suffer from seizure disorders or to dogs that are on phenobarbitol
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