What You Need to Know About Heartworm Prevention

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Heartworm infection has been found in dogs in all 50 states

With spring and warmer weather just around the corner, many pet guardians start thinking of protecting their pets from fleas, ticks as well as heartworm disease. However, according to the Companion Animal Parasite Council (CAPC), “…heartworm infections continue to increase in numbers and geographic distribution.” While the greatest number of cases are seen in the southeastern US, heartworm infection has been found in dogs in all 50 states. Treating heartworm disease in dogs can be difficult and expensive, and although cats are less susceptible than dogs to heartworm disease there is no approved treatment for heartworm infection in cats. The American Heartworm Society recommends year round heartworm prevention and annual testing for your pets. Read More »

Does My Dog Need Heartworm Prevention in the Winter?

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Wondering if your dog needs heartworm prevention in the winter?

One of the more common questions we receive in the veterinary clinic is whether dogs should be on year-round heartworm prevention, even in the winter and colder months. Over 20 years ago I was taught in veterinary school that the average ambient temperature had to be 65 degrees or higher for 30 days in a row for mosquitoes to become infectious and transmit heartworms to dogs. In most areas of the country this transmission season was believed to be 3 to 5 months.

However, in recent years with concerns of global warming and milder winters, veterinary parasitologists have found that it is possible for mosquitoes to carry heartworms even in milder winter months. Because of this and the fact that many people travel with pets back and forth to warmer areas of the country, most veterinarians and the American Veterinary Heartworm Society now recommend year-round heartworm prevention for dogs in most areas of the country. An added benefit of most monthly heartworm preventatives including Heartgard and Iverhart Max is that most of these preventatives also treat and control many intestinal parasites, which can also be a problem any time of year. Read More »

The Symptoms of Heartworm Disease in Pets

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Heartworm transmission occurs through the bites of infected mosquitoes

Heartworm disease has been increasingly reported in recent years in dogs and cats. Transmission occurs through the bites of infected mosquitoes. In some pets, particularly cats, there may be no clinical symptoms observed. In many pets, particularly dogs, increasing respiratory difficulty, including coughing and shortness of breath is often observed. Nonspecific symptoms of lethargy, vomiting and loss of appetite will occur in many pets. In some pets with severe infections, abdominal distention from right-sided heart failure also may occur. While symptoms may suggest heartworm infection, the only definitive diagnostic test is through a blood test performed by a veterinarian.

Remember, it is always better to prevent heartworm with appropriate heartworm preventative medication than to treat heartworm disease.

Heartworm Disease and Your Pet

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Heartworm infection is seen primarily in dogs and less commonly in cats and ferrets

The following post is from Molly Foreman, DVM:

What causes heartworm?

Heartworm infection is caused by a filarial organism known as Dirofilaria immitis.  Mosquitos serve as intermediate hosts which help to spread the disease to animals as the mosquito takes a blood meal and bites your dog or cat. Infections are possible in numerous wild and companion animals. Wild animal reservoirs can include wolves, coyotes, foxes, California gray seals, sea lions, and raccoons. In companion animals, heartworm infection is seen primarily in dogs and less commonly in cats and ferrets.

The heartworm life cycle

The life cycle of Dirofilaria immitis takes place with certain stages of growth while in the mosquito and then while in the infected host. Mosquito vector species acquire the first stage larvae (microfilariae) while feeding on an infected host. Development of microfilariae to the second larval stage and to the infective third stage, occurs within the mosquito in approximately 1 to 4 weeks, depending on environmental temperatures. When mature, the infective larvae migrate to the mouth parts of the mosquito so that as the mosquito feeds, the larvae can migrate into the bite wound, beginning the mammalian portion of their life cycle.

Once in the infected pet, the infective larvae molt into a fourth stage in 2-3 days. After remaining in the subcutaneous tissue for close to 2 months, they molt into young adults that migrate through host tissue, arriving in the pulmonary arteries approximately 50 days later. Adult worms develop primarily in the pulmonary arteries of the lung over the next 2 to 3 months. They reside mostly in the pulmonary arteries but can move into the right ventricle of the heart when the worm burden becomes high. Microfilariae are produced by gravid females approximately 6 to7 months post infection

Symptoms of heartworm disease

Live worms can have an immunosuppressive effect; however the presence of dead worms leads to immune and allergic reactions. Long term infections, due to all of the factors noted (ie, direct irritation, worm death, and immune response) result in chronic lesions and secondary scarring. Active dogs tend to develop more pathology than inactive dogs for any given worm burden.  Frequent exertion increases the problems that occur in the heart and lungs, which can lead to overt clinical signs such as coughing, exercise intolerance, and even congestive heart failure.

When heartworm positive dogs are not administered a preventative and are not appropriately tested or treated, clinical signs such as coughing, exercise intolerance, unthriftiness, labored breathing, fainting, bleeding from nose, and excess fluid in the abdomen due to right-sided CHF are likely to develop.  Infection can eventually lead to the death of your pet if left untreated.  Treatment is very expensive and there are many complications that can occur.

This is a disease which is easily prevented, so please see your veterinarian today to have your pet tested for heartworm disease and started on the appropriate heartworm prevention medication.

How Are Heartworms Treated?

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The incidence of heartworm is decreasing due to the increase in use of monthly heartworm preventative medication

Fortunately, with the increase in use of monthly heartworm preventative medication such as Sentinel or Heartgard, and/or natural herbal alternatives such as black walnut or quassia bark, the incidence of heartworm disease is decreasing. However, in stressful situations and/or in immune or nutritionally compromised patients, heartworm disease is still being diagnosed in most states. In decades past, heartworm was typically treated with a strong arsenical compound known as Caparsolate intravenously in the veterinary hospital setting. Side effects were common, including inflammation of the blood vessels (known as phlebitis) at the site of injection, as well as sometimes systemic signs including vomiting, diarrhea, coughing, liver/kidney complications, and even acute sudden death.

In recent years, veterinarians are using a safer more modern alternative known as immiticide which is typically given as a series of once-daily intramuscular injections over a few days. While the above side effects may still occur, the incidence of negative reactions is much reduced. During the month of treatment with immiticide, many heartworm positive dogs will also be treated with the antibiotic Doxycycline, which will kill other parasites known as Wolbachia, as well as decrease inflammation and the development of secondary bacterial infections.

In those pets that are geriatric or sick with other illnesses, some veterinarians will use monthly Sentinel or Heartgard in not only preventing heartworm infection, but in preventing the further development of heartworm larvae and microfilaria (baby heartworms) in heartworm positive dogs. When used in this fashion, after a period of 1-2 years of continuous monthly heartworm prevention use, many heartworm positive dogs will become negative. During that time it is important to restrict exercise and to monitor for rare side effects that dying heartworms may have on the body.

On the other hand, holistic veterinarians will work on strengthening the immune system of the pet through diet and nutritional supplementation with herbs including quassia bark, black walnut and hawthorne. Based on the individual constitution of the patient, homeopathic remedies also may be prescribed, which will help decrease susceptibility to secondary organ damage and systemic risk, in hopefully stimulating the pet’s ability to clear the heartworms on their own. No matter which approach is used, some form of conventional or natural heartworm preventative should be used to prevent re-infection in the future.

How Often Does My Pet Need a Heartworm Test?

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It is important for pets to be tested annually for heartworms.

One of the most common questions asked of veterinarians is how often pets need to have a heartworm test.  Both the American Veterinary Heartworm Society and most veterinarians do recommend yearly heartworm testing.   Even though many animal guardians keep their pets on year-round heartworm medication, it is still important to test pets yearly for several reasons.

One of the most important reasons for an annual heartworm test is that, even though most products are highly effective in preventing heartworm infection, there is still no product that is 100% effective.  I have seen many cases in my 20-year veterinary career of pets on year-round heartworm preventative medication that have tested positive for heartworms.  There has also been increasing recent concern about developing heartworm resistance to some of the older products, and until this issue is sorted out, it is still best to have all pets tested every year.   Also in the possibility that a pet is heartworm positive, there can be very occasional severe and even rare fatal reactions should a pet that is positive for heartworms continue to receive monthly preventative.

Shortage of Immiticide

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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.

It is far better to prevent heartworm with regular heartworm preventatives than to try to treat it.

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 Sentinel. 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.

PetMeds® Heartworm Prevention with Iverhart Max

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Iverhart Max protects against heartworms and other internal parasites 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 Sentinel 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.

PetMeds® Heartworm and Flea Control in One: Sentinel

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Sentinel controls heartworms and fleas in dogs with just one pill National Heartworm Month may be officially over, but that shouldn’t prevent pet owners from understanding the importance of giving a heartworm preventative each month. A wonderfully convenient product, Sentinel offers the benefits of Interceptor heartworm prevention and the flea control of Program all in one pill.

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?

April is National Heartworm Awareness Month

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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 Sentinel. 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.  One of my favorite monthly heartworm preventatives is Heartgard Plus, which not only prevents heartworms, but prevents and control intestinal worms as well. Although this pet medication is available at 1-800-PetMeds, it does require a prescription from your veterinarian due to the blood testing involved, which is to ensure your pet does not already have heartworms.