Friday, August 17, 2012

Are Heartworm Medications Necessary in San Diego? Get the Facts.

Written By: Lori Blauert of IB Pet 
I currently do not use a monthly heartworm preventative on my pets.  I've been advised by multiple veterinarians that it is unnecessary in San Diego.  Being from the east coast I understand the risks of heartworm disease and would never recommend forgoing treatment on dog from back east but here in San Diego where mosquitos are scarse and the weather is cooler our dogs are not at risk. Why would I want to give my pets a monthly dose of toxic poison anyway if I don't need too?

It has been abnormally hot in San Diego the past few weeks and I've noticed some mosquitoes bites myself.  A friend of mine even told me she heard there was a case of west nile reported in San Diego.  With all this mosquito talk it got me to wondering about my dogs risk for heartworm so I did a little research on my own.  I first came across this article,  The Truth About Heartworm, which outlines the 7 steps that must be completed to give your dog a dangerous heartworm infestation.  I also found that according to veterinarian Dr. Karen Becker, "Heartworms are a variety of roundworm with the clinical name dirofilaria immitis. They are spread by mosquitoes.  Dogs can only get heartworm disease through infected mosquitoes. They can't get it from other dogs or other types of animals, from dog feces, or from their mothers while in the womb or through nursing.

Only certain mosquitoes can transmit heartworms to your dog. These mosquitoes must meet certain precise criteria, including:
  • They must be female. 
  • They must be of a species that allows development of the worms in the cells of the body (not all species do). 
  • They must be of a species that feeds on mammals (not all do). 
  • They must have bitten an animal infected with stage 1 (L1) heartworms about two weeks prior, since approximately 14 days are necessary for the larvae from the other animal to develop to stage 3 (L3) inside the transmitting mosquito.
  • This mosquito must then bite your dog. When the larvae reach stage L4-L5, which takes three to four months, under the right conditions they can travel via your dog's bloodstream to the lungs and heart. 
If your dog's immune system doesn't destroy these invaders, they will reach maturity (L6), the adult stage, in which males can grow to six inches in length and females to 12.
Two other critically important features in the transmission of heartworm are:
  1. The right temperature. During the time the heartworm larvae are developing from L1 to L3 inside an infected mosquito, which is approximately a two-week period, the temperature must not dip below 57°F at any point in time. If it does, the maturation cycle is halted. According to Washington State University heartworm report from 2006, full development of the larvae requires "the equivalent of a steady 24-hour daily temperature in excess of 64°F (18°C) for approximately one month."
  2. Humidity and standing water. Mosquitoes are a rarity in dry climates."

After reading this and finding the same info from a few other reputable sources I was pretty convinced that my dogs are pretty safe here in San Diego.  I then decided to dig a little deeper and see what some of the local vets in San Diego had to say about it.  I stumbled on some information on
Sunset Cliff's Vet Hospital's website which has me scratching my head again. They state on their website that cases of heartworm have been reported in San Diego and therefore they recommend you must treat your dog.  They also state that these cases are from dogs that have traveled to San Diego from other areas of the the country.  I  guess they are leading your to believe that your dog can get heartworms from other dogs.  As a vet your would think they would know that heartworms can only be spread through a mosquitos bite, right?  I'm not a vet but it sounds to me they are just trying to sell you heartworm preventatives?  

Ok I'm not trying to call out Sunset Cliff's Vet Hospital here but 
I then scroll down and read that they state that flea preventative products such as Frontline and Advantage purchased from anyone other than a vet are harmful to your pet.  Years ago Frontline and Advantage products could only be purchased from a licensed veterinarian but like with many other drugs, once they have been tested over time they can become available over the counter.  This happened a few years ago and these topical flea products can now be purchased from your local pet store, Petco, PetSmart and even at Walmart or Costco.  Sunset Cliff's claims on their website that the products these store are selling are not made by Merial and Bayer, the makers of Fronltine and Advantage.  Well that is just simply not true my friends.  As a pet store owner in San Diego I know for a fact that the Frontline and Advantage products I carry in my store are made by Merial and Bayer.  Obviously as a consumer you always want to make sure you are purchasing your products from a reputable dealer as I am sure knock offs do exist but for them to state that all of these products are fake just blows my mind! They are making these statements simply to scare you, just like with the heartworms.  They are trying to sell medications.  As a pet owner you want to be able to trust your vet but it's confusing and hard to know who to trust.  I guess you just really have to do your homework and know the facts.  



  1. Awesome story! I really appreciate that you took the time to look into this and share!

  2. This information is incorrect. I have worked in the veterinary field for over 12 years. San Diego is not known for it's mosquito population, however as you said yourself, they are here. The veterinary website you referenced simply states that heartworm disease has been diagnosed and treated here in San Diego. They did not say that that means your dog could "catch" it from these dogs that have been diagnosed. If heartworm disease is present in San Diego, it means that there are mosquitos here that are carrying the disease. It must bite an infected dog and then bite another dog to transmit heartworm disease. While this may be somewhat unlikely, it is still possible. Veterinarians highly recommend preventive treatments due to many reasons. Almost all heartworm preventions also treat some of the more common intestinal parasites present in San Diego, especially at the beaches and dog parks (many of which are zoonotic, meaning we can get them). If there is a risk of heartworm disease, it is much easier to prevent it than to treat it. Heartworm infection causes heart disease, and if not caught early enough, causes irreparable damage and can cause death. It is also a very long, expensive treatment protocol. Annual testing is recommended whether or not your pet is on prevention, as once symptoms appear, your pet is already very sick.
    Regarding the internet medications, there is also some misinformation. The manufacturers of Advantage and Frontline used to sell these products only to veterinarians. When you find them online, the products have been diverted in some way. Whether a veterinarian bought them and then illegally sold them to the internet store or they have been counterfeited (seems crazy but it actually happens). Not only do you have no idea where the products have been, whether they have been stored at proper temperatures or whether you even get the product that you ordered, the medications are not coming from the manufacturer directly. The biggest problem with this is that if your pet were to have any kind of allergic reaction to the medication, the manufacturer would not stand behind it. When sold by a veterinarian, if anything happens to your pet because of the medications, although very safe, they are 100% guaranteed. I have also experienced a few horror stories. One in particular where a person ordered a topical flea medication for their cat, applied it, the cat started having seizures and died on the way in to the hospital. The internet pharmacy sent her flea medication meant for a large dog. You just never know what your going to get. Veterinarians don't make a lot of money on these types of products, they just try to educate you on what is best for your pet.

    1. Thanks for your comment Robin and I appreciate you checking out our blog! I do however have to disagree with you. I'm not sure if you read my post in it's entirety but if you had you would have read the part where I referenced Dr. Karen Becker's explanation on how temperature effects heartworm transmission. I've come to learn that many veterinarians (including the one you work for) don't even really understand the science behind the lifecycle of heartworm. I encourage you to research this on your own but to summarize; in order for transmission to happen the temperature must remain above 64 degrees for approximately a month straight or the heartworm larvae maturation is halted. Even in the warmest months of the year in San Diego it still drops below 64 at night. This is why in San Diego I believe heartworm preventatives are not necessary. Like I said, I always encourage people to research things on their own and make their own informed decision. It would be foolish in my experience to take someone’s word on something simply because they are a veterinarian or vet tech and this is what actually inspired me to write this blog post 2 years ago. I had been receiving mixed information for multiple sources and I had to find the facts for myself and so I did.

      Regarding what you are saying about flea medications. The products I carry are not purchased online. I purchase my Bayer (manufacturer of Advantage and K9 Advantix) products from United Pacific Pet. UPP is the only authorized distributor of these products to independent pet stores in Southern California. These products are cold packed and delivered to my shop by UPP (not through the mail) to ensure proper temperatures. SO YES I DO KNOW. I believe that the bad info you've posted about how these products being "diverted in some way" is just another example of things that veterinarians like to say to discourage people from buying their flea meds somewhere else. Bayer is actually coming out to my store, IB Pet, on April 12th to present and educate my customers and staff on their products. You are welcome to attend and see for yourself.