Hello all, as some of you may have read on previous posts we are relocating to Houston, Texas in the coming weeks and I have been told by some local based colleagues they suggest starting our little man on heart worm tablets as they are vital when we move and our new vet will commence them straight away when we arrive so suggest to get him covered before we go......

Anyone have experience of this and any associated side effects etc.....

it is standard practice in USA as heartworm is a big killer.  You use on of the multi parasitic spot on's every month.  Trouble is they often go under different names in teh states to what they do here.  Interceptor is one that ahs a different name here.

Googled heart worm preventatives for dogs. http://www.drsfostersmith.com/pic/article.cfm?aid=579

"Prevention
The good news is that there is no need for your pet to have to endure heartworm disease or its treatment, because it is so easy to prevent. A heartworm prevention program is effective and simple, and consists of three parts:

Regular Blood Testing for Dogs - This ensures your dog is free from heartworms before he begins or continues on his preventive medication. Your veterinarian will advise you as to the recommended frequency of regular blood tests. Interpreting test results in cats is more problematic and you should discuss testing with your veterinarian.

Preventive medication - This means administering a heartworm preventive to your pet year round, regardless of the mosquito season. Prevention for dogs includes monthly oral preparations like Tri-Heart Plus, Heartgard products, Iverhart Plus, Revolution, Interceptor, Advantage Multi, or Sentinel (which includes flea prevention). Heartgard, Revolution, Advantage Multi, and Interceptor also offer a monthly feline heartworm preventive.

Reducing your pet's exposure to mosquitoes - This means making your pet's environment less hospitable to mosquitoes. This decreases the risk of your pet being infected with heartworm in the first place.
Heartworm prevention is safe, easy and inexpensive compared to treating a dog or cat after worms have matured into adults. While treatment for heartworm disease is possible in dogs, it is a complicated and expensive process, taking weeks for infected animals to recover and there is often permanent damage to the heart. For cats, there is no effective treatment to kill the worms. By investing in a preventive medication, you will spare your pet from this deadly disease and its complicated treatment. Talk to your veterinarian today to start a prevention program for your pets. "