Everything you need to know about heartworm in dogs & cats

In this episode:

Pet Joke of the Week: The Dog Dictionary Part II.
Headline pet news: Skittish cat stuck in airport x-ray machine/L.A. cracks down on pet licensure.
Personal comment: Everything you need to know about heartworm disease.

Transcript of personal comment from this episode of The Web-DVM:

My personal comment tonight deals with a topic that far too many pet owners surprisingly know too little about, heartworm disease. This is clearly evident in even my home state of Florida, the perennial heartworm capital of the USA, where veterinary clinics accomplish only 20% compliance for heartworm preventive in canine patients, and less than 8% for feline patients. So tonight I will tell you everything you need to know about heartworm disease in dogs and cats so that you may take it a seriously as it should be taken.

The heartworm is a parasitic worm that colonizes the heart of the definitive host, the domestic dog (I will address its effect on cats later). It is transmitted by the bite of mosquitoes, as the microscopic infective larvae live in the gut of the mosquito. Once in the bloodstream of the dog, the larvae mature to adult worms and then colonize the right ventricle of the heart. The worm also spends part of the time in the lungs, traveling back and forth from the heart and lungs via the pulmonary artery.

The result of the presence of these worms is inflammation of the heart muscle pulmonary vessels leading to scar tissue formation. The mass of the worms also leads to less ability of the affected heart chambers to completely fill, making the heart have to work harder to pump the same amount of blood over time. The combination of these factors leads to heart enlargement, narrowing of the heart chambers, leaky and scarred heart valves and, eventually, heart failure. At the level of the lungs, the worms cause allergic reaction, leading to inflammation, scarring, and chronic bronchitis, all this as the result of a bite from an infected mosquito to an unprotected pet.

The typical clinical heartworm disease patient presents with a severe, sometimes debilitating cough. Diagnostic findings often include fluid in the lungs and enlarged heart visible on chest x-rays, electrical disturbances of the heart in EKG findings, anemia, and high white blood cell count.

For cats, the disease is a little different, less common, but a big problem make no mistake. Since they are not the definitive host of the parasite, worms do not thrive well in the feline body, colonizing the heart as they do in dogs. Instead, the feline immune system attempts to wall off the worms, sometimes leading to the formation of cysts in the brain, lungs, kidneys, and liver. The presence of these cysts causes disease of the organs in which they form, which can include seizure, liver failure, kidney failure, or sudden death. So in cats, while heartworm is not as common as the dog, it can be every bit, if not more, dangerous.

Treatment of heartworm disease is accomplished with an arsenic known as melarsamine, administered by 2 deep intramuscular lumbar injections, each given 24 hours apart. Arsenics can cause secondary liver and kidney toxicity and dangerous allergic reactions to the dead heartworms following treatment can severely compromise the patient’s breathing and circulation. In cats, sensitivity to the arsenic and tendency to throw clots after treatment, has led to death by complication rates as high as 60%-70%, making treatment not an option for cats, but prevention all the more important.

With regard to prevention, this is the easy part. Not only are heartworm preventive medications administered only monthly, but the actual drugs have very favorable safety profiles and are also highly effective, with good client compliance obtaining protection rates as high as 95% or better. For a list of heartworm preventive medications, how they are administered, and which other parasites they protect against, see the Supplemental Information section of this post. If you are not watching this video from the blog or one of our blog syndicates, our blog home page is webdvm.blogspot.com.
For our last heartworm item, I will address the most common question pet owners present to me on this topic, which is, “If my dog is on heartworm prevention year round, why you make me get a heartworm test every year to get more heartworm medication?” There are actually a few reasons for this requirement.

First, while these preventives are very effective, they are not infallible, with failure with treatment still possible as much as 5% of the time. Keep in mind that heartworm preventive medications only kill immature infective larvae, but if they can manage to survive to adulthood, preventives won’t even touch them. Second, pets can engage in behavior that makes the heartworm preventive less effective or even useless, such as vomiting up the pill, spitting the pill out, or not having it absorb optimally because of diarrhea or eating grass. The third reason is human error - it is not uncommon for pet owners to be late on their pet’s heartworm preventive, even under the best intentions to be on time. For these reasons, some manufacturers will not guarantee the safety and effectiveness of their products without up to date yearly heartworm tests on record. On the other hand, if you comply and your pet still gets heartworm, they will pay for all diagnostics and treatments necessary to clear the heartworms and make your pet well.

That is our show for tonight, please help us to continue our discussion by posting your comments at our blog at webdvm.blogspot.com. But, we believe in being democratic here at The Web-DVM, so we are making a little change. I will still address comments posted at our blog on my live BlogTV broadcast sunday night 9:00 pm EST, but I will now also include comments from our faithful commenters at YouTube, as well as those posted by our new friends at the HubPages. I will not have time to address them all, but will be selecting the most thoughtful, unique, and/or well written comments for inclusion in my live show.

Please join us next week when I will be discussing, Spork, the vicious wiener dog. Folks, you are not going to believe this!


Supplemental Information:

Heartworm preventive products

- Heartgard - Monthly chewable flavor tabs; protects against heartworm disease, three species of intestinal parasites.

- Interceptor - Monthly tablet; protects against heartworm disease, four species of intestinal parasites.

- Sentinel - Monthly tablet; protects against heartworm disease, four sepcies of intestinal parasites, and fleas. In my experience, not great against fleas.

- Advantage Multi - Monthly topical treatment; protects against heartworm disease, four species of intestinal parasites, fleas, ear mites, and mange.

- Revolution - Monthly topical treatment; protects against heartworm disease, four species of intestinal parasites, fleas, and mange. In my experience, not great against fleas, and has been reported to be inconsistent in protecting against heartworm in dogs.

Dr. Roger Welton is the President and chief veterinarian at Maybeck Animal Hospital in West Melbourne Florida, as well as CEO of the veterinary advice and health management website Web-DVM.net.

The dangers and consequences of pet obesity

In this episode:

Pet Joke of the Week: The Dog Dictionary.
Headline pet news: West Hollywood petstore dog & cat sale ban/Natural Variety Raw Diet Recall
Personal comment: The dangers and consequences of pet obesity.

Transcript of personal comment from this episode of The Web-DVM:


For my personal comment tonight, I will be addressing an unnecessarily common health issue in dogs and cats, and that is the epidemic of obesity. So if your cat looks like this (see video for image), or your dog looks like this (see video for image), you especially need to pay close attention to what I have to say.

Obesity and the lifestyle that supports it, overeating, the consumption of excess carbohydrates and fats, and being sedentary, causes pets a world of secondary health problems. From a metabolic standpoint, the obese patient is predisposed to life threatening bouts of disease of the pancreas, as well as insulin dependent diabetes. Fat cats especially love to get diabetes, comprising the biggest percentage of diabetic patients in small animal medicine.

From a musculoskeletal standpoint, obesity leads to spinal disc injuries, ligament tears, and early age arthritis due to excessive stress obesity causes to these structures. I have one particular West Highland White Terrier patient that resembles a foot stool she is so fat, that for the past 3 years, literally wobbles her way into my clinic because her obesity decreases her ability to ambulate normally. This Westie now has to come in for regular rehab laser treatments for her knees because her obesity is wearing them out at only 5 years of age.

The owner of this Westie, as is the case of many owners with obese pets, has maintained that he does not over feed her, offering her only the diet food that I prescribed, in the amounts I recommended. I even ran bloodwork on her and checked her thyroid levels to make certain there was not underlying medical disease contributing to the dog’s obesity, which all returned normal; confirming that this owner is lying to me, that this dog is getting overfed despite his protests that this is not the case.

You see folks, animals like people, when overfed gain weight, and when fed less, lose weight. One does not need a veterinary degree to figure that out. So when I have ruled out all known medical causes for obesity, prescribed a weightloss diet that your pet responds to by getting even fatter, you are lying to me and not following my instructions.

With the owner of the fat Westie, it was his wife that ultimately ratted him out, explaining to me that her husband indeed feeds the recommended amounts of the weightloss diet I prescribed, but also continues to offer the dog a portion of whatever he is eating, whether it be bacon, steak, potato chips, or even iced cream!

So because this owner cannot resist his dog’s begging, to date it has cost him $140 in bloodwork, $360 in laser rehabilitation treatments and $150 in anti-inflammatory drugs for the bum knees. The dog’s quality of life is compromised because she is so bloated that she cannot move, and at this rate, her life will surely be shortened.

Ladies and gentlemen, this is just one example of a virtually endless number of patients that have a similar story. Why owners at a huge cost to their pet’s health, as well as their bank accounts, just cannot say no to their pets and ration their eating, is beyond me. I even had one owner tell me that he will never get weight off his dog because, like his own personal approach to life, he would rather let him eat what he wants, live a shorter life and die happy, rather than go through life unsatisfied and live longer.

To that, my reply is this:

Your dog’s life will indeed be shorter, but he will not die happy. On his way to the end of his life that you have decided to hasten, he stands a far greater likelihood than other non-obese pets, of needing surgery to repair ligament tears or spinal disc herniations. Along his shortened journey of life, he may have to be hospitalized for pancreatitis or need to receive insulin injections to manage his diabetes. He may have his vision compromised from diabetic complication of cataracts or because his obesity is causing his body to deposit cholesterol on the corneas of his eyes. And if he survives all of that, at some point, the decision to put him to sleep will ultimately be made because his obesity has stressed his joints to severe level of degenerative disease, the pain of which, all the medications in the world can no longer manage.

Sounds to you like a crappy way to live? Of course it does! So if your pet is fat, take it seriously and start getting some weight off. To help you in your task, I will be posting some general feeding guidelines, as well as some good choices for weightloss diets on the blog, at webdvm.blogspot.com.

That is our show for this Thursday, February 18, 2010. Please help us continue our discussion at our blog at webdvm.blogspot.com. As always, comments posted there will be addressed by me live on my supplemental show Sunday evening at 7:30 PM EST at BlogTV.com. Please join me next week, as I will be discussing heartworm disease in dogs and cats. Is it really that bad of a problem? Can cats get it too? Find out next week.

Natural Variety raw diet recall products:

•3 lb chicken medallions (UPC# 7 69949 60130 2) with a "Best If Used By" date of 11/10/10
•6 lb chicken patties (UPC# 7 69949 60120 3) with a "Best If Used By" date of 11/10/10
•2 lb chicken chubs (UPC# 7 69949 60121 0) with a "Best If Used By" date of 11/10/1

Supplemental Information:

How do I know if my pet is overweight?

Begin assessing your pet’s body condition by simply looking at him. Viewed from above, you should see a noticeable “waist,” which in dogs and cats is a modest tapering just past the rib cage. No visible waist (or the opposite – a pouching out or pear shape) is an indication that the pet is overweight.

Viewed from the side, as your eyes from the chest toward the back end of the dog just past the rib cage, the abdomen should be tucked in. Lack of this (or the opposite – a pot belly) is an indication that the pet is overweight.

(Ideal appeareance)





Run your fingers across the rib cage. You should be able to feel individual ribs. While you should never see rib protrusions, you should always be able to feel them beneath the skin. If you cannot feel ribs, that is an indication that your pet is overweight.

So how do I get weight off my overweight pet?

If your pet is just mildly to moderately overweight, I would begin by simply calculating the daily food intake to make certain that you are not overfeeding. The general guideline that I offer for dogs and cats is one 8 oz cup of food per 20 pounds of body weight per day. Since different foods have different caloric content, this guideline is general, but usually fits fairly well with most normal pets and with most diets. If you are already feeding this much or less and your pet is overweight, try cutting back what you are currently feeding by about 25%, as well as try to increase exercise. In doing these calculations, be sure not to use the pet’s current weight, but the target weight which you or your veterinarian feel would be ideal.

If your pet is substantially overweight and/or the above measures have not helped, then you should select a weightloss diet. Commercially, Science Diet, Eukanuba, Iams, and Royal Canin all make excellent weightloss diets for both dogs and cats. If I had to pick out one of these diets as my favorite as far as most effective, the Science Diet light formulas have historically seemed to be the best in my experience. You would feed these diets under the same 1 cup per 20 pounds per day guideline.

If your pet is morbidly obese and/or even these good commercial weightloss diets have not helped get weight off your pet, then it is time to consider a prescription weightloss diet from your veterinarian. Each vet has his/her own favorite lines of prescription diets, so ask your vet which one he/she recommends. I am a big fan of Hills R/D for this purpose. With these stubborn weightloss patients, it is also a good idea to have the thyroid checked to make certain that hypothyroidism, a.k.a., underactive thyroid, is not getting in the way of proper weightloss.

Dr. Roger Welton is the President and chief veterinarian at Maybeck Animal Hospital in West Melbourne Florida, as well as CEO of the veterinary advice and health management website Web-DVM.net.

Emerging field of veterinary rehabilitation is here to stay

In this episode:

Pet Joke of the Week: Adopted Turtle.
Personal comment: Emerging field of veterinary rehabilitation is here to stay.

Transcript of personal comment from this episode of The Web-DVM:

In my personal comment tonight, I am excited to present to you the emerging field of veterinary rehabilitation, an approach to treating degenerative disease of the joints and spine in a non-surgical, non-intrusive way. It is such innovations as these that make the practice of medicine always novel, enjoyable, and rewarding.

So let us dive right in and talk about some of the conditions where rehabilitation is practically applicable for dogs and cats as, I think you will be surprised at how these common every day conditions may apply to your own dogs and cats. The most common disease that affects aging pets, of course, is arthritis of the joints and spine. Arthritis stems from wear and tear of the cartilaginous surfaces of the bones that comprise a given joint, that leads to inflammation, pain, and eventually degenerative changes that can be rather debilitating to affected pets. While arthritis is associated with age, it can present as an early onset in some patients due to obesity, injury, and inherited deformities like hip dysplasia. Those of us that are life long pet owners certainly have observed first hand how arthritis can cause our pets stiffness and affect mobility.

Spinal disc herniation and subsequent spinal cord and nerve root signature compression is a both a common and serous occurrence in dogs and cats, especially so in small dogs. These injuries cause pain that is often severe, can lead to neuromuscular weakness and dysfunction and even complete paralysis.

While surgery and anti-inflammatory drugs remain invaluable options for the treatment of these and other musculoskeletal diseases, there are now less invasive and far less costly approaches that may help many of these patients, the most innovative of which is the therapy laser. Pictured here (see video for image) is the Cutting Edge therapy laser I have recently added to my own animal hospital. It works by emitting low level photons to an area that has many beneficial effects. From a pain management standpoint, the therapy laser stimulates the synthesis of the body's own natural pain reducing biochemicals, specifically endorphins and encephalin. The therapy laser stimulates muscle and trigger point providing musculoskeletal pain relief.

Accelerated healing is another benefit of the therapy laser, as photons of emitted light penetrate deeply into tissues to stimulate rapid cellular reproduction and growth. These photons also increase the amount of energy available to cells so that they can absorb nutrients while eliminating waste products faster. As a result of all of this, tissues such as tendons, ligaments, and muscle are repaired more quickly.

Another phenomenon of the therapy laser that stimulates faster healing is the opening or dilation of small blood vessels in an area. More blood supply brings in healing cells faster, accelerating the healing process while reducing the formation of scar tissue. Most importantly, the laser accomplishes all this at no risk to the patient, with little to no potential for harmful complications, not even a warming of the skin.

While the therapy laser puts damaged tissues into a cycle of healing, nutritional management provides the raw materials necessary for the restoration of cartilage, ligaments, tendons, and other connective tissues, while also providing additional natural anti-inflammatory relief. Nutriceuticals, as these nutritional supplements are termed, contain varying combinations of glycosaminoglycans, glucosamine, chondroitin, and MSM. But let me warn you, not all nutriceuticals are created equal! These products at this time are not FDA regulated, and thus are not bound by law to have what the label claims. As such, blind studies have found many joint health supplements lacking in ingredients their labels claim they have. For this reason, it is important to select veterinary grade nutriceuticals on the recommendation of you veterinarian.

So let me showcase a typical rehabilitation course. Pictured here is my dog Lulu (see video for image) who, due to her obssession with a certain armadillo in our yard, threw out her back rather badly in hot pursuit of the elusive creature, specifically in the L3-L4 region of her spine. The result of this injury was chronic recurring pain, which necessitated periodic courses of anti-inflammatory medications.

I began Lulu's treatment regimen by starting her on the daily oral nutriceutical, Dasuquin. Each rehab treatment she receives in the clinic consists of a laser infusion in her affected area, an injection of the powerful injectable nutriceutical, Adequan, and therapeutic massage. The protocol calls for a 3 week induction phase, from which she receives 3 treatments week one, 2 treatments week 2, and 1 treatment week 3. Thereafter, Lulu moves to her maintenance phase, where she will remain on daily oral Dasuquin, and get a laser fusion/Adequan injection/therpeutic massage treatment once every 4-8 weeks as her needs dictate. Now just entering week 2, Lulu is acting as if the injury never occurred, the most mobile and pain free I have seen her in months, all without the need for anti-inflammatory drugs. Most importantly, she has once again regained her passion in life, which is to one day, catch her arch nemesis, the armadillo.

That is our show for this Thursday, February 11, 2010. Please help us continue our discussion at our blog at webdvm.blogspot.com. Comments posted there will be addressed by me live on my supplemental show Sunday evening at 4:30 PM EST at BlogTV.com. Please join us next week when I will be discussing the dangers and consequences of pet obesity.

Dr. Roger Welton is the President and chief veterinarian at Maybeck Animal Hospital in West Melbourne Florida, as well as CEO of the veterinary advice and health management website Web-DVM.net.

Thoughts on canine & feline nutrition

In this episode:

Pet Joke of the Week: Clever dog quote from a famous historical figure.
Personal comment: Thoughts on canine & feline nutrition

Transcript of personal comment from this episode of The Web-DVM:

I am once again foregoing the news this week in favor of another rather substantial personal comment. As promised last week following my personal comment about dogs and wolves being very different species that should not be considered the same, and certainly should not be fed the same, this week I turn my attention to canine and feline nutrition. Let me begin by quickly addressing the feeding of a raw meat diet.

In dogs, I already explained last week that having a less acidic gastric pH than their wolf ancestor, dogs do not have a good natural defense against raw meat bacteria and parasites. As such, feeding raw meat carries a high risk of food poisoning in dogs as it does people, some cases of which can be life threatening. Like people, we regularly see cases of raw meat induced food poisoning including salmonella, e. coli, klebsiella, and campylobacter, to name some of the more common ones. And for you raw feeding proponents that think this does not occur because it has not yet happened to your dog? Think again, I have seen it time and again in practice. If your dogs have not gotten sick you have been lucky, and I hope that you do not ever have to face both the expense and emotional toll of your pet getting violently ill, while living with the guilt that your insistence on feeding in a manner that the vast majority of veterinarians recommend against for good reason, was the cause. And if you feed raw because wolves do and you think that dogs should eat the same as a wolf, then I urge you to please watch last week's episode focused on the many ways the two species are different.

Also, feeding a canine an exclusively protein diet is a poor approach to promoting good health. In order to break down protein into smaller chains that can be properly absorbed by the gut, metabolic reactions must occur that generate ammonia as a primary waste product. Thankfully the liver processes this ammonia and converts it into a less harmful analog called urea, which then gets transported to the kidneys for elimination in the urine. However, feeding an exclusive or disproportionately high level of protein, subsqently puts metabolic stress on the liver and kidneys because of this, while starving the body of other important nutrients that the canine needs, such as carbohydrates, fiber, and fat. You see, dogs are not carnivores that require a diet exclusively of meat, nor even mostly of meat. They are, like people, omnivores, requiring a diet properly balanced in nutrients.

Regarding cats well, like in many other ways, they are different from dogs. For one thing, they ARE carnivores, that is, they can thrive on a diet of pure meat protein, having the physiological adaptations to more efficiently create non-protein nutrients from protein. That said, raw meat is still not good idea for them either. While cats seems to be able to withstand raw meat food poisoning a bit better than dogs, I have still treated a number of confirmed food poisoning cases, the most common of which has seemed to be salmonella.

Now, even though cats can thrive on a pure protein, meat diet, they still seem to do better with some degree of vegetable matter in their food, with some fiber, complex carbohydrates, and antioxidants making invaluable contributions to overall health. So while we still like to feed cats diets that are proportionally heavy in protein, it is advisable to offer some vegetable and fibrous carbohydrate sources as well.

Now the breakdown. Starting with dogs, they do best with the following breakdown of nutrients: 25%-35% protein, 35%-45% carbohydrate, 5%-15% fat, and 5-10% fiber. Cats do best with 35%-45% protein, 25%-35% carbohydrate, 15%-25% fat, and 1%-5% fiber. Cats also cannot manufacture the amino acid taurine, making it an essential additive to all feline foods. Deficiency of taurine can lead to severe cardiac disease in cats.

So what kinds of pet food should you select? I am not here to promote any one brand of food nor am I going to blast any particular brands as tempting as it may be to do so. I will offer this, however: avoid grocery store and superstore brands, as these foods are consistently very bad diets, heavy in fillers and poor quality nutrient sources. And, the companies that make them are sneaky.

They make the food so that the nutrient label matches well with better quality diets, but what they do not tell you is that, while a reputable pet food company may use good quality protein sources such as muscle and organs, a grocery store brand will use hoof, hair, and skin. Both technically protein, but the absorption and utilization will not be the same. While a reputable diet may use quality carbohydrate and fiber sources such as rice and vegetables, a grocery store brand may use fillers like corn and wheat. If you want to feed your pets well, resist the temptation to go down that pet food isle while at the grocery store.

Instead, look for diets that are comprised of whole foods and vegetables, with meat and veggies listed first in the ingredients, with byproducts listed further down the list. Many of these better diets are sold at veterinary clinics and large retail pet stores.

If you can fit it into your budget, consider feeding a diet free of preservatives and fillers. These so called holistic diets are made of whole foods, primarily meats and green veggies, omitting the use of chemical preservatives and highly allergenic grain fillers, such as wheat and corn. Confused about which diet to pick in a sea of options? Ask your vet, as he/she is the best source for pet food recommendations.

Regarding texture, I almost always favor a dry diet versus a canned one primarily for the dental health benefits of dry, crunchy food. Chewing a crunchy diet cleans the teeth and massages the gums, promoting good overall oral health.

For more indepth information about canine and feline nutrition broken down even further into specific life stage, please refer to the nutrition page on our parent site, Web-DVM.net.