Yes, heartworm disease in Canada is real.  Yes, heartworm disease can kill your dog.  Yes, cats can develop heartworm disease too.  No, not all dogs and cats in Canada are at risk.  Let’s talk about heartworm disease and how you and your veterinarian decide if your pet requires regular testing and prevention. 

The Ontario Veterinary College published a paper in 2010 which showed that 564 dogs tested positive for heartworm in Canada.  Over 75 percent (431 in total) of these dogs lived in Ontario.  There are also pockets of heartworm disease in southern Manitoba, southern Quebec, and southern mainland British Columbia.  This study showed the presence of heartworm infection in dogs increased by nearly 60% since the last study of its kind in 2002.  Researchers speculate that one factor may be the adoption of heartworm-positive rescue dogs from the southern United States after Hurricane Katrina or through other rescue programs from American states where there is a higher prevalence of heartworm disease.   Other studies suggest that cats may be infected at approximately 1/10 the rate of dogs in heartworm prevalent areas.  

Let’s look at the life cycle of heartworms in the dog.  Dogs become infected with heartworms through mosquito bites.  Mosquitoes “suck up” microfilariae, microscopic larvae, when they bite and feed from dogs, coyotes, and foxes who already have contracted heartworm disease.  The larvae mature in the salivary glands of the mosquitoes who then feed from an uninfected dog.  The larvae are then transferred into the tissues of the new dog and go through a maturation process in the dog’s body.  The larvae eventually become adult worms who travel through the lungs and bloodstream and end up in the pulmonary blood vessels and the heart.  Once they arrive here, they can mate and produce thousands of the tiny microfilariae.  It takes between 5 to 7 months for one female heartworm to mature and begin producing these tiny larvae.  The microfilariae travel through the bloodstream where they are available for the next mosquito to come along and feed.    Thus the cycle repeats itself. 

The adult heartworms can grow to be 15 to 30 centimetres in length.  Severely affected dogs may carry 30 to 100 worms within their hearts and lungs.  The presence of these parasites over time can lead to lung and liver disease and heart failure.  While the worms themselves don’t necessarily kill a dog, these conditions can certainly be fatal.  Treatment often involves the killing of the adult worms with an arsenic-based compound which can result in severe complications.  Prevention on the other hand is quite easy and with minimal adverse effects.  Preventive medication is aimed at killing the microscopic larvae in the dog’s system before they have a chance to reach the heart and the lungs.  Prevention may come in the form of a tablet, a chew treat, or a spot-on product that you apply over your dog’s shoulders and back.  Normally these medications are prescribed on a monthly basis and are given during the summer months, according to a local area’s “mosquito season”. 

The American Heartworm Society recommends annual testing and preventive medication for dogs that live in heartworm prevalent areas of the country.  While we pet parents who routinely give our dogs heartworm medication may wonder why we need to re-test annually, there are a couple of very good reasons.  Some studies suggest that 1 in 10 positive dogs may have been given a preventive in the year prior to having a positive test.  While the medications themselves are very effective, some of us may forget to give the pill on time or may miss a month or two at the end of the mosquito season.  Some dogs are quite wily and will appear to have swallowed their tablet but may spit it out in the backyard or behind the sofa.  A dog who eats grass “just because she likes it” may accidentally vomit the pill in the backyard without your ever realizing it.  These dogs may be unprotected for a whole month of heartworm-infecting mosquito bites.   

Mosquitoes do not discriminate against small dogs and dogs who spend much of their time indoors.  These dogs may be at risk for heartworm disease depending on where you live and will benefit from preventive medication.  Your veterinarian will be able to offer you the specific statistics for heartworm prevalence in your area to help you determine if prevention is a good idea for your dog and how often your dog should be tested.  Also remember that dogs who travel to the United States or areas of Canada with a higher prevalence for heartworm disease should be prescribed a preventive medication during travel and in the month afterward.  These dogs will need to be re-tested 6 to 12 months after they return home. 

Cats are not considered a natural reservoir host for heartworms, but we can still see the disease in this species.  While the life cycle is similar, cats tend to develop infections with smaller numbers of worms and are as likely to develop breathing problems or an asthma-like condition as true heart failure.  Cats most at risk are those who spend time outdoors at dusk and dawn.  Heartworm testing is more complicated in feline patients but preventive medication is available.  Please ask your veterinarian if your cat would benefit from a heartworm prevention program. 

Dr. Colleen Skavinsky
Chief Veterinary Officer
Petsecure pet health insurance

To learn more, visit: www.petsecure.com

In January and February, we held a True Tails contest, asking for story submissions on how Petsecure helped you and your pet, for a chance to win a $500 VISA gift card!

Thank you to everyone who submitted their story. We had a lot of great submissions that were inspiring and heartwarming.

The Grand Prize winner of the "True Tails" contest is.... Emily and her dog Jasper!! Emily has a won a $500 VISA gift card! Congratulations!! Check out Emily's true tail here!

There were also 9 $25 VISA gift card winners:

• Kathleen and her cat Peach
• Diane and her dog Kenzie
• Stephanie and her dog Mason
• Tammy and her dog Carson
• Myrna and her dog Quixote
• Shelia and her dog Ursa
• Tiffany and her dog Bosco
• Amanda and her dog Henry
• Lorraine and her cat Siang

Congratulations to all our winners!

Trees are budding, flowers will soon be blooming, and our April eTails newsletter is out!

 Here you'll find information on allergies in our cats and dogs, who won the True Tails contest, why more likes on our Facebook page will bring more money to charities, and a new contest... the "Best Pet Story" contest.

Check it out for more details! http://www.petsecure.com/etails/april-2012

Spring has sprung across our great land.  Sunny skies, tulips and crocuses...and itchy ears.  Or itchy bellies.  Or itchy paws.  Dogs and cats can develop hay fever or seasonal allergies just like ourselves.  Unlike people, who are prone to runny noses and stuffy sinuses, pets are more likely to show signs associated with skin lesions and ear infections when suffering from this condition.

Atopy is the term we use when we are describing an allergy to different particles in the environment.  The severity is often related to changing seasons.  Pets may become allergic to pollens, moulds, and dust particles (often dust mite “bits”).  We used to categorize atopy as the inhalant-form of allergies.  An animal would breathe in a specific particle that the immune system would recognize as foreign and set up an inflammatory response in reaction.  The inflammatory response usually involves the release of histamine molecules from particular cells concentrated in specific parts of the body-around the face and ears, the paws, belly, and around the anus.  This reaction results in pruritus, also known as itchiness.  The pet may start showing signs for a few weeks during the seasons when the offending particles are present in the air, but over time these periods may lengthen to the point that the pet shows allergic signs year-round.

We know that the inhalant route of exposure is very important, but research shows that dogs and cats are also being exposed to allergenic particles (proteins that cause your pet to develop an allergic reaction) through the digestive system and direct contact with the skin.  For example, during times of high pollen counts, your dog may be literally bathing in these invisible particles every time he goes outside.  When he licks a puddle, he may be drinking in these same particles.  Dogs don’t do well living in bubbles, so how do we diagnose and treat atopy?

Your veterinarian will diagnosis atopy based on a number of considerations.  Certain breeds are more prone to atopy than others including the Golden retriever, Dalmatian, West Highland white terrier, Shar Pei, Labrador retriever, Cairn terrier, Lhasa Apso, Shih Tzu, Boxer, and Pug.  The doctor will look for lesions or signs of scratching.  An atopic pet can have sore ears or red, swollen paws.  Dogs with allergies may have actual crusty sores on their bodies or may only have small areas of missing hair where they have been chewing.  Cats tend to have crusting around their faces and necks with or without signs of ear problems.  There are a number of tests recommended to ensure that there are no concurrent problems.  Skin samples will be taken to look for fleas, lice, Demodex, Sarcoptes, and other critters that can live on the pet and produce skin lesions.  Culture samples may be collected to rule out the presence of bacterial or fungal infections.  A large number of patients will develop secondary infections that require treatment at the same time as the allergies are being addressed.  Other conditions that cause skin disease may also need to be ruled out, and your veterinarian may advise specific testing for thyroid disease and other hormonal or immune-mediated problems.  Specific diet trials may be initiated to ensure that there is no food allergy component to your dog’s condition.  Specialized allergy testing is a great way to determine which allergens affect your pet. 

Intradermal skin testing has long been considered the “gold standard” when diagnosing which specific allergens are causing problems for a pet.  The veterinarian will shave a small area on the patient’s side and draw a grid to keep track of the different allergens being tested.  A small amount of each substance is injected into the top layers of the skin and the spot is monitored for reaction.  Allergic pets will mount a “histamine response”, i.e. there is pin-point swelling and redness in the area.  The degree of reaction is rated by the veterinarian and recorded.  Some dogs and all cats will need to be sedated, because the histamine reaction we are looking for can be very itchy and uncomfortable. 

Serum allergy testing certainly does have its place where clients do not have access to assessment by a dermatologist.  A small blood sample is taken from the patient and sent to a specialized laboratory that measures the amount of immunoglobulin E (a type of antibody) against specific allergens.  As an aside, although serum tests often offer food panels, most veterinarians recommend food allergy assessments through specialized diet trials.  The results for both intradermal skin testing and serum allergy testing need to be interpreted by an experienced veterinarian in light of the individual patient’s clinical symptoms, lifestyle, and environment. 

As you can see, we generally don’t diagnose and successfully treat atopy with one visit to the veterinary hospital.  You may be asked to help control your dog’s environment with regular vacuuming and washing of bedding.  Stuffed toys and indoor plants may need to be removed from the home.  Air filtration devices incorporated into your air conditioning and heating systems can be very helpful in decreasing indoor allergens.  Once the doctor has ruled out other potential problems and treated any secondary skin or ear infections, therapy can be guided toward treating with prescription medications, and using hyposensitization techniques which allow patients to slowly become “immune” to their allergies.  Prednisone and other types of cortisone-type medications can be very useful in relieving allergy symptoms, although they are known to cause a number of side effects when used long-term.  Cyclosporine is another drug which may be of great benefit in the right patient.  Dogs and cats may have only a limited response to over-the-counter antihistamines, and your veterinarian will let you know if your pet is a candidate for these types of medications.  Nutritional supplements and topical products can also be used in addition to these main forms of therapy to decrease inflammation, boost the immune system, and soothe the skin. For most pets, atopy or other forms of skin allergies require chronic management. A great working relationship with your veterinarian will be the biggest factor in successfully reducing your pet’s symptoms and keeping the itchiness under control. 

Dr. Colleen Skavinsky
Chief Veterinary Officer
Petsecure pet health insurance

To learn more, visit: www.petsecure.com

Petsecure was in the news yesterday after having just launched a new partnership with the City of Calgary.

Here is the article that was originally published in the March 5th edition of The Calgary Herald.