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New Georgia study examines causes of death in dogs



Researchers , from the University of Georgia College of Veterinary Medicine studied dogs from 1984 to 2004 in an investigation into age-, size-, and breed-related causes of death(J Vet Intern Med 2011;25(2):187-198). It included 20 years of records from 27 veterinary schools’ and  teaching hospitals.  Author Dr. Kate E. Creevy, an assistant professor at Georgia’s veterinary college, looked at records of more than 74,556 dogs of 82 breeds.

Results indicated that young dogs (2 years or younger) died most commonly of trauma, congenital (inherited), and infectious diseases. Older dogs, died overwhelmingly of cancer and the frequency of cancer peaked in the group that included 10-year-old dogs and then declined with the oldest age group.

Focusing on conditions by weight, large breed dogs died more commonly of musculoskeletal and gastrointestinal causes, whereas small dogs died more commonly of endocrine causes. Cancer was a cause of death more frequently in large-breed dogs. Dogs of small breeds had an increased risk of death associated with metabolic diseases like diabetes and adrenal disorders.

In analyzing specific breeds, researchers found generally unsurprising results, such as Dachshunds having a high percentage of deaths attributable to neurologic disease and Golden Retrievers having the highest percentage of deaths from cancer. Respiratory disease was the most common cause of death in Bulldogs, and Chihuahuas and Maltese died largely of cardiovascular diseases.

In specific breeds, researchers found Dachshunds having a high percentage of deaths attributable to neurologic disease and Golden Retrievers having the highest percentage of deaths from cancer. Respiratory disease was the most common cause of death in Bulldogs, and Chihuahuas and Maltese died of cardiovascular diseases.

Golden Retrievers and Boxers died of cancer more commonly than any other disease and at rates higher than those of most other breeds and the Bouvier des Flandres was the breed with the second highest rate of cancer-related deaths, ranking ahead of the Boxer.

Finally, although cancer generally was the most common process resulting in death in the study there were a few breeds less likely to die of the disease, including several toy breeds—Chihuahua, Pekingese, Pomeranian, and Toy Poodle—and the Australian Heeler and the Treeing Walker Coonhound.

Summarized by Ned Caldwell from article by Malinda Larkin JAVMA News June 1, 2011

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Are Heartworms Winning the War?

Microfilaria in blood of dog

For many years we have been fighting a battle against heartworms. We have great products on our side to prevent this disease, but recent findings about heartworm resistance have many pet owners and veterinarians concerned.

Heartworm disease has been known to veterinarians for more than 120 years. The heartworms are transmitted from any of more than 70 known species of mosquito, and the disease attacks the pulmonary arteries and right side of the heart in dogs.  Heartworms are spread directly to the dog from the mosquito, with no dog-to-dog transmission. 

For more than 4 decades, heartworm disease has been effectively prevented in dogs by using available products.  But recent research indicates this might be changing. At a veterinary conference in 2010, information was released detailing a genetic mutation in heartworms that appears to confer slight resistance to current preventives.  Anecdotal reports in the last 4-5 years also point toward an increase in heartworm prevention product failures in the Mississippi delta region of the U.S.

While lack of efficacy (LOE) to heartworm preventives remains geographically limited, research is ongoing to determine the extent of this problem.  Historically, the LOE was attributed to poor owner compliance in the geographic area, the effects of Hurricane Katrina, increased heartworm numbers within the mosquito vector, and/or the increased sensitivity of heartworm testing.

Two prominent veterinary groups, the Companion Animal Parasite Council (CAPC) and American Heartworm Society (AHS) concluded at a recent council strategy session that most credible reports of LOE are geographically limited at this time.  In addition, the extent of this problem is not truly known.

The lack of conclusive evidence to LOE could also be due to several factors:

• Poor Owner Compliance.

o Are pet owners accurately following the veterinarian recommendations?
o Is the pet given the preventive medication consistently without missing or delaying any treatment?
o Is the pet ingesting the medication? (vomiting, pets spitting out or hiding the medications, swimming or bathing immediately following application can cause a missed treatment).

• Imperfect Clinical Testing & Education
o Dogs with inconsistent heartworm testing are at greater risk and must be tested more often.
o Delayed maturity of heartworms can potentially indicate a “negative” antigen test.  This may lead to a false sense of security with dog owners and reluctance to retest.
o Heartworm tests may also have become more sensitive (i.e. more accurate), than older generation tests.  

Whether there is indeed resistance to heartworm, this same study group (CAPC and AHS) concludes: “The potential for lack of efficacy of traditional control products is not a reason to abandon their use.  ” They place additional emphasis on the importance of annual heartworm testing.

Although research into heartworm resistance is on-going, the veterinary industry does recognize the dire consequences if resistance is confirmed.  The American Heartworm Society will continue to support and monitor research in this area.  And if resistance is confirmed, changes to preventive and therapeutic strategies may need to be implemented in the future.

Key recommendations for veterinarians include:
• Proper use of current heartworm preventives remains effective in the vast majority of dogs.
• Prevention strategies should not be abandoned.
• In the case of confirmed heartworm disease, stage-specific medical management should be implemented.
• CAPC and AHS guidelines should be followed in the “face of reports of lack of efficacy”.

Key recommendations for dog owners include:
• Annual testing for heartworm disease; more often if preventives are missed or high risk. 
• Don’t vary from label directions on the dose and frequency.
• Make sure the dog ingests the medication.
• Reduce exposure to mosquitoes
• Get examined by veterinarian immediately if symptoms appear in your dog…i.e. persistent cough, exercise intolerance, body wasting.
• Follow veterinary recommended treatment if dog is diagnosed with heartworm disease.
Heartworm disease is a complex issue.  Until more is known about the extent of the issue, pet owners should trust that current heartworm products are still the best choice for prevention in the vast majority of dogs.

No matter where you live, following your veterinarian’s recommendations and giving heartworm prevention every month, year-round as well as annual testing gives you the peace of mind that you are protecting your pets.

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