Fleas, Ticks, and the FDA.

We’ve gotten several calls about the FDA press release last month with respect to oral flea and tick control products and adverse effects.  Considering that here we are, well into November and the temperature is still cracking 60 degrees, well above the active temperature minimum zone for parasite activity, I thought that I would address the issue.

Flea and Tick Diseases

First off, I think it is important to realize that ticks and fleas should be a concern beyond the icky factor that bugs crawling on our pets elicit.  These parasites carry diseases.  We know that ticks carry Lyme disease which can infect dogs, cats and us.  But they also carry Ehrlichia, Anaplasma, Rocky Mountain Spotted Fever as well as a host of other diseases.  One tick causes an allergy in people (and possibly pets) to red meat.  That’s right, one bite and say good bye to slow cooked barbecue next summer. Fleas can carry a host of diseases as well including Bartonella (cat scratch disease) as well as typhus, plague, and tularemia. So the question is not should you use flea and tick control, but rather which product is the safest and most effective.

What We Used to do About Fleas and Ticks

Historically, (going way back to ancient history), we used really toxic products, many banned due to their horrific side effects for pets and people.  These sprays, dips and powders killed fleas and mammals.  I think back with a shudder to the summers that I worked in kennels as a student applying organophosphate dips to dogs.  No fleas on them, and no mosquitoes on me. Hopefully, I’ll have no long term ill effects.

A revolution in flea and tick control came about with the release of Frontline.  The active ingredient is Fipronil to kill adult fleas and ticks paired with a growth inhibitor to prevent the immature fleas from developing into adults.  The product was safe for mammals and when applied once a month prevented fleas and ticks from pestering our pets.  It is actually used in agriculture as well to treat food crops.  It was rapidly followed to market by Advantage and Advantix (dogs only) for topical use to prevent flea and tick infestations in our pets. A host of over the counter products made their way to market, some less effective, many more dangerous.  A few years ago, we started to notice that there was resistance developing in the fleas and ticks and these products were starting to lose their effectiveness.

What We Do Now About Fleas and Ticks

Bayer had the next innovation in external parasite control.  The Seresto collar kills fleas and ticks for up to 8 months.  We have found them to be very safe and effective, for both dogs and cats.  The efficacy is diminished by frequent bathing so we recommend changing the collars every 6 months.  This is the product that I use on Bella. 

Many people don’t like the idea of a collar and their cats do not go outdoors.  That does not put them at zero risk for fleas or heartworm, although the chances of picking up a tick is quite low. For these pets we recommend Advantage Multi or Revolution once a month.  This product will safely prevent fleas, heartworm and intestinal parasites.  Combine with the collar for full protection.  We did have a case of feline heartworm this month in a cat that hasn’t been outdoors for over 10 years.  Go figure, mosquitoes can get in the house.

The next round of products to market was for dogs.  Isoxazolines are an oral product that will kill fleas and ticks, some for up to 3 months (although not all ticks and not as well as the monthly products).    These are the products that the FDA released the new warnings about, so let’s talk about that for a bit.  

The FDA 

When a new drug is approved, it must go through thorough testing for both safety and efficacy.  Drugs must be shown to be effective, that’s why we picked the two drugs that we prescribe, Simperica and Credelio, both are very effective over the dosage interval of once a month.  As far as safety, new drugs must be given to a group of animals at the label dose, as well as 3x and 5x the label dose, alone and in combination with other commonly administered medications.  All side effects must be reported.  A single dog, under 6 months of age, had transient neurological side effects at 5x the label dose of Simperica.   Therefore, the FDA granted a label for Simperica for dogs over 6 months of age.  Credelio did not report this side effect so was given a label for dogs over 8 weeks of age.  We are currently following the label recommendations.  Puppies under 6 months old get Credelio, over 6 months we are satisfied with the safety and efficacy of Simperica.  We have had no side effects from either medication in our patients.  Furthermore, when I questioned my colleagues, none have reported any side effects in their patients.  However, there must have been some side effects reported to the FDA, because they are working on adding more information to the labels for all drugs in this class.  Keep in mind, that the current package insert already carries this information where applicable.  Furthermore, if you read the entire press release, beyond the sensational headlines that are springing up all over the internet, you will find that the FDA says that “these products continue to be safe and effective for the majority of animals”, adding that it <the FDA> carefully reviewed studies and other data on Bravecto, Credelio, Nexgard, and Simparica prior to approval. The agency is asking the manufacturers to change product labeling in order to provide veterinarians and pet owners with the information they need to make treatment decisions for each pet on an individual basis.”

We recognize our clients’ concerns for their pets’ safety and continue to monitor studies as they become available.  Not using flea and tick control is not safe either as insect borne diseases are seriously dangerous to our pets and ourselves.  We are striving to provide a balance so that we can keep our pets and families safe.

Preventing Infectious Kidney Failure

In the past few months I've seen two heartbreaking cases of dogs that were diagnosed with acute renal failure that probably could have been prevented.  But before we talk about failing kidneys, let's talk about what healthy kidneys do for our pets. (and us for that matter).

The major functions of the kidneys is to filter waste products of the blood into the urine, maintain a state of homeostasis (constant state in the body), and stimulate red blood cell production.  There are other hormonal functions but let's stick to the biggies here.  When we do a blood test and tell you that your pet's kidney function is good, we are actually measuring the levels of Urea Nitrogen and Creatinine (two toxic by products of protein metabolism).  these levels will be maintained within a narrow normal range until about 75% of the filtering units  (glomeruli) in the kidneys are damage.  Kidney function can also be evaluated by measuring the concentration of the urine as well as looking for things in the urine that shouldn't be there, such as protein and cells. When the filtering units are damaged, the waste products build up and the condition is called azotemia, or uremia.  hen the tubules ( different part of the kidneys) are damaged, we will see dilute urine or cast like structures in the urine.  Leaking membranes in the glomeruli may allow the filtering of wast products but facilitate the leakage of protein into the urine.  When caught early, the progressive nature of renal disease can often be mitigated.  However, once the glomeruli are damaged, they are gone, and no new ones will replace them.

We had a dog present to the clinic a few months ago.  It lived in Nassau county, never went out east, mostly lived in the yard in a suburban environment that was not particularly wooded.  This labrador was not feeling well and when blood work was performed, it was in azotemic (elevated BUN/Creatinine) renal failure with severe levels of protein in the urine.  It was also positive for exposure to Lyme disease.  The owners had not vaccinated it against Lyme disease because they did not think it was at risk for exposure.  Indeed it was at low risk based on life style assessment, but no dog on Long Island is at no risk.  They also were not using any flea or tick control.  Lyme nephritis is a kidney disease caused by the body's reaction to Borrelia burgdorferi, the bacteria that causes Lyme disease.  (Note Lyme not Lyme's).  Unfortunately for this dog, once the kidneys are involved, the prognosis is guarded.  In fact, this dog did not make it and was put to sleep after a week in the hospital receiving intensive care.  While we do not see a lot of dogs in our practice that are ill with Lyme disease, we do see many that are exposed to the bacteria and therefore at risk.  This is why we recommend testing every dog every year for heartworm and tick borne diseases.  we also recommend tick control for all dogs.

The second dog presented two weeks ago with a rapidly worsening, acute renal injury.  This young German Shepherd Dog was losing weight, not eating, and had decreased energy, His blood work showed a worsening azotemia, increased levels of protein in a dilute urine, and he tested positive for leptospirosis, a bacterial disease.  Leptospirosis is spread by the urine of infected animals, in our area, dogs, raccoons, mice and rats.  While usually more common in the summer, it is obviously around all year here on Long Island.  It's prevention is complicated by the fact that there are many serovars (types of Lepto bacteria), and the vaccination only covers the 4 most common and virulent.  Many clients are reluctant to vaccinate because they have read that the vaccine causes reactions, or is dangerous.  The truth is that while vaccine reactions do occur, most often, they are similar to the type of reaction we get when we get a flu vaccine or a tetanus shot. And while we hate our dogs to have any reaction, it is better than renal failure.  Lepto is also contagious to people so having a dog that is unknowingly shedding this bacteria in the urine puts all of us at risk.  This puppy (he is only 2 1/2 years old) is still undergoing treatment with antibiotics and Intravenous fluids.  It looks like he may make it but will most likely have permanent damage to it's kidneys.

We have to remember that there are many diseases that can affect our pets (and sometimes us).  prevention is always better than treatment.  While vaccination is not always a completely benign procedure, modern vaccine science has come a long way in our fight to protect our pets from infectious diseases.