Monday, October 31, 2011

Atopy - Airborne Allergies in Pets - Dr. Lewis

Airborne Allergies or Atopy

Just as airborne allergy is common in people; it is also common in dogs and cats. Common allergens are pollens, dander, grasses, trees, and fabrics; any airborne particle can potentially become an allergen. 

Features of Atopic Dermatitis
  • Atopy usually produces a seasonal itchiness though after several years, the duration of the itchy period extends. Finally, the pet is itchy nearly all year round.

    Seasonal itchiness due to atopy tends to begin early in a pet's life (between ages 1 and 3). Flea allergic dermatitis, the other prime cause of seasonal itchiness, tends to begin later (between ages 3 and 5).
  • Itchiness due to atopy responds rapidly to cortisone-type medications (prednisone, depomedrol, dexamethasone, azium etc.)
  • Atopy is associated with irritation in certain parts of the body. In dogs, these areas are the feet, armpits and belly, under the tail, and around the eyes and muzzle. In cats, the allergic pattern may be facial, may be reflected as hair loss, or may show as a rash of tiny seed-like scabs (called miliary dermatitis) in various areas of the body. They also may overgroom large sections of their body until they are bald.

What to do for Atopic Dermatitis?

Prednisone (and other related steroids)
These cortisone-type medications tend to be useful as the first line of defense against itchy skin. A higher dose is used at first but this is quickly tapered down once the condition is controlled. Prednisone is given every other day so as to allow the pet one day of recovery from the prednisone's hormonal actions. An atopic dog will respond within days. For cats, long-acting cortisone-type injections are more frequently used as cats are often a challenge when administering pills.

Problems arise when the pet's need for itch control demands excessive use of prednisone. Prednisone is a hormone, affecting all body symptoms. Side effects include:  excess thirst, excess appetite, urinary incontinence, muscle breakdown, immune suppression, termination of pregnancy, inflammation of the pancreas, lethargy/panting If your pet has an unacceptable side effect, you should consider trying alternative therapy for itchy skin.
If your dog is on every other day prednisone often throughout the year, you should consider one of the following: alternative therapy, further diagnostics (There may be a more specific treatment for your pet), referral to a specialist, or continued steroid use but with monitoring tests (annual blood panel, re-check exam, and urine checks 3 to 4 times a year) 

Cats are more resistant to the negative effects of steroid hormones thus they are able to take long acting injections as frequently as every three months. If a cat seems to require an injection every other month, efforts should be made to seek an alternative form of management due to the increased risk of diabetes.

Alternatives to Steroids
There are many alternatives to prednisone; unfortunately, none produce as reliable a response.

Antihistamines - These are far less harmful than prednisone but only 10% to 20% of dogs will respond to any given antihistamine. Our hospital uses a testing protocol using four antihistamines, showing benefit to approximately 30% of the dogs who try it. Animals that cannot get by on antihistamines may be able to lower their prednisone requirement when using antihistamines together with prednisone. It should be noted that antihistamines are far more effective in cats than in dogs. Reliable itch control is frequently obtained but the down side is that the cat in question must take medication twice a day, potentially indefinitely. 

Fatty Acid Supplements - These products are NOT analogous to adding oil to the pet's food. Instead, these special fatty acids act as medications, disrupting the production of inflammatory chemicals within the skin. They are often used in conjunction with antihistamines. 

Cyclosporine [Atopica®]) - This is a fairly recent product for dogs (not approved for cats but sometimes used in cats). It is a pill shown to be as effective as prednisone for the treatment of atopic dermatitis. This product, which modulates the abnormal immune reaction in atopy, has been a true breakthrough in reducing the need for steroids. It is a relatively expensive medication compared with steroids but does not lead to long term debilitating side effects as steroids can. 


Just as people have allergy shots, so can pets; however, the process is not without difficulty and one should not expect hyposensitization to end all itchy skin concerns.
  • Allergy shots require approximately 6 to 12 months to begin working.
  • 25% of atopic dogs will not respond (these are usually the animals allergic to multiple allergens.)
  • 25% will require prednisone at least at some times.
  • You will have to give the allergy shots yourself.

Is Your Pet a Candidate?
Testing is best done during your pet's non-itchy season (if there is one) so that the skin responses of the test will not be clouded by active inflammation. The test involves injections of small amounts of allergen extracts into the skin. Reactions noted are compared to reactions produced by two controls: pure histamine (very inflammatory) and pure saline (very non-inflammatory).
In order to take the test the following medication withholding scheduled should be followed. Your dog may not have had:
  • Depomedrol injections within 8 weeks
  • Vetalog injections within 6 weeks
  • Antihistamines within 1 week
  • Topical steroids (such as panalog) for 1 week
  • Oral steroids (such as prednisone) for 4 weeks
Guidelines for cats are generally stricter. Check with a specialist for their recommendations. 

These requirements come from one board certified dermatologist; other veterinary dermatologists may have other requirements. It is often useful to have ruled out food allergy with an elimination diet trial prior to the skin test as food allergy/intolerance responds much more rapidly to diet correction than atopy does to hyposensitization. Food allergy and atopic dermatitis both present a similar distribution of itchiness and can be difficult to distinguish. 

Allergic skin testing is generally performed only by specialists. 

You May Hear about Blood Testing

As an alternative to skin testing, several blood tests have been developed to check for the presence of allergy-type antibodies in the blood. These tests can be submitted by any veterinarian (no specialist need be involved) and drugs need not be withheld prior to testing (though the test may not be valid for animals that have had hyposensitization in the past). This type of testing is fraught with controversy. It appears that the results of such tests do not correlate well with the results of skin testing (our traditional test). It is difficult to say how this kind of testing will ultimately fit in to the treatment of atopic dermatitis but seems best at this time for animals suspected of having inhalant allergies who simply cannot go without medication, who have negative skin testing, or for whom skin testing is unavailable due to other reasons.

Itch Relief

Topicals to Try
When using any dip on inflamed skin one should be aware that the use of cool water is considered much more soothing than warm water.  Dips, soaks, shampoos, and ointments may also be a helpful addition to one's anti-itch armament. The disadvantage is that these products must be applied or utilized often. 

Topical Steroids? - It seems clear that taking steroids orally may be harmful to the body with chronic use but are topical creams safe for long term use? We now know that topical steroids (cortisone creams and related products) are absorbed through the skin and into the bloodstream but the hormonal side effects with topical use do seem blunted. For small irritated areas (hot spots), topicals can provide excellent relief without the systemic effects of hormones.  Excessive application and licking of topical steroids will have the same harmful effects as oral steroids however.

Colloidal Oatmeal Shampoos and Cream Rinse - At first, these products were only available for human use, as powdered soaks to pour into bath water.  Once their value in itch management was determined, their use quickly spread to the veterinary field. Colloidal oatmeal actually pulls inflammatory toxins out of the skin, generally yielding 1 to 3 days of relief. The cream rinses are meant to yield longer acting relief. They are available plain or combined with local anesthetic formulas to soothe itch.

Lime Sulfur Dip - This product kills parasites, ringworm fungi, and bacteria.  It also dries moist, weeping skin lesions and helps dissolve surface skin proteins that are involved in itchiness. Many veterinary dermatologists recommend it regularly to control itch; however, it has several disadvantages. It smells terrible.  The sulfur ingredient smells like rotten eggs and this is how your bathroom or bathing area will smell during the pet's bath. This dip can stain jewelry, metal bathroom fixtures, clothing, and will temporarily turn white fur yellow. 

Other Shampoos
Itchy skin can be the result of skin infection, excess oil accumulation, yeast infection, even parasitic infection. The list goes on. The shampoo products listed above can be used against any itchy skin disease but it should be noted that there are many other shampoo and cream rinse products that can be used against the specific skin diseases listed. If some other type of shampoo product has been prescribed to you for an itchy skin disease, it is important that you use it allowing at least a good 10 minutes of skin contact time before rinsing. 


By: Dr. Dana Lewis
Dr. Dana assists families with Pet Hospice and Euthanasia in the Raleigh North Carolina area (Raleigh, Durham, Chapel Hill and the greater Triangle, as well as Wake, Durham, Orange, and Chatham counties.)

Saturday, October 29, 2011

Flea Allergies In Dogs and Cats

The Flea Factor

Some animals have many allergies. It would not be particularly unusual for an animal with a food or inhalant allergy to also be allergic to flea bites, especially considering that flea bite allergy is extremely common among pets. Because allergies add to each other, it is possible that a food-allergic dog will not itch if its fleas are controlled. Since new technology has made flea control safe and convenient, it is especially important (and no longer difficult) to see that fleas are not complicating a pet's itching problem. 

Ensure immaculate flea control for any itchy pet!
Fleas: Know your Enemy

Despite numerous technological advances, fleas continue to represent a potentially lethal plague upon our pets. Current products are effective so there is little reason for this; the problem seems to be one of understanding.

There are over 1900 flea species in the world but only one is species attacks your pets, commonly called the cat flea (but it also attacks dogs).

What Kind of Damage Can Fleas Cause?

It would be a grave mistake to think of the flea as simply a nuisance. A heavy flea burden is lethal, especially to smaller or younger animals. The cat flea is not at all selective about its host and has been known to kill dairy calves through heavy infestation. Conditions brought about via flea infestation include:

• Flea Allergic Dermatitis (fleas do not make animals itchy unless there a flea bite allergy)
• Flea Anemia. Puppies and kittens die daily in the United States from fleas sucking them dry.

• Feline Infectious Anemia (a life-threatening blood parasite carried by fleas)
• Cat Scratch Fever/Bartonellosis (does not make the cat sick but the infected cat can make a person sick)
• Common Tapeworm infection (not usually harmful but cosmetically unappealing)

Fleas can kill pets.  This is so important that we will say it again: Most people have no idea that fleas can kill. On some level, it is obvious that fleas are blood-sucking insects but most people never put it together that enough fleas can cause a slow but still life-threatening blood loss. This is especially a problem for elderly cats who are allowed to go outside. These animals do not groom well and are often debilitated by other diseases. The last thing a geriatric pet needs to worry about is a lethal flea infestation and it is important that these animals be well protected.

Flea Myths
• My pet cannot have fleas because he lives entirely indoors:  Fleas thrive particularly well in the well-regulated temperatures in the home.
• My pet cannot have fleas because if there were any fleas they would be biting (insert name of a person in the family reportedly sensitive to flea bites). Since this person is not being bitten, there must not be any fleas:  Despite Ctenocephalides felis’(the cat flea’s Latin name) ability to feed of a wide variety of hosts, this flea definitely does not prefer human blood and won’t eat it unless absolutely necessary. A newly emerged adult flea is hungry and may well take a blood meal from the first warm body it finds. An adult flea knocked off its normal host will also be desperate to find a new host and may feed on the nearest warm body it can find. In general, adult fleas regard human blood as a last choice and humans tend not to be bitten unless flea population numbers are high.

• We do not have fleas because we have only hard wood floors:  Fleas love to develop in the cracks between the boards of hard wood floors.

• My pet cannot have fleas because I would see them:  You cannot expect to see fleas as many animals, particularly cats, are adept at licking them away. Sometimes all that is seen is the characteristic skin disease.

The Flea Life Cycle

There are four life stages of the flea and it is important to know how to break this life cycle in more than one place. This two-step approach provides the most rapid control and the least resistance to flea control agents in future flea generations.

About one third of the flea population in someone’s home is in the egg stage. The adult female flea lays up to 40 eggs daily. The eggs are laid on the host where they fall off to hatch in the environment. Eggs incubate best in high humidity and temperatures of 65 to 80 degrees-in other words, just the environment people like to maintain in their homes all year long. 

Just over half of the fleas in someone’s home are in the larval stage. Larvae are like little caterpillars crawling around grazing on the flea dirt that is generally in their vicinity. Flea eggs and flea dirt both fall off the host. This is the stage that picks up tapeworm eggs, which are likely to be in the vicinity, as they graze.  As they get to a certain age and size, a molt occurs. After the third molt, the larva is capable of spinning a cocoon and pupating.

The time between hatching and pupating depends on environmental conditions. It can be as short as 9 days.

Note: Larvae are killed at 95 degrees. This means that they must live in some area where they are protected from summer heat. This means the shade of the yard or indoors.

By this pupae or cocoon stage many young fleas have been killed off by an assortment of environmental factors. Less than 10% make it to the pupal stage but once they have spun their sticky cocoons they are nearly invincible. Inside the developing cocoon, the pupa is turning into the flea that we are familiar with. They are especially protected in the carpet, which is why carpet has developed such a reputation as a shelter for fleas.  The pupa can remain dormant in its cocoon for many months, maybe even up to a year as it waits for the right time to emerge.
After the pupa develops, it does not automatically emerge from its cocoon. Instead, it is able to remain in the cocoon until it detects a nearby host. The mature pupa is able to detect the vibrations of an approaching host, carbon dioxide gradients, and sound and light patterns. When the mature pupa feels the time is right, he emerges from the cocoon, hungry and eager to find a host.

Photo Credit: Trifexis

Here’s the story: a dog is boarded during the owner’s vacation. The owner picks up the dog from the boarding kennel and returns home. The mature pupae have been waiting for a host and when the dog enters the home, a huge number of adult fleas emerge at once and attack the dog creating a sudden, heavy infestation. Often the boarding kennel is blamed for giving the dog fleas. What really happened was that the pupae waited to emerge while there was no host present and then they all emerged suddenly when the host arrived.  An unfed flea is able to live for months without a blood meal.  Once it finds a host, it will never purposely leave the host.  After the adult flea finds a host and takes its first blood meal, the female flea begins to produce eggs within 24 to 48 hours of her meal and will lay eggs continually until she dies.  The average life span of the adult flea is 4 to 6 weeks, depending on the grooming abilities of the host. (For those of you who are grossed out by fleas:  40 eggs daily, 7 days a week, times 6 week life span=1,680 eggs.  Just under 10% of which reach adulthood, so say 160 adult fleas from every female! YIKES!)


Years ago, flea control meant foggers, shampoos, powders, collars, and sprays. While these products are still available, they have fallen largely aside in favor of the next generation products.

Photo Credit:
The next generation started in 1995 with the introduction of Program, an oral product that could be given once a month to a dog or cat and would sterilize - but not kill - any flea that bit the pet. The following year came Advantage and Frontline, topical products that could efficiently kill fleas for a month following an easy application. From there, Advantage has been modified to control additional parasites such as ticks and heartworm (Advantix, Advantage Multi), Frontline has been supplemented with flea sterilizers (Frontline Plus), and new insecticides (Revolution, Comfortis, Vectra, Promeris, Capstar) have been introduced.

Is Resistance Futile?
Photo Credit:
We learned long ago that insecticide use represents a selection factor in a flea population. The resistant individuals survive and pass their genes on to offspring. Eventually a resistant population is produced. We want to avoid creating a population of fleas who laugh at our best insecticides. There are two ways of doing this:

The First Way to Avoid Resistance: Change Products Periodically
Resistance is an important phenomenon and it should not be ignored. You may inadvertently be promoting resistance without realizing it.  If you want to make a resistant population, then keep exposing the population to the same insecticide and after enough generations your population will be resistant. If you switch to another insecticide, the group will be totally sensitive to the new insecticide. After a few more generations, change again.

Working against this method is the fact that advertisers encourage people to continue to use a product they like and this is, in fact, what people tend to do. The power of marketing is strong though, technically, it is better in the long run if a household alternates between two flea products each year.

The Second Way to Avoid Resistance: Use a Flea Sterilizer
A group of fleas that survives exposure to Frontline or Advantage cannot pass on their resistance genes if they have been sterilized by a second product. Program interferes with the production of chitin (the hard material making up the insect exoskeleton). The adult flea has already made its chitin but its off-spring need to develop a chitin egg-tooth to escape their eggs after development into larvae. A larva whose mother has had a big drink of lufenuron-laden blood will not be able to hatch.

Another such sterilizer is methoprene. Methoprene was developed as an additive to flea sprays used to treat the house, it is totally non-toxic, and represents a group of insect control agents called insect growth regulators.  This is a great way to break the flea life cycle before it reaches adulthood in your house; use a product containing an insect growth regulator.  Methoprene mimics a youth hormone of the flea so that larvae who consume it in flea dirt cannot mature and eggs laid by female fleas that have been topically treated with it cannot develop. Twenty years ago, this compound was a miracle in flea control. For the first time it enabled the life cycle to be broken in two places. Newer insect growth regulators have been released and are also in use.

By: Dr. Dana Lewis
Dr. Dana assists families in the Raleigh North Carolina area (Raleigh, Durham, Chapel Hill and the greater Triangle, as well as Wake, Durham, Orange, and Chatham counties.)

Friday, October 28, 2011

Allergies in Dogs and Cats - Part one - Food

Your Pet’s Itchy Skin

Itchy skin on your pet can be due to parasites, (fleas and sarcoptic mange) food allergy, and inhalant allergy (atopy).  Itchy and inflamed skin oozes and gets traumatized by the pet causing secondary infections.  Sometimes the secondary infection causes added itching! Ears are a continuation of your pet’s skin-if they have recurring ear infections (otitis), think allergies!  (Most people think itchy ears are mites, but out of all the dogs we see every day as veterinarians, probably one in one hundred has mites.  Cats and kittens are more commonly having mites in the ears, but this is easily treated and cats are much less commonly suffering from allergy related ear infections).

What Kind of Allergy?
The food allergy is one of the itchiest conditions known to cats and dogs. Animals eat a variety of processed food proteins, fillers, and colorings that are further processed inside their bodies. 

Proteins may be combined or changed into substances recognized by the immune system as foreign invaders to be attacked. The resulting inflammation may target the gastrointestinal (GI) tract or other organ systems, but in dogs and cats it is the skin that most often suffers from this activity. 

The top four allergenic foods in dogs are beef, dairy, wheat and chicken.  In cats, it’s beef, dairy, and fish.  But don’t assume that if you eliminate one or all of these proteins that your pet doesn’t have a food allergy.  Discuss how to do a proper diet trial with your veterinarian.

Many people erroneously assume itching due to food allergy requires a recent diet change of some sort.  But food allergy requires time to develop; most animals have been eating the offending food for a long time (months to years) with no trouble. 

To determine whether or not a food allergy or intolerance is causing the skin problem, a hypoallergenic or novel protein diet(a protein that the pet has never eaten before such as kangaroo, venison, duck, or hydrolyzed soy protein, etc. ) is fed for a set period of time, usually recommended to be 12 weeks.   

During this initial period, the skin infections need to be cleared up as best as possible to assess the pet’s level of itching and inflammation.  If the pet is not itching on the novel protein diet, food challenges can be fed for up to two weeks to see if itching resumes. (For example, we add chicken to the diet for two weeks to see if the pet itches or becomes red or smelly, then we try beef for two weeks, etc.)  

If the pet begins to itch within 2 weeks, then that protein source represents one of the pet's allergens. Return to the test diet until the itching stops and try another pure protein source. If no itching results after two weeks of feeding a test protein, the pet is not allergic to this protein.  

If we see recovery with the test diet and itch with another protein, then food allergy is diagnosed and the pet is returned to either the test diet or another appropriate commercial food without the offending protein(s) indefinitely. 

Photo Credit: Garry Cook
Many people do not want to take a chance of returning to itching if the patient is doing well; it is not unreasonable to simply stay with the test diet if the pet remains free of symptoms. It is important that no unnecessary medications be given during the diet trial. No rawhides or bones, dog biscuits, rice cakes or puffs, table food, etc. should be given

Treats must be based on the same food sources as the test diet-I actually recommend feeding the dry kibble as a treat, a bit of the canned food, or you can bake the canned food version into a “cookie”. Check and see if your pet’s chewable heartworm preventives are flavored with real proteins. If so, they should be replaced with tablets.

Most commercial diets used in food allergy trials have a 100% guarantee. This means that if your pet doesn’t like the food, the food can be returned for a complete refund, even if the bag is opened. This is especially helpful for feline patients, as cats are famous for being choosy about what they are willing to eat.

Sarcoptic mange and inhalant allergy (also known as atopy) are the two conditions which must be ruled out from food allergy.  Lots of time and money can be wasted as the treatment for each is totally different. 

Please consider the following clues that contribute to pointing us towards the food allergy as a diagnosis. Your pet demonstrates:
  • Your pet has been treated for sarcoptic mange without any positive change.
  • Your pet's itchiness is not and has never been a seasonal problem.
  • Your pet has responded poorly or only partially to cortisone-type (steroids, prednisone) medications.
  • Your pet has had a skin biopsy demonstrating changes often associated with allergy or, more specifically, food allergy. 
Stay tuned for our next blog on Flea Allergies!

By: Dr. Dana Lewis
Dr. Dana assists families in the Raleigh North Carolina area (Raleigh, Durham, Chapel Hill and the greater Triangle, as well as Wake, Durham, Orange, and Chatham counties.)

Wednesday, October 26, 2011

Heartworm Disease in Dogs and Cats

Heartworm Disease and Treatment Shortage

Heartworm infection is a disease we see in both dogs and cats.  Heartworms are transmitted to the dog and cat via mosquito bite.  Due to the high prevalence of mosquitos in Florida (and the whole South-East US), our pets are particularly susceptible to infection.

Fortunately, heartworm disease is both treatable and preventable. HOWEVER, as Immiticide, the only FDA approved treatment for heart worm infection is in short supply for an unknown period of time, we must all be very diligent with our prevention strategies!  I like to use Trifexis or Heartgard Plus for my heartworm prevention options in dogs.

Heartworm disease causes a number of problems:

  1. Damage to the pulmonary (lung) arteries
    • Coughing and exercise intolerance result as areas of the lung are affected.
    • Nose bleeds may occur due to abnormal blood clotting in the lung.
    • A form of non-infectious pneumonia (pulmonary eosinophilic granulomatosis) can result from excessive infiltration of inflammatory cells into the lung in response to the parasite.
  2. Heart Failure
  3. Chronic Immune Stimulation -This immune stimulation causes problems with the eyes, kidneys, blood vessels, and joints resulting in tremendous tissue damage and pain.

Heartworm in Cats

Heartworm disease in cats is quite a bit different from dogs. Cats are so small that only one adult worm can be enough to cause heart failure, plus in cats there is much more inflammation involved with the immature worms. Unfortunately in cats there is NO treatmentPrevention is our only option.  Revolution is my favorite cat preventative.

Blog by:
Kim Simons, DVM
Pet Hospice and In Home Pet Euthanasia
Dr. Kim Simons services all towns in and around Palm Beach county including Boynton Beach, Boca Raton, Highland Beach, Delray Beach, Lake Worth, Palm Beach, and Jupiter.