Many pets itch. Sometimes it is obvious, and sometimes it is fairly well hidden, or only performed when their owner is not around.
In dogs, itching shows up as scratching, chewing, rubbing, scooting, or licking. Foot licking is a very common form that this takes, and often goes unrecognized as itching. Many times people think that their dog is just cleaning himself, or grooming, as cats do. Dogs do not generally exhibit grooming behavior, and this symptom usually indicates some chronic itching of the feet.
Cats, on the other hand, rarely chew or scratch at themselves. When cats are itchy, they will usually groom themselves excessively, often leaving areas where the hairs have been broken off or “barbered.” In some cases, they will groom themselves to the point of making sores on their skin.
There are multiple causes for itching, but the most common are allergy, infection, or parasites. Allergies are a very common cause of chronic itching, but allergies are only “diagnosed” by first ruling out other potential causes of itching.
Causes of itching can include: bacterial infections, yeast infections, parasites (Sarcoptes mites in dogs, Demodex gatoi mites in cats), immune-mediated diseases, and contact dermatitis. There are also diseases that are not itchy themselves, but become itchy when secondary infections develop. These include: fungal infections (ringworm), other parasites (Demodex canis mites in dogs), hormonal diseases (hypothyroidism and Cushing’s syndrome), tumors (lymphoma, etc.), and other less common causes, such as reactions (other than allergic) to chemicals and plants.
TESTING AND TREATMENT FOR THE ITCHY PET:
Once a complete physical exam has been performed, your veterinarian will check for various types of infections, as well as other causes of itching. Generally the initial tests recommended for itchy pets are:
1) Skin cytology, to check for bacterial and yeast infections on the skin.
2) Skin scraping, to look for parasites.
3) Ear cytology to check for ear infections (which commonly occur with skin problems).
4) Tests for ringworm fungus (Wood’s lamp exam and dermatophyte culture)
5) Blood test including a thyroid screen.
Based on the initial assessment, your veterinarian may:
1) Treat with antibiotics for bacterial infections.
2) Treat with oral and/or topical antifungals for yeast infection.
3) Treat with medicated shampoos.
4) Treat with medication for possible parasites (Sarcoptes, Demodex gatoi).
5) Start some initial symptomatic treatment for itching (antihistamine, steroid, Omega-3 fatty acids, etc.)
In the future, your veterinarian may also do a food allergy diet trial, skin cultures, skin biopsies, or other tests, as indicated. Skin and ear cytology often will be repeated intermittently, because a particular pet’s infection may change from bacteria to yeast, or the reverse, during the course of treatment. Also, there are different types of bacteria that tend to develop when an infection has been present longer term.
ALLERGY INFORMATION AND TYPES OF ALLERGIES:
You may be familiar with allergies in people, or even have allergies yourself. Allergies in people are different than allergies in pets, because of how the body is put together. Allergies, as with most things that happen in the body, are caused by chemical reactions. One of the primary chemicals that causes the itch, inflammation, and swelling associated with allergies is a chemical called histamine. Histamine is made by a type of cell called a mast cell.
People have a large number of mast cells present in the mucous membranes, especially the conjunctiva of the eyes, the nasal passages, and the lining of the airways. When we get allergies, our mast cells release histamine in these areas, which results in the familiar symptoms of: runny eyes, runny nose, sneezing, coughing, and bronchospasm.
However, animals have their mast cells concentrated more in areas of their skin, especially around the face and head, the feet, and the area under the tail. Therefore, when our pets get the same allergies that we do, they show signs of itching, foot licking, scooting on the ground, head shaking, and face rubbing.
Types of allergies include: Atopy (also called seasonal allergies or inhalant allergies), food allergy, contact allergy, and flea allergy.
Contact allergy is an allergic reaction to something in the environment, often a protein, such as plants, wool, etc. Contact allergies are the least frequent allergies that we see, and will not be discussed in this article.
Flea allergies are actually an animal’s allergic reaction to flea saliva. Since we do not have a significant level of fleas inLas Vegasand the surrounding areas, this type of allergy is rare here, and this topic will not be discussed further.
Atopy and food allergy will be discussed in detail subsequently.
Dogs that have allergies are itchy, and cannot resist the temptation to chew, scratch, or lick themselves. This subsequently causes damage to the outer layers of the skin, and opens up a doorway for secondary infections to develop.
Be aware that dogs with allergies have a very high likelihood of concurrent bacterial and/or yeast infections.
In fact, the 2 most common problems secondary to allergies are skin infections and ear infections. Again, these infections can be caused by bacteria, yeast, or both. The organisms that cause these infections are very common organisms that are found on the skin of most dogs and people. They are what are called “opportunistic’ organisms. This means that they only cause problems when the right opportunity or opening presents itself. Because these organisms are so common, these infections secondary to allergies are almost never contagious, since most dogs and people have the organisms on their skin already.
These infections are a contributing factor to the level of itchiness, in addition to the itch caused by the allergy itself. Part of getting the problem under control is controlling the secondary infections. Controlling the infections will reduce the level of itchiness, but the underlying itch from the allergy will persist, if not treated. Often, these infections secondary to allergies will recur, even if they are successfully treated. In other cases, the infections may not resolve, even with appropriate therapy. These infections may show up as scabs or sores on the body, patches of lost hair, or maybe just as areas of redness or thickening above and beyond what is present in other areas of the skin.
Antibiotic and/or antifungal therapy is warranted in most animals that have uncontrolled allergies, and often even when allergies are being controlled. A simple in-house test called cytology can be done to help diagnose these skin and ear infections, and help guide us to the best recommended treatment.
CAN ALLERGIES BE CURED?
It is important that you understand that allergies are not curable. However, with the right combination of medications/treatments, control of the secondary infections, and with or without diet adjustment, they can usually be effectively controlled. It may take some time and “fine-tuning” of medications to find the right combination for your pet. However, the goal is long-term comfort, and there is no one right answer for every pet that has allergies.
There is a very good animal dermatologist here inLas Vegas, who is regularly available. Her name is Dr. Kim Coyner, and she practices out of the Las Vegas Animal Emergency Hospital building (on West Charleston, between Jones and Decatur) on most days of week, and out of the Animal Emergency Center (in the Green Valley area) on certain days. At any point during the treatment that you want to see a skin & ear specialist, or if you find that you are getting frustrated with the progress that we are making, we can set up a referral to the dermatologist.
Dr. Coyner on the west side of town: 821-1002
Dr. Coyner in Green Valley: 434-1002
Atopy, also called inhalant allergies, atopic dermatitis, or seasonal allergies, is the most common type of allergy. In general, there are 7 or 8 dogs with atopy for every 1 dog with a food allergy. However, there are certain breed groups, such as Retrievers and Spaniels that seem to be more prone to food allergies.
Atopy tends to be seasonal, but can be low-grade year-round, as well. The year-round part of the allergy is generally due to allergens like house dust mites, molds, storage mites, or other insects that are present in the environment at all times. Other allergens in the category of atopy include grasses, weeds, trees, and flowers. Avoidance of the allergens is of limited value, since they are usually airborne. So, treatment of atopy is usually accomplished with medications, and sometimes with environmental control. One symptom that is frequently associated with atopy is chronic licking or chewing of the feet. This is often misinterpreted by owners as “grooming” behavior, such as they will see in their 4-legged feline companions.
The starting point for treatment of atopy is what is often called the “Three-Way” treatment. The three-way treatment is as follows:
1) Omega-3 fatty acids, at the appropriate dose of 180 mg per 10 pounds body weight daily.
2) Antihistamines, as needed for itching. Generally over-the-counter antihistamines are acceptable to start with. However, in some cases we will use prescription strength antihistamines, or even a drug called Temaril-P, which is a prescription strength antihistamine combined with low-dose (2mg) of the steroid, prednisone. The Temaril-P is more effective than antihistamines, due to the steroid, and has such a low dose of the steroid that steroid side effects are minimized. However, some pets will experience negative side effects from this drug more than others.
3) Frequent bathing (generally once or twice weekly) with a soap-free, hypoallergenic shampoo. This can be enhanced further by following bathing with a hypoallergenic rinse or conditioner, or sprays that can enhance the effect of the shampoo (in the case of the Douxo products).
There are separate handouts available on the “3-Way Treatment” and on “Antihistamines.”
Be aware that this “three-way” treatment is a conservative treatment. It is conservative in that, if it is effective, it can be continued long term with no significant side effects (the exception may be for pets who are taking Temaril-P, as noted above). It is also conservative in that is not, by itself, strong enough to handle anything more than mild to moderate allergies. However, it is still the starting point of treatment for most cases of atopy.
For atopy, if the “three-way” treatment is not effective, we must add additional treatments. The options of treatments for atopic dermatitis in addition to the “three-way” treatment are:
1) Allergy testing and creation of a hyposensitization vaccine. This approach has the advantage of being very safe, as well as being very effective for 60-80% of the dogs that are treated this way. The disadvantage is that there is expense in allergy testing, the injections have to actually be given by the owner at home, and that the response can take 6-9 months for full effect (longer, for older pets). This means that allergy treatment with hyposensitization is most effective for long-term control, rather than immediate control of allergies. The allergies being treated in the current season very often need to have additional treatments, until the allergy hyposensitization injections have taken full effect. Allergy testing can be performed one of 2 ways:
a) Blood testing. The blood test for allergies measures levels of specific antibodies in the blood that are directed toward the allergens.
The advantages of the blood test are that it can be performed in our office by doing a simple blood draw, and that it is the less expensive approach to allergy testing. The main disadvantage of this test is that it can have what are called “false negatives.” This means that there may be things that the tested pet is allergic to, that don’t show up positive on this test. There are numerous factors that can account for these false negatives. However, any positive result on this test can be confidently assumed that it is a true allergy that this particular pet has.
b) Intradermal testing. Intradermal testing is the “gold standard” for allergy testing. This involves injecting a very small amount of potential allergens into the skin, and seeing if the body reacts to that allergen, indicating a positive allergy to that particular item. Intradermal testing is accurate, and will detect some allergies that do not show up on blood testing.
The disadvantage of intradermal testing is that it is a very specialized procedure that generally must be performed by a dermatologist. Therefore intradermal testing requires referral to a dermatologist (Dr. Coyner), which makes it less convenient and more expensive than blood testing for allergies. However, the other advantage of intradermal testing is that it is also accompanied by a complete assessment and consultation with the dermatologist.
2) Treatment with steroids, such as prednisone or triamcinolone. This is the opposite end of the treatment spectrum from hyposensitization. It is what I refer to as the “quick fix.” The advantage of steroids is that they tend to be very effective for atopy (not as much for food allergies), and are very inexpensive. The disadvantage is that steroids have side effects on many parts of the body, over time. There can be negative effects on the bones, muscles, liver, kidneys, elevation of blood pressure, suppression of the immune system, difficulty healing, and a shortened lifespan.
Some allergies are severe enough that, even with other therapies, steroids will be a part of the treatment plan. If steroids are used to treat allergies, every effort is made to taper the dosage to the lowest dose that still helps to relieve the symptoms, in order to minimize the side effects. In some cases, only low-dose topical steroids, such as “Genesis” spray are used. This reduces the amount of steroid that is introduced into the body, and therefore reduces the side effects.
3) Other medications, such as “Singulair” (monteleukast) and “Atopica” (cyclosporine). These medications are more effective than antihistamines alone; however they tend to be more expensive than antihistamines.
Singulair is a human anti-inflammatory medication that was originally developed for asthma in humans. However, it is also very effective for some allergies. It is not strong enough to be used alone, and is generally always used in combination with an antihistamine, to “boost” the effect of the antihistamine. The advantages of Singulair are that it is very safe, even for long-term use, and it is a good added treatment for allergies. The disadvantage is that there is no generic available yet, and it is still expensive ($50-100, or more, for a 1-month supply, based on the size of the pet).
Atopica (cyclosporine) is a medication that is often used in humans to stop the body from rejecting organs that have been transplanted. It is a very effective drug at controlling the allergic response. In fact the response is very similar to the response seen by steroids. However, it does not affect the entire body as steroids do. The advantage is that Atopica is almost as effective as steroids at controlling the atopy, without the steroid side effects. The disadvantage is that it is more expensive than the steroids. In addition, about 20-30% of dogs taking this medication get some vomiting or diarrhea for the first 3-5 days. If this occurs in your dog, keep giving the medication, because this effect is almost always temporary.
Food allergies are not unusual. With food allergies, the pet is generally itchy year-round, with no time of the year that the pet is completely itch-free. Also, food allergies do not respond well to medications. Some common signs that can also be associated with food allergies are: infections and inflammation below the base of the tail and around the anus, scooting the rear end on the ground, increased number of bowel movements in a day, and even intermittent vomiting or diarrhea. Also, pets that first develop their allergies when they are less than 1 year old or greater than 5 years old are more likely to have food allergies.
Food allergies are not to a brand of food, but are to certain specific components, usually proteins, such as beef, chicken, soy, etc. If dogs have food allergies, it is usually to 1 or 2 (occasionally 3) proteins, only. The top 7 food allergens are: beef (the most common food allergy), dairy (the 2nd most common food allergy), chicken, corn, wheat, soy, and egg.
In addition, a food allergy to a specific protein will often develop after a pet has been exposed to that protein for years, rather than showing up the first time that a pet eats that food.
There is testing available for food allergies, but it is inaccurate and generally not recommended.
The testing and treatment for food allergies is with avoidance of the allergens.
If we suspect or want to rule out food allergies, then we need to do a trial elimination diet.
An elimination diet consists of feeding the pet a food with proteins that they have not been exposed to on a regular basis, and therefore would not have developed allergies to. There are 3 options of elimination diets.
1) Unique ingredient diets. These are balanced diets that contain proteins that are not commonly found in foods. This could be kangaroo, fish, venison, duck, etc. The advantage of these diets is that they are balanced diets. If they are effective, they can be used for long-term feeding. The disadvantage is that, since they are balanced, they contain more ingredients. With more ingredients, there is a low chance that the dog will be allergic to one of the less common ingredients used to balance the diet.
2) Hydrolyzed antigen diets. These diets are made with common proteins, but the proteins are broken down (hydrolyzed) to change how they appear to the body. The body can still use the protein nutrients, but does not recognize them as allergens, and therefore does not react to them. These are more balanced diets, but are still not recommended for long-term feeding, and occasionally cause reactions, usually diarrhea.
3) Home made diets. This is a diet that consists of one protein source (usually tuna, pinto beans, or turkey) and one carbohydrate (rice or potato). This diet can be made fresh daily or pre-made and kept refrigerated or frozen. The advantage is that this is the most limited diet, and therefore most likely to rule out food allergies. The disadvantages are that it is inconvenient for the owner to prepare and store, and that it is not a diet balanced for long-term feeding. If it is effective for the allergies, then we have to start adding things in one at a time to determine what foods this pet can tolerate, and to make it more balanced for long-term feeding.
With an elimination diet, there are 3 critical factors:
1) The diet must be very strict. The pet is allowed to eat only this diet and water. No rawhides, pig ears, bones, treats, table food, flavored vitamins, or anything with any routine flavoring at all. However, take heart, because there are a few treats that can be given. Our office has specific hypoallergenic treats that can be used. In addition, hypoallergenic rawhides made of fish or rabbit can be ordered online at the website: www.sitstay.com. In addition, baby carrots may be used as hypoallergenic treats.
2) The owner must commit to 2-3 months of feeding this diet. It can take that long to see the full effect, so it requires some patience on the owner’s part.
3) Any concurrent infections must be controlled. If a diet is effective, but there is an untreated infection present, the itch will not improve. In fact the itch from the infection is often worse than that from the allergies themselves.
After the 2-3 month elimination period, if there has been improvement, then you may try adding certain individual food products or treats to your pet’s diet, if you wish. However, if anything is to be added, only select one item at a time, and wait several weeks after the introduction of a new food item to see if the skin problems resume with the feeding of this food product