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Itching Problems - Causes and Treatments
Understanding Itchiness
Will flaxseed help itchy, flaky skin
Itchy skin in Terrier with Diabetes and Cushing's
Itching not responsive to corticosteroids
What makes my dog itch
Stopping the itch
Itchy skin problems and hot spots in older Lab
Itching and scratching in Goldens
Itchy dog
Itching and fleasalso see Cushing's
also see Diabetes
also see Hot Spots
also see Skin
also see Allergy
also see Parasites
also see Demodex
One of the most important concepts to understand about itchiness in dogs and cats is that the itchy feeling that the pet has is the cumulative result of everything affecting it that contributes to itching. Most pets can tolerate a certain level of itchiness without feeling the need to scratch or bite at themselves. Once that level of itchiness is exceeded, they may bite and scratch frantically. From a practical standpoint this means that some pets will tolerate low levels of fleas with no sign of problems or they may tolerate a food allergy with no visible symptoms -- but if they are tolerating the food allergy and then fleas are added they may become miserable quickly. This means that it is critical to control any and all sources of itchiness that occur in pets who are scratching or biting at themselves in an effort to push the itchiness level down below the threshold for scratching. In some cases when it isn't possible to eliminate one source of itchiness, such as an allergy to pollens, the pet can live with the allergy comfortably as long as no other source of itching is present.
There are many things that can be helpful in eliminating itchiness in pets. Looking at the following list and picking out as many of these things to do as seems possible for your pet may be the difference between dealing with chronic scratching, biting, hair loss and secondary bacterial or yeast infections and having a dog who looks and acts normal.Without question, the first step in controlling itchiness in pets is to ensure that they are free of fleas. Nothing made a bigger dent in the number of itchy dogs and cats in our practice than the arrival of the first really good flea control products several years ago. These are the truly effective products for flea control:
1) Imidocloprid (Advantage Rx, Advantix Rx): There are two versions of this product, the original Advantage, which only controls fleas and the newer product Advantix, which aids in the control of ticks and is available for dogs only. Imidocloprid provides good flea control for about three weeks and the permethrin which is added to Advantix to control ticks works pretty well for 10 to 14 days. Imidocloprid can be washed off more easily than fipronil and this should be considered in pets who need frequent baths.
2) Fipronil (Frontline Spray Rx, Frontline Topspot Rx, Frontline Topspot Plus Rx): This product has three versions. The "Plus" is the addition of methoprene, an ingredient that can help prevent flea reproduction. The pricing of the Frontline products is a little peculiar and by examining it closely it is possible to purchase the least expensive version for an individual pet. The Frontline Spray will treat 180 pounds of body weight at the normal dosage and 90 pounds of body weight at the dosage advocated for long haired pets. This means that 1 bottle of spray is usually enough to treat a cat for an entire year -- for about the same price a one package of the Frontline Topspot that will last three months. The disadvantage is the fact that most cats don't like to be sprayed with anything -- but especially not with flea control products. Small dogs often can be treated for the entire flea season with one bottle of spray and most dogs are better about tolerating being sprayed than cats. Conversely, a bottle of spray might only treat a big dog once or twice and costs about the same as the large dog Topspot vials which will treat the dog 3 times. Fipronil is very effective for about 3 weeks and then the effect on fleas does diminish. It is resistant to being washed off the pet but very frequent bathing will diminish its usefulness. It is extremely important to follow the directions for the use of the spray. Applying an occasional light mist of Frontline Spray is not going to work to control fleas, you must use the correct dosage of 1 or 2 pumps of the sprayer per pound of body weight in order to get the full effect of the fipronil. The Frontline Topspot products take several hours to kill fleas so it isn't unusual to see live adult fleas on the pet while using these products until the fleas are controlled in the pet's environment so they are not available to jump onto the pet. This can be confusing to pet owners but you just have to give the product two or three months to clear out the fleas before deciding that it isn't working.
3) Selamectin (Revolution Rx) kills fleas, kills one type of tick, prevents heartworms and may also help in control of ear mites and sarcoptic mange. It is available for both dogs and cats. It is systemically absorbed so bathing after it has had a chance to be absorbed doesn't affect it much. It also produces its strongest effect in the first three weeks after it is applied. The efficacy of selamectin for heartworm prevention is estimated to be 90% based on recent studies. The failure rate for prevention of heartworms in the monthly oral tablet forms (ivermectin and milbemycin) is not known with certainty but is estimated to be about 99% at the present time.
4) Lufenuron (Program Rx, Sentinel Rx) is an oral tablet that must be given at meal times. It interferes with flea reproduction. If it is used consistently over time in pets confined to a controlled area, it will eliminate the flea population in that area. This process may take several months, though. Lufenuron can be combined with nitenpyram (Capstar Rx), also an oral tablet, which kills only adult fleas on the dog at the time the pill is administered. Typically the Capstar is given twice a week for the first 6 weeks or so when the two tablets are used together and then Program is continued long term. The combination can be very effective at controlling fleas.
With the advent of the flea products listed above there has been less need to treat the pet's environment to kill fleas there before they can attack the pet. Despite this it can be very helpful to kill the fleas in the house or yard, especially when first trying to get boom in the flea population in your pet's environment under control. It is absolutely essential that all pets in the household be treated with flea control products in order to get a flea problem completely under control. This is probably the most important reason for failure of flea control in our practice. Too many clients think they only need to control the fleas on the pet with flea allergies and that just doesn't work very well.
Fleas aren't the only insects whose bites can cause itchiness. Avoid mosquitoes, biting flies and biting gnats as much as possible. It is OK to spray a pet with a pyrethrin based flea control product to repel mosquitoes and flies while on a walk. Products such as Adams Flea and Tick Mist (tm) can be sprayed lightly on the pet prior to walks and is safe to use in combination with any of the flea products listed above.
While I haven't seen any scientific evidence for this, I am convinced that air conditioning during the hot months is the next best thing for pets with itchiness. Keeping the pet cool seems to limit the onset of secondary infections associated with causes of itching such as allergies and just seems to aid in the control of itchiness in general. The exception to this might be pets who are allergic to dust mites and therefore do better when they can be outside.
Dr. Keith Hnilica, a veterinary dermatologist at the University of Tennessee, has a good web site on ways to control itchiness in allergic dogs: www.utskinvet.org. On this site he advocates throwing out any dog bed over a year of age and washing all dog bedding every 7 days using hot water to kill dust mites, since they are a very common allergen for dogs. He also advocates keeping the pet away from cigarette smoke, strong perfumes (this isn't on his site but has mentioned it in continuing education lectures) and keeping the humidity in the house at 40% or less, if possible.
Bathing itchy pets, or even just running cool water over them for 10 minutes or so, can help to relieve itchiness for several hours to several days. Many of my clients are reluctant to bathe pets on a regular basis, fearing that it will cause more problems than it solves. Our experience strongly suggests otherwise. Pets who are bathed once or twice a week have fewer skin problems than pets who are bathed less frequently. For itchy pets the use of a soothing shampoo, such as an oatmeal shampoo, can be very helpful. If it is necessary to use an anti-bacterial or anti-yeast shampoo to control secondary infections or an antisebborheic shampoo to cut down on greasiness these can be followed with a soothing creme rinse. There are creme rinses with oatmeal or with ingredients like hydrocortisone or pramoxine to aid in itch control.
The use of antihistamines can help control itching in a small group of pets. Antihistamines seem to be effective about 10 to 15% of the time in controlling itchiness in pets. While this is a low rate of effectiveness these are over-the-counter products that are readily available and so it is worth trying them for 7 to 10 days to see if they will help. In cats the antihistamine of choice seems to be chlorpheniramine (Chlortrimeton tm, 2mg/cat every 12 hours) and in dogs the two that seem to work the most often in studies are diphenhydramine (Benedryl tm), 1mg/lb of body weight, and clemastine (Tavist tm) 0.02 to .04mg/lb of body weight .
Adding marine fish oil to the diet, or some other source of omega-n3 fatty acids, can also help in control of itchiness. The veterinary product most often recommended for this is 3V Capsules (tm) or 3V Caps Liquid Skin Formula (tm). Increasing the omega n3 fatty acids in the diet can control itchiness in dogs and cats about 10 to 15% of the time. Combining fatty acid supplementation with antihistamine therapy is supposed to provide an additive effect that makes it more likely the combination will work than either product alone.
If secondary infections do not seem to be present the next step up in itch control is the use of a triamcinilone spray (Genesis Spray tm) to control itchiness. If secondary infections are present it is better to treat them first and then to use the spray only if control of the secondary infections doesn't control the itchiness. Using Genesis spray is kind of a compromise between not using cortisones at all and using oral cortisones. It is not as effective as oral cortisones but it doesn't have as many side effect, either. The spray is surprisingly effective for some dogs but doesn't work well for all dogs. It is not approved for use in cats and we have not tried it in cats to see what the effect might be. It is plausible that it would work well, as some veterinary dermatologists feel that triamcinolone is the best corticosteroid to use orally in cats with skin disease.
Control of secondary infections is a critical issue in controlling chronic itchiness in dogs. Cats develop secondary infections from itchiness less commonly than dogs but when they do occur they need to be controlled, as well. By far the most common secondary infections in dogs with allergic or other itch producing disorders are bacterial infections from some form of Staphylococcus (Staph) bacteria. These can generally be controlled with antibiotics but it is essential that antibiotics be used long enough. The minimum recommended dosing period for antibiotics for skin disease is three weeks -- and it often takes 6 to 8 weeks or even several months to control skin infections completely. There are a few antibiotics that tend to work reliably for skin disease and it is reasonable for your vet to dispense an antibiotic without identifying the bacteria involved -- at least the first time that a skin infection occurs. If the response to antibiotics isn't as good as expected then it is better to try to obtain a culture from the skin to identify the bacteria and to allow sensitivity testing to see which antibiotics are most likely to kill it successfully.
Secondary yeast (Malassezia) skin infections are common in dogs and occur occasionally in cats. In dogs these infections produce a very characteristic thickening of the skin (elephant skin) that is almost diagnostic for yeast infection, although it does sometimes occur with hormonal diseases and once in a while due to bacterial skin infection. Still, if your pet has been itchy for some time and has thickened skin that is often gray to black colored it is important to think about the possibility of a yeast infection. These can sometimes be treated with shampoos with yeast killing ingredients like chlorhexidine or ketaconazole but it is usually necessary to use oral ketaconazole to obtain control of long standing yeast infections. Treatment is usually only necessary for 30 days.
A few dogs who appear to have allergic skin disease actually have sarcoptic mange infestations. This mite is hard to find even when careful skin scrapings are done looking for it and it is frequently overlooked simply because it isn't considered as a potential cause of the itchiness. This is a particularly important consideration when multiple dogs in a household are itchy, even if only one has hair loss, enlarged lymph nodes or other signs that might be associated with mite infestation. Cats have a similar problem with demodectic mange going undiagnosed at times. If your pet isn't responding to treatment for itchiness it may be a good idea to ask your vet about treating for sarcoptic mange to rule it out or at least doing skin scrapings to try to make sure it isn't present.
Food allergies are not all that common in dogs and cats but they occur frequently enough that they have to be considered when a pet is itchy. Even in pets in which a food allergy can't be demonstrated there is often at least a partial response to diets intended for allergic dogs or dogs with sensitive skin or to using a home made diet that is high in polyunsaturated fatty acids (omega n3 fatty acids) and is made from a protein source not commonly found in dog foods such as fish or turkey. Cats will often respond well to the sensitive skin diets as well. In addition, we think that we sometimes see improvements in skin condition in cats who are eating the diets made to control hair balls.
Many dogs and a few cats with allergies develop ear infections or ear inflammation. In many cases the ear inflammation or infection is the first sign that allergies are present and in some cases the allergies never cause any other problems. This group of pets does best when the ears are consistently cared for. It is very helpful to use an ear cleaning product that has some astringent effect and which lowers the pH of the ear canal on a regular basis. EpiOtic (tm) is one such product that is popular among veterinary dermatologists but there are others that work pretty well, such as Tris8 (tm) or TrisEDTA (tm). Some vets like Novalsan Otic (tm) best because it is a little less irritating than these other cleansers but it doesn't seem to work quite as well, overall, in our clinic. We do keep it on hand for patients with sensitive ears, though.
Persistence in controlling all potential causes of itchiness is clearly helpful. Our patients who have owners who are willing to take all, or at least most of, the necessary steps to reduce itchiness tend to do much better over the course of their lives than pets whose owners wait to treat them for itchiness only after it has gotten out of hand -- even if they then work hard to control it until the itchiness stops before waiting for the cycle to start again.
Dr Mike Richards, DVM
11/01/2004
Will flaxseed help Itchy, flaky skin - Irish Setter
Question: Dear Dr. Mike,
I read with great interest you responses to the questions on itchy skin. Your recommendation was
very sequential and makes great sense. In the case of my 2 1/2 year old male Irish setter who is
currently one major from finishing his CH, the sudden onset of huge flakes of "dandruff" on his back
between the hip bones, threw us into a tail spin. My vet went ahead and put him on cephalexin and
recommended a no wheat, no barley food because his line has the wheat allergy and staph
problems. I'm keeping the flakes under control with DermaPet Malcidic shampoo and
conditioner--great products I searched for and found after absorbing the info in your articles. I
suspect stress of showing is a factor for this very sensitive boy. He will break out in red blotches on
his stomach when we reach a hotel on a show weekend and be perfectly clear of the rash when he
settles in.I read also your recommendations on the type of fatty acid supplements to use. I have DermCaps
on the way, but can you tell me where flaxseed oil fits into the picture? I had just recently visited
the health food store and purchased very pricey "organic, veg based cold pressed flaxseed oil."
Does flaxseed oil measure up to EFA-Z and DermCaps.?When the problem arose, I too hastily removed this dog from a product I love, called DogBloom.
Pigment has started to fade and I want to put him back on it. In retrospect, I think he was on it far
too long for it to be the culprit. I would appreciate your opinion on this product if you are familiar
with it. I believe it is wheat free. We are also using kelp. A thyroid panel has been sent to U. of
Michigan and is not back yet.Thank you so much for your articles. It is great to some background knowledge when you consult
your vet.Ann
Answer: Ann-
There is not a great deal of information on the use of flaxseed oil in dogs that I can find and the
information available seems to conflict. In general omega n-3 fatty acids are thought to be the most
helpful for skin disease at the present time. From this standpoint, flaxseed oil looks pretty good,
since it has very high levels of n-3 fatty acids. However, the n-3 fatty acid it is mostly composed of is
alpha-linolenic acid (ALA) and one report states that this is not converted to the eicosapentaenoic
acid (EPA) and docosahexaenoic acid (DHA) which are the active forms of the essential fatty acids
(Wynn 2000). On the other hand, I found a couple of reports that suggest that the ALA in flaxseed
oil is converted to these compounds, or at least that the EPA and DHA levels rise in the cells of
dogs fed flaxseed oil (Hickman 1998, Bauer 1998 ). Fish oils have these fatty acids in the form
required by the body and are currently favored as an essential fatty acid source, for this reason. If
flaxseed oil can be converted to EPA and DHA it probably is equal to or superior to EFA-Z (tm)
and DermCaps (tm) based on the percentage of omega n-3 fatty acid in the flaxseed oil.I am not personally familiar with the Dogbloom (tm) product, but I looked it up online
(http://www.pfwh.com/supp/analysis.html) and based on their analysis and feeding directions, the
only ingredients that appear to be present in significant amounts are Vitamin A and Vitamin D. The
maximum recommended Vitamin A level for dog food is 250,000 IU per kg of food (AAFCO), so
there is not much chance of toxicity associated with the use of the DogBloom (tm) product, as it
should supply about 17,500 IU per day based on the feeding directions. For Vitamin D, the
maximum recommended supplement is 10,000 IU/kg of food and the DogBloom product supplies
3150 IU per day if fed at the maximum recommended level according to the tables on their web site.
So that would also be safe to feed. I suspect it would be less expensive to buy Vitamin A and/or D
capsules and use them, but I have not priced these products to be sure and if you like the DogBloom
there is no compelling reason to switch. Just to be sure that I am being fair to the company, this is
how I made these calculations:According to their site, one pound of DogBloom supplies 1,000,000 units of Vitamin A and
175,000 units of Vitamin D and costs $6.72 per pound. They state that the maximum daily usage
should be 12 cents per day, so I divided 672 cents by 12 cents/day and got 56 days. Then I divided
1,000,000 and 175,000 by 56 to get the amount fed per day.It would be pretty unusual for a 2.5 year old dog to have clinical signs due to hypothyroidism.
Hopefully, your vets requested the panel from Michigan State that includes free T4 analysis by
equilibrium dialysis, as this is a more accurate way to assess the probability of hypothyroidism than
total T4 analysis.Stress does seem to play a role in a number of diseases and disorders. I don't have any really good
suggestions for reducing the stress associated with traveling. There are just so many different factors
that can upset a dog when traveling that it is hard to figure out which ones are the ones that a
particular dog finds stressful.Hope this helps some.
Mike Richards, DVM
1/15/2001
Itchy skin problem in Terrier with Diabetes and Cushing's
Question: Dr. Richards,
Skippy is doing well on his insulin and I am doing home bg testing. I also
make all of Skippy's food now. A little history:2 years ago Skippy had an acute pancreas attack which sent him to the
hospital for at least a week....he was in terrible shape. The attack was
brought on by a garbage raid. Now that I am a little educated on diabetes,
etc., I know that after Skippy got better, we should have been looking for
signs of diabetes...but my vet never said anything. Ever since that attack,
Skippy's skin was getting worse and worse. I felt so sorry for him. I was
always giving him baths and spraying him. The vet said it was probably
allergies and gave him some cortisone, which helped for a while, but never
got rid of the problem. I changed vets, since the problem was not getting
better and this past summer Skippy was on more cortisone for his itching.
I was away a lot during the summer so Skippy was also a little stressed. He
was at home in his environment, but he is a momma's boy and misses me.Early October, the vet decided to run blood tests to find out what really
was going on. The result was that Skippy had to go into the hospital with
his BG levels through the roof. The vet also said that Skippy may have
Cushings. Skippy was home in about 2 weeks and almost $1000 is gone! (He
is worth it) So now Skippy is on 5 units twice a day. We have held off
testing for the Cushings again until the BG's are under control.Well, it appears that Skippy is getting under control and feeling great!
Much thanks to the "Petdiabetes" mailing list! The only problem now is the
original problem...the itchy skin. He has many small growths the size of a
pimple, mostly on his back and rear end. The vet told me not to use
anything with cortisone. I do bath him in a shampoo for dry itchy skin and
a good sea kelp conditioner. I comb him whenever it gets too itchy and
there is a lot of dry skin and hair in the comb. This only helps for a
short period of time. Please, if you have any suggestions on this problem
I would appreciate it.Joyce
Answer: Joyce-
In this circumstance, I would try antibiotic therapy first, unless there is
absolutely no sign of infection (which doesn't seem to be the case based on
your description of the problem but is hard to verify without being able to
see Skippy). Diabetes lowers the immune response and allows bacterial skin
infections pretty frequently. Cushing's disease does the same thing, even
though I would be hopeful that is not a complicating factor.To directly control itching without making a big impact on insulin
requirements, it is possible to try several things that might help.
Antihistamines help some dog with itchiness caused by allergies. The most
successful antihistamine in clinical trials that I can find information on
is clemastine (Tavist tm). Usually it is used at 1 tablet per 60 lbs. of
body weight twice a day but I have seen other dosages mentioned in clinical
reports. Other possible antihistamine choices include hydroxyzine (Atarax
Rx), diphenhydramine (Benedryl tm), chlorpheniramine (Chlortrimeton Rx) and
most other available antihistamines. Some dogs seem gain comfort from the
use of cimetidine (Tagamet Rx), which has some antihistamine effects. Using
a fatty acid supplement, such as DermCaps (tm), OmegaDerm (tm), EFA-Z (tm)
or 3V Capsules (tm) may also be beneficial. Some dogs seem to be comforted
by the use of amitriptyline (Elavil Rx), which is an anti-depressant and
may work because it has secondary itch control properties or because it
makes the dog less worried about the itching. Aspirin therapy helps some
dogs. Bathing with soothing shampoos, such as oatmeal based shampoos or tar
and sulfer shampoos is helpful for a couple of days in some dogs.
Pentoxifylline (Trental Rx) has recently been advocated as a substitute for
prednisone in some itchy dogs. We have not used this medication so I do not
have a personal perspective on its use. These are some of the available
alternatives for itching in dogs. One of the reasons there are so many
alternatives is that none of them work in all cases. It often takes
combinations of several approaches to control a problem with itchiness.Cushing's disease can make some dogs itchy. So it is worthwhile to check
for this at some point, if the itchiness can not be controlled. Treating
for the Cushing's syndrome will resolve itchiness associated with the
disorder in most patients.When we absolutely have to, we have used prednisone in dogs that we were
treating for diabetes with insulin. It does increase the necessary dosage
of insulin in most dogs but it is possible to reach a new maintenance
dosage that works well, most of the time. I would consider this to be a
last resort, but if Skippy is very uncomfortable without it an no other
solution can be found, it is an option.Hope this helps.
Mike Richards, DVM
11/22/2000
Itching not responsive to corticosteroids - Westie
Question: Thank you for your respones to my email that i sent to you this month about
my dog (westie)
In you email you asked me what has been done so far to help stop her from
lossing her hair well so far the vet has given her some tablet's called
PREDNISOLONE 5mg & he has given me a spray to put over the coat to keep the
flea's away NUVAN TOP plus a spray to put around my house where my dog's gose
called INDOREX the spray that i put on her coat is keeping the flea's away
but it still leave's me with the problem of her pulling her hair out .
l have asked the vet that i goto if it could be the grass & the vet is not
sure about that she asked me if i had a cat i told the vet that i do not have
any cat's in the house but when i go for a walk with my dog on one of the
street's there is over 30 cat's all living in one house & some of them are in
poor health.
As for the itching my dog still dose that more then ever now i have kept my
heat off of a day & only have it on for an hour of a night to see if that
will help but sadly it dose not help i even changed the way i go out for a
walk by keeping her away from the grass & that dose not help.
May i ask if there is any thing that you can tell me that i can do now for my
dog are even ask for from my vet that may help with all of the thing's that
is going on with my dog please.Your's Sincerely
SharonAnswer: Sharon-
When we have a patient who is on prednisone (similar to prednisolone) and
it is not controlling the itching, we try to look for causes of itching
that do not respond well to corticosteroids, which is the class of
medications that prednisolone belongs to.I think that the most common cause of itching that does not respond to
corticosteroids is pyoderma, or bacterial infection of the skin. There are
times when it is very hard to distinguish allergic itching from itching
caused by skin infections. Most dogs will do reasonably well if antibiotics
are used to control bacteria while prednisone is used to control itching,
but this combination can cause problems. In some patients, the
corticosteroid use is just enough keep the body from fighting the bacteria
and itching persists. Less commonly, the suppression of immune function
that can occur with prednisone can lead to bacterial infections that
continue to get worse over time. This is one possible problem. It can be
very frustrating to stop prednisolone, since itching may get much worse,
and then use antibiotics long enough to tell if they will work, which can
take several months. Sometimes, this won't help even after all that work
and frustration but it is still a good idea to try to rule out bacterial
infection at some point in this sort of a skin problem.The next most common cause of itching that responds poorly to
corticosteroids is probably sarcoptic mange. It is worthwhile to rule out
this parasite, even if it is never found on skin scrapings during the
diagnostic process. We treat for sarcoptic mange using ivermectin in most
patients, but there are a number of medications that will kill this mite
and your vet may prefer trying a different one. In any case, it is worth
trying a medication that can kill the mite, even if it doesn't really seem
like the cause of the problem.Sometimes food allergies won't respond very well to corticosteroids. Trying
a specialized diet to rule out food allergies is also a reasonable thing to
do. There are a number of these diets available commercially. Limited
antigen diets have to be given for at least 6 weeks, and no other food
should be fed, even in very small quantities, during that time.There are some dogs who have inhalant allergies that do not respond totally
to reasonable corticosteroid dosages who will respond to combinations of
corticosteroids, antihistamines and essential fatty acid supplements such
as 3V Capsules (tm) or DermCaps (tm).Immune system disorders can cause itching that will not respond to
corticosteroids. Due to the very high dosages of corticosteroids or
combinations of corticosteroids and other immunosuppressive drugs necessary
to control itching in these dogs, a really good attempt at a diagnosis
should be made. Skin biopsies can be a good first step in identifying these
problems.You may have to work with your vet to rule out several of these conditions
prior to finding a solution to your Westie's problem. Please continue to
work with your vet to find a solution -- in most cases it is possible to
find one.Mike Richards, DVM
10/26/2000
Pruritis is the name for itchiness that causes pets to scratch. Several chemical reactions occur in the skin that stimulate the nerves, causing the brain to feel the itch. We treat a scratching pet by attempting to eliminate these reactions at the source and controlling the body's response to them as well. Some of the chemicals involved in itching are prostaglandins, arachodonic acid (a specialized fatty acid) and leukotreines. By using treatments that inhibit the action of these factors at the skin level, such as antihistamines and fatty acid competitors, we can sometimes control the itching without using corticosteroids such as prednisone. If we work to control other irritating factors such as fleas, dry skin and secondary bacterial infections we can also further reduce itching. Each of these steps is very important because pets have an "itch threshold". This is the point where all of the sources of itching finally add up to enough irritation to cause the irresistible urge to scratch. Just like pain thresholds, these levels vary from pet to pet. Control of every possible factor is important to your dog's health and comfort.
Pruritis is a complication of many diseases. Only by careful examination, diagnostic tests and sometimes even trial and error can we come to understand what causes the itching in a particular pet and how we can best control it.
Mike Richards, DVM
Cold water will usually reduce itching and produce temporary relief. It doesn't really matter how the water is applied, but it must be at least cool. This effect doesn't last long, usually less than one-half hour. Adding Episoothe Oatmeal Shampoo, Episoothe Oatmeal Creme Rinse, Aveeno Colloidal Oatmeal, Relief Shampoo or Domeboro's solution helps to prolong the effect. All of these products are available over-the-counter. If you use Aveeno, one to two tablespoons per gallon of water, applied as a rinse, works best. Follow the directions on the Domeboro packet and also apply as a rinse. Shampooing will sometimes help to control itching. Some shampoos such as Pyoben and Oxydex, act to reduce the bacteria level on the skin, one cause of itching. Seba Lyt and other sulfer/salicyclic acid shampoos reduce scaling. Lytar, Clear Tar and other tar containing shampoos reduce itching and oiliness. An emollient or moisturizer used after shampooing will restore some moisture to the skin and this also reduces itching. Expar Creme Rinse can be used to kill fleas after itching and moisturize the skin.
Antihistamines are useful in the treatment of itching in some dogs and cats. Used alone, about 15 to 25% of dogs will respond to antihistamines. Used in combination with fatty acid inhibitors, such as DermCaps, EFA-Z and Omega EFA capsules, about 25 to 40% of dogs will respond, reducing scratching behavior to acceptable levels. Antihistamines available over-the-counter are Benedryl (diphenhydramine, 25mg capsules) and Chlortrimeton (chlorpheniramine maleate, 4mg tablets). There are prescription antihistamines, notably Atarax (hydroxyzine) that work better in some cases. It is necessary to get a dosage for your particular dog or cat from your vet. Dogs and cats have individual reactions to antihistamines. Since some dogs will respond better to one than another, it is best to try more than one antihistamine before giving up on them to control itching. Some pets will become drowsy when taking antihistamines. If this is unacceptable, they can not be used, or might be best to use at bedtime. Occasionally a pet will get excited when given antihistamines. These pets should not be given these products.
Fatty acid derivatives compete with arachadonic acid, the trigger for itching in the body. By replacing this compound with an inactive competitor, itching can be reduced. It is important that the fatty acid derivative chosen have gamma-linoleic acid, eicosapentanoic acid, or both. These products work best at high dosage levels and when given with a low-fat canned food such as W/D, which is available through veterinarians. Although they can be fairly expensive, their use is preferable to cortisones if they are effective. It is necessary to use these products for at least 6 to 8 weeks to judge their full effect. EFA-Z and DermCaps are examples of these medications.
Antibiotics are used to control skin infections associated with scratching. The itching leads to scratching, which damages the skin. The damaged skin is easier for bacteria to grow in. The bacteria then contribute to the itching, leading to more skin damage. As this cycle progresses, deeper and deeper layers of the skin are affected, sometimes leading to systemic bacterial infections that can even be fatal. Control of skin infections with antibiotics takes time. The usual defense mechanisms of the body, fever, white blood cells and antibodies do not work as well on the skin surface. Antibiotics must do more of the work alone. For this reason, 3 weeks is the minimum recommended time that antibiotics should be given for skin infections. Often, antibiotics must be continued for 8 weeks or longer to control skin disease. Several antibiotics seem to work consistently in skin disease. When these antibiotics fail, it is necessary to culture the skin lesions to identify which antibiotic might be appropriate in an individual case. Occasionally it is necessary to continue antibiotic therapy indefinitely to control severe bacterial skin disease.
Some dogs appear to be unable to prevent penetration of staph (staphylococcus) bacteria into the skin. These dogs can be benefited by the use of a product to promote immune responses. Similar to vaccinations (but short acting), these products help the body learn to fight off staph bacteria. They are Staph Lysate and Immunoregulin. Although somewhat expensive and necessitating weekly injections, these products can cost less to use than frequent or continuous antibiotic therapy. We have better success with Staph Lysate.
Hyposensitization, or allergy "shots", are used in dogs. Their use in cats is very limited due to difficulties in testing cats accurately for individual allergens. Similar to their use in people, these injections help many pets, but not all. To be used properly, it is necessary to identify the allergy agents affecting a dog and then treat accordingly. This can be done by skin testing, where small quantities of allergens (allergy causing agents such as pollens), are injected into the skin and the response to this monitored. Often, it is necessary for a general veterinary practitioner to refer a pet to a veterinary dermatologist for this testing. Recently, blood tests have been developed to allow allergy testing without injections into the skin. These have become better understood recently and are correlating with the skin testing fairly well, although it is generally agreed that skin testing is still more accurate. Allergy injections require a consistent effort from the pet owner. They are the preferred treatment for inhalant allergies if that is the only condition affecting dog, when effective. Currently, about 70% of dogs are thought to benefit from this therapy.
Fleas cause most the allergic reactions in pets. Flea control is essential to our success in treating itchy dogs. Please ask for flea control information if you have any problem at all with fleas on your pet!
When itching can not be adequately controlled by one of the above methods, we usually use a corticosteroid, such as prednisone. Cortisones are the most consistently effective anti-itch medications that we have. They do have several drawbacks, however. Cortisones increase the amount of water your pet drinks, making it urinate more, too. Sometimes this becomes a problem. These drugs increase appetite and weight control can be difficult while using them. If proper dosage schedules are not followed there can be long-term side effects such as decrease in bone density or an increased chance of pancreatitis. Cortisones depress lymphocytes, a type of white blood cell, making it easier for bacterial infections to occur. Accidental overdosage with these medications or inappropriate long-term use can lead to medication induced Cushing's disease, a cause of hair loss, muscle weakness and other problems. For these reasons, we insist on monitoring a pet on cortisones through follow-up office visits. We may ask that you allow us to examine your pet prior to refilling prescriptions for these drugs. In spite of these side effects, cortisones can be the best drugs to make an extremely itchy pet comfortable. If they are the only effective drugs for your pet they are worth the small risk to an individual pet of side effects. These drugs are reasonably safe for long term use if given according to directions. Allowing your pet a good quality of life, by controlling the itching, is worth the small risk of using prednisone and related compounds.
These are the methods we use to treat pruritis, the itchiness that causes your dog or cat to scratch. It may take several tries to work out the proper medications and dosage schedule for your pet, but is worth the effort.
Mike Richards, DVM
Itchy skin problems and Hot spots in older Lab
Question: Dear Dr MIke
I've had a read through your site, but still need to ask a
question .One of our dogs, Scrumpy, age 11, labrador retriever, has been very itchy
since March when she started moulting. She was on a diet of 28% protein,
gluten free. We have just recently swapped her onto a hypoallergenic, lamb
based, gluten free 20% protein diet (James Wellbeloved). At one point she
lost quite a lot of hair on her legs and we had a skin biopsy and scrape
done which showed no mite or mange problems. She doesn't have fleas and she
is wormed regularly. We live in Ireland, with a maximum temperature in the
summer of 25. This year it hasn't gone much above 22. I want to give the
new diet a chance, she's only been on it a week. We supplement with corn
oil, about 4 desertspoons a day. I noticed that you recommend
Fatty acid derivatives compete with arachadonic acid, the trigger for
itching in the body. By replacing this compound with an inactive competitor,
itching can be reduced. It is important that the fatty acid derivative
chosen have gamma-linoleic acid, eicosapentanoic acid, or both.on your site. Would evening primrose oil be better than corn oil? Or would
another oil be better?More worrying:
On Saturday we noticed that she had a grazed, red raw area about the 1.5
inches across between her shoulder blades. We thought it might be a wound,
it was clean, so we left it alone. On Monday night, she rolled on the
carpet and the area reopened and bled. It is like a graze, with the white
skin looking reasonably healthy round it and some part of the graze being
still covered in hair. But in that area the hair has completely gone. I've
pplied some vitamin E oil to it, but otherwise left it alone. If you touch
her near the area, she immediately wants to scratch her stomach, but she
doesn't try to scratch her back. Is this wound likely to be associated with
the itching? Or is it probably just a wound!Thank you for your help.
Regards, Elizabeth
Answer: Elizabeth-
At the present time, the best oils for anti-inflammatory purposes are
thought to be fish oils. The n-3 omega fatty acids are the most directly
responsible for anti-inflammatory purposes. There are times when the
addition of any oil seems to help skin problems. The linolenic acid in
primrose oil is thought to be helpful for some skin conditions but if you
can find a marine fish oil source, it would probably be the most helpful.I think that the wound you are describing is most likely an area of acute
moist pyoderma, which is often referred to as a "hot spot". These can
occur very rapidly and progress to weepy, scabby wounds so quickly, in some
cases, that they are frightening. Keeping these wounds dry with the use of
a mild astringent solution or an antibiotic/cortisone powder can be very
helpful. I like NeoPredef Powder (tm) which is available in the U.S. but
anything that is astringent, controls itchiness or provides antiseptic or
anti-bacterial action may help.There has to be an underlying cause for this itchiness. In an eleven year
old dog, there are several possible problems that come to mind. The
likelihood of any of these conditions will depend on other symptoms that
you may or may not be seeing.Hyperadrenocorticism (HAC, Cushing's disease), can cause itchiness in some
dogs. We have seen a couple of patients in which itchiness was the primary
sign noted by their owners. Hyperadrenocorticism can cause increased
thirst, increased urination, slight to moderate weight gain, thinning of
the hair coat or loss of hair, a pendulous look to the abdomen, scaling
skin sores that can be very itchy, increased susceptibility to urinary
tract infections or skin infections and muscular weakness. Few, if any,
dogs exhibit every sign but most dogs have at least two or three of the
conditions. When itchiness is the primary problem, a hint that this
condition might be present would be skin sores (usually crusty and often
located on the flanks) or itchiness that doesn't respond to cortisone
administration or responds poorly to it.Sometimes, parasitic skin disease does show up at a later age.
Demodecosis does this in some dogs. This can be due to stress on the
immune system from systemic disorders like liver disease, diabetes or
cancers. It occurs for no apparent reason at times, to. Usually it is easy
to find the mites on skin scrapings but it is worth repeating these two or
three times before ruling this cause out.Sarcoptic mange can occur at any age after exposure to another dog affected
by this organism. It can be very hard to find sarcoptic mange mites, so we
usually just treat for this mite early on in itchy dogs for which there is
no other apparent reason for the itchiness. It is easy to treat for with
several effective products available, including organophosphate dips
(Paramite tm, is one), selamectin (Revolution Rx), ivermectin (Ivomec Rx),
lime-sulfer (Lime Dip tm) dips and fipronil ( Frontline tm) all being
effective against this parasite.Fleas sometimes occur after years of good control, or good luck, in a
patient's environment. Fleas are the number one cause of itchiness in dogs
in the world, almost without question. If you are not doing something that
will effectively control fleas, even if you aren't seeing them, it would be
a good idea to consider using one of the really effective flea control
measures that have become available in the last couple of years.A food allergy developing at this age would be unusual. That would also be
true of atopy (inhalant allergies). Still, working to eliminate these
possibilities is still a good idea. A novel protein diet, such as the lamb
and rice, can be helpful in establishing whether a food allergy exists.
This is not a true hypoallergenic diet --- it is a diet designed to include
ingredients the dog doesn't usually eat --- so you have to be sure that is
the case. If your dog has had these food ingredients in the past it would
be necessary to use something else that is truly novel to rule out food
allergies.Atopy is almost always seasonal, at least at first, so if this problem
persists year round, atopy isn't likely to be the cause.Bacterial or yeast skin infections can sometimes develop in dogs that are
stressed for some other reason, so it is worth considering a course of
antibiotics to rule out this possibility. We do not usually routinely use
oral anti-fungal agents to rule out yeast infections, but we do use 4%
chlorhexidine shampoo to see if it will help, since it can help a great
deal with yeast infections. If we see a lot of improvement, but no cure,
then we consider oral anti-fungal agents (or if an impression smear from a
skin sore shows a large number of yeast organisms). Looking for an
underlying problem, such as liver disease, kidney disease, diabetes or
hormonal diseases (HAC, hypothyroidism) is also a good idea. A general
blood panel and T4 testing is a good start, then more specific blood
testing can be done if it seems to be indicated by the general lab work.Mast cell cancers sometimes cause dogs to be very itchy with no visible
skin tumor or easily located internal mast cell tumor. This is something to
think about but diagnosis is pretty difficult until more signs develop.
Gastrointestinal disorders, especially ulcers, and increases in blood
clotting times are sometimes clues of a mast cell tumor affecting internal
organs.There are probably other conditions that I am not able to think of right
now. It sometimes takes a lot of persistence to get to the bottom of one
of these unexplained itching cases. It can be very frustrating to treat for
problems without any response, just to rule them out one by one, but it is
often the only way to finally find the underlying cause of a problem.
Finding this cause may be the only way to control the itching --- so the
best course of action is to start somewhere, as you and your vet have done,
and then move onto the next thing, if necessary.Using corticosteroids to control itching can make some of the diagnostic
work hard to interpret but they may be necessary at times. Antihistamines
help some dogs with itchiness and do not interfere with testing, as
much. I like clemastine (Tavist tm) the best, right now, but it only helps
about 30% of dogs. We use 3V Capules (tm) containing fish oils, in
conjunction with antihistamines when owners are willing to try something
that only helps a small percentage of dogs significantly.Hope this helps some.
Mike Richards, DVM
8/29/2000
Itching in scratching in Goldens
Q: Dr. Mike:
I have 3 adult male Golden Retrievers 2, 6 and 10
years old, and participate in breeding and showing. I am not a novice at
this because I have been involved with the Goldens since the mid 1960's.
Currently I am showing the 2 year old and the 6 year old champion who is
also used at stud.These dogs are all in tip top condition but have developed scratching and
itching for the past month. The 2 year old has also been pulling out
quantities of hair on the underside. My vet and I have inspected these guys
thoroughly. There are no fleas, flea bites, flea dirt, hives, skin
irritation, etc. Tried a leave-in cortisone conditioner, tried an anti-itch
shampoo with no results. Dogs were put on Atarax (2 twice a day) and Keflex
(1 three times a day) for a week with no noticeable results.I live on an acre in SE Michigan and have about 30 large trees on the
property. The 2 year old appears to have some sort of "September" allergy
since last year he ate his tail feathering off of the last 1/4 of his tail.
But the 6 year old has never had any skin problems his whole life. I might
add that we have had a particularly hot and very dry summer.There has been no change in their diet which consists of IAMs Mini Chunks,
KalKan Pedigree Chopped Beef, heart worm meds, Dog Bloom VM250 vitamins.
The 10 year old male has exhibited none of the problems the other 2 seem to have.Thank you for taking the time to read through this long e-mail. I.Y.
A: I.Y.
When two our of three patients in the same household, with no prior history
of itchiness get itchy at the same time I think of parasites first. There
are several possible parasites. Even if I did not see fleas, I think that
it is usually best to initiate good flea control. The best products for
this in dogs that are already itchy are Frontline spray or Frontline
Topspot (TM) and Advantage (TM). I would also treat for sarcoptic mange
even if I couldn't find the mites. This is pretty easy to do now. Frontline
spray at twice the recommended dosage for fleas is supposed to be effective
for sarcoptic mange and ivermectin is effective, too. The older standbys of
organophosphate dips and lime-sulfer dip are also effective. If treatment
for fleas and sarcoptic mange did not resolve the problem pretty quickly,
then the problem is going to be harder to sort out.There are a lot of other possible problems. Allergic skin disease would be
not be especially unusual to encounter in two dogs and goldens are among
the breeds that seem to be predisposed to allergies, so it is definitely
possible. Especially in the one that had symptoms in the fall of the year
before. Yeast infections do not appear to be especially contagious but they
would produce itchiness that didn't respond well to antibiotics and
sometimes not to corticosteroids, either. Atarax (Rx) is only effective in
about 10 to 15% of the dogs it is administered to for the control of
itchiness. It is a good first try because it has fewer side effects than
corticosteroids. It may be worthwhile to consider other antihistamines
since dogs that don't respond to one will sometimes respond to others.
Clemastine (Tavist Rx) is supposed to be the most effective antihistamine
in dogs but it only works about 30% of the time, or less. If this problem
is confined to one or two months of the year it is reasonably safe to use
corticosteroids to control the itching.Hope this helps. I know it is a pain to treat for a mite that may not be
present but sometimes it is very helpful to do so.Mike Richards, DVM
9/24/99
Q: Dr. Mike, My three year old dog, Emma has had an itching problem for about two years. The vets have prescribed Prednisone, Cephalexin, Amitripylline, and many other mediations and remedies that have not worked. The Prednisone caused her to have so many urination accidents it practically ruined our carpet. Her diet consists of Iams Low Active and Iams Canned Low Active dog food. Her skin has a symmetrical pattern of hair loss and black pigmentation of the skin. It appears on her fore legs, back legs, and the sides of her body. She is constantly scratching and also rubbing her nose. Does she have Hyperthyroidism? What else could it be? We bath her in the Episoothe Oatmeal Shampoo and apply the same conditioner, but it doesn't really seem to help her. Awaiting your advice, Donna
A: Donna- It is possible, but not very likely, that Emma could have hypothyroidism (too low a level of thyroid hormone in the body). It is unusual for dogs to have high thyroid levels (hyperthyroidism), which is more common in cats. Low thyroid hormone levels can lead to chronic skin disease but usually this affects dogs slightly older than yours.
The most economical thing to do for the long run may be to ask for referral to a veterinary dermatologist. Specialists tend to see the chronic and odd cases, so often recognize unusual syndromes a general practitioner may miss. If this is not possible, allergy testing and perhaps even skin biopsies may be helpful. Not all dogs with allergies respond well to prednisone. Flea control is almost always indicated in itchy dogs, even if no fleas at all are seen. It is amazing how often it helps even when fleas do not seem to be the problem. Using one of the new flea products, Frontline (Rx), Advantage (Rx) or Program (Rx) could make a big dent in the expense. Good luck with this. Most skin problems can be controlled if a diagnosis can be made.
Mike Richards, DVM
Q: Dr. Mike:First, I would like to thank you for your help re: Belle, my dog with her itching and biting problem. I did follow your suggestion to bathe her in cool water and I added some corn starch for a soothing effect. Is this a good idea? While I bathed her, I found at least 10 fleas on her tail and back side where she bites the most and has red patches. I also applied some polysporin on her wounds until I can afford to go back to the vet as explained to you in previous e-mail. I washed everything that she sleeps on as well as vacuumed carpets and couch thouroughly!!!
A: I do not know if cornstarch will help control the itching or not. I can't see where it would cause any harm, though. And on the fleas -- it is a lot cheaper to use a good flea control product like TopSpot, Advantage, Frontline or Program than to treat skin disease. Often good flea control is all that is necessary to resolve skin problems.
Mike Richards, DVM
Last edited 02/16/07
