VetInfo Digest April 2005

Table of Contents:

Ear Disease in Dogs and Cats

Basic Information

Outer Ear Infection

Outer Ear Medications

Middle and Inner Ear Disease

Ear Surgery

Hematomas

Cancers affecting Ears

Deafness

Hormonal Disease and Ears

This Month's Note:

We recently had a medical miracle at our practice. Several times in the course of my 26 years as a veterinarian I have had cases that simply defy normal expectations. This particular case involved spontaneous remission of cancer. Our patient is a golden retriever who developed an aggressive tumor in her ear canal around Thanksgiving. It appeared suddenly and grew to a significant size quickly. We made plans to identify the type of tumor and discussed what we would do with that information with the dog's owner. Since our best option in these cases is surgical removal of the entire ear canal, which is a painful surgery and one that renders the patient deaf on one side, the owners opted to leave the tumor alone as long as possible and to do surgery as a last resort. Their hope was that their golden would live out a normal life span without having to deal with the tumor. We watched the tumor grow larger over the course of a couple of months and then stabilize for a couple of months, checking it once a month. On this month's checkup the tumor was completely gone. At first we thought we were checking the wrong ear. After checking both ears several times we finally decided that the tumor was indeed gone. Not just smaller --- completely gone.

This was one of those times when we felt fortunate about several things. For our part, we were glad that we had a video otoscope and had let our client look at the images of the tumor each month because we don't know how we would have explained this if she hadn't seen the tumor, too. We were also glad we hadn't tried any particular treatment because I'm sure we would have subjected every pet with an ear tumor to whatever treatment we had used until it became apparent that it wasn't the cause of the tumor's disappearance. For our client and for her pet, we were glad that the problem had resolved without the discomfort, hearing loss and expense that surgery would have entailed. It is important to remember that sometimes things happen that just can't be easily explained. Every pet is an individual and average outcomes just can't tell us what the course of a disease will be in a particular pet. And every once in a while the outcome of an illness falls so far outside the normal range that you just have to call it a miracle.

Ear Disease

Ear disease is a very common problem in dogs and cats. There are a number of reasons for this, but the biggest one is that ear problems are often an indication of other diseases or disorders. In the absence of an underlying disease ears seem to function really well and to rarely develop infections or problems until old age, when deafness becomes a common problem, especially in dogs.

Starting with the basics

Ears are very specialized organs. They have several functions. The most important function is to aid in establishing balance or equilibrium. It may seem strange to place this function above hearing but most pets can function reasonably well without being able to hear but it is much harder to function if you can't maintain balance at all. Fortunately, the portions of the ear which help to maintain balance are only rarely damaged enough to cause problems and we do not have to worry about this function much. Hearing is important to pets and to pet owners but it is very difficult to assess. There is no really good way to test hearing in dogs and cats without the use of specialized equipment that can register the brain's response to auditory stimuli, a test referred to as a brainstem auditory evoked response or BAER test. There are a number of places where this test can be run and list of them is compiled at this web URL: http://www.lsu.edu/deafness/baersite.htm Simple tests of hearing involve response to sound, recognizing words that have some meaning to the pet, such as "out", "dinner" , "go for a ride" or whatever works for your pet.

The best approach to routine ear care is still debatable among veterinarians but it is probably best to individualize the care to the specific pet whenever possible. In general it is best to leave cat's ears alone unless there is an obvious problem with the ear. For dogs more ear care than that may be necessary, depending on the breed. Some dog breeds, such as schnauzers, tend to have a lot of hair in their ears. Whether to remove this hair on a routine basis or to leave it alone is one area of debate among veterinarians, groomers and pet owners. My personal opinion is that it is best to leave the hair in the ears alone as long as the ears are not having problems. It hurts to remove the hair and sometimes removal causes inflammation that can lead to infections. On the other hand, if there is already infection or inflammation on a chronic basis and the ears must be treated regularly it is sometimes easier to remove the hair to allow medications and ear cleansing solutions to work well.

Dogs may need to have their ears cleaned on a regular basis. Keeping the ears clean can help to prevent infections in dogs who are prone to them. There are lots of different recommendations for ear care and many ear cleansing products on the market. Veterinary dermatologists have long recommended strict ear cleansing, usually under anesthesia, as the first step in treating chronic ear inflammation or infection. The reasoning has always been that it is difficult for pet owners to clean their pet's ears effectively and that it is difficult to tell if the ear drum is intact or how deeply an infection extends into the ear without first cleansing it. While this is still probably good advice it often isn't followed in real life. Veterinary clients are justifiably hesitant to allow general anesthesia unless it is necessary and many veterinary practices are simply too busy to stop everything and launch into a thorough ear cleaning procedure during an office visit that was supposed to be routine. For this reason, an alternative that works well is to use an ear cleansing solution two or three times a weekly in a very liberal manner, basically filling up the ear canal to overflowing with the solution and then letting the pet shake out the excess. Wipe the outer ear clean and repeat the process on a regular basis as necessary to keep the ears clean.

There are a number of ear cleansers on the market and most of them have at least some advantage to them. The most popular ear cleansers are probably Nolvalsan Otic (tm) and EpiOtic (tm). Nolvalsan seems to be a nice gentle cleanser and the blue color seems to make people more willing to use it. EpiOtic (tm) seems more effective for ears with a lot of cerumen accumulation. Veterinary dermatologists seem to favor products containing EDTA, such as Tris80 (tm) or TrisEDTA (tm), probably because these products can be combined with antibiotics and used as both treatment and cleansers and also because EDTA seems to have some effect against Pseudomonas bacteria, which are a commonly encountered and stubborn cause of bacterial ear infection. MalAcetic (tm) and other ear cleansing solutions that acidify the ear canal are helpful in preventing yeast and bacterial infections when used on a regular basis. Some people prefer to simply mix 1 part vinegar with 2 parts water and to make their own ear cleansing solution in this manner. The home made solution stings a little more in sensitive ears but it is inexpensive and this encourages regular use. Mixing 2% hydrogen peroxide half and half with water is also popular as home made ear cleansing solution. It takes a little longer to get a dog's ears really clean by using a cleanser on a regular basis rather than going through the process of anesthesia and then thorough cleaning but it works well in our experience and Dr. Hnilica at the University of Tennesssee recommends this method, as well.

It is hard to injure a dog's ear using a cotton tipped swab to clean the ears due to the location and depth of the ear drum in dogs but it is still probably best to avoid doing this. It is more important not to try to clean cat's ears with a cotton tipped swab because even minor damage to the ear canal in cats can lead to secondary infections.

One of the more important things that you can do for your dog or cat is simply to look at the ears carefully once or twice a month. If you start when your pet is young and has normal ears you will have a lot better idea later on that a problem is developing if the appearance of the ear changes. The skin on the inside of the ear should be smooth and clean. The ear canal should look clean. If there is excessive redness, a rough appearance to the skin surface, excessive wax or debris or any evidence of an odor then it is best to let your vet examine the ears to determine if there is a problem with them.

Infections of the outer ear and external ear canals (Otitis externa)

Dogs owners are often pretty good at identifying ear infections or inflammation based on clinical signs. Dogs tend to scratch at their ears with a back foot, shake their head persistently , rub their ears on furniture or on the ground and to have odors associated with infections that are noticeable. Some dogs don't seem to have much sign of discomfort when they have ear infections, though. We find ear infections in dogs whose owners were completely unaware of the problem while doing routine physical examinations on a fairly regular basis.

Cats tend to have much more subtle signs of ear infection, often having no signs at all. Cats with ear mites tend to be very itchy early in the mite infestation but may not show much itchiness at all later on. We have noticed over the years that a lot of cat owners bring their cats in for ear infections when they actually have flea infestations. A cat scratching due to fleas often looks like it is trying to scratch its ear. It can be quite hard to decide if a cat has an ear infection even after examining its ears, in some cases. When we are not sure we usually opt not to treat the ears and to recheck them at a future date. In many instances treatment never becomes necessary.

The first and most important rule of external ear infections in dogs is that you have to view ear infection and ear inflammation as something that will have to be managed long term. Very few dogs have simple ear infections that can be treated until they are gone and then will not recur. Most dogs have ear infections due to underlying causes that must also be treated, or managed, over time. If you do not approach ear infection or inflammation in the dog with the idea in mind that you must identify an underlying cause if at all possible and then treat the underlying cause and periodically treat for ear infections that occur even when you're doing a good job of prevention, you will not succeed in keeping your dog comfortable.

Many of our pet owners who have both dogs and cats notice that we treat ears in cats much differently than we treat them in dogs. Cats tend not to have persistent or recurrent ear inflammation or ear infections and we do not start out with the idea in mind that the ear infection will be long term problem. In most cases in cats it is better to plan to use ear medications for the shortest possible time and to leave the ears alone if it is possible to do so. Cats frequently react to topical ear medications and failure to recognize this can lead to chronic therapy that is making the whole situation worse instead of better. In cats, when an ear infection is not responding to treatment it is often better just to stop medications to see what happens. It isn't unusual for the medication to have controlled a bacterial infection and then for a reaction to the medication to make it appear that the problem has returned. If the original problem was controlled by the medication then stopping the medication will stop clinical signs entirely.

Ear mites are a frequent cause of ear inflammation in cats and a less frequent cause of this problem in dogs. Ear mites live in the external ear canals primarily but they can and do travel across the skin surfaces to get to the other ear and can live in the hair coat for some time. For this reason it is important to use an ear mite medication with a residual effect, such as Milbemite (tm) or Acarexx (tm) or to use a flea treatment that can kill the mites on the body while using an ear mite medicine to kill the mites in the ears. It is generally necessary to treat with pyrethrin based ear mite medications at one week intervals for three weeks to kill the ear mites and any babies that hatch from eggs that are already in the ears. If milbemycin (Milbemite) or ivermectin (Acarexx) based ear mite medications are used it is generally not necessary to treat the body due to the longer lasting effect of these medications.

Ear mites do not cause problems in dogs as frequently as in cats. The intensity of the itchiness in dogs with ear mites, especially early in the infestation, is often remarkable. Some dogs can hardly walk because they keep sitting down to use the rear legs to scratch at their ears. This itchiness tends to diminish some over time but usually dogs continue to be itchy and to show it by scratching at their ears or by shaking their heads. There are no long acting ear mite specific products approved for dogs. Our experience with selamectin (Revolution Rx), a product that has multiple uses, is not very good for ear mites, despite the label claim that it kills them. We use the pyrethrin or rotenone based ear mites medications once a week for three weeks in dogs.

For both dogs and cats it is critically important to treat all pets in the household when treating ear mites. Treating only one or two pets in a multiple pet household or treating only the cats in a household that has both dogs and cats often won't work and just results in a situation in which ear mite infestations recur on a regular basis.

Cats with chronic ear inflammation often seem to be cats who are infected with feline herpes virus (rhinotracheitis virus) chronically and who have other signs of chronic herpes virus infection such as runny eyes, intermittent sneezing or nasal discharges. These other signs can be very subtle in cats but it is worth looking for them carefully. A thin black crust around the nostrils or an eye that is just a little weepy in the morning can indicate that there is an ongoing problem even though it isn't severe. Cats who have excessive cerumen and minor ear inflammation that seems to be associated with feline herpesvirus often just need gentle ear cleaning with saline solution rather than antibiotic or antibiotic/corticosteroid medications for the ears.

Dogs with ear inflammation or ear infections almost always have an underlying cause that is driving the ear infection/inflammation. The most common of these is allergic disease of some type, usually either food allergies (uncommon) or allergies to pollen, molds, dust mites or other inhaled allergens (atopy). Our best guess in our practice is that over 90% of the dogs we see with recurrent or intermittent ear infections have allergies. Other underlying causes include hormonal diseases such as hypothyroidism and Cushing's disease , primary pyodermas (generalized skin infections) and immune mediated disorders. A few dogs have primary ear infections that are occurring without an underlying cause but these usually do respond well to treatment and do not recur.

Dogs with allergic skin disease may have ear infection or inflammation as the only sign. This is not especially uncommon. There are usually other signs, such as licking or chewing at the feet, infections or inflammation between the toes, itchiness around the eyes and face and hair loss around the face, base of the tail or down the rear legs. Hair loss in the front of the body is usually due to food allergies or atopy and hair loss around the rear end of the body is usually due to flea allergies but these are not hard and fast rules, so you have to be suspicious of all types of allergies when any sign of allergy is present. The incidence of allergic skin disease varies widely from one area of the country to another so this may or may not be as big a factor in ear disease where you live. Treating for all causes of itchiness and considering the use of antihistamines, omega fatty acid supplementation or corticosteroids if necessary, can help to lower the incidence of recurrent or persistent ear infections.

Some dogs who have otitis externa have yeast infections or infections containing a mix of bacteria and yeast. The most common yeast species to invade ears are Malassezia species of yeast. Almost all yeast infections are secondary to an underlying cause. When yeast organisms are present there can be extreme itchiness in some dogs and it is not uncommon for dogs with yeast infections to have thickened "elephant" skin around the ears, between the toes, on the underside of the neck and in the inquinal regions, as well.

Medications used to treat external ear disease:

Ear mite medications have already been discussed but there are a number of other medications that can be used to treat ears and some treatments, such as ear cleaning, can be very helpful without the use of medications. One medication that works for ear mites as well as infections is Tresaderm Otic (tm).

Antibiotics may be used by injection (not commonly), orally or topically to treat ear infections in dogs and cats. In dogs it is customary to start with topical antibiotics in most cases for simple otitis externa. In cats some vets prefer to start with oral medications and use topicals only if absolutely necessary due to the increased risk of drug sensitivity reactions to topical medications in cats. It is usually necessary to use oral antibiotics for at least three weeks to obtain a really good effect in ears. Topical medications are used for variable lengths of time but 7 to 14 days is probably most common.

Almost all the available topical ear medications for dogs contain an antibiotic from the aminoglycoside class of antibiotics. These include neomycin, gentamicin and amikacin. If one of these medications doesn't work well, switching to another one containing a similar antibiotic often won't work. It is necessary in that case to use one of the less common ear medications that contains an alternative antibiotic such as enrofloxacin (Baytril Otic tm) or chloramphenicol. (Chloromycetin Rx).

Aminoglycoside antibiotics used topically or injectably can cause deafness in dogs. This can be difficult to detect when treating a single ear but if you are using any of the common medications containing an aminoglycoside, such as MalOtic (tm), Otobiotic (tm), Otomax (tm) or Panalog (tm) you should watch for signs of deafness. If any sign of deafness occurs, stop the medications and let your vet know immediately. We have seen this problem at least twice in our practice over the years and in both cases discontinuing the medications resolved the problem over the course of a couple of weeks.

Yeast ear infections will usually respond to topical treatment with miconazole or clotrimazole, both of which are found in several ear medications. If topical medications won't work the yeast infections are also usually susceptible to ketaconazole (Nizoral Rx) used orally. In most cases yeast infections will resolve on their own if the underlying disease process can be well controlled but this is hard to do for conditions like allergies. Frequent use of ear cleansers with an acidic pH such as EpiOtic (tm) or Malacetic (tm) can be helpful in preventing future yeast infections and in some cases in treating existing ones. A home made acidic ear cleansing solution is easy to make by mixing two parts water and one part vinegar. The advantage of commercially available ear cleansers is buffering to remove some of the sting when the solutions are used in inflamed ears.

It is best when dealing with ear infections to have a follow up visit with the veterinarian to assess whether the ear medication has been completely effective. It is not uncommon for ear medications to resolve visible clinical symptoms almost entirely without completely eliminating the ear infection. If there is a residual infection when treatment stops it is almost a guarantee that ear problems with continue. If your vet has a video otoscope take a look at the monitor to see how ears should look when they are clean so that you can recognize a problem when it first occurs. You won't have a video otoscope at home but once you see the difference between healthy ears and infected ears you can usually notice problems much earlier.

Once you know that your dog is susceptible to intermittent or chronic ear infections there are a number of things that you can do at home that might help to reduce the number of infections or even prevent them entirely in some cases. Routine ear cleaning is very helpful. Veterinary dermatologists seem to vary a lot in their choice of favorite ear cleansers for dogs but TrisEDTA (tm) and Tris80 (tm) are popular, as well as EpiOtic (tm), Malacetic (tm) and Nolvalsan Otic (tm). There are lots of different recommendations on how to best clean the ears but the one that we like the best is simply to fill the ear canal with the cleanser, squish it around some by massaging the base of the ear and then letting the dog shake out the excess. Doing this as frequently as seems necessary, usually once or twice a week, seems to help a lot in reducing ear infections.

If your cat is prone to ear infections or gets excessive ear wax accumulation without infections there isn't much disagreement among veterinary dermatologists about their favorite treatments --- almost all veterinary dermatologists recommend cleaning a cats ears with sterile saline solution or not cleaning them at all. It is best to fill the ear canal with body temperature saline solution, massage the base of the ear some, let the cat shake it out and then to repeat as necessary to keep the ears clean. This is much more time consuming than using a commercial ear cleaner but it seems to prevent a lot of problems in cats caused by the ear cleaners or by rough handling of the ear canal tissue while trying wipe out ears. Cats are simply not dogs when it comes to ear disease and sometimes for them minimal treatment works much better than the kind of vigorous treatment that is often necessary for ear problems in dogs.

Chronic ear irritation in cats is sometimes due to nasal polyps which have extended into the Eustachian tube and sometimes all the way to the middle ear. This is a bigger problem in young cats than in older cats and is not really a common finding but it is definitely something to consider if there is persistent ear disease in one ear in a cat that won't respond to treatment. Nasal polyps can sometimes be seen in the pharynx using a dental mirror to examine the back of the nasal passages. The best way to identify them is through the use of MRI examination but this is not something that is routinely available in many areas of the country.

Sometimes it can be very helpful to use over the counter medications to comfort the ears or to reduce allergy symptoms that are contributing to ear disease, such as congestion. In dogs we have had a few patients whose external ear infections ceased when we used pseudoephedrine (Sudafed Rx) orally to treat congestion, for instance. It can also be helpful in some dogs and cats to use appropriate antihistamine therapy. In dogs we favor diphenhydramine (Benedryl Rx) and clemastine (Tavist Rx) and in cats we favor chlorpheniramine maleate (Chlortrimeton Rx). Some of our allergy patients respond pretty well to the use of 1% hydrocortisone cream ( Lanacort tm, CortAid tm) applied to the non-haired portions of the flap of the ear by rubbing it onto the skin surface. This sometimes works for dogs who have "fly bite" dermatitis affecting the tips or folds of the ears, as well.

Surgery for external ear disease

There are two surgical procedures that are sometimes attempted in an effort to treat external and middle ear disease in dogs. Lateral ear canal resection, sometimes referred to as a LaCroix or a Zepp procedure, is removal of the outer wall of the ear canal to allow easier treatment of the ear. This procedure does nothing for the underlying causes of ear disease which means that dogs who have had this procedure still require as much treatment as dogs who have not, it is just slightly easier to administer. The second surgical procedure that can be done is a total ear canal ablation. In this procedure the ear canal and middle ear (or at least major portions of it) are removed entirely. The surgery works pretty well but is not completely successful in all patients in resolving ear disease. It produces deafness on the side it is performed on. Facial paralysis that is temporary is a fairly common complication and the post-surgical period is painful, although this can usually be controlled with pain relief medications. If you reach the point of desperation with ear disease total ear canal ablation is a better procedure than lateral ear canal resection.

Middle and inner ear disease in dogs and cats.

The middle ear is the portion between the ear drum and the inner ear. No one knows for sure what percentage of dogs and cats who have external ear infections also have middle ear infections but it is enough of them that some consideration should be given to treatment for middle ear infection whenever external ear infections recur constantly or when they do not respond to treatment as expected. Most middle ear infections in pets are thought to be caused by external ear infections that have caused rupture of the ear drum but middle ear infections can occur for other reasons. In cats two causes of middle ear infections in the absence of external ear infections are nasal polyps blocking the auditory (Eustachian) tube and chronic upper respiratory infections. In dogs foreign bodies sometimes cause middle ear infections (things like fox awns) and there appear to be some dogs with inhalant allergies who develop middle ear inflammation and infection without having external ear infections.

Dogs and cats with middle ear infections may have severe ear pain, facial paralysis or Horner's syndrome - a condition in which one pupil is constricted and the third eyelid is often visible. There may be no symptoms other than those associated with external ear infections such as head shaking, discharge from the ears or a bad odor near the ears.

Inner ear infections usually cause balance problems. There is a fairly common condition in dogs (less common in cats) called peripheral vestibular syndrome, which also causes balance problems. One of the challenges for veterinarians is distinguishing between these conditions since peripheral vestibular syndrome does not require therapy and usually improves rapidly while internal ear infections can occur as suddenly but tend to get worse over time rather than better. It is important to use antibiotics if an inner ear infection is suspected so sometimes your vet just has to make a best guess as to which condition is present and then to treat accordingly.

Hematomas of the Pinna (ear flap)

A frequent problem in dogs is an ear flap that has suddenly swollen to two or three times its normal thickness. Usually this is due to a ruptured blood vessel in the ear flap and the swelling is caused by blood, a condition referred to as a hematoma. Some dogs with hematomas have very swollen ears and no apparent discomfort and other dogs appear to be in moderate to severe pain from the condition. It is likely that this difference occurs due to the pain varying based on the underlying cause and to some extent the amount of bleeding that has occurred. Hematomas occur in cats but at a much lower frequency than in dogs.

A fair number of dogs have ear hematomas with no apparent cause for them. There is some chance that this group of dogs has an underlying immune system problem leading to the disorder although this is based on a single study that has not been repeated. Many other dogs do have an underlying cause. Anything that leads to excessive shaking of the ears can cause a hematoma and sometimes they are the result of trauma, such as a dog bite. Common underlying causes are allergic ear inflammation and ear infection from any other cause. Failure to recognize the underlying problem can complicate the treatment of the hematoma.

When hematomas are not treated the ear flap may scar severely and crumple up. This creates a look that is sometimes referred to as "cauliflower ear". The ear can be pretty ugly after this happens but that is only part of the problem. If the ear canal is blocked by the flap of the ear as it crumples then there is a risk that future ear infections will be much more difficult to treat. Between these problems and the pain felt by some patients, it is usually best to treat ear hematomas, although very small hematomas may heal satisfactorily without treatment.

Traditionally the treatment for ear hematomas has been surgery. An incision is usually made on the non-haired portion of the ear flap to drain the blood and to allow the removal of any blood clots or fibrin clots that won't drain out on their own. Then sutures are passed completely through the ear and back out, creating a look to the ear that resembles a mattress. There are a few surgical devices that can be used to secure sutures or to provide even pressure across the ear surface if necessary. Most dogs and cats who have had an ear hematoma surgically repaired won't have a recurrence in the same ear, although this does happen occasionally. The ear tends to hurt more for the first few days and the use of pain relievers post-surgically is best due to this.

An alternative treatment to surgery is the use of corticosteroids during the healing period to limit scar production and to reduce the risk of scarring as the hematoma heals. This is a reasonable approach for hematomas that are not painful or that are small enough that they seem likely to resolve successfully over time without surgical intervention. We treat about half of the hematomas that occur in dogs and cats in our clinic using prednisone or other corticosteroids. This works well to prevent scarring and can help with the underlying causes of some ear infections, especially ones that occurred due to allergies. One problem we have seen using medical treatment is that the incidence of recurrences of hematomas seems to be higher when medical treatment is used instead of surgery. Medical therapy can be repeated if this occurs or it is possible to opt for surgical treatment if the hematomas return.

Cancers affecting the ears

In cats the most common cancer that we see affecting the ears is squamous cell carcinoma (SCC). This cancer typically starts on the tips of the ears and often looks like a sunburn or non-healing sore in its earliest stages. Later in the disease it usually seems like something is eating away at the tissue along the ear margins. SCC is more common in cats who have white haired ear flaps. If the cancer is recognized early enough it is usually possible to remove some portion of the flap of the ear around the tumor or to remove the entire pinna and this is usually curative. Once these tumors spread away from the tip of the ear they become pretty aggressive and it is sometimes not possible to remove enough of the ear flap to prevent them from spreading to other areas of the body.

In dogs the most common ear cancers are ceruminous gland adenomas or adenocarcinomas. These form in the ear canal and can vary from smooth lumps to weepy greasy ulcerated lumps in appearance. Cats also get both of these tumors The adenomas are benign and surgical removal is usually successful. The adenocarcinomas are aggressive tumors and it is generally necessary to remove the entire ear canal and part of the middle ear in order to have any chance of success in dealing with these tumors. In cats the surgery tends to be less successful with about half of cats living less than a year after surgery. About half of dogs who have surgery will live over 2 years. Due to the difference in surgical technique and success rate between cerminous gland adenomas and ceruminous gland adenocarcinomas it is advisable to have a biopsy specimen taken and examined by a pathologist prior to the actual surgical removal of these tumors.

Both dogs and cats get lesions in their ears at times that resemble tumors but are not cancerous. Cats tend to get blue to purple lumps in the ear canal associated with chronic irritation pretty frequently and dogs get these occasionally. It is important to distinguish these benign conditions from tumors.

Deafness

As dogs age it is not unusual for them to develop some degree of deafness. Age related deafness sometimes occurs in cats but not as commonly. To the best of my knowledge, there is no treatment for the gradual deafness that occurs in older pets. It is worthwhile to examine the ears and to make sure that there is not visible reason for the deafness. Occasionally we do find problems that are either contributing to hearing loss or even causing it in older pets when we do physical examinations. Most of the time, though, this is a condition that just has to be adapted to and lived with.

Hormonal Disease affecting the Ears

Once in a while we see a dog or cat with persistent ear disease whose problems appear to be due to underlying hormonal diseases. This is more common in dogs than in cats. It is an unusual cause of ear disease in both species but it bears mentioning since ear disease is sometimes the first hint of a bigger problem.

Hypothyroidism is reported to cause an increased susceptibility to skin infection and this can translate into an increased susceptibility to ear infection. Hypothyroidism most commonly shows up in dogs between the ages of 3 and 8 years, although it isn't unusual for it to occur at older ages, as well. Loss of hair on the end of the tail, the tips of the ears and on the trunk can occur with hypothyroidism. Some dogs gain weight and become lethargic as the disease progresses. Others have subtle signs of muscular weakness, incoordination or other slight neurologic signs. Some dogs drink more and urinate more when they have hypothyroidism. If your dog has persistent ear disease and doesn't appear to have allergies it is worth checking for hypothyroidism.

Cats with hyperthyroidism sometimes develop ear problems. While I can't say for sure what the cause of the ear problems is in cats with hyperthyroidism it really appears as if they may be experiencing pain or possibly some sensation like ringing in the ears. This would make some sense because high blood pressure is one symptom of hyperthyroidism and that can cause ringing in the ears. Usually cats with hyperthyroidism are eating well but losing weight anyway. Some cats do feel sick and won't eat with this condition but most eat more than they have in the recent past. It is important to check for hyperthyroidism if symptoms are present as this disease does eventually cause death.

Both dogs and cats sometimes develop ear infections when they have diabetes. Skin infections are not an uncommon reason for people to bring their pets who have undetected diabetes to the office. When asked most owners of diabetic pets have noticed an increase in drinking but may or may not have detected an increased need to urinate. It is pretty easy to eliminate diabetes or to find it using blood testing or urine testing. It is reasonable to test for this if there are signs of increased drinking and thirst accompanied by ear disease that just won't clear up.

The One Thing to Remember:

The most important thing to remember about ear disease is that it is often a problem that must be managed over the life time of the pet. It is really important to keep this in mind because watching closely for signs of ear infection or inflammation and treating quickly will limit the potential for infections to spread to the middle ear and will provide your pet with a great deal more comfort than letting ear disease develop until it causes enough problems to make itself obvious and then treating the ears. Take the time to look at your pet's ears, inside and out so that you are familiar with what they look like. If you know what the ears look like when they are normal it will help you a great deal when attempting to determine if something might be wrong.

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