What Are Those Painful-Looking Red Sores On My Cat’s Lip Or Body? EGC

Eosinophilic Granuloma Complex aka Lick Granuloma, EGC, FEGC

Ron Hines DVM PhD

If your veterinarian tried Apoquel® for this problem I would appreciate your letting me know

 Redonyl Ultra?

This mysterious and perplexing disease of cats goes by many names: rodent ulcer (they thought rats spread it), lick ulcer, eosinophilic granuloma disease, eosinophilic complex etc. And despite the tremendous progress that has been made in veterinary medicine over the years, why it occurs remains an enigma. The less one understands a disease, the more names veterinarians tend to give to them. EGC is probably the leader of the pack in that respect.

Although its causes remain hard to pin down, most veterinarians today believe that EGC is some sort of allergy or allergies. Guesswork as to what that might be is the norm and hard facts are few. In many cases, the skin, mouth or eye lesions (wounds) spontaneously vanish or improve with time or environmental changes – a new home, a new diet, better flea control. In some cases a single episode occurs in your cat, vanishes or responds to treatment once in your cat’s life and never again. In others the lesions are stubborn, resistant to treatment and return again and again. In some cases cats are very itchy (pruritic), in others, the lesions are ignored.  EGC episodes can come up quite suddenly or develop gradually over an extended period of time.

When pathologists began to examine these lesions under their microscopes, they noticed that they all contained abnormally high numbers of your cat’s inflammatory cells called eosinophils , accompanied by another inflammatory cell, the neutrophil , and with time, scar tissue. In my practice, the lip form is the most common. But a second form that causes inflamed skin patches (plaques) and a third that produces lightening-like (linear) lines of inflammation on your cat’s body is said to be more common. In a rarer form, the cornea of your cat’s eye can be affected. Eosinophils are defensive cells that are part of your cat’s immune system. Once they are activated by something, they have very limited  ways they can respond. They do so by releasing toxic granules. ( read here ) So EGC could well be the end result of many different sensitivities and health issues, not a single disease. The disease variability between cats leads me to suspect that is true. Why eosinophils do what they do is highly complex and poorly-understood. ( read here ) Even the presence or absence of sex hormones has been noted to affects how eosinophils react. ( read here )  

When These Ulcers Form On Your Cat’s Lips

This is the most striking way that EGC affects cats. Puffy, thickened ulcers appear on the margin (edge) of the cat’s lip. Usually it is on one side of the pet’s upper lip (~80% of the time) – somewhere between the lip cleft below it’s nose and its large canine tooth. It can be on one side of the head or both sides. The ulcerated area can be small, or the entire upper lip can be involved. With time, lips can be permanently disfigured with scaring. These ulcers will bleed – but never profusely. Over time, the ulcers often become concave (eroded in the center) with a firm-to-hard feel if you touch them. There is a lot of color variation, but the periphery (edges) are often a darker reddish brown than the center which has a glistening pink to yellow or whitish tone. My clients used to bring these cats to me thinking this was a burn from chewing on an electrical cord.

It is said by some that these lesions are not painful and do not appear to itch or burn. But cats with this problem always appear dejected to me. They are certainly painful for me to look at. Some of these cats are reluctant to eat.

Farmers occasionally saw this problem in their barn cats. They got the mistaken idea that EGC was associated with eating rodents – hence the name, rodent ulcer. Wounds that will not heal are called indolent. In a few long-standing cases, the lymph nodes on your cat’s neck might be enlarged (=peripheral lymphadenopathy). Regional lymph nodes enlarge in response to any inflammation.

In some cats, the problem is not confined only to the upper lips but involves the lower lip and chin as well, giving the cat a “fat lip” or pouting appearance and in some unfortunate cats the tongue and roof of the mouth are involved as well.

In the various form of EGC, some veterinarians inject their medications (long-acting corticosteroids+antibiotics) directly into and surrounding the lip lesions themselves. The dense scarring that accompanies this problem can make that difficult. I do that as well, but I cannot say that an intramuscular injection of the same ingredients at any place on your cat’s body would not produce the same effect.

Inflamed Areas In Your Cat’s Mouth

 

Sometimes, these lesions begin in the cat’s mouth. In other cases, the lip form precedes the oral lesions. Often it is the upper portion of the mouth that is affected – the soft palate, the tongue and even as far back as the pharynx and frenulum.

Naturally, these poor cats usually drool (ptyalism) , have a strong fetid breath (halitosis), are reluctant to eat and have difficulty swallowing (dysphagia). It is always a good idea to check a pet with lip ulcers to be sure none are present in its mouth as well. These lesions, and the mouth of cats in general, are always a potential source of dangerous bacteria if you are bitten. ( read here ) So it is much wiser to let your veterinarian and his/her staff do the inspection. Not every cat with the symptoms I described has EGC lesions in its mouth. There are a large variety of non-EGC problems that occur in the mouth of cats that are more common. They can occur when EGC is present elsewhere on the body or in cats that do not suffer from EGC at all. Mouth infection in your cat (stomatitis) cause by bacterial or fungal infections and not by EGC also causes halitosis, drooling and mouth pain. Cat that have been in car accidents often have fractures of the jaw or broken teeth that cause similar signs. Cats with heavy tooth tartar or resorptive dental lesions also show similar symptoms. Cats can have things lodged in their mouth or upper throat do too. When a playful cat swallows sewing thread, sometimes the needle at the end gets lodged and infected in its mouth or the thread wraps around its tongue.

Cats in kidney failure (renal failure) are more prone to many forms of non-EGC stomatitis. The body-wide debility of the common cat viruses of feline leukemia  and feline immunodeficiency as well as feline calicivirus, also make cats more susceptible to stomatitis.  Immunosuppressive drugs, like cyclosporin (Atopica®) can also result in mouth inflammation.  Elderly cats are susceptible to tumors (adenocarcinomas) of the mouth. Those need to be ruled out too (with a biopsy ).

Eosinophilic Plaque = Linear Granuloma = Eosinophilic Granuloma = Collagenolytic Granuloma 

Most veterinary practices in the USA and Western Europe find this form of EGC to be the most common form in their patients. We usually see this in younger cats (~1.5-6 years old).

The body sores these cats develop are either roughly circular or streaks and lines. There may be only one, or there may be several. They are slightly raised and tend to be a red to salmon pink in color.  They look somewhat like the road rash one suffers when falling off a moving bicycle or skate board. They can form anywhere on the cat’s body; but the ventral (lower) abdomen and rear thighs are common locations. When it affects the cat’s rear or front legs, it is often on the inner (medial) side. The cat’s neck, throat and anal area can be other sites for the problem.

They often itch intensely causing the cat spends its time licking and causing the wounds to ooze fluid (blood serum), glisten  and loose the hair that once covering the area. The rough tongue of house cats quickly make these lesions raw and angry if the cat is not placed in some sort of restraint (Elizabethan collar). Despite their intensity, I have never seen bacterial infections associated with these open ulcers to be more than a superficial, minor problem. 

Biopsies of these areas show that they are heavily infiltrated with eosinophils. Neutrophils often congregate in these areas as well and, although not recognizable on routinely processed tissue, mast cells have also accumulated in these areas. 

If your veterinarian stains and examines glass slides that were pressed onto the affected area, bacteria, and remnants of eosinophils, neutrophils might be seen as well.

In this form of EGC, the cat’s blood is more likely to have circulating eosinophils that are more numerous than normal.  It is also common for the lymph nodes that drain the affected areas to be moderately enlarged (regional lymphadenopathy).

This , and the miliary dermatitis form form of EGC are the ones most likely to be associated with flea infestation. Many improve without medication when the cat is moved to an environment that is totally free of fleas.

Miliary Dermatitis

Miliary dermatitis is another way that the skin form of EGC can present itself. In this form, the skin inflammation occurs in many small reddened pox-like areas rather than large plaques. These areas quickly become crusty.

This form is usually quite itchy and it is common for the cat’s hair coat to be quite thin as a result of all the licking they do (cats can develop hair balls or constipation due to all the ingested hair).  

In some cases of miliary dermatitis, the red papules are not as apparent as in others and the symptom most noticed by owners is a patchy, thin hair coat. Those cases need to be differentiated from stress induced over grooming (psychogenic alopecia  although Wikipedia is confusing the two issues). When amitriptyline is helpful, I am always suspicious that psychogenic alopecia, rather than EGC  is the underlying problem. Sarcoptic or notoedric mange can also be confused with miliary dermatitis caused by EGC.

When it is not, flea allergy, atopic allergies and food allergy are the first things that come to mind.

Cats that are positive feline immunodeficiency virus (feline AIDS) or for feline leukemia can also present with perplexing skin disease. So all cats with skin problems ought to be tested for them as well.

Eosinophilic Granulomas On Your Cat’s Foot Pads And Paws

In some cats, the pads of the feet are the site of Eosinophilic granuloma complex EGC. Those pets are often brought to me because they are limping. It is usually a young cat (under 2-3 years old). On examination, one of more of their foot pads is inflamed, swollen, damp and painful. The foot often has an unhealthy odor and it is common for them to be ulcerated as well.

 When cats come in with tender or swollen paws, broken toe nails, evidence of a poorly-performed declaw operation or a penetrating thorn always need to be looked for. Paws are also a common site for abscesses that occur after cat fights. Those cats are often running a fever if the abscesses resulting from the fight has not begun to drain. Infected feet are often warm to the touch. They are not when EGC is the cause.

When the foot pad form of EGC has just begun, pain and a loss of toe pad pigment can be the only signs. It is also common for there to be cracks in the foot pads. Of course, if EGC lesions are present or begin to occur at other locations on the pet’s body, what you are seeing in its paw is most likely part-and-parcel of the same underlying disease.

When the foot pad form of EGC occurs, a cat-litter sensitivity has occasionally been implicated. So a change in your cat’s litter is always a simple and prudent thing to do. The same goes for cleaning products used around the home.

Cats occasionally suffer from a foot pad condition that appears quite similar to EGC.  It is called Plasma Cell Pododermatitis and it too appears to have a basis in your cats immune system. However, when biopsies of the affected paw(s) are examined, plasma cells, (another cell of your cat’s immune system) rather than eosinophils are found to be in excess. You can read more about that condition and its successful treatment with doxycycline here: (ask me for Bettenay2003).

No matter which of the two previous conditions are diagnosed, an FeLV and FIV test would be a good idea if they have not been performed recently.

Mosquito Bite Hypersensitivity

Some cats develop distinctive raw, inflamed areas on the bridge of their nose that also contain eosinophils. This is the least common of the syndromes that are generally included in ECG. It is thought to be due to an allergy to components of the saliva that mosquitoes leave behind after drawing blood. The edges of the ears and other areas on the cat with scant hair are also susceptible.

When mosquitoes are the source of your cat’s problem, you might notice that lesions only occur during mosquito season.

There are veterinarians that believe that a mosquito bite allergy can be the cause of the other forms of EGC as well. So keeping your cat indoors is a wise move when dealing with any form of EGC.

Bacterial Infections that follow EGC-related nose problems can obscure the microscopic changes that veterinary pathologists use to diagnose EGC. But be suspicious of EGC or an autoimmune disease when your pet’s nose becomes inflamed for no apparent reason. As with the other forms of EGC, an FLV/FIV test is advisable.

You can read an article about Eosinophilic Complex related to mosquitoes here.

Eosinophilic Inflammation Of The Cornea Of Your Cat’s Eye = Eosinophilic Keratitis

Eosinophilic keratitis is not often included in the diseases thought to comprise eosinophilic complex. I  deal with it here simply because eosinophils appear in great numbers in the affected eye tissue. In this problem, the outer clear cornea of the cat’s eye develops a amber pink-to-grey raised, roughened area – usually near the cornea’s center. Usually, only one eye is involved. Unlike simple cuts and abrasions to this area, eosinophilic keratitis lesions fail to heal with time, antibiotics or protective eye drops.

Unlike the other forms of accepted EGC disease, the herpes 1 (rhinotracheitis, FHV-1) virus is thought by many to be the underlying cause for these eye lesions. This is the same virus that causes discharges, conjunctivitis, sneezing and sometimes hypersalivation and coughing in cats when they are initially infected. You can read about that virus here . However, evidence of FHV-1 virus cannot be found in all cases of eosinophilic keratitis so some cases probably have a different origin. 

Most of these cases respond well to topical steroid-containing eye drops (eg prednisolone or dexamethasone) and some to anti-herpes medications (eg trifluridine/Viroptic®). But the cats must be watched closely to be sure a rupture (descemetocele) does not occur in the cornea until it has healed. When medications are ineffective, surgery to scrape the lesion free of debris and dead tissue that impede healing, cryosurgery or radiation therapy is sometimes required. You can read about these eosinophilic eye lesions and their treatment here.

Eosinophil-related Problems Of Your Cat’s Digestive Tract = Eosinophilic Enteritis =EE

As with the eye form, eosinophilic digestive tract problems are not an accepted form of EGC. But occasionally, the inflammation associated with eosinophils occurs in the walls of your cat’s stomach or intestine. When this occurs the main signs are diarrhea, vomiting and weight loss. Although it shows many similarities to EGC, this particular problem is usually considered as a form of inflammatory bowel disease IBD. Which signs predominate depend on which portion of your cat’s digestive tract is most inflamed. Diagnosis requires a biopsy sample. This is not a common disease in cats but it has occurred in felines 1.5-11 years of age. Food allergies, autoimmune disease and pre- cancerous changes within the bone marrow that produce eosinophils are all suspected causes. Like EGC, corticosteroids, diet changes and, when required, immunosuppressive agents like cyclosporin or chlorambucil are treatment choices.

A Bit About Your Cat ‘s Eosinophils – Where They Come From & What They Do

Eosinophils are one of the soldier cells of your pet’s immune system – an army of neutrophils, eosinophils, macrophages, dendritic cells, natural killer cells and basophils. They form in your pet’s bone marrow and are released into its blood stream. We believe that the eosinophil ‘s normal job is to destroy parasites. Eosinophils do not stay there long. Soon, they migrate into sold tissue throughout your pet’s body. There, they remain “in touch” with another cell of the pet’s immune system, the mast cell. When a mast cell “believes” that it has recognized a foreign invader, something that does not belong in the pet’s body and to which prior antibodies (IgE) were produced, it releases chemicals designed to alert nearby eosinophils and summon more of them. Those eosinophils, in turn, release chemicals designed to destroy the invader. That is just fine when the foreign substance is a parasite; but when it was summoned due to an IgE that was mistakenly produced against, say, pollen, a food protein, flea saliva, etc. ; the chemicals that the eosinophil releases cause damage to the pet’s own surrounding tissues. The non-threatening things in the pet’s environment that can cause these “mistaken IgEs” are called allergens. When your pet has them, it has become allergic. Because parasites are often located or enter through the body surface, eosinophils tend to hang out just under the skin and glistening membranes that line entrances to your cat’s body. ( read here )    I gave you a very simplistic explanation. If you want the real story, go here.)

How Old Are Most Cats When They Begin To Develop Eosinophilic Problems?

The majority of cats that develop EGC do so between 2 and 6 years of age. Some develop it earlier, but it often takes a year or three for cats to develop severe enough allergies for owners to take notice.

  

Does EGC Affect Male And Female Cats Equally?

I have not noticed that male or female cats have a higher incidence of EGC than their opposite sex. But some veterinarians think that they see the problem more frequently in female cats. A Cornell Veterinary School’s handout out EGC suggested that. But when the medical records of 55 cats admitted to Cornell with EGC or the 1407 with assorted skin problems were examined, male cats predominated. (read here)   So your cat ‘s sex is probably irrelevant to its chances of developing EGC.

  

Is My Cat’s Genetics Involved?

One respected textbook states that Siamese and Siamese crosses are at a higher risk of EGC ( read here ) but the Cornell study found that of Siamese-type cats, only Himalayans had that increased risk. Veterinarians do know that a pet’s genetics occasionally does play a part in eosinophilic diseases. In dogs, Siberian huskies account for 76% of the cases of eosinophilic granuloma and one report in 2005 found a particularly high number of kittens from a specific breeder later developed EGC even though they had completely different lifestyles and diet at their new homes. ( read here )

How Will My Veterinarian Be Sure Of The Diagnosis?

When your cat ‘s visual symptoms and history are typical of EGC the diagnosis is rather easy for your veterinarian. But occasionally questions remain. In those case your cat’s blood analysis might show increased numbers of eosinophils in its circulation ( eosinophilia ) which might add to the suspicion that EGC is the underlying cause of your cat’s skin problem. However, many cats with EGC have normal blood eosinophil numbers. Blood work, including blood chemistry values also help veterinarians rule out other possible underlying causes. In unusual cases it might take a skin biopsy – a small snippet of tissue from your cat’s lesion – to confirm that EGC is its underlying problem. Veterinary pathologists rely on the overabundance of eosinophils in the biopsy specimen to confirm that your cat suffers from EGC. However, there are occasional cases where it is primarily an overabundance of  mast cells  that are found to be present. (read here) Treatment for those cats, and probably causes as well, are the same as for more typical EGC.)

Whenever your veterinarian is worried about a possible tumor masquerading as EGC (particularly when the problem is in its mouth), a biopsy specimen examined by a pathologist is a wise choice to set everyone’s mind at ease. Fungal or bacterial disease, foreign bodies and tooth-related issues can all appear similar.  

Allergy testing for fleabite sensitivity, food allergy or other allergens is rarely helpful. Many cats that never develop EGC come up positive on those tests as well. The only valid way to rule out those common allergies is to remove them from your cat’s environment and life and see if your pet improves. To read about how most veterinarians would go about diagnosing EGC, ask me for Bloom2006.

Do Veterinarians Know What Causes This Group Of Problems?

Most veterinarians will tell you that EGC is a “hypersensitivity reaction” or “allergy”. That is almost certainly true – since that is what activated eosinophils cause. Beyond that, everything is much less certain. There are probably very many “triggers” that allow this disease to occur.

Here Are What Most Of Us Think The Common Causes Are:

A Flea Allergy

Many cases of Eosinophilic complex go away when your cat is no longer exposed to fleas. We believe that some cats become more sensitive to components of flea saliva than others. Some of those cats develop intense itching and subsequently damage themselves scratching (flea allergy dermatitis, FAD); but others seem to go on to develop one of the various forms of eosinophilic complex. A cat’s rough tongue can cause more damage than the allergic reaction itself.

It was recently discovered that parasite bites can cause allergies to things other than the parasite that bit them. Children and adults that have been bitten by ticks appear more prone to develop food allergies. (read hereMight tick, or flea saliva be doing something similar to sensitize cats? Might those parasites be carrying a pathogen we do not know about? We do not know. There are also veterinarians who wonder if the grain mite antigen so common in cat food plant ingredients might cross react with other antigens a cat has become allergic too. ( read here )

Fleas are not the only skin parasite capable of causing itchy open lesions on cats. But be particularly suspicious of them if more than one cat in your household has an EGC problem. ( read here )

Food Allergies

Most veterinarians believe that food allergies account for some of the cases of EGC that they see. This is particularly true of the miliary dermatitis form. ask me for Bryan2010 if you want to read more about that.  These are cats that do not seem to have a particular time of the year when they are prone to their EGC problems. Some show other indications that their diet is not optimal for them such as periodic diarrhea, vomiting or hives. A food allergy diagnosis is probably also more likely when EGC problems develop on multiple areas of the body and when itching is significant. But one needs to be sure that the hair loss and licking is not a simple reaction to stress occurring in your cat’s life (psychogenic alopecia or hair loss). Trial elimination diet need to be fed for at least 6 weeks. That duration needs to be extended if the secondary skin or ear infections have not cleared up yet or if your cat shows improvement but not complete resolution of clinical signs. 

Contact Sensitivities

Cats can also become sensitive to contact with things in their environment. So some veterinarians suggest changing from plastic to stainless steel food dishes, changing brands of litter, switching laundry detergent, etc. Some veterinarians have seen something similar to EGC develop at the site where flea-control products have been applied to cats (eg imidacloprid, Advantage®, fipronil, Frontline®).

Inhaled allergies = Atopy=Atopic Dermatitis=Atopic Skin Disease

We know that far more dogs are allergic to things they breath than to things that they eat. We know much less about cats. Veterinarians an cat owners tend to focus on food allergies over inhaled allergens because food allergens are the only ones that can be readily eliminated from your pet’s life. Specialty cat food manufacturers heavily encourage that belief because those diets are highly profitable to them. Since these diets are restricted to sale by licensed veterinarians only, they serve as a revenue stream for veterinarians too.

There are specialty veterinarians who administer desensitization shots to allergic cats. The results are mixed. Some claim an optimistic 60-70% success rate after 3-12 months of injections. I am less optimistic about the success rate when dealing with EGC. ( read here ) Some of the antigens that have been implicated or suggested as being involved in EGC are house dust mites, pollens and molds.

Might This Sometimes Be An Autoimmune Or Misdirected Immune Disease?

An older research study found that 68% of cats with eosinophilic granuloma complex had antibodies in their system that were directed against the cat ‘s own skin. ( read here )  However, they were unable to determine if preexisting EGC was the cause of this antibody or if the antibody was the cause of EGC. These sort of phenomena also occur in humans. ( read here Another more recent study found indications that some cats with EGC might have actually become allergic (developed antibodies against) to their own saliva ! (read here) With a problem as difficult to deal with as EGC, theories abound.

Could  Other Infectious Organisms Be Involved?

The Feline herpes virus 1

Some time ago, two Washington State veterinarians reported that they had identified portions of the feline Herpes-1 virus in the eosinophilic granuloma lesions on the face and nose of cats. That is the same virus that cats routinely get vaccinated for to prevent respiratory disease. Herpes-1 virus was also identified in cheetahs that suffered from EGC. ( read here ) The problem is that that lingering virus usually first infects cats when they are very small kittens – some weeks before combination shots against feline Herpes-1 and other pathogens like panleukopenia are given. After one week at an animal shelter half the cats can be shedding Herpes-1. ( read here ) Like the human herpes viruses of fever blisters and chicken pox, once infection has occurred, vaccinations against them are valueless. So the fact that EGC cats showed evidence of feline herpes1 virus really doesn’t tell us much. Veterinarians at the University of Sydney found only 2 out of 30 cats with EGC-like disease were positive for feline herpes-1. They did point out that herpes-1 should be considered if your cat doesn’t respond to corticosteroids treatments for EGC. Veterinarians in Italy came to the same conclusion. (read here) When eosinophilic disease affect the cornea of your cat’s eye, perhaps herpes-1 is a more likely to be involved. That is where eye drops such as Viroptic® might be helpful.  

The Feline Immunodeficiency Virus

FIV virus does not cause EGC. But chronic inflamed areas of the mouth (chronic ulceroproliferative stomatitis) that might be confused with EGC can be a symptom of FIV virus infection in cats.  So an in-office  FIV/FLV test  is always a wise decision before treatment begins.

Calicivirus

Feline Calicivirus does not cause EGC either. But it is another infection that needs to be considered when dealing with ulcers within your cat ‘s mouth or on its tongue or skin because that virus has the potential to cause them as well.

What Are The Treatment Options For My Cat?

Aggressive And Persistent Flea Control

The first thing to do is to confine you cat to indoors. You will never succeed in completely ridding and in-and-out cat of its last flea no matter what chemicals you apply to the cat. None of these compounds kill instantly. And one flea bite can be sufficient to set off an allergic cascade. We know a lot more about allergic cascades in humans. Once they are triggered, the proceed on their own. ( read here ) We know that fleas and Eosinophilic Granuloma Complex go hand in hand. (read here)  So strict flea control must always be part of your plan. You can still apply one of the monthly flea control products (imidocloprid, fipronil, selamectin, spinosad, etc.)  Even if you have never see a single flea on you cat, if it develops EGC consider an aggressive flea control program essential. If you ever see tapeworms  in your cat assume fleas are present in its life. That is how the most common tapeworm of cats is spread. ( read here Every pet in your household (dogs,cats, ferrets, bunnies) need to be treated with appropriate flea control products – not just your cat with EGC.  

Corticosteroids

Almost all treatment plans for initial bouts of Eosinophilic granuloma complex will require a corticosteroid medication. You probably know the drawbacks of long-term corticosteroid administration – but one course of corticosteroids, given in appropriate amounts, is not going to harm an otherwise health cat. It will give your cat almost immediate relief, allow the lesions to heal and give you and your veterinarian time to devise a long-term plan. While your cat is receiving that medication, its appetite and thirst will increase. Limit its food to prevent weight gain – but do not limit its water intake. Eosinophils quickly dissipate when exposed to corticosteroids. So when oral or injectable corticosteroids, given at acceptable doses, fail to promptly improve the problem a biopsy is a wise choice. Perhaps you are dealing with a problem other than Eosinophilic Granuloma.

With repeated relapses of EGC, corticosteroids can be less effective and the dose required may be considerably larger. In those cases, be sure that you have tried all other common treatments. When you have and the EGC problem persists, don’t feel guilty about it – many humans, faced with autoimmune disease or organ transplants take corticosteroids for their entire life. They have just made the decision that the potential side effects of corticosteroid medications are less important than what they would be facing without them.

Many veterinarians rely on one or two injections of a long acting corticosteroid called methyprednisolone acetate (Depomedrol® or just “Depo”) to bring EGC lesions under control. If further corticosteroids are required, they are generally given in tablet form. Prednisolone is the most common one used. Generally , those tablets are not given daily – at least not after the first 7 days. The break between tablets is to help prevent a decrease in your cat’s adrenal glands to produce its own natural corticosteroid, cortisol. Others prefer triamcinolone. All cats receiving long term corticosteroids need close monitoring and periodic check ups to catch potential side effects early.

When you cat is receiving long-term corticosteroids, its appetite will probably increase and it may gain weight. Make a determined effort to avoid that weight gain by feeding only the amount of food (calories) that maintains a healthy body weight. Fat cats are at a much higher risk of developing diabetes. ( read here )

Lower The Stress In Your Cat’s Life

Stress makes most diseases worse. The biggest stressors for cats are other cats in the household. This is particularly true in cats that develop skin disease due to over grooming (psychogenic alopecia/dermatitis). Try to remember that what you and I find stressful or enjoyable might be quite different than your cat ‘s feeling in the same situation.

A Trial Course Of Antibiotics

Few if any veterinarians believe that EGC is caused by bacterial infections. It is true that almost all EGC lesions are colonized by bacteria – but those bacteria are just opportunists living in superficial tissue layers rich in dead and devitalized tissue. It is certainly not helpful to your cat for them to be there and allergies to staphylococcus bacteria have been known to occur. So I see not problem with including antibiotics in your cat’s EGC therapy. There is a report of cats with EGC improving when antibiotics were the only medical treatment they received. But they received flea control products during the study as well. ( read here Another possible rational for giving antibiotics is that high doses of corticosteroids and other immunosupressive drugs lower your cat’s resistance to infection and antibiotic “cover” (protection) in those situations might be desirable. Besides the Clavamox®/Augmentin® (amoxicillin + clavulanic acid) mentioned in the prior reference your veterinarian might administer periodic Convenia® (cefovecin) antibiotic injections or rely on doxycycline. Doxycycline is in the tetracycline family of drugs; and those drugs are known to sometimes have beneficial effects in allergic conditions. No one knows why. ( read here ) Pets receiving doxycycline tablets or capsules of any kind need to be given water or food by hand immediately thereafter to prevent the doxycycline from causing inflammation to their esophagus. 

A Trial Period For Your Cat On A New Diet

Changing your cat ‘s diet for 8-10 weeks is something simple you can try that really has no down side. I generally suggest you make the diet at home if you have the time. I would base it on Cornish hens to begin with because that has worked so well for cats with IBD and for now, feed without supplements or additions. Buy a meat blender and include the finely ground up bones as well to provide adequate calcium. American “Cornish hens” are actually just chickens that are less than 5 weeks old and by USDA rules must weight 2 lbs/1 kg or less. So their ground up bones are still quite soft and digestible. If the diet improves your cat’s health, start adding necessary vitamins and other ingredients after that one-by-one, no more than one added per week, and observe if the problem returns. You never know how those supplemental products will affect them so I begin without them. You can read some suggestions on preparing a diet for your cat here. I would not feed a home-prepared diets raw – particularly if the cat is also on corticosteroids or other immunosuppressive drugs as those medications can decrease a cat’s ability to handle things like toxoplasma and salmonella Alternatively, use one of the hypoallergenic cat diets in which antigenic particles have been destroyed (hydrolyzed protein) such as HA®, z/d® etc. However a lot of cats refuse to eat it.

Avoiding Potential Contact Allergens As Best You Can

Pet owners and some veterinarians believe that things in your pet’ environment might be a  trigger for EGC.  Since it is only a modest effort, you might consider changing the brand of your detergents, home cleaning products, pet bedding, cat litter etc.  Some veterinarians suggest substituting stainless steel or ceramic food and water dishes for those made of plastic.  If your cat’s condition improves, perhaps that helped, perhaps it didn’t, but little was lost in the effort.

Progestational Hormonal Drugs

These are the hormone preparations associated with reproduction. The most common ones once given to cats with EGC is medroxyprogesterone acetate  (Depopovera®) and Megesterol  acetate (Megace®/Ovaban®). They will, without a doubt, put most cases of EGC into remission. However their effect is no better than giving intermittent corticosteroids like prednisolone orally and their side effects are probably considerably worse. In cats, weight gain, diabetes and the potential for malignant mammary tumors are the most well known side effect. Sometimes the cat’s blood sugar level returns to normal when these drugs are discontinued; but sometimes it doesn’t.

Cyclosporine = Atopica®

This immunosuppresant drug is sometimes offered as  an alternative to long term corticosteroid medications. Read more about it here. It is about as effective as prednisolone. But in my opinion its potential side effects are just as serious as long term prednisolone and other corticosteroids (just not the same ones). I would reserve it for cats that, after multiple flare ups, no longer respond to corticosteroids and environmental changes. Generic cyclosporin tastes exceptionally bad. Whenever you suppress your cat ‘s immune system, with cyclosporin-like drugs or corticosteroids, there is the danger of reactivating latent toxoplasmosis that could be a threat to your family’s health as well as your cat’s. Please, no raw meat diets or outside hunting for cats on those products. Read about toxoplasmosis here.

Chlorambucil

Chlorambucil (Leukeran®) is a drug used in human chemotherapy – primarily for people who have developed leukemia. Some veterinarians add it to a cocktail of steroids in a last ditch effort to cure cats with EGC that have not responded to other treatments. I have no experience using it and never intend to.

Special Collars  Elizabethan Collars

It is true that some cats with the skin form of EGC will improve if they are placed in Elizabethan collars with, or without topically applied corticosteroid sprays and ointments or lotions. I just find these sort of restraints too stressful for most cats to wear. 

Topical Corticosteroid Sprays Creams And Lotions

I have not found them to be very effective. First, cats tend to lick them off quickly. So whatever corticosteroid content these products (eg GentaSpray®)  contain is probably absorbed through their intestines, not their skin. Secondly, they do not seem to penetrate deep enough into the lesions to resolve them. 

Surgery (Rarely the answer)

The only time I suggest that EGC affected areas be surgically removed from your cat or cauterized is when they are present in its mouth and when they are preventing your cat from eating. Even then, I would not consider it until all traditional medications have failed to shrink the lesions. If performed, I would suggest  cryosurgery, radiation therapy or perhaps laser surgery to shrink the lesion . With all those procedures, relapse is quite likely because the underlying problem has not been addressed.

When faced with a stubborn eosinophilic granuloma affecting your cat’s cornea, surgical debridement  (scraping) is a much more accepted treatment.

A Home Change

If you and your cat are faced with a lifetime of EGC problems, perhaps you should consider finding it another quite different but happy home or perhaps a complete lifestyle makeover for both you and your cat. I explained to you that there is probably a large environmental component in determining which cats develop EGC and which do not.

I once owned a cat named Bubbles. When she was about 3 years old, she developed her first bout of EGC. I had met an old veterinarian some years before who told me that a cat was once brought to him with EGC. Being busy at the time, he had his kennel boy place the cat in his upstairs kennel. The cat then slipped from his mind as several weeks went by. When he finally remembered the cat and had it brought down for an examination, he found that the EGC lesions had all disappeared. When our  cat, Bubbles, developed lip ulcers, I would place her in my second story hospital cattery. She was obviously unhappy there. But invariably within a month, her EGC problems resolved without medications. I do not know why – most likely whatever was causing the problem in our home environment was not present at my animal hospital. I am not suggesting that this works for every cat with EGC – but it worked for Bubbles.

Scientifically Unproven Remedies

When you are dealing with a problem like EGC that naturally waxes and wanes (naturally increases and decreases in severity)  it can be difficult to decide if improvement was due to the medications you administered to your cat or if it would have gotten better on its own. These natural ups and downs of EGC cats probably explain why unproven, far-fetched or outlandish treatments sometimes appear to work. I personally have no faith in them. Cortisol is your cat’s natural corticosteroid. Its level in the body fluctuates based on many factors. (read here  &  here ) When scientifically unproven remedies do work, it might just be that they raised your cat’s cortisol level.  

For Instance:

An Israeli vet cures her EGC cases by administering a homeopathic snake venom remedy. 

Some vets administer alpha-Interferon and claim improvement.

Some veterinarians administer gold salts and claim improvement.

Some give compounds known as “Immunomodulator” that include levamasole and concoctions of homogenized bacteria (bacterins) and claim improvement.

Some veterinarians apply DMSO to EGC lesions and claim improvement.

Antihistamines And Fatty Acid Supplements

I put antihistamines and fatty acid supplements (eg EFAs, Derm® Capsules etc.) here as well. I have not been impressed with the effects of either when dealing with EGC. The exception might be Periactin® (cyproheptadine) antihistamine which seems to have a calming effect on most cats and might aid in relieving stress. It , like corticosteroids, can also give cats the munchies (increased appetite) and occasionally it will have a reverse effect on cats and cause agitation. Cats on a bizarre, unbalance diet that does not contain sufficient EFAs might benefit from an EFA supplement.

Will My Cat Face This Problem Again?

There are veterinarians who will tell you that your cat ‘s EGC problem will not return when we find the underlying cause or causes and eliminate them from its life. Unfortunately in the majority of cases even veterinary dermatology specialists are never entirely certain what those underlying causes include. There are a few cases where extensive skin testing discovers one or more possible underlying causes. But in many more cats, multiple changes you make in your cat’s lifestyle leave those and other problems behind – whatever they may have been. Veterinarians cannot predict which cats will have a single bout of EGC and which will have many throughout their lifetime. We do know that those that have had more than one attack are more likely to have many more during their lifetime.

If you care to write to me about your experiences facing EGC in your cat, I will set up a cat owners experience page for EGC.

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