Eosinophilic granuloma complex (EGC)

Eosinophilic granuloma complex, commonly abbreviated as EGC, is a group of inflammatory skin conditions in cats characterized by an accumulation of eosinophils, a type of white blood cell associated with allergic and parasitic responses. The complex encompasses three distinct but related clinical presentations: the eosinophilic or indolent ulcer, the eosinophilic plaque, and the eosinophilic granuloma. These conditions share a common underlying inflammatory process but present differently in terms of location, appearance, and behavior. EGC is one of the most common skin conditions seen in cats and can cause significant discomfort and disfigurement if not properly managed.

The underlying cause of eosinophilic granuloma complex is most commonly an allergic reaction, with flea allergy, food allergy, and environmental allergies being the most frequently implicated triggers. In these cases, the eosinophilic skin lesions represent the cat's abnormal response to an allergic stimulus. However, some cases occur without identifiable allergic triggers and are considered idiopathic. The eosinophilic response, while normally a component of the body's defense against parasites and allergens, becomes pathological in EGC, causing tissue damage rather than protection. Understanding the allergic nature of most cases is crucial for effective long-term management.

The impact of eosinophilic granuloma complex on affected cats varies depending on the type and severity of lesions. Eosinophilic ulcers, typically affecting the upper lip, can be cosmetically disfiguring and may interfere with eating if severe. Eosinophilic plaques cause intense itching and discomfort, often prompting cats to traumatize the affected areas through licking and scratching. Eosinophilic granulomas can occur in various locations including the skin, oral cavity, and footpads, and may cause pain, swelling, or difficulty eating or walking depending on their location. Some cats have recurrent or chronic disease that significantly affects their quality of life.

Eosinophilic granuloma complex is generally manageable with appropriate veterinary care, although some cases prove challenging to control. Treatment typically involves addressing any underlying allergic triggers along with anti-inflammatory therapy to resolve the eosinophilic lesions. Many cases respond well to initial treatment, but recurrence is common if the underlying allergic cause is not identified and controlled. The prognosis varies from excellent for cases with identifiable, avoidable triggers to guarded for cats with severe, recurrent, or idiopathic disease. Early veterinary evaluation and comprehensive management offer the best outcomes for cats with this frustrating but treatable condition.

The primary causes of eosinophilic granuloma complex are allergic reactions that trigger an abnormal accumulation of eosinophils in the skin. Flea allergy dermatitis is one of the most common underlying causes, with hypersensitivity to flea saliva prompting the eosinophilic response even in cats with minimal visible flea burden. Food allergy, particularly to protein sources in the diet, is another frequent trigger. Environmental allergies, or atopic dermatitis, caused by sensitivity to pollens, dust mites, molds, and other environmental proteins, can also result in EGC lesions. In some cases, multiple allergies may be present concurrently, complicating identification of specific triggers.

Genetic factors appear to play a role in eosinophilic granuloma complex, although the specific inheritance pattern has not been clearly defined. The condition seems to run in certain family lines, suggesting a genetic predisposition to developing the abnormal eosinophilic response. Some cats may have inherited differences in immune system regulation that make them more prone to eosinophil-mediated inflammation. Female cats appear to be affected more commonly than males in some studies, although both sexes can develop the condition. Certain breeds may have higher prevalence, suggesting breed-specific genetic factors. However, EGC occurs across all breeds and mixed breed cats as well.

Environmental and lifestyle factors influence both the development of EGC and the frequency of flares in affected cats. Exposure to fleas, even minimal exposure in highly sensitive cats, can trigger or exacerbate lesions. Indoor versus outdoor lifestyle affects exposure to different allergens, with indoor cats more exposed to dust mites and molds while outdoor cats have greater pollen exposure. Geographic location determines the types and seasonal patterns of environmental allergens. Dietary factors are important because food allergies can only develop after exposure to specific dietary proteins. Stress may exacerbate symptoms in some cats, potentially through effects on immune regulation.

Risk factors for developing eosinophilic granuloma complex include pre-existing allergic conditions and individual immune system characteristics. Cats with a history of other allergic manifestations, such as atopic dermatitis or food allergies presenting as gastrointestinal disease, may be at increased risk for developing EGC lesions. Young to middle-aged cats are most commonly affected, with lesions often first appearing between two and six years of age. Prior episodes of EGC increase the risk of future recurrences. Cats in environments with high allergen loads, whether from fleas, environmental allergens, or potentially allergenic foods, have increased exposure to potential triggers.

The mechanism underlying eosinophilic granuloma complex involves dysregulated eosinophil recruitment and activation in response to allergens or, in idiopathic cases, unknown stimuli. When an allergic cat is exposed to a triggering allergen, the immune response includes production of cytokines that attract eosinophils to the site of allergen contact. In cats prone to EGC, this eosinophil recruitment is excessive and the eosinophils become activated, releasing their granule contents including enzymes and toxic proteins. These substances cause local tissue damage and perpetuate inflammation, leading to the characteristic lesions. The specific pattern of lesion development, whether ulcer, plaque, or granuloma, may depend on the location, chronicity, and specific characteristics of the inflammatory response in that individual cat.

Early warning signs of eosinophilic granuloma complex depend on the type of lesion developing but often include subtle changes that may initially escape notice. Cats developing eosinophilic plaques may begin scratching or licking particular areas with increased frequency before visible lesions appear. Early lip changes that will become indolent ulcers may appear as slight redness or swelling of the upper lip margin. Owners may notice their cat spending more time grooming certain body areas. Mild behavioral changes such as restlessness or decreased playfulness may reflect emerging discomfort. Because cats are adept at hiding signs of illness and discomfort, these early signs often go unrecognized until more obvious lesions develop.

The three types of lesions in eosinophilic granuloma complex have distinct presentations. Eosinophilic ulcers, also called indolent ulcers or rodent ulcers, typically appear on the upper lip, often adjacent to the philtrum. These lesions present as well-defined, shallow to deep ulcers with raised edges and a reddish-brown center. They are usually not itchy or painful, and affected cats may not show obvious discomfort despite significant disfigurement. Eosinophilic plaques are raised, red, moist, and intensely itchy lesions that most commonly affect the abdomen and inner thighs. They have a characteristic appearance of well-defined, eroded plaques with a cobblestone or granular surface. Eosinophilic granulomas present as firm, raised, yellowish to pink nodules or linear lesions and can occur on the skin, oral cavity, footpads, and other locations.

Behavioral changes associated with EGC reflect the nature and location of the lesions. Cats with eosinophilic plaques typically exhibit intense scratching and licking of affected areas, often to the point of causing self-trauma. They may be restless and unable to settle comfortably. Cats with oral granulomas may have difficulty eating, drool excessively, or show reluctance to groom. Those with footpad involvement may limp or be reluctant to walk on hard surfaces. Even cats with indolent ulcers, which are typically not painful, may show subtle behavioral changes. General irritability, hiding, or decreased interaction with family members may indicate discomfort from any type of EGC lesion.

Physical signs of eosinophilic granuloma complex vary by lesion type but include characteristic findings on examination. Eosinophilic ulcers on the lip may cause visible asymmetry of the face and can be quite disfiguring in advanced cases. The ulcerated area may have a yellow-brown or white center with distinct raised edges. Eosinophilic plaques appear as raised, red, often weepy areas that may be surrounded by hair loss from the cat's licking. They commonly have a characteristic geographic or map-like outline. Eosinophilic granulomas may present as firm nodules, elongated linear lesions on the back of the thighs, or swollen chins. Oral granulomas appear as raised masses on the tongue, palate, or other oral structures. Regional lymph node enlargement may be palpable in some cases.

Symptom progression in EGC varies depending on the lesion type and whether the underlying cause is addressed. Untreated eosinophilic ulcers typically remain stable or slowly enlarge over time, potentially causing significant disfigurement of the lip. Eosinophilic plaques may expand in size and number, and intense self-trauma can lead to secondary bacterial infection. Eosinophilic granulomas may gradually enlarge if untreated. With appropriate treatment, lesions typically begin to improve within weeks, although complete resolution may take longer. Without identification and control of the underlying allergic trigger, recurrence after treatment discontinuation is common.

While eosinophilic granuloma complex is not typically a medical emergency, certain situations warrant prompt veterinary attention. Large oral lesions that interfere with eating or breathing should be evaluated urgently. Severely infected secondary to trauma requires treatment to prevent systemic spread of infection. Rapidly enlarging lesions, while usually still benign, should be examined to rule out other conditions. Any lesion that does not respond to appropriate treatment or that has an unusual appearance may require biopsy to confirm the diagnosis and rule out other conditions including neoplasia. Cats showing signs of systemic illness such as fever, lethargy, or significant weight loss along with skin lesions need comprehensive evaluation.

Diagnosis of eosinophilic granuloma complex typically begins with recognition of the characteristic clinical appearance of the lesions during veterinary examination. The three presentations of EGC have sufficiently distinct appearances that experienced veterinarians can often make a presumptive diagnosis based on physical examination. However, confirmation through cytology or histopathology is recommended, particularly for atypical lesions or those not responding to initial treatment. A thorough history is obtained, including information about flea prevention, diet, environmental exposures, previous skin problems, and any family history of skin disease. The veterinarian will also assess for concurrent signs of allergic disease that might suggest the underlying trigger.

Diagnostic testing for EGC often includes cytology and may include skin biopsy for histopathology. Cytology, obtained by impression smears or fine needle aspiration of the lesion, typically reveals numerous eosinophils along with other inflammatory cells, bacteria if secondary infection is present, and sometimes mast cells. This quick, inexpensive test can support the diagnosis and guide initial treatment. Skin biopsy with histopathological examination provides definitive diagnosis and is particularly valuable for atypical lesions or those not responding to treatment. Histopathology reveals eosinophilic inflammation and can help rule out other conditions such as neoplasia. Bloodwork may be performed to assess overall health and may reveal peripheral eosinophilia, although this finding is inconsistent.

Differentiating EGC from other conditions is important because several diseases can produce similar-appearing lesions. Squamous cell carcinoma can present as ulcerative lip lesions similar to eosinophilic ulcers, making biopsy important for any atypical or non-responsive lip lesion. Other neoplastic conditions can mimic EGC nodules or plaques. Infectious causes of nodular or ulcerative skin disease, including fungal infections and mycobacterial disease, must be considered. Autoimmune skin diseases can produce similar lesions in some cases. Other causes of ulcerative or plaque-like skin lesions should be considered in the differential diagnosis. Histopathology is the most reliable way to confirm the diagnosis and exclude other conditions.

Once EGC is confirmed, investigation of the underlying cause, particularly allergic triggers, is important for long-term management. A strict flea control trial should be implemented even in cats without visible flea evidence, as flea allergy is a common trigger. Food elimination trials using a novel protein or hydrolyzed diet for eight to twelve weeks help identify food allergy as a cause. If flea control and food trial do not identify the trigger, environmental allergy testing may be pursued through intradermal skin testing or serology. In some cases, no specific trigger is identified despite thorough investigation, and these idiopathic cases are managed symptomatically. Identifying the underlying cause, when possible, allows for more targeted long-term management and reduces reliance on immunosuppressive medications.

Initial treatment of eosinophilic granuloma complex often involves corticosteroids to rapidly reduce inflammation and allow lesion healing. Corticosteroids can be administered as injections, typically long-acting depot formulations such as methylprednisolone, or as oral medications such as prednisolone. Injectable corticosteroids provide convenience and reliable drug delivery but offer less dosing flexibility than oral medications. Response to corticosteroid therapy is often rapid and dramatic, with significant lesion improvement within days to weeks. However, corticosteroid treatment alone does not address the underlying cause, and lesions typically recur when the drug effect wears off unless the trigger is identified and controlled.

Long-term medical management of EGC focuses on controlling symptoms while minimizing medication side effects, and ideally addressing the underlying allergic cause. For cats with identified allergic triggers, allergen avoidance or specific treatment is the primary approach. Strict lifelong flea control is essential for cats with flea allergy. Dietary management with avoidance of identified food allergens helps food-allergic cats. Environmental allergen reduction, while difficult to achieve completely, may help atopic cats. For cases requiring ongoing immunosuppressive therapy, cyclosporine is an alternative to long-term corticosteroids with a different side effect profile. Antihistamines may provide partial benefit as adjunctive therapy. Essential fatty acid supplementation may have mild anti-inflammatory effects and support skin health.

Surgical intervention is occasionally considered for eosinophilic granuloma complex but is not a primary treatment modality. Surgical excision of granulomas may be performed if lesions are discrete and in locations amenable to surgery, but recurrence is common if the underlying cause is not addressed. Laser ablation or cryosurgery has been used for some lesions with variable success. Surgery is more appropriately considered when biopsy is needed to confirm diagnosis or rule out neoplasia. The mainstay of treatment remains medical management rather than surgical removal.

Supportive care measures help maintain skin health and comfort in cats with EGC. Managing secondary bacterial infections with appropriate antibiotics prevents worsening of lesions and systemic spread. Keeping affected areas clean and protected from further trauma supports healing. Elizabethan collars may be needed for cats causing significant self-trauma through licking or scratching eosinophilic plaques. Nutritional support with a high-quality diet supports overall skin health and immune function. Environmental management to reduce exposure to identified allergens or potential triggers contributes to long-term control.

Alternative and complementary treatments have been explored for eosinophilic granuloma complex with varying levels of evidence. Omega-3 fatty acid supplementation may have modest anti-inflammatory effects and is generally safe. Allergen-specific immunotherapy, while a conventional treatment for allergies, may help reduce EGC flares in cats with environmental allergies. Some practitioners use traditional Chinese medicine or herbal therapies, although evidence for efficacy is limited. Interferon therapy has shown promise in some studies. These alternative approaches should not replace proven conventional treatments but may be considered as adjuncts under veterinary guidance.

Treatment decisions for EGC consider multiple factors including lesion severity, presence of identifiable triggers, response to previous treatments, and owner factors. Mild cases with identifiable triggers may be managed primarily through allergen avoidance with minimal medication. Moderate to severe cases typically require immunosuppressive therapy, at least initially. The choice between corticosteroids and alternative immunosuppressants depends on the expected duration of treatment, the cat's other health conditions, and potential side effects. Cost is a consideration, as long-term cyclosporine therapy is more expensive than corticosteroids. Lifestyle factors, including the owner's ability to administer oral medications or pursue dietary trials, influence treatment planning. The goal is to achieve disease control with the minimum effective intervention.

Recovery from eosinophilic granuloma complex episodes depends on the type of lesion, severity, and effectiveness of treatment. Eosinophilic ulcers typically show visible improvement within two to four weeks of effective treatment, with complete resolution taking six to eight weeks or longer for severe lesions. Eosinophilic plaques often respond more rapidly, with decreased itching within days and visible healing within one to two weeks. Eosinophilic granulomas are often slower to resolve, potentially requiring months for complete regression. The underlying tissue changes may take longer to normalize than the visible lesion, and patience is needed during the healing process.

Post-treatment care for EGC involves monitoring for complete lesion resolution and watching for recurrence. Any medications prescribed should be administered according to the veterinarian's instructions, with gradual tapering of corticosteroids rather than abrupt discontinuation. Follow-up veterinary appointments assess healing and allow for treatment adjustment if needed. Ongoing implementation of allergen avoidance measures, including flea control and dietary management if applicable, helps prevent recurrence. Owners should monitor for any return of symptoms and report changes promptly. Complete healing may leave some residual changes such as hair loss or minor scarring, particularly with severe lesions.

Prognosis for cats with eosinophilic granuloma complex varies based on the underlying cause and response to treatment. Cats with identifiable, avoidable triggers such as flea allergy or specific food allergies have excellent long-term prognosis when allergens are successfully avoided. Cases responsive to treatment but without identified triggers have guarded prognosis for long-term control, as recurrence is likely when treatment is discontinued. Some cats require lifelong intermittent or continuous therapy to maintain disease control. Severe or refractory cases may have more guarded prognosis. The prognosis for any individual cat depends on response to treatment trials and ability to manage underlying allergic disease.

Long-term outlook for cats with EGC requires acceptance of the chronic, often recurrent nature of the condition. Some cats achieve long-term remission with identification and avoidance of allergic triggers. Others require ongoing management with periodic treatment of flares or continuous low-dose therapy. Quality of life can be excellent for well-managed cats, with minimal impact on daily activities between flares. The condition is not life-threatening in most cases, and affected cats can live normal lifespans with appropriate care. Success requires commitment to ongoing monitoring, prompt treatment of recurrences, and long-term allergen management when applicable.

Primary prevention of eosinophilic granuloma complex focuses on preventing or minimizing allergic sensitization, which is challenging because allergies develop from complex interactions between genetic susceptibility and environmental exposure. Strict flea prevention for all cats, regardless of lifestyle, reduces the risk of developing flea allergy, which is a common trigger for EGC. Early-life dietary management, while not proven to prevent food allergies, involves feeding high-quality diets and potentially limiting exposure to a wide variety of protein sources. Minimizing exposure to known common allergens in the environment, while impractical to achieve completely, may reduce sensitization risk. For cats with family history of EGC or allergic disease, extra vigilance and proactive allergen prevention may be warranted.

For cats with established EGC, preventing recurrence focuses on identifying and controlling allergic triggers. Lifelong, consistent flea prevention using effective products is essential for cats with flea allergy, even when no fleas are visible. Strict dietary compliance with avoidance of identified food allergens prevents food allergy-related flares. Environmental allergen reduction through air filtration, frequent cleaning, and humidity control may help cats with environmental allergies. For cats on allergen-specific immunotherapy, continuing treatment as prescribed helps maintain tolerance. Regular grooming to remove environmental allergens from the coat may reduce allergen contact.

While dietary factors do not specifically prevent EGC, nutrition supports overall skin health and immune function. Feeding a high-quality, balanced diet provides nutrients necessary for skin barrier function and healthy immune responses. Omega-3 fatty acid supplementation may support skin health and have mild anti-inflammatory effects. For cats with suspected food allergies, working with a veterinarian to identify safe diets prevents inadvertent exposure to triggers. Maintaining healthy body weight through appropriate feeding supports overall health. Any dietary changes should be made gradually and under veterinary guidance.

Regular health maintenance supports early detection and management of EGC. Routine veterinary examinations allow for monitoring of skin health and early identification of developing lesions. Regular home monitoring by owners, including observation for increased scratching or grooming and inspection of common lesion sites, catches problems early. Consistent use of prescribed preventive medications, including flea prevention and any allergen immunotherapy, maintains protection. Prompt veterinary attention for any new skin changes allows for early intervention before lesions become severe.

Early intervention when EGC flares occur prevents lesion progression and reduces overall treatment burden. Owners should learn to recognize early signs of lesion development and seek veterinary attention promptly. Having a relationship with a veterinarian familiar with the cat's history allows for efficient flare management. For cats with frequent recurrences, having treatment protocols in place allows for rapid response. Early treatment of developing lesions typically requires shorter courses and lower doses of medication than treatment of established, severe lesions. Proactive management optimizes outcomes for cats with recurrent EGC.

Daily management for cats with eosinophilic granuloma complex involves consistent implementation of preventive measures and ongoing monitoring for disease activity. Flea prevention should be administered reliably according to the product schedule, as even brief lapses can allow flea exposure that triggers flares in sensitive cats. Cats on prescription diets for food allergy management must be kept strictly on the diet without exposure to other foods, including treats and flavored medications unless approved by the veterinarian. Daily observation for signs of itching, lesion development, or behavioral changes indicating discomfort allows for early detection of problems. Monitoring specific sites where the cat has previously developed lesions helps catch recurrence early.

Creating an optimal home environment supports cats with EGC, particularly those with environmental allergies. Air filtration with HEPA filters reduces airborne allergens. Regular vacuuming with HEPA-filtered vacuum cleaners and frequent washing of cat bedding reduces environmental allergen accumulation. Maintaining indoor humidity below fifty percent discourages dust mites. Minimizing clutter that accumulates dust reduces allergen reservoirs. For cats with outdoor access, limiting time outside during peak pollen seasons may reduce exposure. Keeping the indoor environment clean and well-ventilated supports overall respiratory and skin health.

Maintaining quality of life for cats with EGC requires balancing disease management with normal daily activities. Most cats with well-controlled EGC can participate in all normal activities without restrictions. Providing environmental enrichment including play, climbing structures, and mental stimulation maintains wellbeing. Regular, gentle grooming helps remove environmental allergens from the coat and allows owners to inspect the skin. Maintaining consistent routines reduces stress, which may exacerbate symptoms in some cats. Ensuring comfortable resting areas and access to resources supports overall wellbeing. The goal is for disease management to be integrated into normal life rather than dominating it.

Ongoing monitoring and veterinary care are essential components of long-term EGC management. Regular veterinary check-ups allow for professional assessment of disease control and adjustment of management strategies. Owners should know which symptoms indicate stable disease versus developing flare and when to seek veterinary attention. Keeping records of flares, treatments, and responses helps identify patterns and optimize management. Communication with the veterinary team about concerns, challenges with treatment compliance, or changes in the cat's condition ensures appropriate care. For complicated cases, referral to a veterinary dermatologist provides specialized expertise.

Support for owners managing a cat with eosinophilic granuloma complex addresses both practical and emotional aspects of long-term disease management. The financial burden of ongoing prevention, monitoring, and treatment of flares can be significant, and discussing cost concerns with the veterinary team helps identify cost-effective management strategies. The frustration of managing a chronic, recurrent condition is normal, and understanding that many cases can be well-controlled with appropriate management provides perspective. Online support groups and forums for owners of cats with skin disease can provide practical tips and emotional support. Celebrating periods of disease control and focusing on the cat's quality of life between flares maintains a positive outlook.

While eosinophilic granuloma complex can occur in cats of any breed, some evidence suggests certain breeds may have increased susceptibility. Norwegian Forest Cats have been reported to have higher incidence of EGC in some studies. Siamese and other Oriental breeds may also be at increased risk according to some reports. Domestic shorthair cats, being the most common cats overall, account for many cases, but whether they have truly increased risk relative to their population proportion is unclear. Female cats appear to be affected more frequently than males in some studies, although both sexes can develop the condition. The breed associations reported in the literature are not consistent across all studies, and further research is needed to clarify breed predispositions.

Mixed breed cats commonly develop eosinophilic granuloma complex, and no cat is immune to the condition based on breed status. The primary determinants of EGC development appear to be individual immune system characteristics and exposure to allergic triggers rather than breed-specific factors. Cats with personal or family history of allergic disease, including atopic dermatitis or food allergies, may be at increased risk regardless of breed. Young to middle-aged cats, typically between one and six years of age, are most commonly affected. The condition can occur at any age, including in kittens and senior cats, but the typical age of onset falls within this young adult to middle-aged range.

Screening recommendations for EGC relate more to individual risk factors than breed-specific testing. For cats from lines known to produce affected individuals, monitoring for skin changes and early veterinary evaluation of any suspicious lesions is prudent. Implementing thorough flea prevention for all cats, but especially those with family history of allergic disease, may reduce the risk of flea allergy-related EGC. Prospective owners of breeds suggested to have increased EGC risk should be informed of the possibility and prepared for potential long-term management needs. Breeders observing patterns of EGC in their lines should consider this in breeding decisions, although complete elimination of susceptibility from breeding populations is not currently feasible given the complex genetics involved.

Eosinophilic granuloma complex commonly occurs in association with other allergic conditions, reflecting the underlying allergic predisposition of affected cats. Atopic dermatitis, caused by environmental allergens, frequently occurs concurrently with EGC and may be the underlying trigger for eosinophilic lesions. Food allergy is another common concurrent condition that can cause EGC lesions along with other manifestations such as gastrointestinal symptoms. Flea allergy dermatitis is strongly associated with EGC and is one of the most common underlying triggers. Some cats have multiple allergies present simultaneously, complicating identification of specific triggers. Comprehensive allergy evaluation and management addresses all contributing factors for optimal EGC control.

Several conditions may be confused with eosinophilic granuloma complex and must be differentiated for appropriate management. Squamous cell carcinoma, particularly on the lip or oral cavity, can closely resemble eosinophilic ulcers or granulomas, making biopsy important for definitive diagnosis of atypical or non-responsive lesions. Other neoplastic conditions, including mast cell tumors and lymphoma, can produce skin masses that might be confused with granulomas. Infectious skin diseases, including cryptococcosis, sporotrichosis, and mycobacterial infections, can cause nodular or ulcerative lesions. Autoimmune skin diseases may produce similar clinical appearances. Biopsy with histopathology is the most reliable way to confirm EGC and exclude these differential diagnoses.

Complications of eosinophilic granuloma complex primarily involve secondary changes from chronic inflammation or self-trauma. Bacterial infection of eosinophilic plaques can occur from constant licking and scratching, requiring antimicrobial treatment. Significant self-trauma may cause scarring or permanent hair loss in affected areas. Chronic or severe lip ulcers may cause disfigurement even after healing. Oral granulomas, if large, can interfere with eating and cause weight loss. Footpad granulomas can lead to lameness and difficulty walking. These complications underscore the importance of prompt, effective treatment and long-term disease management to prevent progression to these secondary problems.