Stomatitis

Stomatitis is a general term denoting inflammation of the oral mucosa, encompassing the lips, buccal mucosa, tongue, gingiva, and hard/soft palate. In veterinary medicine, it is often classified into focal, multifocal, or generalized forms, with chronic ulcerative paradental stomatitis (CUPS) being a severe variant in dogs, and feline chronic gingivostomatitis (FCGS) being a distinct, debilitating syndrome in cats. Stomatitis can be primary (idiopathic, immune-mediated) or secondary to systemic diseases, infections, toxins, or trauma. It is characterized by erythema, edema, ulceration, proliferation, and pain, leading to dysphagia, ptyalism, halitosis, and weight loss. The condition significantly impacts quality of life and requires a multimodal diagnostic and therapeutic approach.

The etiology of stomatitis is multifactorial. Primary causes include immune-mediated disorders (e.g., lymphocytic plasmacytic stomatitis, pemphigus vulgaris, bullous pemphigoid, systemic lupus erythematosus), viral infections (feline calicivirus, feline herpesvirus-1, feline immunodeficiency virus, feline leukemia virus, canine papillomavirus), bacterial infections (anaerobes, Pasteurella, Streptococcus, Staphylococcus, and periodontal pathogens like Porphyromonas), fungal infections (Candida albicans, Cryptococcus, Histoplasma, Blastomyces), parasitic infestations (Leishmania, Spirocerca lupi), toxic exposures (caustic agents, plants, drugs like methimazole, chemotherapeutics), nutritional deficiencies (niacin, riboflavin, vitamin C, zinc), and neoplastic conditions (squamous cell carcinoma, melanoma, fibrosarcoma, lymphoma). Traumatic causes include foreign bodies, dental disease, electrical cord burns, and thermal injury. In cats, FCGS is strongly associated with chronic viral infections, particularly calicivirus, and an exaggerated immune response to dental plaque. In dogs, CUPS is often linked to immune dysregulation and bacterial plaque accumulation.

Stomatitis occurs in both dogs and cats, with FCGS affecting up to 0.7% of feline patients, with a higher prevalence in purebred cats (e.g., Persian, Siamese, Abyssinian) and older cats (mean age 7-10 years). Canine stomatitis is less common but can affect any breed, with a predisposition in small breeds (e.g., Maltese, Cavalier King Charles Spaniel, Greyhound) for CUPS. No sex predilection is consistently reported. Viral stomatitis is more common in multi-cat households, shelters, and outdoor cats. Geographic variation exists for fungal and parasitic causes, such as histoplasmosis in the Mississippi River Valley and leishmaniasis in Mediterranean regions. Seasonal patterns may be seen with certain viral infections.

The pathophysiology of stomatitis involves a complex interplay of microbial, immunological, and inflammatory cascades. In FCGS, chronic viral infection (especially calicivirus) triggers a dysregulated T-cell response, with infiltration of lymphocytes and plasma cells into the oral mucosa. Pro-inflammatory cytokines (IL-1, IL-6, TNF-alpha) and matrix metalloproteinases are upregulated, leading to tissue destruction. Dental plaque acts as a bacterial reservoir, perpetuating inflammation. In CUPS, an abnormal immune response to plaque antigens results in ulcerative lesions. In immune-mediated diseases, autoantibodies target desmosomal or basement membrane proteins, causing acantholysis or subepithelial blistering. In infectious stomatitis, pathogens directly invade mucosal cells, causing cytolysis and inflammation. Systemic diseases (e.g., chronic kidney disease, diabetes mellitus) can impair mucosal immunity and healing. Pain and inflammation lead to decreased food intake, weight loss, and secondary nutritional deficiencies.

Predisposing factors include genetic susceptibility (breed predispositions), age (older cats), immunosuppression (FIV, FeLV, chronic corticosteroid use), concurrent systemic diseases (diabetes, renal disease), poor oral hygiene, dental calculus, and dietary factors (soft food, lack of abrasive texture). Environmental stress, overcrowding, and poor ventilation increase viral transmission. Certain drugs (e.g., methimazole, chemotherapeutics) can induce stomatitis. Nutritional deficiencies, especially B vitamins and zinc, compromise mucosal integrity. In cats, chronic calicivirus carriage is a major risk factor for FCGS.

Clinical signs vary with severity and cause. Early signs include mild erythema, halitosis, and increased salivation. As inflammation progresses, patients exhibit ptyalism (often blood-tinged), dysphagia, anorexia, weight loss, and pawing at the mouth. Oral examination reveals erythematous, edematous, ulcerated, or proliferative lesions on the gingiva, buccal mucosa, tongue, and palate. In FCGS, lesions are often bilateral and symmetrical, with severe inflammation of the caudal oral cavity (fauces, palatoglossal folds). In CUPS, ulcerative lesions are present at the gingival margin and may extend to the alveolar mucosa. Systemic signs include fever, lethargy, and lymphadenopathy. Chronic cases may develop periodontitis, tooth resorption, and oronasal fistulas. In severe cases, patients may become dehydrated and emaciated.

Differential diagnoses include: (1) Periodontal disease – characterized by gingivitis, calculus, and periodontal pockets, but inflammation is localized to gingiva and tooth-supporting structures; (2) Eosinophilic granuloma complex (in cats) – presents with raised, ulcerated plaques on lips, tongue, and palate, with histopathology showing eosinophilic infiltrate; (3) Squamous cell carcinoma – often a solitary, proliferative, or ulcerated mass, confirmed by biopsy; (4) Feline calicivirus infection – acute onset, with lingual ulcers and upper respiratory signs; (5) Feline herpesvirus-1 infection – associated with conjunctivitis and corneal ulcers; (6) Chronic kidney disease – oral ulceration due to uremia, with elevated BUN/creatinine; (7) Autoimmune diseases (pemphigus vulgaris, bullous pemphigoid) – vesiculobullous lesions, confirmed by histopathology and immunofluorescence; (8) Systemic lupus erythematosus – multisystemic signs, positive ANA; (9) Leishmaniasis – nodular or ulcerative lesions, with positive serology/PCR; (10) Toxic exposure – history of caustic ingestion, acute onset. Definitive diagnosis relies on history, clinical signs, laboratory tests, and biopsy.

The diagnostic approach begins with a thorough history and physical examination, including a complete oral examination under sedation or anesthesia. Step 1: Assess for systemic signs and obtain baseline bloodwork (CBC, biochemistry, urinalysis). Step 2: Perform viral testing in cats (FeLV/FIV serology, calicivirus PCR, herpesvirus PCR). Step 3: Obtain dental radiographs to evaluate for tooth resorption, periodontitis, or periapical disease. Step 4: Perform oral biopsy for histopathology and culture (aerobic/anaerobic) if infection is suspected. Step 5: Consider advanced imaging (CT, MRI) if neoplasia or deep tissue involvement is suspected. Step 6: In cases of suspected immune-mediated disease, perform immunofluorescence or ELISA for autoantibodies. Step 7: Rule out systemic diseases (renal, hepatic, endocrine) with appropriate tests. The algorithm emphasizes early biopsy to differentiate neoplastic and immune-mediated causes.

Hematology may reveal neutrophilia with a left shift in bacterial infections, lymphopenia in viral infections, or eosinophilia in parasitic or allergic conditions. Anemia may be present in chronic disease. Serum biochemistry may show hyperglobulinemia (especially in FCGS and leishmaniasis), hypoalbuminemia, and elevated liver enzymes in systemic disease. Azotemia (elevated BUN, creatinine) suggests renal disease. Electrolyte imbalances may occur due to dehydration. Urinalysis may reveal proteinuria, casts, or low urine specific gravity in renal disease. Blood gas analysis may show metabolic acidosis in severe systemic illness. Specific biomarkers: feline calicivirus PCR (RT-PCR) from oral swabs, FeLV antigen test, FIV antibody test, and feline herpesvirus PCR. In immune-mediated cases, antinuclear antibody (ANA) and anti-desmoglein antibodies may be positive. C-reactive protein (CRP) may be elevated in inflammatory conditions.

Radiography: Dental radiographs are essential to evaluate tooth roots, alveolar bone loss, and tooth resorption. Thoracic radiographs may be indicated if metastatic disease is suspected. Ultrasonography: Abdominal ultrasound may be useful to assess for systemic disease (e.g., hepatomegaly, lymphadenopathy). Computed Tomography (CT): CT of the head provides detailed assessment of the oral cavity, mandibular lymph nodes, and bone involvement, especially in neoplastic cases. Magnetic Resonance Imaging (MRI): MRI is superior for soft tissue contrast and can delineate deep tissue extension. Endoscopy: Oral endoscopy allows direct visualization and biopsy of lesions. Fluoroscopy: Not commonly used but may aid in assessing swallowing function.

Cytology: Fine needle aspirates of oral masses or lymph nodes may reveal inflammatory cells (neutrophils, lymphocytes, plasma cells, eosinophils) or neoplastic cells. Impression smears of ulcers may show bacteria, fungal organisms, or acantholytic cells. Histopathology: Biopsy is the gold standard. In FCGS, histopathology shows dense lymphocytic-plasmacytic infiltration, often with ulceration and fibrosis. In CUPS, ulcerative lesions with neutrophilic and plasmacytic infiltrate are seen. In immune-mediated diseases, acantholysis (pemphigus) or subepithelial clefting (bullous pemphigoid) is characteristic. Special stains (Gram, PAS, Giemsa) help identify infectious agents. Immunohistochemistry can differentiate T-cell vs. B-cell infiltrates.

Treatment is multimodal and tailored to the underlying cause. Emergency stabilization: Address dehydration and malnutrition with IV fluids (e.g., Lactated Ringer's solution at 40-60 ml/kg/day) and nutritional support (esophagostomy tube if anorexic). Pain management: Use opioids (buprenorphine 0.01-0.02 mg/kg q8-12h IV/SC, or fentanyl CRI 2-5 mcg/kg/hr) and NSAIDs (meloxicam 0.1 mg/kg q24h PO in dogs, but caution in cats; robenacoxib 1-2 mg/kg q24h PO in cats). Antimicrobial therapy: For bacterial infections, use amoxicillin-clavulanate (12.5-25 mg/kg q12h PO) or clindamycin (10-20 mg/kg q12h PO). For anaerobic coverage, metronidazole (10-15 mg/kg q12h PO). Antifungal therapy: For fungal stomatitis, itraconazole (5-10 mg/kg q24h PO) or fluconazole (5-10 mg/kg q24h PO). Immunosuppressive therapy: For immune-mediated stomatitis, use prednisolone (1-2 mg/kg q24h PO, tapering) or cyclosporine (5-10 mg/kg q24h PO). In refractory FCGS, consider feline interferon-omega (1 MU/kg q24h SC for 5 days, then q48h). Surgical intervention: Full-mouth or partial-mouth tooth extraction is the most effective treatment for FCGS, with reported improvement in 60-80% of cases. For CUPS, professional dental cleaning and extraction of affected teeth are recommended. Supportive care: Oral hygiene (chlorhexidine rinses 0.12% q12h), soft diet, and nutritional supplements (omega-3 fatty acids, vitamin B complex).

Prognosis depends on the underlying cause. For acute infectious stomatitis, prognosis is good with appropriate therapy. For FCGS, prognosis is guarded to fair; tooth extraction leads to significant improvement in many cats, but some require ongoing medical management. For CUPS, prognosis is fair with dental treatment and immunosuppressive therapy. For neoplastic causes, prognosis is poor to grave depending on tumor type and stage. Immune-mediated stomatitis can be controlled but often requires lifelong therapy. Negative prognostic indicators include severe systemic signs, weight loss, and lack of response to initial therapy.

Follow-up is essential. Re-check examinations should be performed at 2-4 weeks after initiation of therapy, then every 3-6 months. Serial bloodwork (CBC, biochemistry) is recommended to monitor for drug side effects (e.g., cyclosporine levels, renal/hepatic function). Dental radiographs should be repeated if dental disease is present. In FCGS, assess response to tooth extraction at 4-6 weeks. Adjust immunosuppressive doses based on clinical response and adverse effects. Long-term management includes regular dental cleanings, oral hygiene, and dietary modifications. Monitor for recurrence of lesions and systemic complications.

Pearls: (1) Always perform a thorough oral examination under anesthesia to fully assess lesions. (2) In cats with stomatitis, test for FeLV/FIV and calicivirus. (3) Early tooth extraction in FCGS can dramatically improve quality of life. (4) Use multimodal analgesia to manage oral pain. (5) Consider biopsy early to rule out neoplasia. Pitfalls: (1) Do not use NSAIDs in cats with renal disease or dehydration. (2) Avoid long-term corticosteroid use without a definitive diagnosis. (3) Do not overlook systemic diseases that may cause stomatitis. (4) Do not delay extraction in severe FCGS. (5) Avoid using chlorhexidine in cats with severe ulceration as it may cause irritation.

Based on Plumb's Veterinary Drug Handbook: (1) Amoxicillin-clavulanate: 12.5-25 mg/kg PO q12h for 7-14 days. (2) Clindamycin: 10-20 mg/kg PO q12h for 7-14 days. (3) Metronidazole: 10-15 mg/kg PO q12h for 7-14 days. (4) Itraconazole: 5-10 mg/kg PO q24h for 30-60 days. (5) Fluconazole: 5-10 mg/kg PO q24h for 30-60 days. (6) Prednisolone: 1-2 mg/kg PO q24h, tapering over 4-6 weeks. (7) Cyclosporine: 5-10 mg/kg PO q24h, adjust based on trough levels (target 300-500 ng/mL). (8) Feline interferon-omega: 1 MU/kg SC q24h for 5 days, then q48h for 30 days. (9) Buprenorphine: 0.01-0.02 mg/kg IV/SC q8-12h. (10) Meloxicam: 0.1 mg/kg PO q24h in dogs; in cats, 0.05 mg/kg PO q24h for up to 3 days, then 0.025 mg/kg q24h. (11) Robenacoxib: 1-2 mg/kg PO q24h for up to 6 days. (12) Chlorhexidine 0.12% oral rinse: apply to gingiva q12h. Adjust dosages in renal/hepatic impairment; contraindications include hypersensitivity, pregnancy, and concurrent use of nephrotoxic drugs.

Key studies: (1) A study by Lommer (2013) demonstrated that full-mouth extraction in cats with FCGS resulted in clinical remission in 60% of cases, with 80% showing improvement. (2) A consensus statement from the American Veterinary Dental College (AVDC) recommends tooth extraction as the first-line treatment for FCGS. (3) A study by Hennet et al. (2011) showed that medical management with cyclosporine and prednisolone was less effective than extraction. (4) A study by Southerden and Gorrel (2007) reported that CUPS in dogs responds well to dental scaling and extraction of affected teeth. (5) A meta-analysis by Winer et al. (2017) found that feline calicivirus is a major etiologic agent in FCGS. (6) The ISCAID guidelines (2019) recommend antimicrobial stewardship, avoiding antibiotics unless a bacterial infection is confirmed. (7) A study by Verhaert and Van Wetter (2010) evaluated the use of CO2 laser therapy in FCGS, showing some benefit as an adjunct. (8) A study by Bellei et al. (2008) reported that oral administration of lactoferrin reduced inflammation in cats with stomatitis. (9) A study by Rocha et al. (2019) evaluated the use of mesenchymal stem cells in refractory FCGS, showing promising results. (10) A study by Niemiec (2008) emphasized the importance of dental radiography in diagnosing tooth resorption and periodontitis in stomatitis cases.