NAVLE Gastrointestinal and Digestive

Canine Periodontal Disease and Gingivitis Study Guide

📅 March 28, 2026 ⏱ 25 min read

Periodontal disease is the most common disease diagnosed in dogs, affecting approximately 80% of dogs over 2 years of age.

Overview and Clinical Importance

Periodontal disease is the most common disease diagnosed in dogs, affecting approximately 80% of dogs over 2 years of age. This inflammatory condition of the supporting structures of the teeth (the periodontium) progresses from reversible gingivitis to irreversible periodontitis if left untreated. Understanding the pathophysiology, staging, diagnosis, and treatment is essential for the NAVLE.

Periodontal disease is significantly underdiagnosed in primary care. Visual assessment of conscious dogs reveals diagnosis rates of only 9-18%, while examinations under anesthesia show prevalence of 44-100%. This diagnostic gap highlights the silent progression of periodontal disease.

Tooth Type	Function	Number of Roots	Clinical Note
Incisors	Tearing, nibbling, grooming	1 root	First affected in toy breeds
Canines	Grabbing, tearing, protection	1 root (very long)	High jaw fracture risk in small dogs
Premolars	Holding, carrying, shearing	P1: 1; P2-P3: 2; P4: 3 (max), 2 (mand)	Furcation disease common
Molars	Grinding	Max: 3; Mand M1-M2: 2; M3: 1	Carnassials commonly fractured

Canine Dental Anatomy

Dental Formula

Adult dogs have 42 permanent teeth: 12 incisors, 4 canines, 16 premolars, and 10 molars. The dental formula is 2(I3/I3, C1/C1, P4/P4, M2/M3).

Puppies have 28 deciduous teeth: 12 incisors, 4 canines, and 12 premolars. Deciduous teeth erupt by 2 months; permanent teeth complete by 7 months.

Root Anatomy by Tooth Type

The Periodontium

The periodontium comprises four structures that support and anchor the tooth:

1. Gingiva

The gingiva is keratinized oral mucosa covering alveolar processes. Key components: Free gingiva (not attached; forms sulcus), Attached gingiva (bound to bone), Gingival sulcus (space between tooth and gingiva; normal 0-3 mm in dogs), and Junctional epithelium (attaches gingiva to tooth).

High-YieldNormal gingival sulcus depth in dogs is 0-3 mm. Depths greater than 3 mm indicate periodontal pocketing and attachment loss. In cats, normal is only 0.5-1 mm.

2. Periodontal Ligament (PDL)

The periodontal ligament is fibrous tissue (collagen fibers) anchoring cementum to alveolar bone. Functions as shock absorber during chewing. Radiographically appears as thin radiolucent line around root. Widening indicates pathology.

3. Cementum

Cementum is bone-like tissue covering the tooth root, serving as attachment for PDL fibers. The cementoenamel junction (CEJ) marks the transition between enamel and cementum - a critical landmark for measuring attachment loss.

4. Alveolar Bone

The alveolar bone forms the tooth socket. Key structures: Lamina dura (dense bone lining socket - white line on radiographs), Alveolar margin (normally 1-2 mm apical to CEJ), and Furcation (where roots divide in multirooted teeth).

Stage	Clinical Findings	Radiographic Findings	Treatment
Stage 1 Gingivitis	Gingival inflammation Bleeding on probing No attachment loss	Normal alveolar margin No bone loss	Professional cleaning Home care education REVERSIBLE
Stage 2 Early Periodontitis	Less than 25% attachment loss F1 furcation possible	Less than 25% bone loss Widened PDL space	Subgingival scaling Root planing Local antimicrobials
Stage 3 Moderate Periodontitis	25-50% attachment loss F2 furcation possible Deep pockets	25-50% bone loss Horizontal/vertical bone loss	Periodontal surgery GTR possible Extraction if no home care
Stage 4 Advanced Periodontitis	Greater than 50% attachment loss F3 furcation (through-and-through) Tooth mobility	Greater than 50% bone loss Pathologic fracture risk	Extraction usually indicated

Pathophysiology of Periodontal Disease

Plaque Formation and Progression

Plaque is an invisible bacterial biofilm that forms on tooth surfaces within hours of cleaning. This is the primary etiologic factor - not tartar (calculus). Tartar is just mineralized plaque.

Disease Progression Timeline

Plaque Formation (Hours): Bacteria attach to tooth surface. Initial colonizers are gram-positive, aerobic bacteria.
Bacterial Shift (Days): Biofilm matures, invades sulcus, creating anaerobic environment favoring gram-negative bacteria (Porphyromonas, Treponema).
Calculus Formation (Days-Weeks): Calcium salts mineralize plaque into calculus, providing rough surface for more plaque.
Gingivitis (Weeks): Host inflammatory response causes gingival inflammation, redness, bleeding. THIS STAGE IS REVERSIBLE.
Periodontitis (Months-Years): PDL destruction and alveolar bone loss. THIS STAGE IS IRREVERSIBLE.

NAVLE TipPLAQUE (not tartar) is the enemy! A dog can have severe periodontal disease with minimal visible tartar, or heavy tartar with only mild periodontitis. Always probe and radiograph - never rely on visual assessment alone.

Stage	Description	Prognosis
F1	Probe extends less than halfway under crown	Good with treatment
F2	Probe more than halfway but not through-and-through	Guarded; surgery or extraction
F3	Through-and-through; probe passes buccal to lingual	Poor; extraction

Staging Periodontal Disease

The AVDC classifies periodontal disease into four stages based on clinical and radiographic findings. Each tooth should be staged individually.

Furcation Involvement Classification

High-YieldF3 (through-and-through) furcation requires extraction regardless of overall periodontal disease stage. The defect cannot be adequately cleaned or regenerated.

Highest Risk Breeds	Prevalence	Contributing Factors
Greyhound	32%	Unique genetic susceptibility
King Charles Spaniel	30%	Brachycephalic, dental crowding
Toy Poodle	26%	Small narrow mouth, crowding
Yorkshire Terrier	22%	Early onset (less than 1 year), genetics
Chihuahua	High	Severe crowding, retained deciduous teeth

Breed Predispositions and Risk Factors

Small and toy breeds are significantly predisposed. Dogs less than 6.5 kg are up to 5 times more likely to develop periodontal disease than giant breeds greater than 25 kg.

NAVLE TipYorkshire Terriers develop "disease-like" bacterial profiles at less than 1 year of age. 98% have at least one tooth with early periodontitis by 37 weeks. Canines and incisors are affected first.

Stage	Treatment Protocol
Stage 1	Supragingival and subgingival scaling, polishing, 0.12% chlorhexidine rinse, home care education
Stage 2	Stage 1 plus: closed root planing, local antimicrobials (Doxirobe) for pockets greater than 5 mm
Stage 3	Periodontal flap surgery, guided tissue regeneration, or extraction if no home care commitment
Stage 4	Extraction usually indicated; careful technique to prevent iatrogenic jaw fracture in small dogs

Clinical Signs and Diagnosis

Clinical Signs

Halitosis (bad breath) - the primary sign owners notice
Visible calculus (brown/yellow deposits)
Red, swollen, or bleeding gums
Gingival recession exposing roots
Tooth mobility or missing teeth
Difficulty eating, preference for soft food
Facial swelling or draining tracts (abscess)

Diagnostic Approach

COHAT (Comprehensive Oral Health Assessment and Treatment) requires general anesthesia and includes:

1. Periodontal Probing

Graduated periodontal probe inserted at 6 points around each tooth. Normal depth 0-3 mm in dogs. Greater than 3 mm indicates periodontal pockets.

2. Dental Radiography

Full-mouth dental radiographs are essential - 40% of pathology is missed without them. Findings include:

Horizontal bone loss: Generalized, parallel to CEJ
Vertical bone loss: Localized, extending apically along root
Widened PDL space: Indicates inflammation/infection
Loss of lamina dura: Loss of white line around root
Furcation radiolucency: Dark area between roots

High-Yield40% of bone must be destroyed before radiographic bone loss becomes visible. Radiographic evidence always indicates significant, long-standing disease.

Drug	Dose	Notes
Clindamycin	5.5-11 mg/kg PO q12h	Excellent bone penetration; most common for dental infections
Amoxicillin-Clavulanate	12.5-25 mg/kg PO q12h	Broad spectrum; good for mixed infections
Metronidazole	10-15 mg/kg PO q12h	Effective against anaerobes; often combined
Chlorhexidine 0.12%	Topical rinse	Gold standard local antimicrobial; high substantivity

Treatment

Professional Dental Treatment

Requires general anesthesia. "Anesthesia-free" dentistry is inadequate because it cannot address subgingival disease, obtain radiographs, or properly probe teeth.

Antimicrobial Therapy

Systemic antibiotics are NOT routinely indicated for dental prophylaxis or after uncomplicated extractions. Per AAFP/AAHA Guidelines: "Systemic antimicrobials are not a substitute for surgical treatment."

Home Care Prevention

The gold standard is daily tooth brushing with veterinary toothpaste. Bacteria repopulate within days of cleaning. Use VOHC-approved products (dental chews, diets, water additives). Avoid hard chews (bones, antlers) that fracture teeth.

Organ	Pathophysiology	Clinical Significance
Heart	Bacteremia causes valve attachment; inflammatory mediators damage endothelium	1.4x higher cardiac valve pathology per cm² PD; endocarditis risk
Kidney	Immune complex deposition; direct bacterial invasion	1.4x higher kidney pathology per cm² PD; association with CKD
Liver	Bacteremia and endotoxins cause inflammation	1.2x higher liver pathology per cm² PD; increased hepatic enzymes

Systemic Consequences of Periodontal Disease

Bacteremia occurs during chewing and dental procedures. Chronic exposure to bacteria and inflammatory mediators affects distant organs.

Local Complications

Oronasal fistula: Communication from maxillary canine periodontal disease
Pathologic jaw fracture: Weakened mandible; common in small dogs with Stage 4 disease
Tooth root abscess: Periapical infection with facial swelling/draining tract

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