halitosis.JPG (6060 bytes)Halitosis

Halitosis, also called bad breath, foul breath, malodor, foetor ex ore, and fetor oris is defined as an offensive odor emanating from the oral cavity. Bad breath is a common pet odor complaint. Causes may be oral (most common) or extraoral (rare).

The sour milk odor accompanying periodontal disease may result from the bacterial population associated with plaque, calculus, unhealthy tissues, decomposing food particles retained within the oral cavity, or the rotten meat odor emanating from tissue necrosis. Contrary to common belief, neither normal lung air or stomach aroma contributes to halitosis.

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Grade 4 periodontal disease with

The most common cause of halitosis is periodontal disease caused by plaque (bacteria). Bacteria is attracted to the pellicle (an acellular film formed from the precipitation of salivary glycoproteins). In the freshly cleaned and polished tooth a glycoprotein layer forms over the tooth as soon as the patient starts to salivate. Bacteria attaches to the pellicle within 6-8 hours. Within days, the plaque becomes mineralized producing calculus. As plaque ages and gingivitis develops into periodontitis (bone loss), the bacterial flora changes from a predominantly non-motile gram-positive aerobic coccoid flora to a more motile, gram-negative anaerobic population including: Bacteroides, Fusobacterium, and Actinomyces species.

Calculus’s rough surface attracts more bacteria while irritating the free gingiva. As the inflammation continues, the gingival sulcus is pathologically transformed into a periodontal pocket. The pocket accumulates putrified food debris, bacterial breakdown products, and resorbing bone leading to halitosis. The primary cause of malodor is gram negative anaerobic bacterial putrefaction causing the generation of volatile sulfur compounds (VSC), such as hydrogen sulfide, methyl mercaptan, and dimethyl sulfide. The volatile sulfur compounds also may play a role in periodontal disease affecting the integrity of the tissue barrier allowing endotoxins to produce periodontal destruction.

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Grade 2 periodontal disease

Most patients suffering from halitosis have oral causes, the remaining are caused by, dermatologic, metabolic, respiratory, or gastrointesinal disease.


Species: more prevalent in dogs compared to cats

Breed Predilections: small breeds and brachycephalic breeds are more prone to oral disease because the teeth are closer together, the smaller animals live longer, and their owners are more prone to feed softer food

Mean Age & Range: older age more predisposed

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Certified veterinary
technician examining
periodontal pocket depths

Signs: when due to oral disease, ptyalism, pawing at mouth, anorexia, may occur. In most cases there are no clinical signs other than the malodor

Causes & Differential Diagnosis: Halitosis has multiple causes including: eating malodorus food, metaboloic (diabetes, uremia,), respiratory (rhinitis, sinusitis, neoplasia), gastrointestinal (megaesophagus, neoplasia, foreign body), dermatologic (lip fold pyoderma), dietary (fetid foodstuffs, coprophagy), oral disease (periodontal, orthodontic, pharyngitis, tonsilitis, neoplasia, foreign bodies, trauma ( electric cord injury, open fractures, caustic agents,) infectious ( bacterial, fungal, viral), autoimmune diseases, eosinophilic granuloma complex

Diagnostic Procedures: Hydrogen sulphide and mercaptans are the primary components of halitosis. An industrial sulphide monitor can be used to measure sulfide concentration in peak parts per billion hydrogen sulphide equivalents

Additional diagnostic procedures to evaluate periodontal disease include: intraoral radiography, probing pocket depths, and attachment levels.

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Veterinary technician cleaning teeth to
treat halitosis

Treatment: Once the specific cause of halitosis is diagnosed, therapy is directed at correcting existing pathology

If on physical examination, gingivitis is present, and/or when calculus exists on the maxillary fourth premolar, teeth cleaning is indicated. The cleaning must remove plaque and calculus above and below the gumline (with the help of hand instruments or scaler tips designed to be used subgingivally), irrigate debris from the mouth, and polish the teeth.


Clindamycin can be used to destroy most periodontal pathogens. It also can be used in a pulse therapy fashion using the label dosage the first five days of each month. Controlling periodontal pathogens helps control dental infections and accompanying malodor.

The use of oral care products which contain metal ions, especially zinc, will inhibit odor formation because of the affinity of the metal ion to sulphur. Zinc produces a stable complex with hydrogen sulfide forming insoluable zinc sulfide. Zinc interfers with microbial proliferation, and calcification of microbial deposits ( by interferring with the crystal development of calculus).

Chlorhexidine when used as a rinse or paste can also help control plaque decreasing eventual odor. Supplied as: CHX Guard, CHX Guard LA, CET Oral Hygiene Spray (VRx Products, Harbor City, Ca); DentiVet toothpaste and Hexarinse ( Virbac, Ft. Worth, Tx.)

DentTreats (VRx Products, Harbor City, Ca) are breath tablets for dogs, containing Zinc citrate, sodium copper chlorophyllin and essential oils (parsley seed, mint, and rosemary), the product does not treat the specific disease but neutralizes odor.

Client Education: Daily home care mechanical (brushing) aids in the removal of plaque, helps control dental disease and odor.

Surgical Considerations: see periodontal disease expanded problem

Patient Follow-Up: interval depends on stage of periodontal care and patient/owner willingness to provide homecare

Suggested Reading

Oral Hygiene Products and Practice by Morton Pader, 1988


This page last updated on October 31, 2000
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Jan Bellows, DVM
All Pets Dental Clinic
17100 Royal Palm Blvd.
Weston, FL 33326
(954) 349-5800