Learning objective: The importance of the oral examination in general, as well as in patients affected by systemic diseases. Which conditions require monitoring of oral health and which oral lesions may suggest the presence of systemic diseases.

The oral cavity is not an isolated area in animals and many systemic conditions influence oral structures. In carnivores, the oral cavity is not only the beginning of the alimentary tract but also a sensory apparatus and is used for offense and defense. Attention to the patient as a whole is important to avoid tunnel vision and thus missing a precise diagnosis when the oral lesion might be only a part of a wider clinical syndrome. Therefore, on seeing oral lesions, one must take into account their varied possible causes, collect a full general history and perform a thorough general physical examination.

The list of conditions presented below includes selected diseases which, in their clinical appearance, affect oral health or functionality.

Genetic and developmental disorders: Cleft lip, cleft palate, hydrocephalus and deformations of the palate, nose, pharynx, lip or tongue are associated not only with malfunction of the oral cavity but also can lead to severe disease or even death. Masticatory muscle myositis (MMM), craniomandibular osteopathy (CMO) and temporomandibular joint dysplasia affect the functionality of the masticatory apparatus and the comfort of the patient. Von Willebrand's disease is also a genetic syndrome, which can nowadays be diagnosed using a commercial test and in predisposed breeds (e.g., Doberman Pinschers). This test should be performed as a qualification to any surgery in particular when teeth extraction is planned.

Systemic Diseases

Infectious disease: Diseases that are caused by viruses and are associated with oral lesions include viral papillomatosis, feline calicivirosis, feline herpesvirus, feline immunodeficiency virus or feline leukemia virus. Canine distemper and infectious hepatitis can, due to fever and vomitus, influence enamel development and enamel quality in dogs.

Chlamydia spp., Clostridium tetani, Leptospira canicola and Fusobacterium are microorganisms, which cause infections that affect the functioning of the oral cavity.

Although mycotic infections of the oral cavity are uncommon, Candida species can appear as an opportunistic agent in stomatitis.¹ Aspergillus infection mostly affects the nasal cavity and sinus but it may penetrate the nasopalatine ducts and cause oral lesions.² Blastomycosis³ and cryptosporidium are reported as causative factors of oral or oropharyngeal lesions. Actinomyces in rabbits should be considered when a differential diagnosis for facial abscesses is considered.⁴

Immune-related disorders: Erythema multiforme (EM), eosinophilic granuloma complex (EGC), pemphigus vulgaris, mucous membrane pemphigoid, epidermolysis bullosa acquisita and systemic lupus erythematosus are on the list of immune related inflammatory diseases causing oral lesions and oral signalments. Pemphigus foliaceus and bullous pemphigoid do not usually present with oral lesions. In this group, one should also include problems that are exclusively related to the oral cavity and surroundings but severely affect the animal: feline chronic gingivitis stomatitis (caudal stomatitis), plaque-associated stomatitis in dogs, feline juvenile gingivitis. In puppies, juvenile dermatitis present on the face may cause difficulty in eating due to pain.

Metabolic disease: Severe clotting system disorders associated with bone marrow disorders or thrombocytopenia, osteopenia juvenalis very often caused by malnutrition, hyperparathyroidism associated with renal failure, diabetes, hypothyroidism and acromegaly are all maladies that must be taken into account when a differential diagnosis for oral and maxillofacial problems is considered. Additionally, many of them require stabilization and control to efficiently manage periodontal disease.

Toxic conditions: The toxic influence of some medicines can result in intrinsic staining of the dentition, tooth discoloration or proliferation of the gingiva. Poisons, chemical burns, snake or insect bites, which affect the animal through oral cavity, can cause lesions in oral mucosa.

Traumatic conditions: neuropraxia⁵ is a disorder of the peripheral nervous system in which there is a temporary loss of motor and sensory function due to blockage of nerve conduction, usually lasting an average of six to eight weeks before full recovery. It often occurs after overuse of the jaws while, for example, carrying heavy timbers or tyres by ambitious dogs. Seizures, accompanying epilepsy or other neurological disorders, may cause tongue injury during the attack. Similar injuries can happen after prolonged desensitization of tongue after a badly performed nerve block.

Idiopathic problems: vitiligo, myositis atrophicans, proliferative stomatitis.

References

1.  Jadhav VJ, Pal M. Canine mycotic stomatitis due to Candida albicans. Rev Iberoam Micol. 2006 Dec;23(4):233–234.

2.  Harvey CE. Oral lesions of soft tissue and bone: differential diagnosis. In: Small Animal Dentistry. Mosby; 1993:42–49.

3.  Salinardi B et al. Pharyngeal - laryngeal blastomycosis in dog. J Vet Dent. 2003;146–147.

4.  Tyrrell KL, Citron DM, Jenkins JR, Goldstein EJ. Periodontal bacteria in rabbit mandibular and maxillary abscesses. J Clin Microbiol. 2002 Mar;40(3):1044–1047.

5.  Robins GM, Robins GM. Dropped jaw - mandibular neurapraxia in the dog. J Small Anim Pract. 1976;17:753–758.