CHAPTER 7 Fig. 7-1 Palatoschisis and cheiloschisis, hard and soft palate, puppy. The gross lesions of the vesicular stomatitides are epithelial. Fluid-filled vesicles are present in the oral cavity, lips, rostral palate, and tongue (Fig. 7-2, A). Entry of virus in these cases is most likely oral into areas of temporary loss of mucosa as the result of normal mastication and trauma. The viruses are cytolytic, and the resultant release of virus from cells infects neighboring cells. The lesions enlarge centripetally, forming vesicles. Bullae result from coalescence resulting in erosions and ulcers. These ulcers are typically hyperemic (Fig. 7-2, B). Viremia, often transient, sometimes occurs. Fig. 7-2 Cutaneous vesicles, vesicular exanthema, snout, pig. Web Fig. 7-1 Cutaneous vesicles, San Miguel sea lion virus infection, foreflippers, northern fur seal. Erosions are defined by a loss of part of the thickness of the surface epithelium, whereas ulcers are full-thickness epithelial losses exposing the basement membrane. Thus erosions may progress to ulcers, which in hollow organs may become perforating ulcers. Erosive and ulcerative stomatitis can have a variety of causes. Agents responsible include the viruses of bovine viral diarrhea (BVD) (Fig. 7-3), rinderpest, malignant catarrhal fever (Fig. 7-4), feline calicivirus, and bluetongue, and in equids, nonsteroidal antiinflammatory drugs (NSAIDs). Other causes include uremia (Fig. 7-5); ingested foreign bodies, such as foxtail awns; the feline eosinophilic granuloma complex; and vitamin C deficiency in primates and guinea pigs (Web Fig. 7-2). Often, the oral lesions must be evaluated in the context of the clinical signs, together with histopathologic findings and ancillary testing, to arrive at a definitive diagnosis. Additionally, the vesicular stomatitides can progress to ulceration secondary to abrasion to the point that they cannot be distinguished from the ulcerative stomatitides. Fig. 7-3 Erosions and ulcers, bovine viral diarrhea virus infection, hard palate, cow. Fig. 7-4 Erosions and ulcers, malignant catarrhal fever, hard palate, dental pad and buccal papillae, cow. Fig. 7-5 Uremic ulcers, hard palate, dog. Web Fig. 7-2 Ulcerative gingivitis secondary to scurvy (vitamin C deficiency), gingiva, monkey. The two major diseases in this category, bovine papular stomatitis and contagious ecthyma, are zoonotic. Bovine papular stomatitis is recognized by papules on the nares, muzzle, gingiva, buccal cavity, palate, and tongue (Fig. 7-6). Lesions also occur in the esophagus, rumen, and omasum. Microscopically, acantholysis is responsible for the macule and ballooning degeneration of these cells, which may contain intracytoplasmic eosinophilic parapoxvirus inclusions at a later stage (Fig. 7-7; also see Fig. 1-12). Erosion of the infected cells accompanied by a neutrophilic infiltrate heals readily from the unaffected basal epithelium. The disease is more common in immunosuppressed animals such as those persistently infected with BVD virus. In humans, the disease is called milker’s nodules and is characterized by papules of the hands and arms. Fig. 7-6 Epithelial plaques, papular stomatitis, hard palate mucosa, calf. Fig. 7-7 Hydropic change, papular stomatitis, hard palate mucosa, cow. Contagious ecthyma, sore mouth or infectious pustular dermatitis, is a condition of sheep and goats characterized by progression of the stages typical of pox viruses—macules, papules, vesicles, pustules, scabs, and scars in areas of skin abrasions, including the corners of the mouth (Fig. 7-8; also see Fig. 17-43), mouth, udder, teats, coronary bands, and anus. Occasionally, the mucosa of the esophagus and rumen also can be affected. The virus is quite hardy and can survive for 50 to 60 days in the summer and longer in cold weather. At room temperature, scabs containing virus can be infective after 10 years. Eosinophilic cytoplasmic inclusion bodies are visible at microscopic examination of lesions early in the course of disease. The condition in humans is called orf. Fig. 7-8 Contagious ecthyma, oral mucous membranes, lamb. Fig. 7-9 Necrotizing stomatitis, calf diphtheria, tongue, calf. In cats, lip lesions are commonly visible near the philtrum and may extend through the adjacent haired skin. Oral lesions may occur anywhere in the mouth, including the gingiva, hard and soft palates, oral and nasal pharynx, tongue, and occasionally draining lymphoid tissues, excluding the tonsils, which do not have afferent lymphatic vessels (Fig. 7-10; also see Fig. 17-21, C). In dogs, eosinophilic granulomas typically are raised, fungating masses on the ventral and lateral lingual epithelium and palate. Collagenolysis (because collagen is acellular, it cannot undergo necrosis) is characteristically central in the lesion. The surrounding inflammatory tissue contains mixed inflammatory cells with increased numbers of eosinophils, mast cells, and multinucleated giant cells (see Web Fig. 3-14). Lesions grouped as the eosinophilic granuloma complex of cats include eosinophilic ulcer, linear (collagenolytic) granulomas, and eosinophilic plaques. The latter two lesions are strictly cutaneous and do not affect the oral cavity. No proven etiologic link has been established between these cutaneous conditions (linear granulomas and eosinophilic plaques) and oral eosinophilic granulomas. The cause of the canine lesions is unknown. Fig. 7-11 Lymphoplasmacytic stomatitis, gingiva, cat. Hyperplastic Diseases: Gingival hyperplasia is a simple overgrowth of gum tissue, principally the fibrous submucosa. The hyperplasia can become so severe as to bury incisor teeth (Fig. 7-12). Gingival hyperplasia is most common in brachycephalic dog breeds and is present in 30% of boxer dogs older than 5 years. Fig. 7-12 Gingival hyperplasia, gingiva, dog. Fig. 7-13 Fibromatous epulis, left mandible, molar teeth, dog. Neoplasia: In the dog, 70% of tumors of the alimentary system are in the oral cavity and oropharynx. These tumors run the gamut of biologic behavior from simple epithelial hyperplasia to malignant neoplasms with metastases to distant sites. Squamous cell carcinomas occur in the oral cavity, particularly in old cats, in which they account for 60% of oral neoplasms. They generally occur on the ventrolateral surface of the tongue and tonsils. Lingual squamous cell carcinomas occur more commonly in felids, and tonsillar squamous cell carcinomas are more common in canids. Although often appearing histologically aggressive, only a small percentage of lingual neoplasms metastasize, most commonly to draining lymph nodes, the mandibular and medial retropharyngeal. Unfortunately, most tonsillar carcinomas metastasize, initially to regional lymph nodes and then to distant sites. Fig. 7-14 Squamous cell carcinoma, palate, woodchuck. Fig. 7-15 Amelanotic melanoma, mandibular symphysis, dog. Fig. 7-16 Prognathia, head, horse. Web Fig. 7-3 Overgrown teeth, head, guinea pig. Fig. 7-17 Enamel hypoplasia, permanent incisor teeth, dog. Chemicals, most notably tetracycline antibiotics ingested during the process of mineralization, can cause yellowish, permanent discoloration (see Fig. 1-58). Congenital porphyria, a defect in red blood cell production, may result in incorporation of porphyrins into dentin, resulting in pink discoloration of the teeth (pink tooth) (Web Fig. 7-4). Both tetracycline and porphyrins fluoresce under ultraviolet light, dramatically demonstrating these lesions. Web Fig. 7-4 Pink tooth, congenital porphyria teeth, adult ox. Web Fig. 7-5 Fluorosis, cheek teeth, cow. Fig. 7-18 Dental attrition, molar teeth, antelope. Feline External Resorptive Neck Lesions: Cats suffering from feline external resorptive neck lesions often have pain upon chewing that may be reflected by inappetence and/or abnormal masticatory movements. External neck resorption of the cheek teeth of otherwise dentally normal cats is caused by odontoclastic resorption of cementum, particularly in the neck area or root of the tooth. Osteoclast ingrowths partially or completely line the resorption cavity. The resultant cavity may harbor bacterial plaque, resulting in intense inflammation and further osteoclastic resorption of dental tissue, including dentin and the root canal. The primary cause of this condition is not known. Fig. 7-19 Odontoma, incisor teeth, cow. Tonsils do not possess afferent lymphatic vessels and do not serve as lymph filters. Therefore only primary (or direct) or hematogenous infections occur (tonsillitis) (Fig. 7-20), as well as primary neoplasms of either the lymphoid (lymphoma) (Fig. 7-21) or epithelial (squamous cell carcinoma) (Fig. 7-22) components. In many viremias of mammals, such as pseudorabies of pigs, virus may be isolated from the tonsils. Fig. 7-20 Necrotizing tonsillitis, tonsils, dog. Fig. 7-21 Lymphoma (lymphosarcoma), tonsil, dog. Fig. 7-23 Ranula, mandibular salivary duct, dog. Fig. 7-24 Sialolith, horse.
Alimentary System and the Peritoneum, Omentum, Mesentery, and Peritoneal Cavity*
Introduction
Oral Cavity
Developmental Anomalies
The lateral palatine processes have failed to fuse during the first trimester of gestation (palatoschisis). In dogs, palatoschisis has been attributed to genetic abnormalities, excessive intake of vitamin A during gestation, and the administration of cortisone during gestation. The upper lip is also cleft (cheiloschisis). (Courtesy Dr. H. Gelberg, College of Veterinary Medicine, Oregon State University.)
Vesicular Stomatitides
A, Vesicles, both intact (upper vesicle) and ruptured (lower vesicle), are present on the planum rostrale and are caused by the infection of injured mucosal epithelial cells with vesicular exanthema of swine virus, a calicivirus (vesivirus). B, Ruptured vesicles with cutaneous ulceration, vesicular exanthema (later stage of the disease). Note the ruptured vesicles which can cause pain resulting in inappetence. (A from Gelberg H, Lewis RM: Vet Pathol 19:424-443, 1982. B courtesy Dr. H. Gelberg, College of Veterinary Medicine, Oregon State University.)
Specific Vesicular Diseases
On the nonhaired portion of the foreflipper are vesicles both intact (arrow) and ruptured, caused by the infection of injured mucosal epithelial cells with San Miguel sea lion virus, a calicivirus (vesivirus) These vesicles will rupture with trauma, resulting in cutaneous erosion and ulceration. (Courtesy Dr. H. Gelberg, College of Veterinary Medicine, Oregon State University.)
Erosive and Ulcerative Stomatitides
Erosions and ulcers caused by this pestivirus are particularly evident on the mucosal epithelial surface of the caudal hard palate. These lesions are characteristic of the ulcerative stomatitides, which, unlike the vesicular disease viruses, do not form vesicles. (Courtesy Dr. M.D. McGavin, College of Veterinary Medicine, University of Tennessee.)
The erosions and ulcers (red areas on mucosal surface) are due to malignant catarrhal fever virus, a herpes virus, but are characteristic of many ulcerative stomatitides. (Courtesy Dr. H. Gelberg, College of Veterinary Medicine, Oregon State University.)
Ulcers present on the transverse palatine ridges and periodontal gingiva are secondary to vascular damage associated with increased concentrations of plasma blood urea nitrogen and creatinine from kidney failure. Affected animals often have an ammoniacal or uremic odor to the breath. (Courtesy Dr. H. Gelberg, College of Veterinary Medicine, Oregon State University.)
There is a deep ulcer at the commissure of the mouth and smaller ulcers periodontally. Vitamin C deficiency in primates and guinea pigs can result in gingival erosions and ulcers, and even tooth loss. (Courtesy College of Veterinary Medicine, University of Illinois.)
Parapox Stomatitides
Virus-induced (parapoxvirus) epithelial plaques and papules are present on the mucosal epithelium of the hard palate and adjacent gingiva (arrows). (Courtesy Dr. M.D. McGavin, College of Veterinary Medicine, University of Tennessee.)
There is massive cytoplasmic swelling of the epithelial cells of the stratum spinosum. At a later stage, these cells may contain intracytoplasmic eosinophilic parapoxvirus inclusions (not visible here). H&E stain. (Courtesy Dr. M.D. McGavin, College of Veterinary Medicine, University of Tennessee.)
Note crusts around nose and lips. Multiple pustules and coalescing ruptured pustules covered by scabs are present on the skin. The parapoxvirus induces epithelial proliferation (acanthosis), followed by vesicle formation. These vesicles rupture and are quickly covered by scabs. Lesions develop at the sites of trauma, such as occur with a nursing lamb, where damage to the superficial oral epithelium allows entry of the virus into skin. (Courtesy Dr. M.D. McGavin, College of Veterinary Medicine, University of Tennessee.)
Necrotizing Stomatitides
The dorsal surface of the tongue is ulcerated, and the ulcers are covered by a diphtheric membrane. Calf diphtheria is caused by infection with the bacterium Fusobacterium necrophorum secondary to abrasion and/or trauma to the mucosal epithelium of the oral cavity or larynx. (Courtesy Dr. M.D. McGavin, College of Veterinary Medicine, University of Tennessee.)
Eosinophilic Stomatitides
Lymphoplasmacytic Stomatitis
This chronic condition of cats is characterized by red, inflamed gums, fetid breath, and inappetence. The oral mucosa can also be hyperplastic and ulcerated. Inset, There is a florid infiltrate of mixed inflammatory cells, including many lymphocytes and plasma cells in the submucosa beneath the epithelium. H&E stain. (Figure courtesy Dr. C. Patrick Ryan, Veterinary Public Health, Los Angeles Department of Health Services; and Noah’s Arkive, College of Veterinary Medicine, University of Georgia. Inset, Courtesy Dr. J.F. Zachary, College of Veterinary Medicine, University of Illinois.)
Oral Mucosal Hyperplasia and Neoplasia
Hyperplastic gingiva has enveloped the lower incisor teeth. Dental calculus (tartar, brown) is also present on both upper and lower incisor, canine and molar teeth. (Courtesy Dr. H. Gelberg, College of Veterinary Medicine, Oregon State University.)
This growth is an epulis (fibromatous type); however, epulides are often grossly indistinguishable from gingival hyperplasia. Epulis is a term used to designate a growth of the gingiva that is firm, periodontal, and usually solitary, in contrast to gingival hyperplasia. This distinction is not just an academic exercise because, although all epulides are considered benign, one form, acanthomatous ameloblastoma, is locally invasive. It invades bone and can be quite destructive. (Courtesy Dr. J. King, College of Veterinary Medicine, Cornell University.)
A mass of proliferating neoplastic squamous epithelial cells has displaced and replaced the mucosa and underlying tissue of the left hard palate and gingiva. (Courtesy Dr. H. Gelberg, College of Veterinary Medicine, Oregon State University.)
A proliferative, ulcerated, nonpigmented mass is present on the oral mucosa at the mandibular symphysis and protrudes into the oral cavity, likely resulting in malocclusion. Incisor teeth have been lost. Note the absence of pigmentation (melanin) in this tumor. (Courtesy Dr. M.D. McGavin, College of Veterinary Medicine, University of Tennessee.)
Teeth*
Malocclusions
The mandible is elongated compared with the maxilla. (Courtesy Dr. H. Gelberg, College of Veterinary Medicine, Oregon State University.)
The incisors and molars are longer than normal and the tongue is entrapped by the lower molar teeth, which will lead to starvation unless corrected. (Courtesy Dr. H. Gelberg, College of Veterinary Medicine, Oregon State University.)
Anomalies of Tooth Development
There is a lack of enamel formation with resultant discrete deep pits and exposure of the dentin (light yellow to beige areas of the teeth), the result of infection with canine distemper virus and necrosis of the ameloblasts during enamel formation. Permanent adult teeth (shown in illustration) are infected with virus before their eruption and while they are still within their sockets (dental alveoli). (Courtesy Dr. H. Gelberg, College of Veterinary Medicine, Oregon State University.)
The teeth are discolored brown from the accumulation of porphyrins in the dentin. (Courtesy Dr. M.D. McGavin, College of Veterinary Medicine, University of Tennessee.)
The enamel is chalky and weak, and the teeth are rapidly worn down. (Courtesy Dr. L. Krook, College of Veterinary Medicine, Cornell University.)
Lesions Caused by Attrition and Abnormal Wear
Age-associated dental wear results in improper mastication of feedstuffs and malnutrition. This condition occurs most commonly in horses and is referred to as “step-mouth” or “broken mouth.” (Courtesy College of Veterinary Medicine, University of Tennessee.)
Miscellaneous Dental Lesions
Dental Neoplasia
This is a hamartoma (a benign tumorlike nodule) of the enamel organ that in this case has expanded bilaterally on the rostral mandibles. There is extensive hemorrhagic ulceration over the tumor. Diagnosis can be confirmed by radiographic and histopathologic examination. (Courtesy Dr. M.D. McGavin, College of Veterinary Medicine, University of Tennessee.)
Tonsils
Portals of Entry
The palatine tonsils are enlarged and discolored. The right tonsil is covered by a diphtheritic membrane, and the left tonsil is extensively ulcerated. Because there are no afferent lymphatics to the tonsils, infection is either primary (by direct spread) or hematogenous. (Courtesy Dr. M.D. McGavin, College of Veterinary Medicine, University of Tennessee.)
Proliferation of malignant lymphocytes has expanded the tonsils so that they now protrude beyond their crypts. (Courtesy Dr. M.D. McGavin, College of Veterinary Medicine, University of Tennessee.)
Salivary Glands
Miscellaneous Diseases or Conditions
This is a cystic distention of the left mandibular salivary duct along the ventral-lateral aspect of the tongue. (Courtesy Dr. P. Stromberg, College of Veterinary Medicine, The Ohio State University.)
Pressure necrosis from this large stonelike mass (arrows) has destroyed the gland in which it formed. (Courtesy Dr. B. Cooper, College of Veterinary Medicine, Oregon State University.)You may also need
Alimentary System and the Peritoneum, Omentum, Mesentery, and Peritoneal Cavity
Only gold members can continue reading. Log In or Register to continue
WordPress theme by UFO themes