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77 Cards in this Set
- Front
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Vesicular diseases
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oFoot and mouth disease
Picornavirus infection of pigs, cattle, and sheep oVesicular stomatitis Rhabdovirus infection of horses, cattle, and pigs oVesicular exanthema Caused by a calici virus in pigs oSwine vesicular disease Caused by an enterovirus in pigs oFeline calici virus Mainly a respiratory problem, but can also cause vesicles and ulcers in the mouth oHepes B virus Infection in primates that is a fatal zoonotic disease in man and non-rhesus monkeys Rhesus monkey is a carrier of the virus and develops gingival ulcers resembling cold sores oPemphigus vulgaris and bullous pemphigoid Autoimmune disease of the dog and cat producing vesicles that quickly ulcerate |
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Ulcerative/Necrotizing diseases of the oral cavity
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•Bovine virus diarrhea (BVD) of cattle
oProduces ulcers all through the GI tract including the oral cavity and the tongue, but primarily affects the esophagus and the small intestine •Malignant catarrhal fever oA disease of cattle caused by a gamma herpes virus oCarried by the wildebeest in Africa and sheep in America oHas the same presentation as BVD, except you can see ulcers in the eye as well •Blue tongue oInsect transmitted orbivirus of sheep oCauses ulcers in the mouth and hemorrhages in the forestomach, coronet, pulmonary artery, and elsewhere •Uremia oAccumulation of toxins due to renal failure in the dog and cat oCan cause ulcers on the tongue and in the stomach •Eosinophilic granuloma complex oGroup of 3 diseases affecting cats and dogs caused by a hypersensitivity reaction probably to parasites oProduces ulcers in the mouth (dog, cat) and skin (cat) •Aeromonas oGram neg. bacterial infection of fish and reptiles causing septicemia oNecrosis with hemorrhage are seen in the mouth and other organs |
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Proliferative diseases of the oral cavity
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•Ovine contagious ecthyma
oPox virus infection of sheep and goats oProduces crusty lesions on the lips, face, and feet oTransmissible to people and other animals •Bovine papular stomatitis oParapox virus infection producing discrete, circular, slightly raised lesions in the mouth and esophagus oUsually an incidental finding •Fusobacterium necrophorum oGram negative bacterial infection of young cattle oProduces ulcerative and caseous proliferative lesions in the mouth and larynx oOrganism is a secondary invader following trauma to the mucosa •Actinobacillus oGram negative bacteria causing wooden tongue oFirm, fibrous, nodular thickenings of the tongue oSecondary invaders through damaged mucosa •Actinomyces oGram positive bacteria that causes lumpy jaw oFirm, fibrous, nodular thickenings of the jaw oSecondary invaders through damaged mucosa •Gingival hyperplasia oA proliferation of the gingival in dogs, usually in response to chronic periodontal disease |
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3 main neoplasms of the mouth
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•Melanoma
oTumor of melanocytes oCan be found in the oral cavity of the dogs 90% of these melanomas are malignant Quite common Usually single and may be pigmented or non-pigmented •Squamous cell carcinoma oMost common tumor of the cat tongue oSolitary nodule that is locally invasive, but slow to metastasize oCan also occur in the tonsil of the dog where it is more malignant •Fibrosarcoma oTumor of fibrobalast that can occur in the oral cavity of dogs oSolitary nodule that is locally invasive with a moderate rate of matastasis |
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Epulis
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oA benign tumor of the gingiva in the dogs
oResembles gingival hyperplasia grossly oArises from the periodontal ligament Characteristic microscopic appearance that looks like the periodontal ligament |
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Papilloma
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oWart caused by infection with the papilloma virus
oCan occur within the oral cavity of the dog and the rumen of cattle |
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Tooth germ tumors
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oA group of rare tumors of the dog, cat, and bovine occurring in the jaw
oCome from primitive structure of developing teeth oSolitary nodules that are benign oAmeloblastoma Most primitive oOdontoma Most mature (look more like teeth) |
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Pathology of the teeth
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oEnamel hypoplasia
Failure to form enamel on the teeth Teeth become chipped, misshapen, and stained brown Causes •Infection of young dogs with canine distemper virus while the permanent tooth is developing •Flourosis in cattle oExcessive tartar Can lead to periodontal disease and eventual tooth loss |
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Mucocele
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A cyst that forms when a salivary duct ruptures and saliva accumulates in the adjacent soft tissue
Occur in the oral cavity or the submandibular region A mucocele of the sublingual salivary gland forms a cyst at the base of the tongue and is called a ranula |
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Sialoadenitis
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Inflammation of the salivary gland
Only ever see in the rat •Caused by corona virus |
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Neoplasm fround in the salivary gland
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-salivary gland adenocarcinoma
Occurs rarely in the dog and cat and will metastasize to local lymph nodes and lung Present as a solitary nodular growth in the submandibular region |
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Ulcerative problems in the esophagus
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BVD and malignant catarrhal fever
•Cause ulcers in the bovine esophagus •The ulcers are usually linear Choke •Occurs in the horse when fed dry, coarse feed, apples, or other similar objects •If prolonged, the esophagus may ulcerate, producing annular ulcers |
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Proliferative diseases of the esophagus
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All proliferative diseases of the esophagus are similar grossly and cause white to yellow caseous material that forms plaques on the mucosa
Causes •Avian pox oVirus infection that produces white to yellow caseous plaques on the mucosa of the oral cavity, crop, and esophagus •Hypovitaminosis A oA rare disease causing keratinization of the esophagus and internal glands •Candida oAn opportunistic yeast infection that occurs in immunocompromised animals oCalled thrush when it’s on the tongue •Trichomonas oProtozoan infection of the crop and esophagus in birds, principally pigeons |
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Megaesophagus
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•Marked dilation of the esophagus
•Seen in young dogs that have a persistent right aortic arch oMeans the ductus arteriosus must cross over the esophagus to join the pulmonary artery and aorta oThis constricts the esophagus causing it to dilate cranially •Can also occur congenitally in dogs where the cause is unknown •May occur secondary to myasthenia gravis in dogs |
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Edema of the stomach
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Edema of the stomach wall occurs in animals that have hypoproteinemia
Edema disease of swine is an E. coli infection that produces edema of the stomach, subcutis, mesentery, and sometimes other sites |
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Ulcerative diseases of the stomach/abomasum
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Ulcers of the esophageal portion of the stomach in pigs are common
•Uncertain etiology, but finely ground rations are implicated along with genetics •Some ulcers can lead to fatal bleeding and sudden death Gasterophilus larvae •Stomach bots are a common cause of ulcers in the horse and occur along the margo plicatus •Incidental findings and cause no clinical disease Stress is considered a cause of gastric ulceration in all species Steroids and non-steroidal anti-inflammatory drugs are common causes of gastric ulcers, particularly in the horse |
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Hemmorhage of the stomach/abomasum
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Heavy metals, like arsenic and mercury, will cause ulceration with hemorrhage in the abomasums and intestine of cattle
Uremia in the dog causes gastric ulceration and hemorrhage because the uremic toxins damage blood vessels |
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Physical displacement of the stomach/abomasum
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Bloat
•Occurs most commonly in the horse that engorges on grain oExcess carbohydrate is fermented producing CO2 gas oGas distension lead to cardiovascular failure, shock, and death oThe stomach may rupture, causing peritonitis and death Gastric distension with volvulus •Occurs in deep-chested breed of dogs shortly after having eaten •Aerophagia and food that expands after eating are implicated as factors •Stomach distends and then rotates around its axis Displaced abomasum •In cattle •Occurs at parturition and up to several weeks later •That abomasum moves to the left or right and distends with gas Stomach rupture •Occurs most commonly in horses with colic from intestinal obstruction or gastric distension from grain overload Phytobezoars and trichobezoars •Are plant (phyto) or hair (tricho) balls, respectively, that can be found in the stomach •Incidental findings unless one blocks the pylorus leading to gas distension |
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Hyperplasia of the gastric mucosa
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•Occurs in animals with gastric parasites
•Occurs most commonly in cattle with Ostertagia oProduces small (<1 mm) slightly raised white plaques on the mucosa •Trichostrongylus axei in the horse, but the disease is not common |
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Neoplasia of the stomach
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•Gastric carcinoma
oHighly malignant tumor of the dogs causing marked thickening and fibrosis of the stomach wall oOften see a large ulcer in the mucosa oThe tumor often metastasizes Carcinomatosis – seeds the abdomen with metastases •Squamous cell carcinoma oIn the horse oAn ulcerated fibrous mass in the nonglandular stomach •Lymphoma oIn the dog and cat oMass of homogenous tan tissue in the wall without fibrosis •Leiomyoma oIn the dog and cat oBenign smooth muscle tumor and presents as a discrete tan nodule in the wall beneath the mucosa oProtrudes into the lumen of the stomach |
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Eosinophilic gastroenteritis
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•A rare disease in the dog that is similar to carcinoma grossly
•The stomach wall is infiltrated with eosinophils and fibrosis •Due to a hypersensitivity reaction |
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Draschia megastoma
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•Nematode parasite of the horse that burrows into the glandular stomach producing nodules with a central pore
•Incidental findings causing no clinical signs |
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Bloat of the rumen
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•A common problem in ruminants and is usually caused by grain overload
oCarbohydrate ferments, producing CO2 and lactic acidosis •Ingestion of certain legumes high in soluble protein can also produce bloat oLeads to the production of small gas bubbles that are very stable and do not breakdown •Rumen is filled with foam and froth •Lactic acid damages the rumen mucosa producing ulcers Bloat line •May be visible at necropsy in some cases of bloat •A line of demarcation in the esophageal mucosa at the thoracic inlet •The cranial esophagus is congested and the intrathoracic esophagus is blanched and pale (normal) oPressure for bloat leads to congestion of the cervical region Secondary infection of rumen ulcers with fungi or Fusobacterium may occur in some cases of grain overload |
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Papilloma of the rumen
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•Occurs in the rumen as white, wart-like growths
•Caused by papilloma virus and are usually an incidental finding |
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Ulcerative diseases of the small intestine
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Salmonella
•Important bacterial infection of large animals affecting the large intestine of horses and pigs and the small intestine of cattle •Infection produces ulcers, hemorrhage, or fibrinous lesions BVD •In cattle •Produces ulcers over Peyer’s patches that are nearly diagnostic Amoeba •An important cause of ulcerative enteritis in reptiles •Entamoeba is the most common species and it produces distinct ulcers Ulcerative enteritis •Important disease of young poultry and upland game birds •Caused by Clostridium colinum •Produces discrete ulcers and multifocal yellow foci in the liver |
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Fibrinous diseases of the small intestine
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Salmonella infection usually produces a fibrinous enteritis, but ulcers and hemorrhage may also occur
Necrotic eneteritis •An important disease in chickens •Caused by Clostridium perfringens A •Produces diffuse necrosis with a fibrinonecrotic pseudomembrane |
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Hemorrhagic diseases of the small intestine
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Disseminated intravascular coagulation (DIC)
Heavy metal toxicosis in ruminants with arsenic and mercury Parvovirus Hookworms •Important nematode parasite of the dog producing hemorrhage in the intestine •Worms are visible grossly Clostridium perfringens types A and C •Important bacterial infections of large animals in the first 2 weeks of life •Intestine has diffuse hemorrhage Clostridium difficile •Causes hemorrhagic enteritis of foals Hemorrhagic bowel syndrome •In adult dairy cattle •Has hemorrhage and blood clots in the duodenum and jejunum with high mortality •Cause is unknown, but Clostridium type A infection is suspected Proximal enteritis •In adult horses •Disease of unknown cause producing hemorrhage in the duodenum Coccidia •Protozoa causing infection in many species •In young avian and ruminants with heavy infections, an acute hemorrhagic enteritis may be seen •In chronic infection, there is the production of small nodules or plaques in the mucosa •In many cases no lesions are seen and the disease is an incidental finding |
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Parvovirus
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•Important viral infection of cats and dogs
•In the dog causes hemorrhagic enteritis oSegmental hemorrhage that only affects certain areas •Microscopically the virus destroys crypt epithelial cells leading to villous collapse and ulceration •In the cat causes panleukopenia oDepletion of red and white cells in the bone marrow oUsually no hemorrhage |
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Proliferative diseases of the small intestine
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Lawsonia intracellularis
Granulomatous enteritis •Horse •Rare disease of unknown cause •The mucosa is infiltrated with macrophages Mycobacterium avium Coccidia •In the chronic form of the disease in sheep produces focal 1-2 mm raised plaques or nodules Idiopathic muscular hypertrophy Chronic obstruction of the intestinal lumen •Causes the muscularis to thicken at the site Hemomelasma ilei |
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Lawsonia intracellularis
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•A bacterial infection of pigs causing marked thickening of the mucosa with necrosis and hemorrhage
•The mucosa has a corrugated appearance and may also have a fibrinonecrotic pseudomembrane •Disease also occurs in hamsters and rarely horses and dogs |
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Mycobacterium avium
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•Bacterial infection of birds and occasionally mammals that results in diffuse thickening of the mucosa
•Caused by granulomatous inflammation with acid-fast bacteria in macrophages •Disease in mammals is typically seen in immunosuppressed animals |
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Granulomatous enteritis
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•Horse
•Rare disease of unknown cause •The mucosa is infiltrated with macrophages |
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Idiopathic Muscular hypertrophy
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•Occurs in the distal ileum and esophagus of the horse
•Incidental finding •Cause is unknown •No clinical disease occurs except in rare cases where the ileum may become obstructed |
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Hemomelasma ilei
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•Horse
•Single or multiple, red to brown plaques on the serosa usually near the ileum •Incidental finding of unknown cause |
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Neoplasia of the small intestine and large intestine
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Lymphosarcoma (lymphoma)
•Causes thickening of the intestinal wall that is segmental •May also produce nodules in the intestinal wall •Usually homogeneous tan on sectioning but may have hemorrhage and necrosis Leiomyoma/leiomyosarcoma •Tumors of smooth muscle •Produce a distinct tan nodule in the wall of the intestine usually beneath the mucosa •Leiomyosarcoma is usually low-grade malignancy and has a low potential for metastasis •Can protrude into the lumen of the mucosa Adenocarcinoma •Produces an annular constricting band in the intestine oBecause of abundant fibrous tissue produced by the tumor o“Napkin ring” •Tumor is very malignant and will seed the abdominal serosa and metastasize to local lymph nodes and liver Gastrointestinal stromal tumor •Look just like leiomyomas and are probably more common •Arises from an interstitial cell |
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Torsion of the small intestine
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When the intestine twists on itself
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Volvulus of the small intestine
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•When the small intestine twists on the mesenteric axis
oOccurs much more commonly and is seen frequently in the horse oCuts off blood supply, causing necrosis and hemorrhage oBy the time you see clinical signs, necrosis has already occurred |
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Intussusception
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•Telescoping of the intestine into itself
•Usually secondary to hypermotility from some other problem •Cause hemorrhage and necrosis of the affected area |
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Strangulation of the small intestine
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•Also called incarceration
•Occurs when the intestine is trapped by a band of connective tissue •The usually cause is a lipoma in the mesentery of older horses oThese fatty tumors hang from the mesentery by a long, thin fibrous band and can wrap around the intestine causing strangulation oOccludes blood supply of the intestine |
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Hernia
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•Entrapment of the intestine in constricted openings such as enlarged inguinal rings, an open umbilicus, or a ruptured diaphragm
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Diseases that cause excess fluid within a normal small intestine
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•E. coli infection
oCommon and important disease in young pigs, ruminants, and foals occurring in the first weeks of life •Rotavirus and Coronavirus oImportant viral infections in young ruminants and pigs in the first 1-3 weeks oVirus destroys the epithelial cells on the villi leading to malabsorption and diarrhea Not as bad as parvo; can recover from it •Cryptosporidia oA protozoal infection of young ruminants and pigs in the first 2-3 weeks oProtozoan attaches to the microvillous border of the intestinal epithelial cells •Clostridium perfingens type D oGram positive bacterial infection of sheep oBacteria is part of the normal intestinal flora oDisease occurs with a change of feed from poor quality to good quality which allows overgrowth of the bacteria oBacteria produce and exotoxin which causes enterotoxemia •Lymphangiectasia oDialation of the lacteals in the intestinal villi of the dog oResults in malabsorption •Inflammatory bowel disease oAllergic enteritis in the dog and cat oUnknown cause, but probably dietary antigens oVERY common •Panleukopenia oParvovirus infection of the cat oCauses hypoplasia of all cell lines in the bone marrow and necrosis of the intestinal crypts oIntestine often appears normal with excess fluid content, but an absence of the villi may be seen with careful examination |
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Ulcerative colitis
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•In boxer dogs
•Macrophages in the mucosa along with ulcers oRaised “button ulcers” •Also called histiocytic ulcerative colitis •An ulcerative colitis also occurs in cats with macrophages in the mucosa •The cause is not known |
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Shigella
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•Bacterial infection of primates
•Produces an ulcerative and sometime hemorrhagic colitis |
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Fibrinous/ necrotic/ fibrinonecrotic diseases of the large intestine
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Salmonella
•Ulcerative and/or hemorrhagic or fibrinous or fibrinonecrotic •Affects the colon in horses (small intestine in cattle) Swine dysentery •Colitis of pigs caused by the bacteria Brachyspira hyodysenteriae in association with other bacteria •Disease produces a fibrinous colitis with hemorrhage Yersinia pseudotuberculosis •Bacterial infection primarily of primates and rodents but may be seen in cattle •Produces mulifocal fibrinonecrotic colitis Histomonas meleagridis •Protozoan infection of turkeys producing caseous necrotic cores in the ceca •Transmitted by a cecal worm Trichuris •Whipworms •Affect the cecum and the colon of the pig and dog •Most infections cause no lesions, but heavy infections can produce fibrinouscolitis Fibrinous colitis in the horse •Heavy infections with small strongyles •Certain oral antibiotics •NSAIDs oIn the right dorsal colon |
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Hemorrhagic diseases of the large intestine
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Colitis X
•A disease in the horse, probably caused by an overgrowth of Clostridia bacteria •Produces hemorrhage and edema in the wall of the colon, but no blood in the feces DIC Anticoagulant toxicosis •Usually occurs in small animals that ingest posions containing anticoagulants like warfarin and brodifacoum •Bleeding can occur anywhere in the GI tract |
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Johne's disease
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•Ruminants
•Bacterial infection caused by Mycobacterium avium spbspecies paratuberculosis •Causes thickening of the mucosa due to granulomatous inflammation •Produces folds in the mucosa (corrugated appearance) |
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Impaction
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•An obstruction of the colon
•Caused by feces in small animals and coarse feed or foreign bodies in large animals •Enteroliths oMineralized concretions that build in size over time until they cause impaction of the large colon in horses •Sand can also cause impaction of the colon of horses •In horses the colon may rupture |
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Dilation of the colon
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-megacolon
-can occur secondary to spinal disc disease in some dogs |
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Atresia coli
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-congenital defect in cattle
-colon ends in a blind sac somewhere before the anus |
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Atresia ani
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-congenital defect in cattle
-no anus |
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Potomac horse fever
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•Rickettsia infection of horses transmitted by insect vectors
•Colon is filled with watery content and the mucosa has patchy congestion with no ulcers, fibrin, or hemorrhage •Vaccine, so we don’t see much anymore |
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Ascites
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Accumulation of clear, yellow fluid in the abdomen
Causes •Chronic liver disease •Heart failure (right heart failure) |
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Edema of the peritoneum
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Edema disease of swine caused by E. coli
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Hemoperitoneum
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Blood in abdomen and usually occurs secondary to trauma
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Fibrinous diseases of the peritoneum
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Traumatic reticuloperitonitis
•Occurs in cattle when a wire within the reticulum penetrates through the wall causing fibrinous peritonitis •The wire may also penetrate the diaphragm and pericardial sac causing fibrinous pericardidits Ruptured urinary bladder •Can occur in castrated male cats and steers when the urethra is blocked with mineral deposits •Free urine in the abdomen incites a fibrinous peritonitis Feline infectious peritonitis (FIP) •Coronavirus infection of cats •Causes a high protein fluid to form in body cavities along with fibrin •Small, white plaques form on the mesentery and granulomas may be seen in various organs |
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Fat necrosis
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Necrotic fat becomes mineralized and appears as firm, chalky, yellow to brown plaques or nodules
Causes •Vitamin E deficiency in cats oCauses fat necrosis of the subcutis, omentum, and mesentery oVitamin E is an antioxidant and a deficiency leads to oxidation of fat and necrosis •Pancreatitis of the dog and cat oLeads to a leakage of enzymes from the pancreas oCauses necrosis of the mesenteric fat around the pancreas •Idiopathic fat necrosis oOccurs in the mesentery of Jersey and Guernsey cattle •Fescue toxicosis oCattle (commonly no Jersey or Guernsey) oCauses fat necrosis in the mesenteric fat •Lipomas oOccur in the mesentery of aged horses oOften hang by a fibrous stalk which causes occlusion of the blood supply to the lipoma oFat becomes necrotic and mineralized |
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Proliferative diseases of the peritoneum
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Chronic peritonitis
•Chronic inflammation of the peritoneum will resolve with fibrous tags on the peritoneum oMakes the peritoneum appear shaggy •Adhesions of the intestine to itself or other organs is usually seen as well oAdhesions can block the intestine somewhere leading to colic Mesothelioma •A rare neoplasm of the mesothelial cells •Occurs most commonly in calves as a congenital disease or in the adult dog •Produces multiple white nodules and plaques in the abdomen, thorax, or pericardial space Feline infectious peritonitis •Produces small white plaques on the mesentery and/or nodules in the abdominal organs |
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Hypoplasia of the pancreas
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Rare disease of young German Shepherds in which the exocrine pancreas fails to develop
Endocrine pancreas is normal Dogs have a voracious appetite and large voluminous, foul-smelling feces |
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Acute pancreatitis
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•Serious disease in the dog of unknown cause
•Pancreas has necrosis and hemorrhage and is edematous •Fibrin is also deposited around the pancreas |
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Chronic pancreatitis
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•Dogs often suffer repeat bouts of acute pancreatitis and the pancreas heals by scarring
•The pancreas is pale tan, firm, and nodular |
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Neoplasia of the pancreas
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oBoth adenoma and adenocarcinoma occur in the endocrine and exocrine pancreas
Endocrine – islet cell tumors •Insulinomas •Glucagonomas Exocrine •Acinar cell adenoma or adenocarcinoma oAppear similar grossly for both tissue types Adenoma is usually a single yellow to white nodule which may be very small Carcinoma is larger and infiltrative oThese tumors occur most commonly in the cat and dog |
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Hyperplasia of the pancreas
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•Occurs in the exocrine tissue of the pancreas occurs as an incidental finding in aged dogs and cats
•1-3 mm tan to white nodules in the pancreas |
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Color changes of the liver
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Pale tan or brown
•Modest amounts of fat or glycogen within the liver cells will produce this color change •Change may be diffuse affecting the whole liver or it may be multifocal oDiffuse change is pathologic and usually represents a nutritional or metabolic disease (diabetes, Cushings) oThe focal change represents a physiologic state and is not pathologic Well fed, storing fat, etc. Yellow •Large amounts of fat within the liver •Change may be diffuse or follow the lobular pattern •Liver is often softer Green •Indicates excess bile accumulation •Results in icterus, which is jaundice or a yellow color of the tissues •Usually liver is a more yellow color oCan tell apart from fatty liver because it’s not soft Red or red-brown •Congestion produces this color and it is a very common change seen in most livers at necropsy |
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Causes of a lobular or reticular pattern of the liver
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Causes are NOT infectious
•Vascular problem or a toxin Causes •Passive congestion oMost common cause of a lobular pattern oThe liver is also red or red-brown from the congestion “Nutmeg” liver oHeart failure is the usual cause of passive congestion •Anemia oMay also cause a lobular pattern by causing hypoxia to the centrilobular cells These are the last cells that blood from the portal veins reaches, so the most likely to be affected •Lipid oMay accumulate in the centrilobular area producing a lobular pattern •Hepatotoxin oMany liver toxins damage centrilobular hepatocytes producing a lobular pattern These are the cells that have cytochrome P450 to activate the toxins oCells may be necrotic or accumulate lipid oCauses include drugs, toxic plants, and chemicals •Cholangitis oUncommon disease and usually caused by a bacterial infection Damage to the bile duct of every lobule oLiver may have a lobular pattern or be normal |
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Mosaic pattern in the liver
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This pattern produces large red and yellow areas in the liver that give it a mottled or mosaic pattern
Similar to the lobular pattern but more severe with larger lesions Uncommon pattern in the liver Causes •Massive necrosis oNecrosis of whole hepatic lobules oCaused by drugs, toxic plants, and chemicals Often dose dependent •Smaller does produce a lobular pattern •Larger doses produce a mosaic pattern oVitamin E/selenium deficiency in the pig |
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Focal or multifocal pattern in the liver
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Usually the results of infectious disease or neoplasm
•Viral, bacterial, fungal, and parasitic infectious •Histomonas – “target lesions” Produce multiple random foci of necrosis or nodules within the liver Infections enter the liver hematogenously and thus shower the liver randomly Lesions are yellow, white, or tan and may be flat or raised |
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Hepatocellular carcinoma
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•Rare tumor occurring mostly in the dog
•Usually single masses, but are often large and multilobulated •Brown with yellow areas of fat and red areas of hemorrhage •Texture is similar to normal •Most are malignant and will metastasize |
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Biliary adenoma and adenocarcinoma
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•Occur in the dog and cat
•Adenoma oOccurs most commonly in felids oA single, discrete nodule that is often cystic and contains green or clear fluid oIncidental findings – no clinical signs •Adenocarcinoma oSeen rarely in the dog oMultiple firm, white nodules with depressed centers |
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Metastatic carcinomas and sarcomas in the liver
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•Occur commonly in the liver as this is a common site of metastasis for many tumors
•Appear as multiple, firm, white nodules |
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Hemangiosarcoma
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•May be a primary tumor of the liver in the dog occurring as multiple, red nodules and blood-filled cysts
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Nodular Hyperplasia of the liver
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•Incidental finding in the aged dog
•A solitary, discrete nodule that is soft and tan due to fat accumulation •Some consider these to be hepatocellular adenoma |
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Regeneration of the liver
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•The liver has a remarkable capacity to regenerate itself
•An intact architectural framework is necessary for the liver to regenerate itself to its normal shape •In most liver disease, the architectural framework is disrupted and the hepatocytes regenerate forming regenerative nodules oMay be microscopic or macroscopic oLiver is distorted in shape having an irregular surface •Some diseases inhibit hepatocyte regeneration and regenerative nodules do not occur |
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Cirrhosis
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-when nodular regeneration and fibrosis of the liver occur together
-tawny colored |
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Causes of liver fibrosis
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oChronic hepatitis
Important, common disease in dogs that is of unknown cause Liver is misshapen and has many nodules (cirrhosis) oPost necrotic scarring Healing phase of massive necrosis The necrotic lobule collapse forming bands of fibrous tissue Most animals with massive necrosis do not survive, so the healed phase of post-necrotic cirrhosis is rarely seen Livers are misshapen and have nodules oChronic heart failure Produces chronic passive congestion and the liver has fibrosis in centrilobular areas Liver retains its shape pretty well but is congested with a lobular pattern Regenerative nodules usually are not present but may occur oChronic cholangitis Rare disease of the liver caused by a bacterial infection in the biliary tract Liver is firm and often has a lobular pattern |
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Portosystemic shunt
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oCongenital or acquired shunting of portal blood around the liver
oLeads to atrophy of liver cells and a small liver oAcquired shunts occur at any age following chronic liver disease (cirrhosis) Scarring in the liver increases pressure in the portal veins causing the blood to back up in the portal system Tortuous, distended veins often appear in the mesentery |
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Distended, firm bile ducts of the liver
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•Occur in cattle and sheep with liver flukes
•The bile ducts are visible on the liver surface as white thick, tortuous channels that are often raised above the liver surface oFibrosis of the bile ducts |
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Pathology of the gall bladder
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oHemorrhage
Can occur in any of the bleed disorders such as DIC or anticoagulant toxicosis oFibrinous cholecystitis Occurs in Salmonella infection of cattle Is often not seen in most cases of Salmonella oThick, viscous, opaque bile Seen in animals with anorexia or a few days duration Causes the gall bladder to become distended Normal bile is a clear, yellow-green liquid oCystic hyperplasia Uncommon, incidental finding of unknown cause in dogs Mucosa contains numerous small systs or larger, papillary or nodular growths |
