OVERVIEW
Epithelial (carcinoma), germ cell (dysgerminoma and teratoma), and sex-cord stromal (granulosa cell tumor, Sertoli-Leydig cell tumor, thecoma, and luteoma) tumors
Dogs—rare (0.5%–1.2% of tumors); 40% carcinomas, 10% germ cell, and 50% sex-cord
Cats—extremely rare (0.7%–3.6% of tumors); 15% germ cell and 85% sex-cord
Metastasis common
Some tumors produce hormones.
Monday, March 28, 2011
Oral Ulceration
DEFINITION
Destruction of the oral epithelium, exposing underlying connective tissue
PATHOPHYSIOLOGY
Cell—cell and cell—matrix adhesion proteins are responsible for maintaining the integrity of the mucosal lining of the oral cavity.
Disease processes that destroy keratinocytes or adversely affect their adhesion to one another or to the subjacent basement membrane result in erosions, ulcerations, and desquamation.
Immunologic processes that have a deleterious effect on the integrity of the epithelial—basement membrane submucosa complex may be involved in causing ulcers to form.
Destruction of the oral epithelium, exposing underlying connective tissue
PATHOPHYSIOLOGY
Cell—cell and cell—matrix adhesion proteins are responsible for maintaining the integrity of the mucosal lining of the oral cavity.
Disease processes that destroy keratinocytes or adversely affect their adhesion to one another or to the subjacent basement membrane result in erosions, ulcerations, and desquamation.
Immunologic processes that have a deleterious effect on the integrity of the epithelial—basement membrane submucosa complex may be involved in causing ulcers to form.
Obesity
DEFINITION
The presence of body fat in sufficient excess to compromise normal physiologic function or predispose to metabolic, surgical, and/or mechanical problems
PATHOPHYSIOLOGY
Animal factors—although breed predispositions have been reported, any animal may become obese; inactivity is an important risk factor in both dogs and cats, as are increasing age and neutering.
Dietary factors—no specific diet other than a surfeit of “table scraps” and “treats” has been shown to increase risk in dogs; in cats, consumption of “high-fat” diets reportedly increases risk.
Feeding management—many animals are overfed; reasons for excessive food consumption include ignorance of proper feeding practices, inappropriately generous feeding recommendations by manufacturers, emphasis on food palatability both by owners and manufacturers, and inadequate explanation by veterinarians of appropriate body condition for the pet and how to maintain it.
Owner factors—many owners of overweight pets are overweight themselves and engage in feeding as a social activity; clients also may consider their pet to be “one of the family” and be unwilling to deprive a loved one of food; these factors may undermine simple-minded “eat less and exercise more!” approaches to management of obesity; they must be identified and acknowledged by both client and therapist for long-term resolution of obesity.
The presence of body fat in sufficient excess to compromise normal physiologic function or predispose to metabolic, surgical, and/or mechanical problems
PATHOPHYSIOLOGY
Animal factors—although breed predispositions have been reported, any animal may become obese; inactivity is an important risk factor in both dogs and cats, as are increasing age and neutering.
Dietary factors—no specific diet other than a surfeit of “table scraps” and “treats” has been shown to increase risk in dogs; in cats, consumption of “high-fat” diets reportedly increases risk.
Feeding management—many animals are overfed; reasons for excessive food consumption include ignorance of proper feeding practices, inappropriately generous feeding recommendations by manufacturers, emphasis on food palatability both by owners and manufacturers, and inadequate explanation by veterinarians of appropriate body condition for the pet and how to maintain it.
Owner factors—many owners of overweight pets are overweight themselves and engage in feeding as a social activity; clients also may consider their pet to be “one of the family” and be unwilling to deprive a loved one of food; these factors may undermine simple-minded “eat less and exercise more!” approaches to management of obesity; they must be identified and acknowledged by both client and therapist for long-term resolution of obesity.
Neutropenia
DEFINITION
Neutrophil count < 2900 neutrophils/mL in dogs and < 2500 neutrophils/mL in cats Can develop alone or as a component of pancytopenia Often accompanied by a left shift and toxic change (e.g., cytoplasmic basophilia, cytoplasmic vacuolation, Döhle bodies, and toxic granulation)
PATHOPHYSIOLOGY
Results from one of three mechanisms—(1) deficient neutrophil production in the bone marrow, (2) cells shifting from the circulating neutrophil pool to the marginal neutrophil pool in the blood, and (3) reduced neutrophil survival because of excessive tissue demand or immune-mediated destruction of cells
Most commonly associated with infection, because emigration of neutrophils from the blood into the tissues exceeds the rate at which the bone marrow can replace them.
Neutrophil count < 2900 neutrophils/mL in dogs and < 2500 neutrophils/mL in cats Can develop alone or as a component of pancytopenia Often accompanied by a left shift and toxic change (e.g., cytoplasmic basophilia, cytoplasmic vacuolation, Döhle bodies, and toxic granulation)
PATHOPHYSIOLOGY
Results from one of three mechanisms—(1) deficient neutrophil production in the bone marrow, (2) cells shifting from the circulating neutrophil pool to the marginal neutrophil pool in the blood, and (3) reduced neutrophil survival because of excessive tissue demand or immune-mediated destruction of cells
Most commonly associated with infection, because emigration of neutrophils from the blood into the tissues exceeds the rate at which the bone marrow can replace them.
Nephrolithiasis
DEFINITION
Nephroliths—uroliths (i.e., polycrystalline concretions or calculi) located in the renal pelvis or collecting diverticula of the kidney
Nephroliths or nephrolith fragments may pass into the ureters (ureteroliths).
Nephroliths that are not infected, not causing obstruction or clinical signs, and not progressively enlarging are termed inactive.
PATHOPHYSIOLOGY
Nephroliths can obstruct the renal pelvis or ureter, predispose to pyelonephritis, and result in compressive injury of the renal parenchyma leading to renal failure; see chapters on the different urolith types for pathophysiology of urolithiasis; in cats, nephroliths composed of blood clots mineralized with calcium phosphate can form secondarily to chronic renal hematuria.
Nephroliths—uroliths (i.e., polycrystalline concretions or calculi) located in the renal pelvis or collecting diverticula of the kidney
Nephroliths or nephrolith fragments may pass into the ureters (ureteroliths).
Nephroliths that are not infected, not causing obstruction or clinical signs, and not progressively enlarging are termed inactive.
PATHOPHYSIOLOGY
Nephroliths can obstruct the renal pelvis or ureter, predispose to pyelonephritis, and result in compressive injury of the renal parenchyma leading to renal failure; see chapters on the different urolith types for pathophysiology of urolithiasis; in cats, nephroliths composed of blood clots mineralized with calcium phosphate can form secondarily to chronic renal hematuria.
Nasal and Nasopharyngeal Polyps
OVERVIEW
Protruding, pink, polypoid growths (benign) arising from the mucous membranes
Nasal—originate from the nasal mucosa in dogs and cats
Nasopharyngeal—originate from the base of the eustachian tube in cats; may extend into the external ear canal, middle, pharynx, and nasal cavity
Protruding, pink, polypoid growths (benign) arising from the mucous membranes
Nasal—originate from the nasal mucosa in dogs and cats
Nasopharyngeal—originate from the base of the eustachian tube in cats; may extend into the external ear canal, middle, pharynx, and nasal cavity
Myocarditis
DEFINITION
Inflammation of the heart muscle, often caused by infectious agents affecting the myocytes, interstitium, vascular elements, or pericardium.
Viral, bacterial, rickettsial, fungal, and protozoal diseases are all associated with myocardial inflammation (i.e., myocarditis).
Pharmacologic agents (e.g., doxorubicin) can also be causative.
PATHOPHYSIOLOGY
Mechanisms—toxin production, direct invasion of myocardial tissue, and immune-mediated myocardial damage; vasculitis associated with systemic disease; allergic reactions and direct myocyte damage caused by pharmacologic agents. Protozoa (e.g., Trypanosoma cruzi) lead to granulomatous myocarditis; viral myocarditis is associated with cell-mediated immunologic reactions.
Myocardial involvement may be focal or diffuse. Clinical manifestations depend on the extent of the lesions. Diffuse, severe involvement may lead to global myocardial damage and CHF; discrete lesions involving the conduction system may cause profound arrhythmias.
Inflammation of the heart muscle, often caused by infectious agents affecting the myocytes, interstitium, vascular elements, or pericardium.
Viral, bacterial, rickettsial, fungal, and protozoal diseases are all associated with myocardial inflammation (i.e., myocarditis).
Pharmacologic agents (e.g., doxorubicin) can also be causative.
PATHOPHYSIOLOGY
Mechanisms—toxin production, direct invasion of myocardial tissue, and immune-mediated myocardial damage; vasculitis associated with systemic disease; allergic reactions and direct myocyte damage caused by pharmacologic agents. Protozoa (e.g., Trypanosoma cruzi) lead to granulomatous myocarditis; viral myocarditis is associated with cell-mediated immunologic reactions.
Myocardial involvement may be focal or diffuse. Clinical manifestations depend on the extent of the lesions. Diffuse, severe involvement may lead to global myocardial damage and CHF; discrete lesions involving the conduction system may cause profound arrhythmias.
Mycoplasma
DEFINITION
Class Mollicutes (Latin, mollis, “soft”; cutis, “skin”); > 80 genera; three families: mycoplasmas, T-mycoplasmas or ureaplasmas, and acholeplasmas
Smallest (0.2–0.3 mm) and simplest procaryotic cells capable of self-replication
Fastidious, facultative anaerobic, gramnegative rods
Lack a cell wall; thus plastic, highly pleomorphic, and sensitive to lysis by osmotic shock, detergents, alcohols, and specific antibody plus complement; enclosed by a trilayered cell membrane built of amphipathic lipids (phospholipids, glycolipids, lipoglycans, sterols) and proteins; most require sterols for growth.
Different from wall-defective or wall-less L-form bacteria, which can revert to the normal cell wall strain
Reproduce by binary fission; genome replication not necessarily synchronized with cell division, resulting in budding forms and chains of beads
Ubiquitous in nature as parasites, commensals, or saprophytes in animals, plants, and insects; many are pathogens of humans, animals, plants, and insects.
Class Mollicutes (Latin, mollis, “soft”; cutis, “skin”); > 80 genera; three families: mycoplasmas, T-mycoplasmas or ureaplasmas, and acholeplasmas
Smallest (0.2–0.3 mm) and simplest procaryotic cells capable of self-replication
Fastidious, facultative anaerobic, gramnegative rods
Lack a cell wall; thus plastic, highly pleomorphic, and sensitive to lysis by osmotic shock, detergents, alcohols, and specific antibody plus complement; enclosed by a trilayered cell membrane built of amphipathic lipids (phospholipids, glycolipids, lipoglycans, sterols) and proteins; most require sterols for growth.
Different from wall-defective or wall-less L-form bacteria, which can revert to the normal cell wall strain
Reproduce by binary fission; genome replication not necessarily synchronized with cell division, resulting in budding forms and chains of beads
Ubiquitous in nature as parasites, commensals, or saprophytes in animals, plants, and insects; many are pathogens of humans, animals, plants, and insects.
Metritis
OVERVIEW
Bacterial uterine infection that develops in the immediate postpartum period (usually within the first week); occasionally develops after an abortion or non-sterile artificial insemination—rarely after breeding
Bacteria—ascend through the open cervix to the uterus; a large, flaccid, postpartum uterus provides an ideal environment for growth; gram-negative (e.g., Escherichia coli) commonly isolated
Potentially life-threatening infection; may lead to septic shock
Directly affects uterus; systemic involvement as sepsis develops
Can become chronic and lead to infertility
Bacterial uterine infection that develops in the immediate postpartum period (usually within the first week); occasionally develops after an abortion or non-sterile artificial insemination—rarely after breeding
Bacteria—ascend through the open cervix to the uterus; a large, flaccid, postpartum uterus provides an ideal environment for growth; gram-negative (e.g., Escherichia coli) commonly isolated
Potentially life-threatening infection; may lead to septic shock
Directly affects uterus; systemic involvement as sepsis develops
Can become chronic and lead to infertility
Meningioma
OVERVIEW
Tumors of the meninges most commonly found intracranially over the cerebrum
Usually solitary masses; occasionally multiple
May occur as plaque-like masses on the floor of the calvaria, paranasally, or (rarely) in a retrobulbar location in dogs more than cats; also develop along the spinal cord but less frequently and with an intradural, extramedullary predilection site
Compress the adjacent tissue, causing vasogenic edema
Dogs—tends to be more invasive into brain parenchyma or surrounding vasculature
Tumors of the meninges most commonly found intracranially over the cerebrum
Usually solitary masses; occasionally multiple
May occur as plaque-like masses on the floor of the calvaria, paranasally, or (rarely) in a retrobulbar location in dogs more than cats; also develop along the spinal cord but less frequently and with an intradural, extramedullary predilection site
Compress the adjacent tissue, causing vasogenic edema
Dogs—tends to be more invasive into brain parenchyma or surrounding vasculature
Mastitis
OVERVIEW
Bacterial infection of one or more lactating glands
Result of ascending infection, trauma to the gland, or hematogenous spread
Escherichia coli, Staphylococci, and B-hemolytic Streptococci—most commonly involved
Potentially life-threatening infection; may lead to septic shock
Sepsis—direct effect on mammary glands with systemic involvement
Bacterial infection of one or more lactating glands
Result of ascending infection, trauma to the gland, or hematogenous spread
Escherichia coli, Staphylococci, and B-hemolytic Streptococci—most commonly involved
Potentially life-threatening infection; may lead to septic shock
Sepsis—direct effect on mammary glands with systemic involvement
Malassezia Dermatitis
OVERVIEW
Malassezia pachydermatis (syn. Pityrosporumcanis)—yeast; normal commensal of the skin, ears, and mucocutaneous areas; can overgrow and cause dermatitis, cheilitis, and otitis in dogs
Yeast numbers in diseased areas are usually excessive, although this is a variable finding.
The causes of the transformation from harmless commensal to pathogen are poorly understood but seem related to allergy, seborrheic conditions, and possibly congenital and hormonal factors.
Malassezia dermatitis and Malassezia-associated seborrheic dermatitis—common in all geographic regions of the world
Cats-similar disease, but rare
Malassezia pachydermatis (syn. Pityrosporumcanis)—yeast; normal commensal of the skin, ears, and mucocutaneous areas; can overgrow and cause dermatitis, cheilitis, and otitis in dogs
Yeast numbers in diseased areas are usually excessive, although this is a variable finding.
The causes of the transformation from harmless commensal to pathogen are poorly understood but seem related to allergy, seborrheic conditions, and possibly congenital and hormonal factors.
Malassezia dermatitis and Malassezia-associated seborrheic dermatitis—common in all geographic regions of the world
Cats-similar disease, but rare
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