Page 1162 - Cote clinical veterinary advisor dogs and cats 4th

Leiomyoma, Leiomyosarcoma 579.e3

○ Because most dogs with heart rates < 140 resynchronization by means of biventricular ADDITIONAL SUGGESTED
beats/min have sinus arrhythmia and some pacing results in clinical benefits. This READINGS
VetBooks.ir examining the regularity of rhythm can Technician Tips Miller MS, et al: Electrocardiography. In Fox PR, et Diseases and Disorders
therapy may be used in veterinary patients
degree of irregularity of the heart rhythm,
in the future.
al, editors: Textbook of canine and feline cardiology,
be a helpful clue. A regularly irregular
Philadelphia, 1999, Saunders, pp 84-86.
(cyclically varying) rhythm with QRS
complexes that are all wide, bizarre, and The abnormal conduction that results in LBBB Tilley LP: Left bundle branch block. In Tilley LP,
editor: Essentials of canine and feline electrocardiog-
identical to each other suggests respiratory does not cause direct harm but suggests underly- raphy, Philadelphia, 1992, Lea & Febiger, pp 75-77.
sinus arrhythmia with bundle branch ing heart disease. Vitt J, et al: Incidence of heart disease in cats with
block. In contrast, when ventricular ectopy electrocardiographic evidence of leftward mean
such as ventricular tachycardia produces SUGGESTED READING electrical axis shift [abstract]. J Vet Intern Med
wide, bizarre QRS complexes that are all Kittleson MD: Electrocardiography: basic concepts, 26:714, 2012.
of the same shape, the rhythm is usually diagnosis of chamber enlargement, and intraven- AUTHOR: Meg M. Sleeper, VMD, DACVIM
regular (same R-R interval). tricular conduction disturbances. In Kittleson MD, EDITOR: Leah A. Cohn, DVM, DACVIM
• In human patients with heart failure, the et al, editors: Small animal cardiovascular medicine,
presence of LBBB indicates significant dys- St. Louis, 1998, Mosby, pp 90-94.
synchrony of ventricular contraction. Cardiac

Leiomyoma, Leiomyosarcoma Client Education
Sheet

Clinical Presentation
BASIC INFORMATION factors have been associated with long-term
HISTORY, CHIEF COMPLAINT disease-free intervals or cure as a result of
Definition • GI leiomyoma: incidental finding during resection of the tumor.
• Leiomyoma: uncommon benign tumor of endoscopy or necropsy. Occasionally, • Although not confirmed, leiomyosarcomas in
smooth muscle origin tenesmus or dyschezia if rectal; vomiting the female urogenital organs are thought to
• Leiomyosarcoma: uncommon malignant or regurgitation if gastroesophageal develop secondary to hormonal stimulation.
tumor of smooth muscle origin • GILMS: signs referable to the GI tract,
• Either tumor can be found wherever smooth including chronic vomiting, weight loss, DIAGNOSIS
muscle is present. Most common sites are melena, hematemesis, gastric dilation, and
the gastrointestinal (GI) tract, spleen, and regurgitation Diagnostic Overview
genital tract. • Peripheral leiomyosarcoma: progressive mass The diagnosis is suspected based on GI signs in
noticed by the owner an older dog, typically with a mass visible on
Synonym • Rarely, animals with leiomyosarcoma first abdominal ultrasound. Diagnosis is confirmed
Smooth muscle tumors present for signs related to paraneoplastic by histopathologic and immunohistochemical
syndromes. evaluation.
Epidemiology
SPECIES, AGE, SEX PHYSICAL EXAM FINDINGS Differential Diagnosis
Uncommon in dogs and rare in cats • Abdominal mass possible with any visceral • GI: foreign body, enteritis causing ileus, other
• Gastric leiomyoma: mean age of 16 years leiomyo(sarco)ma GI neoplasms, GI granuloma (fungal, other),
(dogs) • Signs of peritonitis possible as a result of GI inflammation/infiltration (inflammatory
• Colonic leiomyoma: median age of 12 years intestinal rupture, especially with cecal bowel disease), other causes of vomiting
(dogs) leiomyosarcoma (p. 1293)
• GI leiomyosarcoma (GILMS): median age • Abdominal pain, distended loops of bowel, • Other sites: other neoplasms (benign or
of 10.5-12 years (dogs) and/or mass palpable per rectum in some malignant), abscess, granuloma, hematoma
• Genital, urinary tract, or intestinal cases
leiomyo(sarco)ma: female > male • Weakness or collapse due to GI hemorrhage Initial Database
• Subcutaneous mass with peripheral leiomyo- • CBC: 63% of dogs are anemic; features of
GENETICS, BREED PREDISPOSITION sarcoma iron deficiency (microcytosis, hypochromasia)
Leiomyosarcoma: more common in large- • Physical exam may be unremarkable, are possible
breed dogs, notably in German shepherds especially with leiomyoma. • Serum biochemistry panel: 50% are hypo-
(intestinal) glycemic
Etiology and Pathophysiology • Three-view thoracic radiographs: usually
ASSOCIATED DISORDERS • Leiomyomas and leiomyosarcomas (see above normal
Paraneoplastic syndromes (attributed to comments on GIST) have been associated • Abdominal radiographs: may reveal GI mass,
leiomyoma/leiomyosarcoma before awareness with paraneoplastic hypoglycemia. Poten- evidence of lymphadenomegaly, changes
of GI stromal tumors [GIST]): tial mechanisms include excessive glucose consistent with peritonitis, or no abnormalities
• Hypoglycemia metabolism by the tumor, diminished • Abdominal ultrasound: 66% have evidence
• Nephrogenic diabetes insipidus (one dog hepatic gluconeogenic capacity due to of an abdominal mass; lymphadenomegaly
with intestinal leiomyosarcoma) hepatic damage by the tumor, associated may also be noted.
• Erythrocytosis due to elevated plasma peritonitis, and production of insulin-like • Fine-needle aspiration cytology, if possible,
erythropoietin levels (one dog with cecal growth factors by the tumor. Tumors associ- may help identify the tumor type before
leiomyosarcoma) ated with production of insulin-like growth invasive diagnostic testing (biopsy).

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