Anal sac adenocarcinoma
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2008-06-14T02:17:22Z
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[[Image:Anal sac adenocarcinoma cytology.JPG|thumb|Cytology of an anal sac adenocarcinoma]]
An '''anal sac adenocarcinoma''' is an uncommon and aggressive [[malignant]] [[tumor]] found in [[dog]]s that arises from the tissue of [[anal glands|anal sac]]. At least one case has been reported in a [[cat]].<ref>{{cite journal |author=Mellanby R, Foale R, Friend E, Woodger N, Herrtage M, Dobson J |title=Anal sac adenocarcinoma in a Siamese cat |journal=J Feline Med Surg |volume=4 |issue=4 |pages=205–7 |year=2002 |pmid=12468314 |doi=10.1053/jfms.2002.0174}}</ref> They are the second most common cancerous cause of [[hypercalcaemia]] (high serum [[calcium]]) in dogs.<ref name=VetMed>{{cite journal | last = Lucas | first = Pamela | coauthors = Lacoste, Hugues; de Lorimier, Louis-Phillipe; Fan, Timothy M. | title = Treating paraneoplastic hypercalcemia in dogs and cats | journal = Veterinary Medicine | volume = 102 | issue = 5 | pages = 314–331 | publisher = Advanstar Communications | date = May 2007 }}</ref>
==Signs and symptoms==
Anal sac adenocarcinomas first appear as a small lump associated with one of the anal sacs, but they can grow to a large size. Smaller tumors are undetectable without a [[rectal examination]], while larger tumors can cause pain and straining to defecate. Between 25 and 50 percent of dogs with these tumors will also develop hypercalcaemia<ref>{{cite journal |author=Kadar E, Rush J, Wetmore L, Chan D |title=Electrolyte disturbances and cardiac arrhythmias in a dog following pamidronate, calcitonin, and furosemide administration for hypercalcemia of malignancy |journal=J Am Anim Hosp Assoc |volume=40 |issue=1 |pages=75–81 |year=2004 |pmid=14736909}}</ref> through secretion of [[parathyroid hormone-related protein]] by the tumor.<ref>{{cite journal |author=Gröne A, Werkmeister J, Steinmeyer C, Capen C, Rosol T |title=Parathyroid hormone-related protein in normal and neoplastic canine tissues: immunohistochemical localization and biochemical extraction |journal=Vet Pathol |volume=31 |issue=3 |pages=308–15 |year=1994 |pmid=8053125}}</ref> Symptoms of hypercalcaemia include increased drinking and urination, vomiting, loss of appetite, weight loss, and [[bradycardia]] (slow heart rate). Anal sac adenocarcinomas also have a tendency to [[metastasis|metastasize]] to the [[lymph node]]s, [[spleen]], and [[lung]]s.<ref name=Morrison_1998>{{cite book|author=Morrison, Wallace B.|title=Cancer in Dogs and Cats|edition=1st ed.|publisher=Williams and Wilkins|year=1998|id=ISBN 0-683-06105-4}}</ref> The sublumbar ([[iliac lymph node|iliac]]) lymph nodes are the most common site of metastasis and can become larger than the original tumor.<ref>{{cite web | last = Kessler | first = Martin | title = Anal sac carcinoma in the dog | work = Proceedings of the North American Veterinary Conference | date = 2006 | url = http://www.ivis.org/proceedings/navc/2006/SAE/278.pdf?LA=1 | format = PDF | accessdate = 2007-03-29 }}</ref>
==Diagnosis==
Anal sac adenocarcinomas are often suspected due to location and behavior, but a [[biopsy]] is necessary for a definitive diagnosis. [[Needle aspiration biopsy]] is a common first step. [[Cytology]] reveals clusters of [[cell (biology)|cell]]s with uniform round [[cell nucleus|nuclei]]. These cells do not have many of the features usually associated with malignancy, such as a high nucleus to [[cytoplasm]] ratio or prominent [[nucleolus|nucleoli]].<ref name=Cronin>{{cite journal | last = Cronin | first = Kim L. | title = Apocrine gland adenocarcinoma of the anal sac | journal = DVM | pages = 2S–6S | publisher = Advanstar Communications | date = Dec. 2007 }}</ref> [[Medical ultrasonography|Ultrasonography]] and [[radiography]] are performed to look for metastasis.
==Treatment and prognosis==
Aggressive surgical removal of the tumor and any enlarged sublumbar lymph nodes is essential for treatment of the tumor and associated hypercalcaemia. There is a high recurrence rate, although removal of lymph nodes with metastasis may improve survival time.<ref>{{cite journal |author=Hobson H, Brown M, Rogers K |title=Surgery of metastatic anal sac adenocarcinoma in five dogs |journal=Vet Surg |volume=35 |issue=3 |pages=267–70 |year=2006 |pmid=16635006 |doi=10.1111/j.1532-950X.2006.00137.x}}</ref> [[Radiation therapy]] and [[chemotherapy]] may be helpful in treatment. Severe hypercalcaemia is treated with aggressive [[Intravenous therapy|IV fluid therapy]] using [[sodium chloride]] and medications such as [[loop diuretic]]s (increased kidney excretion of calcium) and [[Bisphosphonate|aminobisphosphonate]]s (decreased calcium release from bones).<ref name=VetMed/> A poorer prognosis is associated with large tumor size (greater than 10 cm), hypercalcaemia, and generalized metastasis.<ref>{{cite web | last = Kirpensteijn | first = Jolle | title = Treatment of perianal and anal sac tumors | work = Proceedings of the North American Veterinary Conference | date = 2006 | url = http://www.ivis.org/proceedings/navc/2006/SAE/280.pdf?LA=1 | format = PDF | accessdate = 2007-03-29 }}</ref>
==Commonly affected breeds==
Breeds that may be more commonly affected include the [[English Cocker Spaniel]], [[German Shepherd Dog]], [[Alaskan Malamute]], [[Dachshund]], and [[Springer Spaniel]].<ref>{{cite web | title = Apocrine Gland Tumors of Anal Sac Origin | work = The Merck Veterinary Manual | date = 2006 | url = http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/72209.htm | accessdate = 2007-01-01 }}</ref>
==References==
{{Reflist}}
==External link==
*[http://www.petcancercenter.org/Cancer_Types_Anal_Sac.html ''Anal Sac Tumors in Cats and Dogs'' from Pet Cancer Center]
*[http://www.vetspecialists.co.uk/06_Animal_Welfare/Oncology_Facts/Anal_Sac_Gland_Carcinoma.html ''Anal sac gland carcinoma: veterinary factsheet'' from Davies Veterinary Specialists]
[[Category:Dog diseases]]