Macroscopic,cytological and bacteriological evaluation of anal sac content in normal dogs and in dogs with selected dermatological diseases

Abstract Macroscopic and cytological aspects of anal sac content were evaluated in 40 normal dogs and 10 dogs each with pyoderma, Malassezia dermatitis associated with atopic dermatitis and uncomplicated atopic dermatitis. Bacteria isolated from anal sacs were compared with those from abdominal skin and hair in 20 normal dogs and 10 dogs with pyoderma. There was no difference between the groups in anal sac dimension, or in the colour, consistency or presence of granules in their content. Extracellular bacteria were found in higher numbers in diseased animals, whereas intracellular bacteria were observed in 40% of dogs with pyoderma and in only 2.5% of normal dogs. Malassezia spp. were present in 15.7% of dogs, with no difference between groups. Neutrophils were observed in 12.5% of normal dogs, 30% of dogs with Malassezia dermatitis with underlying atopic dermatitis and in 70 and 80% of dogs with pyoderma and uncomplicated atopic dermatitis, respectively. Seven bacterial species were isolated from anal sacs, with no difference between normal dogs and dogs with pyoderma. In five normal animals and in four dogs with pyoderma the same bacterial strains were isolated from anal sacs and from abdominal skin and hair.     

Quantitative analysis in spontaneous canine anal sac gland adenomas and carcinomas

Stained cytological specimens from 7 canine anal sac gland adenomas and 11 canine anal sac gland carcinomas were analyzed by computer-assisted nuclear morphometry. In each case, the nuclei of at least 100 neoplastic cells were measured, and the mean nuclear area (MNA), mean nuclear perimeter (MNP), mean nuclear diameter (MND) and nuclear roundness (NR) were calculated. The study aimed to evaluate (1) the possibility of using nuclear cytomorphometry as an auxiliary diagnostic method to differentiate between canine anal sac gland adenomas and adenocarcinomas, and (2) the prognostic value of nuclear morphometry in canine anal sac gland adenocarcinomas. The results indicated that (1) MNA, MNP, MND and NR could be used as effective auxiliary tools for differential diagnosis between canine anal sac gland adenomas and adenocarcinomas, and (2) MNA, MNP and MND are reliable prognostic indicators for canine anal sac gland adenocarcinomas.     

Quantitative analysis in spontaneous canine anal sac gland adenomas and carcinomas

Stained cytological specimens from 7 canine anal sac gland adenomas and 11 canine anal sac gland carcinomas were analyzed by computer-assisted nuclear morphometry. In each case, the nuclei of at least 100 neoplastic cells were measured, and the mean nuclear area (MNA), mean nuclear perimeter (MNP), mean nuclear diameter (MND) and nuclear roundness (NR) were calculated. The study aimed to evaluate (1) the possibility of using nuclear cytomorphometry as an auxiliary diagnostic method to differentiate between canine anal sac gland adenomas and adenocarcinomas, and (2) the prognostic value of nuclear morphometry in canine anal sac gland adenocarcinomas.The results indicated that (1) MNA, MNP, MND and NR could be used as effective auxiliary tools for differential diagnosis between canine anal sac gland adenomas and adenocarcinomas, and (2) MNA, MNP and MND are reliable prognostic indicators for canine anal sac gland adenocarcinomas.     

Surgery of metastatic anal sac adenocarcinoma in five dogs

OBJECTIVE: To identify survival and morbidity information after surgery for metastases from apocrine gland anal sac adenocarcinomas (AGACA). STUDY DESIGN: Retrospective study. ANIMALS: Five dogs with AGACA. METHODS: Medical records of dogs that had surgery for treatment of metastatic AGACA between 1993 and 2003 were reviewed. Criteria for inclusion required that dogs had lymphadenectomy, with or without further debulking, as part of their treatment for metastatic AGACA and that the tissue was histologically confirmed as consistent with the primary AGACA. Signalment, history, physical examination findings, clinicopathologic data, imaging findings, surgical complications, number of surgeries, survival times, and cause of death were recorded. All dogs had a complete blood count, serum biochemical profile, serum electrolytes, 3-projection thoracic radiographs, abdominal radiographs and/or abdominal ultrasonography, and histologic confirmation of metastatic AGACA invading the regional lymph nodes and caudal abdomen. RESULTS: No surgical complications occurred. Three dogs were euthanatized; median survival, 20.6 months. One dog was alive for 19 months postoperatively. One dog had 5 sequential surgical procedures: 1 iliac lymphadenectomy and 4 debulking procedures of metastatic neoplastic tissue around and dorsal to the iliac vessels extending into the pelvic cavity, and was alive 54 months after initial surgery. CONCLUSION: Dogs with anal sac adenocarcinoma metastases to the iliac lymph nodes can experience long-term survival after surgical excision of the metastatic lesion. CLINICAL RELEVANCE: Lymphadenectomy may afford long-term survival to patients with metastatic anal sac adenocarcinoma.     

Anal sac tumours of the dog and their response to cytoreductive surgery and chemotherapy

A retrospective study of anal sac tumours without pulmonary metastases, from the author's clinical records for the period July 1989 to July 2002, was conducted to establish the response to treatment with surgery and melphalan chemotherapy. Of 21 dogs with tumours of the anal sacs 19 had apocrine gland adenocarcinomas of anal sac origin, one had a benign papillary cystadenoma and another had a malignant melanoma. Two of the 19 dogs had bilateral anal sac adenocarcinomas. Ten of the 19 dogs with apocrine gland adenocarcinomas of anal sac origin had sublumbar lymphadenopathy. Five dogs were excluded by their owners from recommended treatment. Fourteen dogs with apocrine gland adenocarcinomas of anal sac origin were treated by surgical cytoreduction and chemotherapy with melphalan. Seven of the 14 dogs had regional lymph node metastases. Cytoreduction was by local excision of the anal sac in all 14 dogs and concurrent removal of the sublumbar retroperitoneal lymph nodes in the seven dogs with regional lymph node metastases. The median survival time of dogs with sublumbar nodal metastasis was 20 months and for dogs with tumour localised to the anal sac the median survival time was 29.3 months. There was no difference in median survival of those dogs with sublumbar metastases compared to those without. This study suggests there is a role for melphalan in the treatment of dogs with anal sac adenocarcinoma when combined with cytoreductive surgery, with treatment survival times and the local recurrence rate of the primary tumour comparing favourably with previously published treatment regimes.     

Squamous cell carcinoma of the anal sac in five dogs

Tumors of the perianal area of dogs are common and include multiple tumor types. Whereas perianal adenomas occur often, adenocarcinomas of the apocrine glands of the anal sac occur less frequently. A review of the literature revealed no reports of squamous cell carcinomas arising from the epithelial lining of the anal sac. Squamous cell carcinomas originating from the lining of the anal sac were diagnosed in five dogs. Microscopically, the tumors consisted of variably sized invasive nests and cords of epithelial cells displaying squamous differentiation. Four of the five dogs were euthanatized because of problems associated with local infiltration by the tumors. In the fifth dog, there was no evidence of tumor 7 months after surgical removal, but further follow up was not available.     

Evaluation of the bacterial microflora of the conjunctival sac of healthy dogs and dogs with atopic dermatitis

The aim of this case–control study was to evaluate and compare the bacterial microflora from the conjunctival sac of dogs with atopic dermatitis and healthy dogs. Twenty‐one atopic dogs without clinical and/or cytopathological signs of bacterial blepharoconjunctivitis and 21 breed‐matched healthy dogs were enrolled. Under topical anaesthesia, the inferior conjunctival sac of one eye was scraped twice. Material was collected with a Kimura spatula, spread over a slide and stained with a Diff Quick^®‐type stain (Medion Diagnostics GmbH, Düdingen, Switzerland) for cytological examination. An area of 0.5 cm² was examined at ×1000 magnification, and the types and numbers of cells and bacteria were recorded. A bacterial swab was collected and inoculated into culture media for the growth of aerobic bacteria. Before sampling, each atopic dog was evaluated for severity of cutaneous lesions, pruritus and conjunctival inflammation. Significant differences were observed between atopic and healthy dogs for the presence of bacteria on cytology (P = 0.015), keratinized (P = 0.001) and nonkeratinized epithelial cells (P = 0.013), eosinophils (P = 0.019) and lymphocytes (P = 0.008). Bacteria were recovered from 12 atopic dogs and three healthy dogs (P = 0.004). Staphylococcus pseudintermedius was the most commonly isolated species in atopic dogs (seven of 12). In atopic dogs, no significant relation was found between conjunctival bacterial colonization (on cytology and culture) and the severity of any of the clinical parameters. This study suggests differences in conjunctival bacterial colonization and cytological features between atopic and healthy dogs.     

Open versus closed bilateral anal sacculectomy for treatment of non-neoplastic anal sac disease in dogs: 95 cases (1969-1994)

OBJECTIVE: To determine complications associated with anal sacculectomy in dogs with non-neoplastic anal sac disease and compare complication rates for open versus closed techniques. DESIGN: Retrospective study. ANIMALS: 95 dogs. PROCEDURE: Medical records were reviewed for information on signalment, history, physical examination findings, type of anal sac disease, surgical technique (closed, standard open [surgery performed prior to 19801, or modified open [surgery performed after 19801), and postoperative complications. RESULTS: In 57 dogs, a closed technique was used, and in 38, an open technique was used. Only 3 dogs developed short-term complications (excessive drainage, scooting and inflammation, and seroma formation), and 14 developed long-term complications (continued licking of the surgery site, fecal incontinence, fistulation, and stricture formation). Development of postoperative complications was significantly associated with surgical technique. Dogs that underwent standard open sacculectomy prior to 1980 were 13.67 times as likely to have a long-term complication as were dogs that underwent closed sacculectomy. Weight of the dog, type of anal sac disease, age at the time of surgery, and whether the wound was closed surgically were not significantly associated with whether dogs developed postoperative complications. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that anal sacculectomy is a safe and effective treatment for non-neoplastic anal sac disease in dogs and is associated with a low rate of complications. The standard open technique was associated with the greatest number of complications, whereas complication rates for the closed and modified open techniques were similar to each other.     

Sentinel lymph node mapping of the canine anal sac using lymphoscintigraphy: A pilot study

Sentinel lymph node mapping and biopsy are important parts of oncologic staging in human medicine. Sentinel lymph node mapping enables identification of the first lymph node to receive lymphatic drainage while avoiding unnecessary lymph node dissection. Anal sac adenocarcinoma is the most common malignant neoplasm of the canine perineal area. For dogs with anal sac adenocarcinoma, lympadenectomy and metastasis to the iliosacral lymphocentrum are negative prognostics indicators. The objectives of this prospective, two by two, crossover pilot study were to establish the feasibility of lymphoscintigraphy using Technetium‐99 sulfur colloid of the canine anal sac of healthy dogs, compare two injection techniques, and the time for identification of sentinel lymph nodes using each technique. We hypothesized that both intramural and perimural injections of the canine anal sac would identify similar sentinel lymph node drainage. The sentinel lymph node was identified in all dogs using either technique. Intramural injection of the canine anal sac showed radiopharmaceutical uptake faster than perimural injection technique (P = 0.040). There was concordance between intramual and perimural techniques for the sentinel lymph node identified in 50% of cases. A sacral lymph node was identified as sentinel in three of eight dogs (37.5%). Lymphoscintigraphy of the canine anal sac is safe and feasible in normal dogs; however, the method of injection technique seems to have a significant effect on the sentinel lymph node identified.     

Cytological examination and physical characteristics of the anal sacs in 17 clinically normal dogs

OBJECTIVE: To quantify numbers of leucocytes, keratinocytes and microorganisms in, as well as the turgidity, colour and consistency of, anal sac exudates in clinically normal dogs. DESIGN: Selection criteria were formed based on the absence of clinical signs associated with anal sac disease, and the absence of factors potentially affecting colonic flora. Anal sacs were palpated for turgidity then expressed onto a swab, where colour and consistency were noted. A squash preparation made from any exudate was heat fixed and stained with modified Wright's stain. Eight representative 1000x oil immersion fields from each were examined for leucocytes, erythrocytes, keratinocytes, bacteria and yeast. Results were summarised, and cytological counts grouped into quartiles (minimal, few, moderate, numerous). Due to the multivariate nature of the study and limited subject numbers, further significant statistical analysis could not be performed. RESULTS: Seventeen dogs satisfied the selection criteria. The physical characteristics of the exudate and sac varied, though 31/34 sacs were empty or soft, 22/27 exudates were light or dark brown and 19/27 exudates were a thin liquid. Total leucocyte, keratinocyte and bacilli counts were extremely variable. Yeasts were present in 26/208 microscopic fields examined cytologically. Only 5/208 fields showed numerous cocci. A single instance of intracellular bacteria and a single erythrocyte were noted following examination of all fields. CONCLUSION: In this study, the characteristics of normal anal sacs and their exudate varied but greater than 70% showed similar features. Exudate cytology was highly variable, though yeasts were uncommon, and intracellular cocci and erythrocytes extremely rare.     

Canine anal sac adenocarcinomas: clinical presentation and response to therapy

A retrospective study of 43 dogs with anal sac adenocarcinoma (ASAC) was performed to characterize the clinical presentation and response to treatment. Clinical signs at presentation varied considerably, with signs related either to sublumbar nodal metastasis (tenesmus or constipation) or hypercalcemia (polyuria-polydipsia and anorexia) being the most frequent findings. At the time of presentation, 23 (53%) dogs had hypercalcemia and 34 (79%) had metastases, with the regional lymph nodes (31 dogs, 72%) being the most common site of metastasis. A variety of chemotherapeutic agents were administered, with partial remission (PR) recorded in 4 of 13 (31%) dogs treated with cisplatin and in 1 of 3 (33%) dogs treated with carboplatin. The median survival for all dogs was 6 months (range, 2 days-41 months). There was no statistical association between the presence of hypercalcemia and survival, although the power of the study to detect an increase in survival of 3 months was low (.33). We conclude that platinum chemotherapy has antitumor activity in canine apocrine gland carcinoma and that further study of these agents is warranted.     

Gross and cytological characteristics of normal canine anal-sac secretions

A study was conducted to characterize the gross and cytological characteristics of secretions from normal canine anal sacs. Fifty dogs with no recent history of anal-sac disease were selected consecutively and their anal sacs manually expressed. Of the 47 dogs with known or estimated ages, 27 were < 1 year olds. However, these youngest dogs were not significantly different from the rest in cell counts, viscosity, or presence of dark or light solid portions of the secretions. For all dogs combined, the secretions typically contained 41 (median) corneocytes per 400x magnification microscopic field, lots of basophilic background debris, and a mixture of Gram-positive cocci (173 per field; median), Gram-positive rods (29 per field; median), and Gram-negative rods (two per field; median). Although median counts across 10 400x fields per sac indicated no leucocytes or yeasts, many of the normal dogs had an occasional 400x field with non-degenerate neutrophils and yeasts. Erythrocytes were not a feature of these anal-sac secretions, and mononuclear leucocytes were found only rarely. Extreme heterogeneity existed in gross colour, consistency and the amount of solid material. Thus, these latter parameters probably would not be valid indicators of anal-sac disease.     

Ultrasound and computed tomography of the iliosacral lymphatic centre in dogs with anal sac gland carcinoma

In this prospective study, we hypothesized that computed tomography (CT) would identify more normal and abnormal iliosacral lymph nodes (LNs) than abdominal ultrasound in dogs with anal sac gland carcinoma (ASGC). Twelve client‐owned dogs with ASGC but without distant metastasis were enrolled. Abdominal ultrasound and contrast‐enhanced CT scans of the abdomen were obtained. Iliosacral LNs were counted and assessed for location, laterality and size. Significantly (P < 0.00001) more iliosacral LNs were identified with CT (61) than ultrasound (30), including significantly (P = 0.00012) more medial iliac LNs with CT (33) than ultrasound (19). There was no difference in number of internal iliac LNs identified with CT versus ultrasound. Significantly (P = 0.000061) more sacral LNs were identified with CT (15) than ultrasound (0). Ultrasound identified slightly more (7) abnormal iliosacral LNs than CT (5). Contrast CT was able to identify more normal but not more abnormal LNs than ultrasound.     

Evaluation of clomipramine as an adjunct to behavioural therapy in the treatment of separation-related problems in dogs

Forty-nine dogs showing signs of separation-related problems were randomly assigned to one of three groups: group A (15 dogs) received a placebo twice daily; group B (17 dogs) received clomipramine at 0.5 to 1.0 mg/kg twice daily; and group C (17 dogs) received clomipramine at 1.0 to 2.0 mg/kg twice daily. All the dogs also received behavioural therapy. Their owners were required to complete questionnaires about their dog's behaviour initially, and one, four and eight weeks after the treatment with clomipramine began. Bipolar ratings scales were used to monitor the frequencies of 'general', 'attachment-related' and 'separation-related' behaviours. Kruskal-Wallis tests and Kendall Rank correlations were used to determine any initial differences between the treatment groups, and the association between the initial scores and behavioural changes after one week of treatment with clomipramine. Extended Mantel-Haenszel statistics were used to evaluate the effects of clomipramine treatment versus the placebo, and Page's test was used to assess the effectiveness of behavioural therapy on its own. There were no significant differences in the demographic characteristics of the owners of the dogs assigned to the three groups. The dogs differed slightly in age between groups, and the dogs in the two clomipramine-treated groups were reported as showing problems at a significantly earlier age than those in the placebo group. Clomipramine treatment had a sustained suppressive effect on the dogs' general activity levels, and a more modest suppressive effect on their attachment-related tendency to want much physical contact with their owners. The typical signs of separation-related behaviour problems were not significantly affected by treatment with clomipramine, but behavioural therapy on its own was highly effective in reducing behavioural problems.     

Disease conditions of canine anal sacs

The literature about the anal sacs of healthy dogs and the pathogenesis, diagnosis and therapy of anal sac impaction and sacculitis are reviewed. Knowledge about the physiological role of the anal sacs is still confusing. The colour and consistency of the anal sac contents are variable in healthy dogs and there are no pathognomonic signs of anal sac impaction or sacculitis. The wide variation in macroscopic detail of anal sac secretions may give rise to misinterpretation and thus overdiagnosis of sacculitis. Other diseases such as vaginitis, flea allergy, atopy, proctitis, parasites and perianal fistulae can lead to similar signs and must be eliminated from the differential diagnosis before the anal sacs are incited as the cause of the signs. Further research is necessary on the morphological, physical and biochemical aspects of the anal sacs and their secretions to define more precise criteria for the diagnosis of impaction and sacculitis. It is imperative that controlled therapeutic trials should be performed, and such studies are indispensable for the rational therapy of anal sac disease.     

Cytologically atypical anal sac adenocarcinoma in a dog

A 10-year-old intact female Shetland Sheepdog with tenesmus had a subcutaneous mass at the left ventral aspect of the anus. On cytologic examination, 2 types of cells were observed. Most of the cells were oval to polygonal and had elliptical or elongate nuclei and a moderate amount of pale to basophilic cytoplasm. The remaining cells had round to oval nuclei and pale to basophilic cytoplasm. Cells of both types were loosely adhered to each other and were arranged in rosette-like structures. Both neoplastic cell types had fine homogenous chromatin and either a small indistinct nucleolus or no visible nucleolus. Mild anisokaryosis and anisocytosis were observed. Histologically, the mass consists of glandular structures formed by cuboidal cells admixed with bundles of spindle cells. Eosinophilic PAS- and Alcian blue-positive secretory material was found in the center of some glandular structures. Both neoplastic cell types had positive staining with paradoxical concanavalin A and expressed cytokeratin, but not vimentin, S-100, α-smooth muscle actin, or desmin. Based on location and histologic and immunohistochemical features, the final diagnosis was adenocarcinoma of the apocrine gland of the anal sac, which should be included as a cytologic differential diagnosis when spindle cells and typical epithelial cells are observed in masses in the region of the anal sac of dogs.     

Breed, gender and neutering status of British dogs with anal sac gland carcinoma

This study details the breed, gender and neutering status of a large cohort of British canine patients suffering from histologically confirmed anal sac gland carcinoma. Estimates of the relative risk for the development of this disease attributable to these factors are calculated. To reduce the impact of sampling errors, cases were selected from veterinary histopathology laboratories rather than referral hospital databases, and multiple estimates of the general British canine population were used. The weaknesses of the statistical assumptions made are discussed. There was no evidence to support a gender predisposition for the development of this condition. English cocker spaniels are significantly over‐represented, with a mean relative risk estimate of 7.3. The mean relative risk estimate associated with being neutered was 1.4; the effect of neutering appeared to be more significant in male dogs compared with that in female dogs.     

A relatively high proportion of dogs with small apocrine gland anal sac adenocarcinoma (AGASACA) primary tumours present with locoregional lymph node metastasis

Apocrine gland anal sac adenocarcinoma (AGASACA) is a highly relevant disease in dogs, with a high rate of lymph node (LN) metastasis during the course of disease. A recent study showed that risk for death and disease progression was significantly associated with primary tumour size less than 2 and 1.3 cm, respectively. The objective of this study was to report the proportion of dogs that have primary tumours less than 2 cm in diameter, that are diagnosed with LN metastasis at presentation. This was a single site retrospective study of dogs that underwent treatment for AGASACA. Dogs were included if physical examination primary tumour measurements were available, abdominal staging was performed, and confirmation of abnormal lymph nodes by cytology or histology was done. Over a 5-year period, 116 dogs were included for review with 53 (46%) having metastatic LN at presentation. The metastatic rate for dogs with primary tumours <2 cm was 20% (9 of 46 dogs) compared to 63% (44 of 70 dogs) in dogs with primary tumours ≥2 cm. The association between tumour size group (<2 vs. ≥2 cm) and the presence of metastasis at presentation was significant (P < .0001) with an OR of 7.0 (95% CI: 2.9–15.7). Primary tumour size was significantly associated with LN metastasis at presentation but the proportion of dogs that presented with LN metastasis in the <2 cm group was relatively high. This data suggests that dogs with small tumours may still have aggressive tumour biology.     

Temporally separated bilateral anal sac gland carcinomas in four dogs

Anal sac gland carcinoma arising from the apocrine secretory epithelium in the anal sac wall, is locally invasive and highly metastatic. The majority of anal sac gland carcinomas are unilateral on presentation, but bilateral tumours have been identified. This case series presents the outcome of four unique cases of unilateral anal sac gland carcinoma which subsequently developed contralateral anal sac gland carcinoma 50 to 390 days after removal of the initial tumour. Median survival was 1035 days after initial diagnosis and 807 days after diagnosis of the second anal sac gland carcinoma.     

Evaluation of adjuvant carboplatin chemotherapy in the management of surgically excised anal sac apocrine gland adenocarcinoma in dogs

There is no widely accepted standard of care for canine anal sac apocrine gland adenocarcinoma (ASAGAC). Surgery alone is inadequate in many cases, but the benefit of adjuvant chemotherapy is not well established. The primary objective of this retrospective study was to evaluate the role of carboplatin chemotherapy in the post‐operative management of ASAGAC. Seventy‐four dogs with naturally occurring ASAGAC underwent surgery. Forty‐four dogs received adjuvant carboplatin and 30 did not. Median overall survival (OS) was 703 days. Median time to progression (TTP) was 384 days. Only primary tumour size and lymph node metastasis at diagnosis significantly impacted the outcome. Differences in OS and TTP, between the dogs that received adjuvant carboplatin and those that did not, failed to reach statistical significance. Treatment of progressive disease, whilst not limited to chemotherapy, significantly prolonged the survival. This study shows that adjuvant carboplatin chemotherapy is well tolerated and may have a role in the management of dogs with ASAGAC.