Diagnostic imaging features of normal anal sacs in dogs and cats

This study was conducted to provide normal reference features for canine and feline anal sacs using ultrasound, low-field magnetic resonance imaging (MRI) and radiograph contrast as diagnostic imaging tools. A total of ten clinically normal beagle dogs and eight clinically normally cats were included. General radiography with contrast, ultrasonography and low-field MRI scans were performed. The visualization of anal sacs, which are located at distinct sites in dogs and cats, is possible with a contrast study on radiography. Most surfaces of the anal sacs tissue, occasionally appearing as a hyperechoic thin line, were surrounded by the hypoechoic external sphincter muscle on ultrasonography. The normal anal sac contents of dogs and cats had variable echogenicity. Signals of anal sac contents on low-field MRI varied in cats and dogs, and contrast medium using T1-weighted images enhanced the anal sac walls more obviously than that on ultrasonography. In conclusion, this study provides the normal features of anal sacs from dogs and cats on diagnostic imaging. Further studies including anal sac evaluation are expected to investigate disease conditions.

Evaluation of an anal sac adenocarcinoma tumor in a Spitz dog

A 9-year-old emasculated male Spitz with tenesmus and constipation had a subcutaneous mass at the left ventral aspect of the anus with history of polyuria and polydipsia. A complete blood cell count, serum biochemistry panel, and urinalysis (cystocentesis sample) were evaluated. Abnormalities in the serum biochemistry panel included a mildly elevated serum cholesterol concentration (7.28 mmol/L; reference interval, 2.70-5.94 mmol/L), increased serum alkaline phosphatase activity (184 U/L; reference interval, 9-90 U/L), alanine transaminase (122 U/L; reference interval, 5-60 U/L) activity and aspartate aminotransferase (80 U/L; reference interval, 5-55 U/L) activity, severe increased total calcium concentration (16.3 mg/dL; reference interval, 8.2-12.4 mg/dL or 9.3-11.4 mg/dL), and decreased total calcium concentration (3.4 mg/dL, reference interval, 2.5-5.6mg/dL). Furthermore, testing revealed an increased intact parathyroid hormone concentration (38.6 pmol/L; reference interval, 3-17 pmol/L). On cytologic and histopathologic examinations, various 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. Based on location and histologic 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.

Diferencia en la población de células cebadas de glándulas apocrinas de sacos anales de perros adultos y seniles / Difference in the population of mast cells of anal sac apocrine glands of adult and senile dogs

Se estudió la población de células cebadas (CC) presentes en sacos anales de perros adultos y seniles mediante su conteo en cortes de tejido procesado con la técnica de inclusión en parafina y teñidos con azul de toluidina. El promedio de CC obtenido para el grupo de perros adultos jóvenes fue de 18,16 +/- 7,58 (n=12 perros) y para el grupos de adultos maduros fue de 73,75 +/- 16,29 (n=12 perros). Al comparar el número de células de ambos grupos con la prueba de U Mann-Withney se encontró que son significativamente diferentes (P< 0,0001), siendo mayor en el grupo de perros seniles. Esta mayor población de CC puede estar relacionada con una mayor susceptibilidad de los perros seniles a reacciones inflamatorias del tejido de los sacos anales causadas por cambios en la dieta, obesidad y diarrea crónica.

We studied the population of mast cells (CC) present in anal sacs of adult and senile dogs by its count in tissue processed with the technique of embedding in paraffin and stained with toluidine blue. The average CC obtained for the group of adult dogs (n=12) was 18.16 +/- 7.58 and for group of senile dogs (n=12) was 73.75 +/- 16.29. When comparing the number of cells in both groups with Mann-Whitney U test were found to be significantly different (P0.0001), being higher in the group of senile dogs. The largest population of CC may be related to an increased susceptibility of senile dogs to inflammatory reactions in the tissue of the anal sacs caused by changes in diet, obesity and chronic diarrhea.

Estudios macro y microscópico del saco anal del coipo: myocastor coypus / Macro and microscopic studies of the anal sac of the coypus: myocastor coypus

Fue realizada la disección del saco anal de 44 coipos, de ambos sexos, de distintas edades y procedencias, observándose algunas características similares a los sacos anales del perro y gato, aunque es impar y está ubicado en ventral del ano. Es ovoídeo o piriforme, siendo más grande en los adultos y, entre éstos, más aún en los machos que en las hembras; posee un conducto que desemboca en el canal anal a un centímetro del ano y que se exterioriza en el momento de secretar el producto glandular. Se encuentra rodeado de una cápsula de tejido fibroso e insertado en ella se observa tejido muscular estriado, correspondiente a fibras de los músculos del diafragma pelviano. Microscópicamente está constituido por un tejido glandular tubuloalveolar, con células globosas de núcleo laxo, con uno o más nucleolos. Desde la cápsula hacia el interior se forman tabiques de tejido conectivo que dividen al tejido glandular en lóbulos y lobulillos. Mediante coloraciones especiales se constató la presencia de fibras que contienen colágeno de los tipos I y III, de fibras eleunínicas y oxitalánicas

Trypanosoma cruzi: vertebrate and invertebrate cycles in the same mammal host, the opossum Didelphis marsupialis.

No gamba (Didelphis marsupialis) foi observado um ciclo extracelular do Trypanosoma cruzi: o parasita crescia abundantemente no material de secrecao acumulado no lumen das glandulas anais de animais criados em cativeiro e infectados por via subcutanea com fezes de triatomineos