Diagnosis, Prognosis, and Treatment of Canine Hemangiosarcoma: A Review Based on a Consensus Organized by the Brazilian Association of Veterinary Oncology, ABROVET

Hemangiosarcoma is a mesenchymal neoplasm originating in the endothelial cells of blood vessels; they can be classified as non-visceral and visceral types. Non-visceral hemangiosarcomas can affect the skin, subcutaneous tissues, and muscle tissues; visceral hemangiosarcomas can affect the spleen, liver, heart, lungs, kidneys, oral cavity, bones, bladder, uterus, tongue, and retroperitoneum. Among domestic species, dogs are most affected by cutaneous HSA. Cutaneous HSA represents approximately 14% of all HSA diagnosed in this species and less than 5% of dermal tumors, according to North American studies. However, Brazilian epidemiological data demonstrate a higher prevalence, which may represent 27 to 80% of all canine HSAs and 13.9% of all skin neoplasms diagnosed in this species. Cutaneous HSA most commonly affects middle-aged to elderly dogs (between 8 and 15 years old), with no gender predisposition for either the actinic or non-actinic forms. The higher prevalence of cutaneous HSA in some canine breeds is related to lower protection from solar radiation, as low skin pigmentation and hair coverage lead to greater sun exposure. Actinic changes, such as solar dermatosis, are frequent in these patients, confirming the influence of solar radiation on the development of this neoplasm. There are multiple clinical manifestations of hemangiosarcoma in canines. The diagnostic approach and staging classification of cutaneous HSAs are similar between the different subtypes. The definitive diagnosis is obtained through histopathological analysis of incisional or excisional biopsies. Cytology can be used as a presurgical screening test; however, it has little diagnostic utility in cases of HSA because there is a high risk of blood contamination and sample hemodilution. Surgery is generally the treatment of choice for dogs with localized non-visceral HSA without evidence of metastatic disease. Recently, electrochemotherapy (ECT) has emerged as an alternative therapy for the local ablative treatment of different neoplastic types; the use of radiotherapy for the treatment of dogs with cutaneous HSA is uncommon. There is greater consensus in the literature regarding the indications for adjuvant chemotherapy in subcutaneous and muscular HSA; doxorubicin is the most frequently used antineoplastic agent for subcutaneous and muscular subtypes and can be administered alone or in combination with other drugs. Other therapies include antiangiogenic therapy, photodynamic therapy, the association of chemotherapy with the metronomic dose, targeted therapies, and natural products. The benefits of these therapies are presented and discussed. In general, the prognosis of splenic and cardiac HSA is unfavorable. As a challenging neoplasm, studies of new protocols and treatment modalities are necessary to control this aggressive disease.

Analysis of the Prevalence of Canine Splenic Mass Lesions in Republic of Korea via Histopathological Diagnosis with Immunohistochemistry

The histopathological diagnosis of canine splenic mass lesions is crucial for prognostication. However, thus far, no study has been conducted on the histopathology of canine splenic mass lesions in Republic of Korea. Herein, the prevalence of splenic diseases was analyzed in 137 canine splenic mass lesions via histopathological diagnosis, and the microscopic pattern associated with each disorder was described. Immunohistochemistry was performed for CD31, CD3, PAX5, Iba1, and C-kit for a more accurate diagnosis of splenic tumors. The proportion of non-neoplastic disorders, including nodular hyperplasia (48.2%, n = 66) and hematoma (24.1%, n = 33), was 72.3%. Splenic tumors, including splenic hemangiosarcoma (10.2%, n = 14), splenic lymphoma (nodular and diffuse types, 8.0%, n = 11), splenic stromal sarcoma (7.3%, n = 10), myelolipoma (1.5%, n = 2), and mast cell tumors (0.7%, n = 1), accounted for 27.7% of cases. The results of this study will aid veterinary clinicians in communication with pet owners about prognoses, recommendations for splenectomy, and subsequent histopathological diagnoses. This study will facilitate further investigations with more detailed comparisons of splenic mass lesions between small- and large-breed dogs.

Evaluation of the validity of the double two-thirds rule for diagnosing hemangiosarcoma in dogs with nontraumatic hemoperitoneum due to a ruptured splenic mass: a systematic review

OBJECTIVE

To evaluate the validity of the double two-thirds rule for a diagnosis of splenic hemangiosarcoma in dogs with nontraumatic hemoperitoneum due to a ruptured splenic mass.

SAMPLE

Systematic literature review.

PROCEDURES

3 databases (PubMed, CAB abstracts, and World of Science) were searched in November 2020. Articles were included if data on dogs with nontraumatic hemoperitoneum due to a splenic mass were included and subsequent pathologic diagnosis could be determined.

RESULTS

In total, 2,390 unique articles were identified, with 66 articles meeting the criteria for full-text review and 14 articles included for analysis. A total of 1,150 dogs were evaluated, with 73.0% (840/1,150) of dogs being diagnosed with a malignant splenic lesion and 27.0% (310/1,150) being diagnosed with a benign splenic lesion. Of the malignancies, 87.3% (733/840) were hemangiosarcoma. Levels of evidence were low, and bias was high as most included studies were retrospective case series.

CLINICAL RELEVANCE

The double two-thirds rule should be refined when evaluating dogs with nontraumatic hemoperitoneum from a ruptured splenic mass, with more dogs being diagnosed with a malignancy and hemangiosarcoma specifically than the double two-thirds rule indicates. These findings may be useful in an emergency setting to guide owners on potential diagnoses for dogs with nontraumatic hemoperitoneum due to a ruptured splenic mass. However, there remains a portion of these dogs with benign conditions and nonhemangiosarcoma malignancies that may have a good long-term prognosis compared to dogs with hemangiosarcoma. Studies with higher levels of evidence, lower risks of bias, and large case numbers are needed in the literature.

Outcomes of 43 small breed dogs treated for splenic hemangiosarcoma

OBJECTIVE

To determine outcome and prognostic factors in small breed dogs in which hemangiosarcoma was diagnosed and whether outcomes differed between small and large breed dogs with splenic hemangiosarcoma.

STUDY DESIGN

Bi-institutional retrospective study.

ANIMALS

Forty-three small breed (<20 kg) and 94 large breed client-owned dogs.

METHODS

Medical records were reviewed to identify dogs treated with splenectomy for splenic hemangiosarcoma. Data acquired included signalment, preoperative staging, bloodwork results, surgical findings, histopathologic findings, administration of chemotherapy, presence/absence of metastatic disease, and survival time (ST). Cox proportional hazards regression analysis was performed to assess prognostic factors associated with survival.

RESULTS

The overall median ST was 116 days and 97 days for small and large breed dogs, respectively. The ST for dogs treated with surgery and chemotherapy was 207 and 139 days for small and large breed dogs, respectively. The disease-free interval (DFI) was 446 and 80 days for small and large breed dogs, respectively. Dog size was associated with DFI (P = .02) but not with ST (P = .09). The presence of metastasis at diagnosis was associated with decreased ST in small (P = .03) and large (P = .0009) breed dogs. Administration of chemotherapy (P = .02) was associated with increased ST (P = .02) in small breed dogs.

CONCLUSION

The ST was not different in small and large breed dogs with splenic hemangiosarcoma treated with splenectomy and chemotherapy.

CLINICAL SIGNIFICANCE

Prognosis remains poor despite aggressive therapies in small and large breed dogs.

Influence of use of a bipolar vessel sealing device on short-term postoperative mortality after splenectomy: 203 dogs (2005-2018)

OBJECTIVE

To compare short-term postoperative mortality in dogs after splenectomy performed with or without a bipolar vessel sealing device (BVSD) and to identify variables associated with mortality.

STUDY DESIGN

Retrospective study.

SAMPLE POPULATION

Client-owned dogs (n = 203).

METHODS

Medical records of dogs that underwent splenectomy from 2005-2018 were reviewed. Mortality rates were compared between dogs that underwent splenectomy with or without BVSD. Causes of death and variables associated with short-term mortality were assessed.

RESULTS

Fifteen of 203 (7.4%) dogs died prior to discharge, and seven (3.4%) dogs died prior to suture removal for a total short-term mortality rate of 22 of 203 (10.8%). The estimated difference in proportion of deaths prior to discharge between the BVSD and non-BVSD groups was -0.01 (95% confidence interval = -0.08 to 0.06). Duration of anesthesia was longer when splenectomy was performed without BVSD (median 168 vs 152 minutes; P = .03). Multivariate analysis identified intraoperative (odds ratio [OR] 5.7) or postoperative (OR 13.6) administration of blood products, increasing duration of anesthesia (OR 1.15 per additional 16 minutes), and intraoperative ventricular arrhythmias (OR 6.8) as significantly associated with death prior to discharge. Intraoperative (OR 3.2) or postoperative (OR 7.7) administration of blood products was associated with death prior to suture removal.

CONCLUSION

Use of a BVSD did not appear to increase short-term mortality after splenectomy.

CLINICAL SIGNIFICANCE

Dogs undergoing splenectomy that require intraoperative or postoperative transfusions, experience intraoperative ventricular arrhythmias, or have prolonged anesthesia may be at risk for death in the short-term postoperative period.

Use of contrast-enhanced ultrasound for assessment of nodular lymphoid hyperplasia (NLH) in canine spleen

Background

Nodular lymphoid hyperplasia (NLH) is one of the most common non-neoplastic splenic lesions in dogs, especially in old ones, showing a splenic enlargement. More recent studies have been focused on Contrast Enhanced Ultrasonography (CEUS) analysis of the spleen for establishing normal perfusion patterns and blood pool phase peculiarities of focal lesions.

The aim of the study was to evaluate the qualitative and quantitative CEUS analysis of the canine splenic NLH, characterizing the CEUS pattern of this pathology on 20 clinical cases.

Results

A prospective, observational study was performed using a system equipped with contrast-tuned imaging technology. Mechanical Index was set from 0.08 to 0.11; the contrast medium was a second generation contrast medium composed of sulphur hexafluoride encapsulated of a shell of phospholipids (SonoVue®). Qualitative and quantitative assessment of the enhancement pattern of splenic NLH were performed.

Cytology and histology identified 20 splenic NLH. All of the benign hyperplastic lesions assessed were isoechoic with a homogeneous pattern than the surrounding normal spleen, during the wash-in phase (10–20 s) of the CEUS exam. Before finishing the wash-in phase, 20–45 s from the contrast medium inoculation, 19/20 benign nodules became markedly hypoechoic to the adjacent spleen. Sensitivity of hypoechoic pattern for NLH was 95%.

Conclusions

These findings should prove useful in the evaluation of focal splenic masses in dogs. Since enhancement and perfusion patterns of NLH seem to coincide with some neoplastic lesions of the spleen previously reported, in clinical practice attention must be paid to the final diagnosis of canine splenic lesions using only the CEUS exam.

Evaluation of Nodular Splenic Lesions in 370 Small-Breed Dogs (<15 kg)

Three hundred seventy small-breed dogs (<15 kg) undergoing splenectomy for the presence of nodular splenic lesions were evaluated in a retrospective study to assess associations with breeds, malignancy, hemoperitoneum, and median survival time compared with previous studies. Data analyzed included signalment, histopathologic diagnosis, presence or absence of hemoperitoneum, breed associations, and survival times. In the current study, 44% (163/370) of dogs had nonneoplastic splenic lesions and 56% (207/370) had neoplastic lesions. Hemangiosarcoma was present in 27% (100/370) of splenic lesions. Hemoperitoneum was present in 31% (115/370) of dogs, and of this population, 66% (76/115) had malignant splenic lesions. The most common breeds were miniature schnauzers, dachshunds, and beagles, with beagles exhibiting a positive association with malignancy. The presence of hemoperitoneum was associated with malignancy. Distribution for nodular splenic lesions, correlation of hemoperitoneum to malignancy, and median survival time were similar to previous reports in large-breed dogs. Small-breed dogs who present with hemoperitoneum are 2.6 times more likely to have a diagnosis of a malignant splenic lesion. The most common small-breed dogs with nodular splenic lesions were miniature schnauzers, dachshunds, and beagles. Beagles and small-breed terriers were more likely to have malignant splenic lesions, and small-breed terriers were more likely to present with hemoperitoneum.

Presurgical assessment of splenic tumors in dogs: a retrospective study of 57 cases (2012-2017)

The purpose of this study was to evaluate the clinical and imaging characteristics of canine splenic tumors and to establish guidelines for the presurgical assessment of splenic tumors in dogs. Fifty-seven dogs that underwent total splenectomy for the treatment of splenic tumors were evaluated by examining medical records, hematologic results, diagnostic imaging results, and histopathologic results. The maximum lesion size from ultrasonography was significantly different between malignant and benign tumors (p = 0.002). There was a correlation between tumor margination and type of splenic tumors (p = 0.045). Precontrast lesion attenuation on computed tomography was significantly different between splenic malignant and benign tumors (p = 0.001). The mean ± SD precontrast lesion attenuation of malignant tumors was 40.3 ± 5.9 Hounsfield units (HU), and for benign tumors, it was 52.8 ± 6.8 HU. In conclusion, some variables of the imaging examination could be used to distinguish the type of splenic tumor. Based on the study results, using a diagnostic flowchart would be effective in increasing the survival rate of patients with splenic malignant tumors. In addition, fine needle aspiration or magnetic resonance imaging prior to surgical exploration and histopathologic examination may be useful in achieving a more accurate diagnosis.