Survival time and prognostic factors in dogs clinically diagnosed with haemangiosarcoma in UK first opinion practice

Abstract

Visceral haemangiosarcoma is considered clinically aggressive in dogs, with perceived poor prognosis often leading to euthanasia at presentation. This study aimed to determine survival times and prognostic factors in dogs with haemangiosarcoma under first-opinion care. Dogs clinically diagnosed with haemangiosarcoma in first-opinion practice in 2019 were identified in VetCompass electronic health records and examined to capture variables potentially associated with survival. Median survival time (MST) from diagnosis was calculated for the whole population, those histopathologically confirmed and based on primary tumour location. Binary logistic regression was used to explore differences between dogs that died on the day of diagnosis and those that survived ≥1 day. Cox proportional hazards modelling explored factors associated with time to death in dogs surviving ≥1 day. Across all cases (n = 788), overall MST was 9.0 days (95%CI:5.0-15.0, range: 0-1789) and proportional 1-year survival was 12.0% (95%CI:9.7-15.0%). Dogs with splenic (MST = 4.0 days, 95%CI 0.0-9.0) and cutaneous haemangiosarcoma (MST = 119.0 days,95%CI:85.0-248.0) had MST greater than 0 days. Of dogs with a histopathological diagnosis of haemangiosarcoma, overall MST was longer at 105 days (95% CI 84-133 days) and additionally, location-specific MST were longer. For both clinically diagnosed cases and histopathologically confirmed cases, increasing tumour size was associated with increased hazard of death while cutaneous location and surgery were associated with reduced hazard of death. A very short survival time was identified for haemangiosarcoma under first-opinion care. Although survival time was longest for cutaneous cases, the actualised prognosis was poor overall for haemangiosarcoma. However, a common prevailing view of extremely poor prognosis for haemangiosarcoma could be promoting frequent euthanasia at presentation and therefore leading to a self-fulfilling prophecy and low survival times. Further exploration of the potential effect of perceived prognosis is warranted. This study provides valuable information for contextualised care and dialogues with clients in first-opinion practice.

Fig 1. Grouping of clinical variables coded from electronic health records of dogs presenting with haemangiosarcoma to VetCompass clinics in 2019 (n = 788).

Bar chart colours indicate the group that an individual variable was grouped into: Clinical signs grouped according to their main body system affected (top bar plot), diagnostic tests performed (middle bar plot) and treatment options undertaken (bottom bar plot).

Fig 2. Kaplan-Meier survival curve estimating the survival time of clinically diagnosed haemangiosarcoma cases diagnosed in first-opinion practices in VetCompass in 2019 separated by location affected: cardiac, cutaneous, hepatic, splenic.

Day 0 designates day of first diagnosis. Shaded areas indicate the 95% CI for each curve and crosses indicate censored cases.

Fig 3. Forest plot of final multivariable logistic regression model of haemangiosarcoma cases diagnosed in first-opinion practices in VetCompass in 2019 who died on day of diagnosis (‘Day 0’, n = 381) and those who died ≥1 day of survival post diagnosis (‘Day ≥1’, n = 407).

Day 0 and Day ≥ 1 columns represent number of animals and percentages for each category in the model. OR indicates the odds ratio for each category and its 95% confidence interval (CI) and p-value.

Fig 4. Forest plot of final mixed effects multivariable Cox proportional hazards regression results for factors associated with time to death with haemangiosarcoma in cases diagnosed in first-opinion practices in VetCompass in 2019 with ≥1 day of survival post diagnosis (n = 407).

Cases (%) column indicates the number of cases for each category in the model. HR indicates the hazard ratio for each category and its 95% confidence interval (CI) and p-value. The final model included a frailty term of Clinic ID.

Fig 5. Forest plot of final mixed effects multivariable Cox proportional hazards regression results for factors associated with time to death with haemangiosarcoma in cases histopathologically diagnosed in first-opinion practices in VetCompass in 2019 with ≥1 day of survival post diagnosis (n = 272).

Cases (%) column indicates the number of cases for each category in the model. HR indicates the hazard ratio for each category and its 95% confidence interval (CI) and p-value. The final model included a frailty term of Clinic ID.