Metronomic chemotherapy: bridging theory to clinical application in canine and feline oncology.

Veterinary oncology has experienced significant evolution over the last few decades, with chemotherapy being currently applied to several neoplasms with therapeutic success. Traditionally, chemotherapy protocols are based on classic cytostatic drugs under the concept of maximum tolerated dose (MTD), which has been associated with a greater risk of toxicity and resistance. Thus, new therapeutic alternatives have emerged, such as metronomic chemotherapy (MC), introducing a new paradigm in cancer treatment. MC consists of administering low doses of chemotherapy drugs continuously over a long period of time, modulating the tumour microenvironment (TME) due to the combination of cytotoxic, antiangiogenic and immunomodulatory effects. This multi-targeted therapy has been described as a treatment option in several canine and feline cancers since 2007, with positive results already published in the literature, particularly in mammary carcinomas and soft tissue sarcomas in dogs. The aim of this review article is to describe the current knowledge about the use of MC in small animal oncology, with emphasis on its mechanisms of action, the most commonly used drugs and clinical outcome.

A Review on Blood Reference Values as a Valuable Marker of Wildlife Welfare in Erinaceus europaeus.

The western-European hedgehog (Erinaceus europaeus), in expanding its range towards human habitats, faces exposure to contaminants and biological agents, potentially leading to diseases associated with hematological and biochemical changes. As bioindicators of environmental pollution and carriers of zoonotic agents, hedgehogs play a crucial role in One Health studies, emphasizing the need for a comprehensive understanding of their clinical-pathological aspects. Exploring the blood reference values in healthy animals of this species is crucial for understanding and improving their well-being, and identifying possible diseases/pathogens that may affect its conservation and/or impact human health. This review is focused on analyzing the data available in the literature for Erinaceus europaeus blood reference intervals. A comprehensive literature review of the studies published in Europe is performed, highlighting their specificities, and emphasizing the need for continuous research in this field. Our final goal is to provide a crucial tool for assessing the health status of the species, and underscoring the significance of research in this specific domain.

Clinical management of feline chronic kidney disease in Portugal: a questionnaire-based study.

OBJECTIVES: The aim of the study was to characterise the clinical management of feline chronic kidney disease (CKD) by veterinary practitioners in Portugal. METHODS: A questionnaire-based study was designed to be completed by all veterinarians who had diagnosed and treated at least one case of feline CKD in the previous year. RESULTS: A total of 409 veterinary practitioners responded to the questionnaire, with approximately half of them diagnosing 2-5 cases of feline CKD per month (n = 219, 53.5%). Although a high proportion of these reported using the guidelines published by the International Renal Interest Society (n = 379, 92.7%), only 19.1% (n = 78) systematically performed systolic blood pressure (SBP) measurements in all of their patients. A renal diet was advised by almost all respondents (n = 406, 99.3%), but 36.9% (n = 150) of them considered that it represented less than 75% of the daily food intake for most of their patients. This dietary intervention was often prescribed regardless of stage (n = 298, 73.4%) and without a proper gradual diet transition. Appetite stimulants were frequently prescribed (n = 366, 89.5%), as well as a calcium channel blocker (n = 171, 41.8%) and an angiotensin-converting enzyme inhibitor (n = 245, 59.9%) to control systemic hypertension and proteinuria, respectively. Prescription of a phosphate binder was also common (n = 311, 76.0%). Regarding monitoring, 70.9% (n = 290) recommended that stable patients be reassessed every 2-3 months or more frequently, but only 35.7% (n = 146) were able to comply with this periodicity due to owners' constraints. CONCLUSIONS AND RELEVANCE: The findings showed that although most survey respondents are aware of international guidelines for the clinical management of cats with CKD, the SBP measurement still needs to be more systematic to allow proper substaging and detection of systemic hypertension. The monitoring frequency was lower than recommended. Furthermore, the introduction of a renal therapeutic diet should be refined to improve its acceptance rate.

Canine Mammary Cancer: State of the Art and Future Perspectives.

Mammary cancer is the most frequently diagnosed neoplasia in women and non-spayed female dogs and is one of the leading causes of death in both species. Canines develop spontaneous mammary tumors that share a significant number of biological, clinical, pathological and molecular characteristics with human breast cancers. This review provides a detailed description of the histological, molecular and clinical aspects of mammary cancer in canines; it discusses risk factors and currently available diagnostic and treatment options, as well as remaining challenges and unanswered questions. The incidence of mammary tumors is highly variable and is impacted by biological, pathological, cultural and socioeconomic factors, including hormonal status, breed, advanced age, obesity and diet. Diagnosis is mainly based on histopathology, although several efforts have been made to establish a molecular classification of canine mammary tumors to widen the spectrum of treatment options, which today rely heavily on surgical removal of tumors. Lastly, standardization of clinical study protocols, development of canine-specific biological tools, establishment of adequate dog-specific disease biomarkers and identification of targets for the development of new therapies that could improve survival and have less adverse effects than chemotherapy are among the remaining challenges.

HCV Core-antigen Assay as an Effective Alternative to HCV RNA Quantification in Patients With Hepatitis C.

BACKGROUND/AIM: Hepatitis C virus (HCV) core antigen (Ag) test has been increasingly applied as an effective alternative to conventional molecular tests allowing rapid and affordable diagnosis, which is of paramount relevance to achieve global elimination of HCV infection. MATERIALS AND METHODS: ARCHITECT® HCV Ag test was evaluated in comparison with HCV RNA quantification test (CAP/CTM) to calculate its sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and to determine their correlation level. Its performance, according to low and high viral load values and in different treatment stages [during treatment (T), at the end of the therapeutic protocol (EOT) and when sustained virological response (SVR) was evaluated]. RESULTS: In total, 145 samples were included. Considering CAP/CTM, the sensitivity, specificity, PPV and NPV of the HCV-Ag test were 88.9%, 99.1%, 97.0% and 96.4%, respectively, and the correlation among tests was high (r=0.890), with only five discordant results. A decrease in sensitivity was found for low viral load values (<1,000 IU/ml), but the opposite was verified for high viral concentrations (≥1,000 IU/ml). A good agreement was verified for the T and EOT groups (k=0.789 and k=0.638) and an excellent agreement in the SVR group (k=1.000). CONCLUSION: HCV-Ag seems to be an effective alternative that can be routinely combined with other faster and more accessible tests (e.g., HCV antibody tests) for the identification of new HCV infections in suspected patients, eventually reserving the molecular techniques for samples with discordant results.

Hematology, Biochemistry, and Protein Electrophoresis Reference Intervals of Western European Hedgehog (Erinaceus europaeus) from a Rehabilitation Center in Northern Portugal.

The Western European hedgehog (Erinaceus europaeus) can work as a bioindicator of environmental pollution and be a host for multiple zoonotic agents, making it relevant in terms of One Health studies. It is essential to deepen the knowledge on this species and calculate reference intervals (RIs) for the usual hematological and biochemical parameters. For this retrospective study (2017-2022), the archives of the Clinical Pathology Laboratory (LPC) of University of Trás-os-Montes and Alto Douro (UTAD) Veterinary Teaching Hospital were analyzed. Data of hematology, clinical biochemistry, and protein electrophoresis from 37 healthy hedgehogs of the Wild Animal Rehabilitation Center at UTAD, Northern Portugal, were included. It was possible to calculate RIs for almost all of the variables in the study, using Reference Value Advisor V2.1. Moreover, sex and age effects were investigated: alkaline phosphatase (p = 0.012, higher in males); total proteins (p = 0.034, higher in adults); mean cell volume (p = 0.007) and mean corpuscular hemoglobin (p = 0.010) (both higher in juveniles); and red blood cell distribution width (p = 0.021, higher in adults). Our study allowed for the first time to define RIs for a population of hedgehogs in Portugal, having a potentially relevant impact on species conservation and in the human-animal health interface.

Prognostic factors associated with survival and hospitalization time in pediatric canine patients diagnosed with presumptive acute viral gastroenteritis.

Background and Aim: Acute viral gastroenteritis is one of the main causes of hospitalization in dogs during the 1st year of life. This retrospective study aimed to describe a pediatric canine population presumptively diagnosed with acute viral gastroenteritis and to identify potential prognostic factors that influence hospitalization time (HT) and mortality. Materials and Methods: Canine patients up to 12 months of age diagnosed with presumptive acute viral gastroenteritis were searched retrospectively from two veterinary hospitals during a 5-year period (2015-2020). Information regarding patient signalment, prophylactic care, clinical signs, blood test results, presence of systemic inflammatory response syndrome, and additional treatments were recorded to analyze their association with HT and mortality. Only dogs with a complete medical record until death or discharge were included in the study. Results: Ninety-four dogs were identified: 76 dogs (80.9%) survived with a median HT of 5 days (range: 2-16 days) and 18 dogs (19.1%) died with a median HT of 3½ days (range: 1-8 days) after admission. The presence of fever and fresh frozen plasma (FFP) administration was significantly associated with a lower survival rate (p = 0.021 and p = 0.037) in the multivariate analysis. Among survivors, incomplete primo-vaccination, the presence of hematochezia, and FFP administration were considered independent predictors of time to clinical recovery (p = 0.026, p = 0.047, and p = 0.026, respectively), being associated with higher HT. Conclusion: The presence of fever and FFP administration was significantly associated with a lower survival rate. An inadequate primo-vaccination status prior to admission, hematochezia, and FFP administration was associated with longer HT in surviving patients. Further studies are needed to confirm the present results.

The Nervous System as a Regulator of Cancer Hallmarks: Insights into Therapeutic Implications.

The involvement of the nervous system in the development of cancer is controversial. Several authors have shown opinions and conflicting evidence that support the early effect of the nervous system on the carcinogenic process. For about a century, research has not been enough, questions remain open, ideas are not discarded, and although more research is still needed to answer all the questions, there is now enough evidence to support the theories and give hope of finding one more possible form of treatment. It is clear that malignant neoplasms have endogenous characteristics that allow them to establish and progress. Some of these characteristics known as hallmarks of cancer, are damage mechanisms in the pathology but necessary during other physiological processes which show some nerve dependence. The nervous system communicates with the whole organism, regulating physiological processes necessary to respond to external stimuli and for the maintenance of homeostasis. The modification of nerve activity could generate an overload and deregulate the state of cellular and tissue homeostasis; this could drive cancer development. In this review, we will address the issue in an evidence-oriented manner that supports that the nervous system is able to participate in the initial and progressive process of carcinogenesis by inducing biochemical, physiological, and cellular modifications involved in the hallmarks of cancer.

Hormonal Homologies between Canine Mammary Cancer and Human Breast Cancer in a Series of Cases.

The validity of spontaneous canine mammary cancer (CMC) as a natural model for the study of human breast cancer (HBC) from a hormonal point of view has never been thoroughly investigated. In this study, we analyzed the immunohistochemical expression of aromatase (Arom) and steroid receptors [estrogen receptor α (ER α), estrogen receptor ß (ER ß), progesterone receptor (PR) and androgen receptor (AR)] and intratumor steroid hormone levels of 17ß-estradiol (E2), estrone sulfate (SO4E1), progesterone (P4), androstenedione (A4), dehydroepiandrosterone (DHEA), and testosterone (T) in 78 samples of mammary cancer-51 human breast cancer (HBC) and 27 canine mammary cancer (CMC)-and corresponding controls. Frequency of tumors expressing Arom, ERß, PR, and AR was similar in both species, whereas ERα+ tumors were less frequent in the canine species. There was a closer similarity between premenopausal HBC and CMC. In HBC and CMC, all hormones assayed were increased in tumors compared to control samples. Intratumor androgen levels were similar in the two species, although levels of progesterone and estrogens were higher in the HBC samples than the CMC samples. Statistical associations among Arom, receptors, and hormones analyzed suggest that the major hormonal influence in both species is estrogenic through the ER, being the α isoform predominant in the human samples. Our findings further support CMC as a spontaneous model for the study of HBC, especially premenopausal HBC, although several differences, such as the more prevalent ERα immunoexpression and higher intratumor levels of estrogens and P4 in HBC, should be taken into account in comparative hormonal studies.

A multidisciplinary review about Encephalitozoon cuniculi in a One Health perspective.

Encephalitozoon cuniculi is a microsporidian parasite mostly associated with its natural host, the rabbit (Oryctolagus cuniculus). However, other animals can be infected, like other mammals, birds, and even humans. Although it usually causes subclinical infection, it can also lead to encephalitozoonosis, a clinical disease characterized by neurological, ocular, and/or renal signs that can be even fatal, especially in immunocompromised individuals. Therefore, this multidisciplinary review contributes with updated information about the E. cuniculi, deepening in its molecular and genetic characterization, its mechanisms of infection and transmission, and its prevalence among different species and geographic locations, in a One Health perspective. Recent information about the diagnostic and therapeutic approach in the main host species and the prophylaxis and infection control measures currently suggested are also discussed.

Lower Urinary Tract Diseases in Guinea Pigs: A 14-Year Retrospective Study (2004-2018).

The clinical records of all guinea pigs diagnosed with a lower urinary tract disease in a single veterinary hospital, over a period of 14 years (2004−2018), were retrospectively searched in order to characterize this population and investigate the potential association between the epidemiological and clinical variables. A total of 117 clinical cases were identified, corresponding to 57 animals. Urolithiasis was the most common diagnosis (n = 52; 44.4%), followed by cystitis and/or a urinary tract infection (UTI). Several statistically significant associations (p < 0.05) were found between different variables, showing that female guinea pigs were more likely than the male ones to have a previous family history of urinary disease, to present dysuria and stranguria at admission, and to suffer recurrence. Moreover, males were more prone to urolithiasis and females to cystitis/UTI, and animals diagnosed with cystitis/UTI frequently had more clinical urinary signs and abdominal pain on palpation compared to those diagnosed with urolithiasis. Finally, the use of potassium citrate and the urethrotomy approach were associated with a better therapeutic response. Further studies are needed in larger populations of guinea pigs to confirm the present findings, especially as some of them were described for the first time.

Therapeutic Effect of EPA/DHA Supplementation in Neoplastic and Non-neoplastic Companion Animal Diseases: A Systematic Review.

BACKGROUND/AIM: The aim of this study is to identify and describe randomized controlled studies evaluating the therapeutic effect of EPA and DHA supplementation in companion animal diseases. MATERIALS AND METHODS: A systematic search was conducted in PubMed database and the information collected was summarized and evaluated according to the risk of bias, using the revised Cochrane tool (RoB2). RESULTS: Twenty-three studies were eligible for inclusion: twenty performed in dogs and three in cats. A therapeutic benefit was found in canine allergic dermatitis, haircoat disorder, keratoconjunctivitis sicca, valvular disease, and canine and feline osteoarthritis. Dogs diagnosed with chronic heart failure and lymphoma and cats with allergic dermatitis also seem to benefit from supplementation with omega-3 fatty acids, but studies with improved methodological quality are needed to strengthen this evidence. CONCLUSION: EPA and DHA supplementation has proven benefits in the adjuvant treatment of various neoplastic and non-neoplastic diseases in dogs and cats.

Prognostic value of immunohistochemical markers in canine cutaneous mast cell tumours: A systematic review and meta-analysis.

Histological grading systems remain cornerstones in the prognosis of canine cutaneous mast cell tumours (MCTs), but the distinct biological behaviour of each tumour often necessitates the use of complementary markers. Although a plethora of immunohistochemical markers have been proposed as prognostic factors, few are presently applied in routine diagnosis. This systematic review and meta-analysis was designed to establish which immunohistochemical markers have verifiable prognostic value for cutaneous MCTs in dogs. A Boolean search of five databases identified 200 articles for screening, of which 73 were selected for full-text assessment and 24 ultimately included in the systematic review. Odds Ratio (OR) was adopted as the summary measure for subsequent meta-analysis but only 15 articles, relating to the immunomarkers Ki-67 (9), KIT (5), and BAX (2), provided either a value for OR or sufficient data to calculate this statistic. Meta-analysis verified that canine cutaneous MCTs with elevated expression of Ki-67 or BAX, as well aberrant immuno-expression of KIT, showed an increased odds of death, with respective OR values of 11.2 (95% CI 6.3-20.0; p < .01), 9.9 (95% CI 1.3-73.6; p = .03), and 4.1 (95% CI 1.1-15.3; p = .03). Despite KIT, Ki67, and BAX arise as suitable prognostic factor for canine MCTs, this study highlighted the lack of important clinical and statistical data in many published articles, rendering it impossible to complete the meta-analysis of several potentially valuable immunohistochemical markers.

Immunoexpression and Prognostic Significance of Multidrug Resistance Markers in Feline Mammary Carcinomas.

Feline mammary carcinomas (FMCs) are commonly characterized by high clinical aggressiveness and poor prognosis. FMCs share many features with the corresponding human disease, allowing the comparative investigation of tumour biology and therapeutic strategies, including multidrug resistance (MDR) mechanisms. Although transporting/binding proteins, including permeability glycoprotein (P-gp), lung resistance protein (LRP) and metallothionein (MT), are frequently associated with tumour aggressiveness and unresponsiveness to chemotherapy in human breast cancer, they have not been analysed in FMCs. We investigated the immunoexpression of P-gp, LRP and MT in FMCs and their correlation with clinicopathological parameters and overall survival (OS) time in 46 FMCs, with a median follow-up period of 289 days. These markers were co-expressed in 85% of tumours. P-gp was expressed in 93.4% of FMCs and was positively associated with tumour grade (P = 0.049). While unequivocally observed in all FMCs, LRP immunoexpression did not correlate with any clinicopathological parameters or OS. Expression of MT was significant in triple-negative basal- and normal-like molecular subtypes of FMCs (P = 0.023). The concurrent expression of MDR proteins indicates the potential existence of chemotherapy resistance-related mechanisms in FMCs. The positive association between P-gp and MT immunoexpression and aggressive phenotypes could open new therapeutic and translational strategies for FMCs.

Outcome After Radiation Therapy in Canine Intracranial Meningiomas or Gliomas.

AIM: To characterize a group of dogs diagnosed with meningioma or glioma treated with radiation therapy and assess the clinical impact of diagnosis and radiation protocol on survival time. PATIENTS AND METHODS: Canine patient records from a single veterinary referral hospital, between 2011 and 2015, were searched for intracranial tumour cases treated with radiation therapy, as a sole modality. Thirty-two dogs were included. RESULTS: Median survival times were 524 days [95% confidence interval (CI)=287-677] in total, 512 days (95% CI=101-682) for the glioma group and 536 days (95% CI=249-677) for the meningioma group. No significant difference in survival was detected when using a definitive or a palliative protocol (p=0.130), nor other prognostic factors were found. CONCLUSION: Our results highlight the efficacy of radiation therapy in the treatment of canine meningioma, as well as glioma, suggesting a change in the current perception of the response of glial tumours to radiation.

Genetic variants of BRCA1 and BRCA2 genes in cats with mammary gland carcinoma.

Mammary tumours are the first and third most incident neoplasm in women and cats, respectively. Approximately 85% of feline mammary gland tumours are malignant and aggressive, especially the triple-negative and HER-2+ molecular subtypes. Triple-negative basal-like feline mammary carcinomas (FMCs) are considered suitable models due to the clinical and morphological similarities with human basal-like triple-negative breast cancer (TNBC). In women, TNBC has a poor prognosis and is often associated with mutations in the tumour suppressor genes BRCA1 and BRCA2. In light of this, the aim of the present investigation was to screen somatic and germline variants of BRCA1 and BRCA2 in nine female cats bearing FMCs. Matched whole blood and FMC samples were obtained for genetic analysis. Additional tumour samples were obtained for histopathological and immunohistochemical evaluation. Genomic DNA was isolated and 27 exonic regions of BRCA1 and BRCA2 genes were amplified and screened by next-generation sequencing. A somatic variant with high functional impact was found in exon 11 of BRCA2 at a frequency of 4.34% in one FMC-bearing cat. Four germline variants with moderate impact were detected in three of the nine FMC-bearing cats and were restricted to exon 9 of BRCA1. It is concluded that the germline genetic variants found in one-third of FMC-bearing animals might be associated with a higher risk of hereditary mammary carcinogenesis.

A Role for Angiogenesis in Canine Cutaneous Histiocytoma Regression: Insights into an Old Clinical Enigma.

BACKGROUND/AIM: Canine Cutaneous Histiocytoma (CCH) is a Langerhans' cells benign tumour that undergoes spontaneous regression. The aim of the present study was to investigate the role of angiogenesis, a key step for tumour development, in CCH regression. MATERIALS AND METHODS: 50 CCH samples were classified into 4 histological groups according to a regression scale, and evaluated for expression of vascular endothelial factor-A (VEGF-A) and its receptor VEGFR-2 as well as microvessel density (MVD). RESULTS: Tumours during early stages of the regressive process had a lower MVD compared to later stages, while CCH tumoural cells showed a limited production of VEGF, but higher levels of VEGFR-2. On the contrary, tumours in advanced phases of regression showed a higher number of neovessels, probably associated with the inflammatory state and the healing process. CONCLUSION: Our results suggest that angiogenesis may be compromised at early stages of histiocytoma development and this may be a determinant of regression in this tumour.

Cardiac structural and functional findings in Persian cats with autosomal dominant polycystic kidney disease / Achados estruturais e funcionais cardíacos em gatos persas com doença renal policística autossômica dominante

ABSTRACT: Autosomal dominant polycystic kidney disease (ADPKD) has been related to left ventricular structural and functional abnormalities in human patients. The present study aimed to evaluate the cardiac structural and functional findings in Persian cats with ADPKD. Client-owned ADPKD (n=12) and non-ADPKD (n=12) Persian cats were enrolled in this study. The animals underwent echo- and electrocardiographic (ECG) examinations, and non-invasive measurements of systolic blood pressure (SBP) were obtained. Both groups were similar regarding hematological and biochemical parameters, including white blood cell count and levels of blood urea nitrogen, creatinine, total protein and thyroxine. There were no differences related to ECG parameters between ADPKD and non-ADPKD cats. Left ventricular hypertrophy (LVH) was demonstrated in 6/12 (50%) normotensive ADPKD cats with preserved renal function. There were no differences between animal groups regarding the echocardiographic parameters, including left ventricular ejection fraction and shortening fraction; however, basal interventricular septal thickness at end-diastole near the left ventricular outflow tract and aortic artery flow velocity showed slightly elevated values in ADPKD-cats. Our study revealed that Persian cats with ADPKD do not reproduce the functional and structural cardiac phenotype reported in human patients; however, large-scale cohort studies are necessary to distinguish the possibilities of a true linkage between ventricular myocardial hypertrophy and ADPKD in this breed.

RESUMO: A doença renal policística autossômica dominante (DRPAD) tem sido relacionada a anormalidades estruturais e funcionais de ventrículo esquerdo em pacientes humanos. O objetivo do presente estudo foi avaliar os achados estruturais e funcionais cardíacos em gatos persas com DRPAD. Gatos persas pertencentes à clientes com DRPAD (n=12) e sem DRPAD (n=12) foram envolvidos neste trabalho. Os animais foram submetidos aos exames de eco e eletrocardiografia (ECG) e foram obtidas medições não-invasivas da pressão arterial sistólica (PAS). Ambos os grupos apresentaram valores semelhantes em relação aos parâmetros hematológicos e bioquímicos, incluindo contagem de glóbulos brancos e níveis séricos de ureia, creatinina, proteína total e tiroxina. Não houve diferença em relação aos parâmetros do ECG entre os gatos com ou sem DRPAD. A hipertrofia ventricular esquerda foi demonstrada em 6/12 (50%) dos gatos normotensos com DRPAD e função renal preservada. Não houve diferenças entre os grupos em relação aos parâmetros ecocardiográficos, incluindo fração de ejeção e fração de encurtamento do ventrículo esquerdo, entretanto a espessura septal interventricular basal na diástole na via de saída do ventrículo esquerdo e a velocidade do fluxo da artéria aórtica mostraram valores ligeiramente elevados em gatos com DRPAD. Nosso estudo revelou que gatos persas com DRPAD não reproduzem o fenótipo cardíaco funcional e estrutural encontrado em pacientes humanos. No entanto, estudos de coorte em larga escala são necessários para distinguir as possibilidades de uma verdadeira ligação entre a hipertrofia ventricular do miocárdio e a DRPAD nesta raça.