Demographic risk factors for lymphoma in Australian dogs: 6201 cases

Canine lymphoma in Croatia: a fourteen-year retrospective study

BACKGROUND

Lymphoma is the most prevalent hematopoietic system tumor in dogs and holds significant clinical importance in veterinary medicine. However, the epidemiology of canine lymphoma in Croatia remains understudied. This retrospective study aims to describe the predominant lymphoma types in this population over 14 years and evaluate associations with sex, breed, and age.

RESULTS

Among 28,681 canine cases referred to the Department of Veterinary Pathology, University of Zagreb, from 2009 to 2023, a total of 374 cases (1.30%) were diagnosed with lymphoma. Of these, 282 cases (75.40%) were purebred dogs, with the most affected breeds being Golden Retrievers (23, 6.15%), Labrador Retrievers (23, 6.15%), German Shepherds (14, 3.74%), and Boxers (14, 3.74%). Bullmastiffs (8.14%) had the highest number of lymphoma diagnoses among the referred breeds, followed by Airedale Terriers (6.67%) and German Shepherds (5.09%). The Maltese, though a popular breed, showed a low lymphoma rate of 0.40%, indicating no notable predisposition. Multicentric lymphoma (59, 53.64%) was the most common anatomical classification, followed by cutaneous (33, 30.00%) and alimentary lymphoma (13, 11.82%). The mean age at diagnosis was 8.27 ± 3.07 years, with most cases occurring between 5 and 10 years (207, 55.35%). Males (216, 57.75%) were more frequently affected than females (158, 42.24%), except among Golden Retrievers, where 69.56% of cases were female.

CONCLUSION

Our study reveals that the distribution of dogs with lymphomas, including type and anatomical classification, in terms of breed, sex and age, is consistent with existing literature, except in the cases of Golden Retrievers, Basset Hounds, and Scottish Terriers. Further molecular and environmental studies are recommended.

Demography and Causes of Mortality of Pugs Under Primary Veterinary Care in Australia

Pugs are a popular brachycephalic breed that suffer from multiple chronic disorders linked to their exaggerated phenotypic traits. The contribution of these disorders to early death and euthanasia have not been described and would add urgency to addressing these issues. This study used electronic patient records (EPR) from the Australian VetCompass programme to describe the demography, common causes and risk factors for Pug mortality. The EPR from 691 Pugs which died in a population of 7909 Pugs that received veterinary care over a 10-year period were analysed to determine the cause of death. The median age at death was 10 years. Male Pugs had lower probability of surviving than females (p = 0.02) and entire Pugs died earlier than neutered dogs. The top causes of mortality were Brachycephalic Obstructive Airway Syndrome (8.2%), seizures (6.7%) and degenerative spinal cord disorder (4.7%). Neurological causes (29.6%) were the most common cause of euthanasia whilst amongst non-assisted deaths, respiratory causes were most common (25%). Death from respiratory disorders was found across all age groups. These neurological and respiratory causes of death are linked to brachycephalic conformation and provide evidence for reform of showing and breeding standards to improve Pug welfare and longevity.

What We Know and Do Not Yet Know About the Canine Model of Lymphoma in Human Medicine-The Current State of Knowledge

This review comprehensively compares lymphoma in humans and dogs, highlighting the canine model's utility in translational research. Canine lymphoma (cL), predominantly diffuse large B-cell lymphoma (DLBCL), mirrors human non-Hodgkin's lymphoma (NHL) in its clinical presentation, including lymphadenopathy, systemic symptoms (e.g., fever, weight loss), and hematological abnormalities. Morphologically, cL and NHL share similarities in DLBCL subtypes (centroblastic, immunoblastic, anaplastic), although some variations exist, such as the presence of macronuclear medium-sized cells in canine polymorphonuclear centroblastic lymphoma, not observed in humans. Canine and human lymphomas share molecular mechanisms, including the activation of key pathways like NF-κB and mTOR, and genetic and epigenetic alterations. The tumor microenvironment influences tumor growth and immune evasion in both species. Both species exhibit similar responses to chemotherapy, primarily CHOP-based protocols, although canine lymphoma often progresses more rapidly, offering advantages for shorter clinical trials. Molecular targeted therapy is emerging as a promising treatment, with human therapies like rituximab and chimeric antigen receptor T-cell therapy showing efficacy, and canine treatments still developing. Epidemiological data reveal overlapping risk factors, including exposure to environmental carcinogens (e.g., household chemicals, pollution) and the potential influence of sex hormones, although the role of sex hormones requires further investigation in canines. While staging systems differ slightly (Lugano modification of Ann Arbor for humans, WHO system for dogs), both consider disease extent and systemic involvement. Prognostic factors, such as lactate dehydrogenase (LDH) levels, are relevant in human NHL but have not shown consistent utility in cL. This study concludes that the spontaneous development of cL in immunocompetent dogs, coupled with its clinical, histological, and therapeutic similarities to human NHL, makes the canine model invaluable for preclinical research, accelerating the development of novel diagnostic tools and therapies for both human and canine lymphoma. The shared environmental risk factors and shorter disease progression in dogs further enhance the translational potential of this model, promoting a One Health approach to cancer research.

The Demography, Longevity and Mortality of Bullmastiffs Attending Veterinary Practices in Australia

The Bullmastiff is a giant breed of dog, and there is evidence the breed is predisposed to cancer and musculoskeletal disorders, though the disease investigation of the breed is limited. This study reports on the demography, longevity and mortality of Bullmastiffs attending veterinary practices in Australia over a ten-year period. VetCompass Australia collects patient data from veterinary practices across Australia for epidemiological analysis. All patient records of Bullmastiffs available in the VetCompass Australia database during this decade period were reviewed, with demographic information on the breed inclusive of coat colour, sex, neuter status, weight and location collated. Standardised veterinary diagnostic (VeNom) codes for the most appropriate cause of death were assigned to deceased dogs. The population comprised 2771 Bullmastiffs with an overall median age of 2.8 years. Within the group, 1259 were female (45.4%), 1491 were male (53.8%), and 21 dogs (0.8%) had no recorded sex or neuter status. Dogs grew rapidly in their first year, with an average gain of approximately 1 kg every 10 days. A slower growth rate continued in their second year, and growth plateaued as adulthood was reached, with the mean body weight of adult male dogs (46.6 kg) being heavier than that of females (40.5 kg). The age at death for the group was 8.5 years. The most common causes of death in the breed were mass lesions (28.2%), old age (9.9%), musculoskeletal-related disease (9.9%) and neurological (5.3%) and behavioural disorders (4.8%). Neutering was protective against mortality from urogenital causes (OR: 0.14; CI: 0.02-0.52; p = 0.003) and had a positive effect on longevity. This study provides demographic and health information on a population of Bullmastiffs attending veterinary practices in Australia, which will benefit evidence-based veterinary decisions for this breed. Additionally, the results may assist owners and breeders in making informed decisions on health risks and breeding programmes in the population.

Exploring the impact of epidemiological and clinical factors on the progression of canine leishmaniosis by statistical and whole genome analyses: from breed predisposition to comorbidities

Canine leishmaniosis (CanL), caused by Leishmania infantum, is a complex disease of growing importance in Europe. Clinical manifestations result from the down-modulation of the host immune response through multiple host-parasite interactions. Although several factors might influence CanL progression, this is the first known study evaluating risk factors for its different clinical stages in a large referral hospital population (n = 35.669) from an endemic area, over a 20 year period. Genome-wide scans for selection signatures were also conducted to explore the genomic component of clinical susceptibility to L. infantum infection. The prevalence of CanL was 3.2% (16.7% stage I; 43.6% stage II; 32.1% stage III; 7.6% stage IV). Dog breed (crossbreed), bodyweight (<10 kg), living conditions (indoors), regular deworming treatment, and being vaccinated against Leishmania significantly decreased the transmission risk and the risk for developing severe clinical forms. Conversely, the detection of comorbidities was associated with advanced clinical forms, particularly chronic kidney disease, neoplasia, cryptorchidism, infectious tracheobronchitis and urate urolithiasis, although those did not impact the clinical outcome. Significant associations between an increased risk of severe clinical stages and findings in the anamnesis (renal or skin-related manifestations) and physical examination (ocular findings) were also detected, highlighting their diagnostic value in referred cases of CanL. Sixteen breeds were found to be significantly more susceptible to developing severe stages of leishmaniosis (e.g. Great Dane, Rottweiler, English Springer Spaniel, Boxer, American Staffordshire Terrier, Golden Retriever), while 20 breeds displayed a clinical resistantance phenotype and, thus, are more likely to mount an efficient immune response against L. infantum (e.g. Pointer, Samoyed, Spanish Mastiff, Spanish Greyhound, English Setter, Siberian Husky). Genomic analyses of these breeds retrieved 12 regions under selection, 63 candidate genes and pinpointed multiple biological pathways such as the IRE1 branch of the unfolded protein response, which could play a critical role in clinical susceptibility to L. infantum infection.

Incidence rates of the most common canine tumors based on data from the Swiss Canine Cancer Registry (2008 to 2020)

Monitoring neoplasms in standardized registries facilitates epidemiologic studies of risk factors for tumor development and predisposition. In an observational study, we determined incidence rates (IR) and malignant tumor incidence rate ratios (IRR) by age, sex, and breed in Swiss dogs using demographic data from the official Swiss dog registration database Amicus. The dataset analyzed included 54'986 tumors diagnosed by histology and cytology in four Swiss veterinary pathology laboratories between 2008 and 2020. Diagnoses were coded according to the Vet-ICD-O-canine-1 system. Most tumors occurred in the skin (n = 19'045; 34.64%), soft tissues (n = 11'092; 20.17%), and mammary glands (n = 7'974; 14.50%). The IRs for all and for malignant tumors were 775/100'000 dog-years at risk (95%CI 764-777) and 338/100'000 dog-years at risk (95%CI 333-342), respectively. Females (850; 95%CI 834-853) had a higher overall tumor IR than males (679; 95%CI 666-684). The highest tumor IR was found at 11 years of age (1'857; 95%CI 1'780-1'867). Potential novel breed-specific predispositions were uncovered, with high IRs for several benign and malignant tumors in Polski Owczarek Nizinnys (overall IR: 3'303; 95%CI 2'502-3'864) and high IRs for malignant tumors in Russian Black Terriers (melanomas: 345; 95%CI 138-708), Field Spaniels (adenocarcinomas: 376; CI95% 138-817), Dogo Argentinos (mast cell tumors: 844; CI95% 591-1'169), King Charles Spaniels and Manchester Terriers (lymphomas: 319; CI95% 137-627 and 302; CI95% 98-704, respectively), Landseers (osteosarcomas: 74; CI95% 15-216), Bouvier des Flandres (hemangiosarcomas: 127; CI95% 26-371), and Bearded Collies and Cane Corso Italianos (gliomas: 91; CI95% 45-162 and 34; CI95% 7-99, respectively). Nordic hunting dogs had the highest (8.08; CI95% 3.55-16.7) and Chihuahueno the lowest cancer IRRs (0.42; 95%CI 0.31-0.57) compared to mixed breeds. In conclusion, the calculated IRs and IRRs revealed previously unknown predisposing factors, including novel breed-specific susceptibilities. The results may have implications for cancer screening, diagnostic work-up, breeding management and oncologic and translational research.

Spontaneous Lesions of Endangered Geriatric Julia Creek Dunnarts (Sminthopsis douglasi, Archer 1979) with Emphasis in Reproductive Pathology

Julia Creek dunnarts are an endangered species of carnivorous marsupials and the focus of multiple conservation strategies involving significant resources such as captive breeding programs. Despite the relevance for conservation, no study to date has focused on evaluating geriatric diseases in dunnarts. This study describes the pathology findings in a group of one wild and thirty-five captive-born, mostly geriatric Julia Creek dunnarts that failed to produce offspring over multiple breeding periods. A total of 20 females and 16 males were submitted for a postmortem examination, with ages ranging from 9 to 42 and 12 to 42 months for females and males, respectively. Of these, 10 had unremarkable findings. The most common condition in females was cystic glandular hyperplasia (n = 8), typical of hormonal dysregulation profiles in senescence, particularly hyperestrogenism. Rarely, cutaneous disease represented by unidentified dermal round cell infiltrates was observed in females (n = 2). Primary reproductive hormonal dysregulation was also suspected in males diagnosed with testicular degeneration, aspermatogenesis and/or atrophy (n = 3). Cutaneous round cell infiltrates, possibly compatible with epitheliotropic lymphomas, were seen in males (n = 3), and 2/3 affected males also had concurrent testicular degeneration or atrophy, indicating male sex could be a predictor for lymphoid neoplasia in aged dunnarts, especially in individuals with concurrent testosterone-luteinizing hormone dysregulation as it occurs in gonadectomized animals. The role of an underlying viral etiology is also explored. This study is the first to describe major spontaneous diseases in endangered aged Julia Creek dunnarts, providing an important understanding of senescence and geriatric diseases within a conservation context.

Genomic Analysis of Lymphoma Risk in Bullmastiff Dogs

Lymphoma is the most common haematological malignancy affecting dogs and has a high incidence in the Bullmastiff breed. The aim of this study was to identify risk loci predisposing this breed to the disease. The average age of lymphoma diagnosis in 55 cases was less than 6 years, similar to the median age of 64 cases from our clinical and pathology databases. When fine-scale population structure was explored using NETVIEW, cases were distributed throughout an extended pedigree. When genotyped cases (n = 49) and dogs from the control group (n = 281) were compared in a genome-wide association analysis of lymphoma risk, the most prominent associated regions were detected on CFA13 and CFA33. The top SNPs in a 5.4 Mb region on CFA13 were significant at a chromosome-wide level, and the region was fine-mapped to ~1.2 Mb (CFA13: 25.2-26.4 Mb; CanFam3.1) with four potential functional candidates, including the MYC proto-oncogene bHLH transcription factor (MYC) and a region syntenic with the human and mouse lncRNA Pvt1 oncogene (PVT1). A 380 Kb associated region at CFA33: 7.7-8.1 Mb contained the coding sequence for SUMO specific peptidase7 (SENP7) and NFK inhibitor zeta (NFKBIZ) genes. These genes have annotations related to cancer, amongst others, and both have functional links to MYC regulation. Genomic signatures identified in lymphoma cases suggest that increased risk contributed by the regions identified by GWAS may complement a complex predisposing genetic background.

Lymphoma in Border Collies: Genome-Wide Association and Pedigree Analysis

There has been considerable interest in studying cancer in dogs and its potential as a model system for humans. One area of research has been the search for genetic risk variants in canine lymphoma, which is amongst the most common canine cancers. Previous studies have focused on a limited number of breeds, but none have included Border Collies. The aims of this study were to identify relationships between Border Collie lymphoma cases through an extensive pedigree investigation and to utilise relationship information to conduct genome-wide association study (GWAS) analyses to identify risk regions associated with lymphoma. The expanded pedigree analysis included 83,000 Border Collies, with 71 identified lymphoma cases. The analysis identified affected close relatives, and a common ancestor was identified for 54 cases. For the genomic study, a GWAS was designed to incorporate lymphoma cases, putative "carriers", and controls. A case-control GWAS was also conducted as a comparison. Both analyses showed significant SNPs in regions on chromosomes 18 and 27. Putative top candidate genes from these regions included DLA-79, WNT10B, LMBR1L, KMT2D, and CCNT1.

Environmental exposures and lymphoma risk: a nested case-control study using the Golden Retriever Lifetime Study cohort

Lymphoma is the second most common cancer affecting Golden Retrievers and is hypothesized to arise through a complex interaction of genetic and environmental factors. The aim of this nested case–control study was to investigate the association between potential environmental pollutant sources and lymphoma risk among Golden Retrievers participating in the Golden Retriever Lifetime Study. Forty-nine Golden Retrievers with non-cutaneous lymphoma and 98 Golden Retrievers without a history of cancer matched by age, sex and neuter status were selected from the Golden Retriever Lifetime Study cohort. Geographic proximity between each dog’s primary residence and nine potential sources of environmental pollution was determined. In addition, the average annual ozone and airborne fine particulate matter levels for each dog’s county of residence and owner-reported secondhand smoke exposure were evaluated. Environmental pollution sources of interest included chemical plants, municipal dumps, manufacturing plants, incineration plants, railroad embankment tracks, landfills, coal plants, high-voltage transmission lines, and nuclear power plants. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for each exposure of interest. Subgroup analyses were conducted to evaluate whether associations differed among 1) dogs with multicentric lymphoma, 2) dogs with B-cell lymphoma, and 3) dogs with T-cell lymphoma. No variables reached statistical significance when evaluating all cases together. However, cumulative exposure burden (household proximity to 3 or more pollution sources) approached significance within the multicentric lymphoma subgroup (OR = 2.60, 95%CI 0.99–6.86, p-value = 0.053). Patterns emerged among B- and T-cell subgroups, but none reached statistical significance. Ongoing research is warranted to discern if different environmental mechanisms may be driving B- and T-cell lymphoma immunophenotypes, consistent with previously reported regional differences in subtype prevalence.

Lymphoma is a common cancer affecting dogs, particularly Golden Retrievers. By identifying risk factors for lymphoma, work can be done to reduce harmful exposures or increase monitoring among dogs at a higher risk of disease. Using a subset of dogs from the Golden Retriever Lifetime Study, we sought to investigate whether dogs with lymphoma were more likely to live near certain environmental pollutant sources than dogs without lymphoma.

Forty-nine Golden Retrievers with non-cutaneous lymphoma and 98 Golden Retrievers without a history of cancer were selected from the Golden Retriever Lifetime Study Cohort. We evaluated how close each dog lived to nine environmental pollutant sources: chemical plants, municipal dumps, manufacturing plants, incineration plants, railroad embankment tracks, landfills, coal plants, high-voltage transmission lines, and nuclear power plants. Additionally, we evaluated individual exposure to secondhand smoke, and average annual ozone and particulate matter exposure (as surrogate measures for air pollution) for each dog’s county of residence.

None of the exposures examined were associated with an increased lymphoma risk in this population. More research is needed, including direct biomonitoring, to determine whether specific environmental exposures are associated with lymphoma in the Golden Retriever breed.

Risk of bladder cancer and lymphoma in dogs is associated with pollution indices by county of residence

Human urothelial cell carcinoma (UCC) and non-Hodgkin lymphoma are considered environmental cancers in people, but less is known about environment risk for UCC and lymphoma in dogs. The objective of this study was to determine whether dogs with these cancers, compared to unaffected control dogs, live in counties with higher tap water contaminants or higher levels of air pollution as measured by the Environmental Protection Agency (EPA) and by National Air Toxics Assessment chemical exposure risk estimates. Dogs with available home addresses from two previously published case-control populations were included: 66 dogs with UCC and 70 unaffected controls; and 56 boxer dogs with lymphoma and 84 unaffected boxer controls. Tap water total trihalomethanes, which are water disinfection by-products, were more than threefold higher in UCC case counties of residence compared to controls (p < .0001), and a higher proportion of dogs with UCC lived in counties exceeding EPA ozone limits (41.8%) compared to controls (13.6% p = .0008). More boxers with lymphoma lived in counties exceeding EPA ozone limits (52.1%) compared to controls (29.0%; p = .018), with higher exposure risk estimates for airborne 1,3-butadiene and formaldehyde (p = .004-.005). These data support the hypothesis that tap water contaminants and airborne environmental pollutants contribute to the risk of both urothelial carcinoma and lymphoma in dogs. If these findings reflect causal relationships, then it is possible that tap water filtration units and more effective air pollution controls could decrease the overall incidence of these cancers in dogs.

Prognostic indicators for naïve canine non-indolent T-cell lymphoma treated with combination lomustine, vincristine, procarbazine and prednisolone chemotherapy

Lomustine, vincristine, procarbazine and prednisolone (LOPP) chemotherapy has been suggested to be an effective treatment for dogs with naïve non-indolent T-cell lymphoma (TCL). Studies evaluating prognostic factors for dogs with TCL treated with LOPP chemotherapy are lacking. The aim of this retrospective study was to assess potential prognostic factors for canine naïve non-indolent TCL treated with the LOPP protocol. This was a retrospective cohort study of naïve non-indolent TCL treated with the LOPP chemotherapy protocol at a single specialty veterinary oncology clinic. Sixty-seven dogs met the inclusion criteria. The outcomes assessed included progression free survival (PFS), overall survival time (OST) and duration of complete response (DCR). The overall median PFS was 118 days (range 7-2302 days). The median OST was 202 days (range 8-2302 days). The overall median DCR was 316 days (range 38-2261 days). Number of treatments administered (p < .0001), multicentric disease (p = .044) and the presence of hypercalcaemia (p = .006) were prognostic indicators for PFS. Increasing number of treatments (p < .0001) and age (p = .0088) were prognostic indicators for OST. To our knowledge, this is the first study to describe hypercalcaemia as a positive prognostic indicator of PFS for TCL treated with LOPP chemotherapy. LOPP chemotherapy can be considered as a first-line treatment protocol against naïve hypercalcaemic non-indolent TCL.

Clinicopathological characteristics and prognostic factors for canine multicentric non-indolent T-cell lymphoma: 107 cases

Canine lymphoma, as the most common haematopoietic malignancy, encompasses a group of heterogeneous diseases and even within the T-cell immunophenotype, differences in clinical presentation and responses to treatment exist. The aim of this retrospective study was to determine outcomes and prognostic factors of 107 dogs with multicentric non-indolent T-cell lymphoma (TCL) receiving lomustine-based (70%) and non-lomustine-based (30%) treatment. The majority were Labradors, Boxers, mixed-breed dogs and Dogue de Bordeaux. Eighty-six percent were substage b, 77% had mediastinal involvement, 15% had suspected bone marrow involvement and 12% had other extra-nodal sites of disease. The overall response rate to induction therapy was 80%; dogs receiving procarbazine in the induction protocol (P = .042), dogs with neutrophil concentration below 8.7 × 10e⁹ /L (P = .006) and mitotic rate below 10 per 5 high power field (P = .013), had greater response rates. Median progression-free survival (PFS) for the first remission was 105 days; lack of expression of CD3 on flow cytometry (P < .0001) and pretreatment with steroid (P = .012) were significantly associated with shorter PFS. Median overall survival time (OST) was 136 days; co-expression of CD79a (P = .002), lack of CD3 expression on flow cytometry, presence of anaemia (P = .007), and monocytopenia (P = .002) were predictive of shorter OST. Multicentric non-indolent TCL in dogs is an aggressive cancer with new possible prognostic factors.

Neutering in dogs and cats: current scientific evidence and importance of adequate nutritional management

Neutering or spaying is a commonly recommended veterinary procedure. However, veterinarians are often confronted with conflicting findings and differences in concepts regarding practice and proper nutritional management after the procedure. The objective of the present review was to bring to light the most recent literature, summarise it and discuss the findings focusing on the risks and benefits of neutering in dogs and cats, and to determine the appropriate nutritional management for these animals.

The estrogen effect; clinical and histopathological evidence of dichotomous influences in dogs with spontaneous mammary carcinomas

The purpose of this study was to investigate the associations and explore the relationships between hormonal factors (serum estrogen, estrogen receptors and ovariohysterectomy) and other clinical/histological prognostic factors and their impact on outcome in dogs with mammary carcinomas. Data from two separate prospective studies on dogs with spontaneous mammary carcinomas were used for this research. All dogs underwent standardized diagnostic testing, staging, surgery and follow-up examinations. Serum estrogen was analyzed by competitive enzyme immunoassay or radioimmunoassay, and tumor estrogen receptor (ER) expression was analyzed by immunohistochemistry. A total of 159 dogs were included; 130 were spayed and 29 remained. High serum estrogen was associated with an overall longer time to metastasis (p = 0.021). When stratifying based on spay group, the effect was only significant in spayed dogs, (p = 0.019). Positive tumor ER expression was also associated with a longer time to metastasis (p = 0.025), but similar to above, only in dogs that were spayed (p = 0.049). Further subgroup analysis revealed that high serum estrogen was significantly associated with improved survival in dogs with ER positive tumors, but only in spayed dogs (p = 0.0052). Interestingly, the effect of spaying was the opposite in dogs with ER negative tumors; here, intact dogs with high serum estrogen but ER negative tumors had a significantly longer time to metastasis (p = 0.036). Low serum estrogen was associated with increased risk for the development of non-mammary tumors in the post-operative period (p = 0.012). These results highlight the dual effect of estrogen in cancer: Estrogen acts as a pro-carcinogen in ER positive mammary tumors, but a may have a protective effect in ER negative tumors, potentially via non-receptor mechanisms. The latter is supported by the decreased risk for non-mammary tumors in dogs with high serum estrogen, and explains the increased incidence of certain non-mammary tumors in in dogs spayed at an early age.

Lymphoma in Australian Border Collies: survey results and pedigree analyses

OBJECTIVES

The aims of this study were to (1) describe the results of a survey on the clinical features of lymphoma in Australian Border Collies and (2) investigate familial clustering of lymphoma-affected dogs by means of pedigree analyses.

METHODS

Clinical and pedigree information was collected from surveys completed by owners or breeders of Australian Border Collies. Relationships between dogs were derived from pedigree data and kinship was analysed by network and cluster-based algorithms.

RESULTS

A total of 246 respondents completed the survey and 57 lymphoma-affected Australian Border Collies were identified. The mean age of diagnosis was 9.16 (SD ± 3.43) years and the median was 9.7 years (range 2-15 years). The odds of female dogs affected with lymphoma were twice those of males in the reported data (OR = 2.06; 95% CI = 1.13-3.73; P = 0.02). Multicentric, high-grade B-cell lymphoma was the most common form in these dogs. Pedigree analyses identified 21 affected dogs that descended from two sires and 28 cases with a common female ancestor. Average inbreeding between both affected and unaffected dogs was similar (0.16, SD ± 0.06 and 0.15, SD ± 0.06, respectively).

CONCLUSION

The survey confirmed the presence of a relatively large number of cases of lymphoma in Australian Border Collies, consistent with our previous report of increased risk in this breed. Some dogs were diagnosed at a very young age, but the age ranged over the normal lifespan. Pedigree analyses identified multiple cases within family groups, suggesting a heritable component of the disease in this breed.

Demographic risk factors for lymphoma in Australian dogs: 6201 cases

Background

Lymphoma is common in the dog. Studies of population risk factors primarily have been derived from referral institution or insurance data.

Objective

To identify and quantify the host risk factors for lymphoma in a broad population of Australian dogs.

Animals

Data on 6201 client owned dogs were retrieved from a commercial veterinary laboratory, a general practice group and 2 referral hospitals.

Methods

Data collected included breed, sex, and neuter status. A reference population of 640 105 dogs was generated from the referral hospitals and from council registration data. The risk of lymphoma by sex and neuter status was calculated as odds ratios (OR).

Results

The study identified 30 breeds at increased risk of lymphoma, 15 that have not been reported previously, and 26 breeds at decreased risk, 18 that have not been reported previously. Males were over represented compared to females with an OR of 1.1 (95% CI, 1.1–1.2; P < .001). Neutered animals were at higher risk compared to intact animals with an OR of 3.2 (95% CI, 2.9–3.5) which was found in both males (OR, 2.8; 95% CI; 2.5–3.2) and females (OR, 4.4; 95% CI, 3.5–5.1).

Conclusions and Clinical Importance

Breed, sex, and neuter status alter the risk of lymphoma in dogs. These 3 factors must be considered when evaluating lymphoma risk as potential markers of underlying differences in disease etiology. Comparison of breeds at increased and decreased risk could be advantageous when evaluating specific etiological factors.