Prevalence of obese dogs in a population of dogs with cancer

Obesity, inflammation, and cancer in dogs: Review and perspectives

Obesity is the most common nutritional disease in dogs, and its prevalence has increased in recent decades. Several countries have demonstrated a prevalence of obesity in dogs similar to that observed in humans. Chronic low-grade inflammation is a prominent basis used to explain how obesity results in numerous negative health consequences. This is well known and understood, and recent studies have pointed to the association between obesity and predisposition to specific types of cancers and their complications. Such elucidations are important because, like obesity, the prevalence of cancer in dogs has increased in recent decades, establishing cancer as a significant cause of death for these animals. In the same way, intensive advances in technology in the field of human and veterinary medicine (which even proposes the use of animal models) have optimized existing therapeutic methods, led to the development of innovative treatments, and shortened the time to diagnosis of cancer. Despite the great challenges, this review aims to highlight the evidence obtained to date on the association between obesity, inflammation, and cancer in dogs, and the possible pathophysiological mechanisms that link obesity and carcinogenesis. The potential to control cancer in animals using existing knowledge is also presented.

Keratoconjunctivitis sicca in dogs under primary veterinary care in the UK: an epidemiological study

OBJECTIVES

To estimate the frequency and breed-related risk factors for keratoconjunctivitis sicca (KCS) in dogs under UK primary veterinary care.

METHODS

Analysis of cohort electronic patient record data through the VetCompass Programme. Risk factor analysis used multivariable logistic regression.

RESULTS

There were 1456 KCS cases overall from 363,898 dogs [prevalence 0.40%, 95% confidence interval (CI) 0.38-0.42] and 430 incident cases during 2013 (1-year incidence risk 0.12%, 95% CI 0.11-0.13). Compared with crossbreds, breeds with the highest odds ratio (aOR) for KCS included American cocker spaniel (aOR 52.33: 95% CI 30.65-89.37), English bulldog (aOR 37.95: 95% CI 26.54-54.28), pug (aOR 22.09: 95% CI 15.15-32.2) and Lhasa apso (aOR 21.58: 95% CI 16.29-28.57). Conversely, Labrador retrievers (aOR 0.23: 95% CI 0.1-0.52) and border collie (aOR 0.30: 95% CI 0.11-0.82) had reduced odds. Brachycephalic dogs had 3.63 (95% CI 3.24-4.07) times odds compared to mesocephalics. Spaniels had 3.03 (95% CI 2.69-3.40) times odds compared to non-spaniels. Dogs weighing at or above the mean bodyweight for breed/sex had 1.25 (95% CI 1.12-1.39) times odds compared to body weights below. Advancing age was strongly associated with increased odds.

CLINICAL SIGNIFICANCE

Quantitative tear tests are recommended within yearly health examinations for breeds with evidence of predisposition to KCS and might also be considered in the future within eye testing for breeding in predisposed breeds. Breed predisposition to KCS suggests that breeding strategies could aim to reduce extremes of facial conformation.

A Review of the Impact of Neuter Status on Expression of Inherited Conditions in Dogs

Gonadectomy is an important reproductive management tool employed in many countries, and is highly prevalent in the US with an estimated 85% of dogs being neutered. Despite the societal benefits in pet population control, negative associations between neuter status, and health conditions have been reported in recent years. Most particularly observed are the consequences of early age neutering. Knowing that different physiological systems rely upon gonadal steroids during development and physiological maintenance, studies have been undertaken to assess the impact of neuter status on multiple body and organ systems. For some inherited conditions, neutering is associated with an increased risk of expression. Neutering has also been associated with altered metabolism and a predisposition for weight gain in dogs, which may confound the detected risk association between neutering and disease expression. This review summarizes the effects of neutering on cancer, orthopedic, and immune disorders in the dog and also explores the potentially exacerbating factor of body weight.

Lipid and metabolic profiles in female dogs with mammary carcinoma receiving dietary fish oil supplementation

Background

Dyslipidemias induce angiogenesis and accelerate the development and in vitro growth of breast tumors. The aim of this study was to assess the lipid and metabolic profile of female dogs with mammary carcinomas and their correlations with body condition score and degree of tumor malignancy, as well as to study the effect of dietary fish oil supplementation on these animals.

Results

Overweight or obese dogs had more aggressive carcinomas and higher triglyceride (p = 0.0363), VLDL (p = 0.0181), albumin (p = 0.0188), globulin (p = 0.0145) and lactate (p = 0.0255) concentrations. There was no change in the lipid profile after supplementation with fish oil at any concentration. However, in relation to the metabolic profile, glucose (p = 0.0067), total protein (p = 0.0002) and globulin (p = 0.0002) concentrations were increased when 90% omega-3 fish oil was used as a dietary supplement.

Conclusion

Obese dogs showed altered lipid and metabolic profiles and more aggressive tumors, suggesting an important relationship between dyslipidemia and tumor aggressiveness. Supplementation with fish oil, rich in omega-3 fatty acids, may alter metabolic parameters in cancer patients.

Anorexia and the Cancer Patient

Appetite influences perceived quality of life for a dog or cat with cancer. Inappetence often is multifactorial, complicating treatment. Cancer-related anorexia/cachexia syndrome is a metabolic, paraneoplastic syndrome characterized by decreased food intake, involuntary weight loss, and loss of fat and muscle. If weight loss/cachexia has an impact on canine and feline cancer patients as in humans, management may improve survival times and quality of life. The challenge is having effective, proved therapies available for clinical use. Recent Food and Drug Administration approvals for appetite stimulation have renewed interest and discussion and has the potential to alter the course of case management.

Association between Body Condition Score and Cancer Prognosis in Dogs with Lymphoma and Osteosarcoma

BACKGROUND

In humans and rodents obesity appears to promote some cancers by increasing incidence, tumor aggressiveness, recurrence, and fatality. However, the relationship between obesity and cancer in dogs has not been thoroughly evaluated.

HYPOTHESIS/OBJECTIVES

Whether body condition score (BCS) at the time of lymphoma (LSA) or osteosarcoma (OSA) diagnosis in dogs is predictive of survival time (ST) or progression-free interval (PFI). We hypothesized that an overweight body state at the time of cancer diagnosis would be associated with negative outcomes.

ANIMALS

Dogs with LSA (n = 270) and OSA (n = 54) diagnosed and treated between 2000 and 2010.

METHODS

Retrospective case review. Signalment, body weight, BCS, cancer diagnosis and treatment, relevant clinicopathologic values, and survival data were collected. Dogs were grouped by BCS (underweight, ideal, and overweight) and ST and PFI were compared.

RESULTS

Overall, 5.5% of dogs were underweight, 54.0% were ideal weight, and 40.4% were overweight at diagnosis. Underweight dogs with LSA had shorter ST (P = .017) than ideal or overweight dogs. BCS was not associated with ST for OSA (P = .474). Progression-free interval did not differ among BCS categories for either cancer.

CONCLUSIONS AND CLINICAL IMPORTANCE

Obesity was not associated with adverse outcomes among dogs with LSA or OSA in this retrospective study; however, being underweight at the time of diagnosis of LSA was associated with shorter survival. More research is needed to elucidate the relationship between excessive body weight and cancer development and progression in dogs.

Other Risks/Possible Benefits of Obesity

Obesity is not a cosmetic or social issue; it is an animal health issue. The metabolic effects of obesity on insulin resistance and development of hyperlipidemia and the mechanical stress excess weight places on the musculoskeletal system are well established in the literature. Additional health risks from obesity, such as fatty accumulation in the liver, intestinal bacterial dysbiosis, and changes to renal architecture, are less well understood, but have been demonstrated to occur clinically in obese animals and may lead to deleterious long-term health effects. Keeping dogs and cats lean lowers their risk for development of certain diseases and leads to a longer and better quality of life.

Scope of the Problem and Perception by Owners and Veterinarians

Obesity is a common disease of modern dogs and cats. Dog and cat owners often do not realize their animal is affected. Some pet owners are skeptical of the diagnosis or rationalize the overweight condition of their pets. Animal-related factors associated with obesity in dogs and cats include breed, neuter status, age, and gender, whereas owner-related factors include diet choice, feeding method, and provision of exercise. Owner characteristics, such as age and income, are also potential risk factors for pet obesity. Identifying such risk factors for both animals and owners may help provide targets for prevention or interventional tools.

Relevance of sodium/glucose cotransporter-1 (SGLT1) to diabetes mellitus and obesity in dogs

Glucose transport across the enterocyte brush border membrane by sodium/glucose cotransporter-1 (SGLT1, coded by Slc5a1) is the rate-limiting step for intestinal glucose transport. The relevance of SGLT1 expression in predisposition to diabetes mellitus and to obesity was investigated in dogs. Cultured Caco-2/TC7 cells were shown to express SGLT1 in vitro. A 2-kbp fragment of the Slc5a1 5' flanking region was cloned from canine genomic DNA, ligated into reporter gene plasmids, and shown to drive reporter gene expression in these cells above control (P < 0.001). To determine the effect of the 3 known SNPs in this region on promoter function, new promoter/reporter constructs (all permutations of these 3 SNPs) were created by site-directed mutagenesis. No significant differences in promoter function were seen, suggesting that these SNPs do not have a significant effect on the constitutive transcription of SGLT1 mRNA in dogs. A search for novel SNPs in this region in dogs was made in 2 breeds predisposed to diabetes mellitus (Samoyed and cairn terrier), 2 breeds that rarely develop diabetes (boxer and German shepherd), and 2 breeds predisposed to obesity (Labrador retriever and cocker spaniel). The Slc5a1 5' flanking region was amplified from 10 healthy individuals of each of these breeds by high-fidelity PCR with the use of breed-labeled primers and sequenced by pyrosequencing. The sequence of the Slc5a1 5' flanking region in all individuals of all breeds tested was identical. On this evidence, variations in Slc5a1 promoter sequence between dogs do not influence the pathogenesis of diabetes mellitus or obesity in these breeds.

Cachexia and sarcopenia: emerging syndromes of importance in dogs and cats

Cachexia is the loss of lean body mass (LBM) that affects a large proportion of dogs and cats with congestive heart failure (CHF), chronic kidney disease (CKD), cancer, and a variety of other chronic diseases. Sarcopenia, the loss of LBM that occurs with aging, is a related syndrome, although sarcopenia occurs in the absence of disease. As many of the diseases associated with muscle loss are more common in aging, cachexia and sarcopenia often are concurrent problems. Both cachexia and sarcopenia have important clinical implications because they are associated with increased morbidity and mortality. The pathophysiology of these 2 syndromes is complex and multifactorial, but recent studies have provided new information that has helped to clarify mechanisms and identify potential new targets for treatment. Newly identified mechanisms and pathways that mediate cachexia appear to act by increasing energy requirements, decreasing energy intake, impairing nutrient absorption, and causing metabolic alterations. Whereas cachexia and sarcopenia are important areas of research for drug development in people, they are only beginning to be recognized in veterinary medicine. Greater awareness and earlier diagnosis will help provide practical approaches to managing body weight and lean tissue in dogs and cats, as well as more directed targets for treatment.

Cutaneous MCTs: associations with spay/neuter status, breed, body size, and phylogenetic cluster

Certain breeds are known to be overrepresented among mast cell tumor (MCT) patients, but other risk factors have not been evaluated. This study presents results from a case-control study of 252 dogs with grade 2 or grade 3 cutaneous MCT. Increased risk for MCT development was found in spayed females (adjusted odds ratio [OR], 4.11), boxers (adjusted OR, 6.09), Labrador retrievers (adjusted OR, 3.95), pugs (adjusted OR, 3.17), golden retrievers (adjusted OR, 2.12), the mastiff and terrier phylogenetic cluster (adjusted OR, 3.19), and breeds classified as large (adjusted OR, 2.10) or giant (adjusted OR, 5.44). Additional studies are needed to evaluate the role of these and other potential risk factors in MCT development.

Improvement in insulin resistance and reduction in plasma inflammatory adipokines after weight loss in obese dogs

Obesity is now a major disease of dogs, predisposing to numerous disorders including diabetes mellitus. Adipocytes are active endocrine cells, and human obesity is characterized by derangements in inflammatory adipokine production. However, it is unclear as to whether similar changes occur in dogs. The purpose of the current study was to assess insulin sensitivity and inflammatory adipokine profiles in dogs with naturally occurring obesity and to investigate the effect of subsequent weight loss. Twenty-six overweight dogs were studied, representing a range of breeds and both sexes. All dogs underwent a weight loss program involving diet and exercise. Body fat mass was measured by dual-energy x-ray absorptiometry; plasma concentrations of insulin, glucose, and a panel of inflammatory adipokines (including acute-phase proteins, cytokines, and chemokines) were also analyzed. Body fat mass before weight loss was positively correlated with both plasma insulin concentrations (Kendall tau=0.30, P=0.044) and insulin:glucose ratio (Kendall tau=0.36, P=0.022), and both decreased after weight loss (P=0.0037 and 0.0063, respectively). Weight loss also led to notable decreases in plasma tumor necrosis factor-alpha (TNF-alpha), haptoglobin, and C-reactive protein concentrations (P<0.05 for all), suggesting improvement of a subclinical inflammatory state associated with obesity. This study has demonstrated that in obese dogs, insulin resistance correlates with degree of adiposity, and weight loss improves insulin sensitivity. Concurrent decreases in TNF-alpha and adipose tissue mass suggest that in dogs, as in humans, this adipokine may be implicated in the insulin resistance of obesity.