Canine Obesity: Contributing Factors and Body Condition Evaluation

Abstract

Canine obesity, characterized by the excessive accumulation of adipose tissue, is one of the most prevalent nutritional disorders encountered in veterinary practice. This comprehensive review synthesizes current knowledge on the predisposing factors and methodologies for assessing body condition in dogs. The discussion encompasses genetic, breed-specific, age-related, lifestyle, dietary, hormonal, and owner-related influences contributing to obesity. Key methods for assessing body condition, including the Canine Body Mass Index (CBMI), Body Condition Score (BCS), Relative Body Weight (RBW), and body fat percentage estimation, are critically evaluated for their effectiveness and clinical utility. This review aims to serve as a valuable resource for veterinary professionals and researchers dedicated to the prevention and management of canine obesity, highlighting both established practices and areas needing further investigation.

1. Introduction

Proper nutrition is a cornerstone of animal welfare and longevity, playing a pivotal role in shaping the overall quality of life. While a balanced supply of essential nutrients is fundamental to meeting physiological demands, non-essential components such as specific fatty acids, antioxidants, and dietary fibers also contribute significantly to health maintenance, disease prevention, and metabolic efficiency. When nutritional needs are not adequately addressed, a range of disorders may arise, ultimately impairing the animal’s well-being and vitality [1].

Obesity, among the most prevalent nutritional disorders in veterinary practice, presents a profound challenge due to its widespread occurrence and detrimental impact on animal health. Defined as a chronic, multifactorial condition marked by an excessive accumulation of adipose tissue that impairs physiological functions, obesity must be distinguished from overweight, which refers to a moderate excess of body weight that may or may not be due to increased fat mass. Obesity predisposes animals to a myriad of comorbidities, including respiratory, articular, and locomotor disorders, as well as metabolic and inflammatory complications [2,3]. The prevention, early detection, and management of obesity are critical to ensuring the health and well-being of companion animals.

The etiology of obesity in dogs is multifactorial, encompassing genetic predispositions, breed-specific traits, age, physical inactivity, caloric intake, feeding practices, hormonal imbalances, medication use, and factors related to the owner and environment [3,4,5]. A thorough understanding of these contributory factors and their interactions is vital for developing and implementing effective strategies to mitigate obesity in canines.

Early and accurate diagnosis is paramount in managing obesity and averting its adverse consequences. A variety of diagnostic tools and methodologies are available for this purpose, including the Canine Body Mass Index (CBMI), Relative Body Weight (RBW), body fat percentage estimation (%BF), and Body Condition Score (BCS), alongside direct inspection and palpation techniques [3]. Each method provides valuable insights into the animal’s body condition and informs tailored intervention strategies.

This review endeavors to compile a comprehensive synthesis of current knowledge on canine obesity, delineating its predisposing factors and the most effective methods for assessing body condition. By doing so, it aims to furnish veterinary professionals and researchers with an invaluable resource for advancing the understanding and management of obesity in dogs. Enhanced insight into this critical issue will foster better preventive and therapeutic approaches, ultimately improving the health and longevity of canine companions.

2. Canine Obesity

Obesity in dogs is associated with important metabolic dysfunctions, including low-grade chronic inflammation and hormonal imbalances. Adipose tissue acts as an active endocrine organ, secreting various adipokines such as leptin, adiponectin, resistin, and tumor necrosis factor-alpha (TNF-α). In obese dogs, the dysregulation of these adipokines, particularly increased leptin and TNF-α and decreased adiponectin, contributes to systemic inflammation, insulin resistance, and impaired glucose metabolism [6,7,8]. These inflammatory and hormonal changes significantly elevate the risk for secondary conditions, such as diabetes mellitus. In dogs, obesity can induce insulin resistance and impair glucose tolerance. However, unlike in cats, obese dogs rarely progress to overt diabetes mellitus. This is likely due to species-specific differences, such as the preservation of pancreatic β-cell function and the absence of islet amyloidosis [8]. Therefore, although canine obesity represents a metabolic concern, it is not considered a primary risk factor for the development of clinical diabetes [8,9]. Early recognition and management of obesity are therefore essential to prevent the onset of these comorbidities.

Obesity primarily results from a sustained positive energy balance, in which caloric intake exceeds energy expenditure, leading to the accumulation of excess body fat. The frequent offering of highly palatable and energy-dense foods, especially when combined with a sedentary lifestyle, further exacerbates this imbalance and significantly contributes to the development of obesity in dogs. Conceptually, obesity is defined as a nutritional disorder characterized by the accumulation of fat beyond what is necessary for normal bodily functions, representing a multifactorial pathological condition that adversely affects animal health and well-being [10]. In dogs, obesity is diagnosed when fat accumulation exceeds the ideal by 15 to 20% [11], affecting between 20% and 40% of the canine population [12]. This prevalence underscores that obesity is not only a human health concern but also a significant issue in veterinary and zootechnical contexts.

According to Horwitz and Birk (2023) [13], canine obesity can be classified into two distinct types based on adipose tissue development: hypertrophic and hyperplastic. Hypertrophic obesity, often referred to as simple obesity, is defined by an increase in adipocyte size, whereas hyperplastic obesity involves an increase in adipocyte number. These mechanisms are not mutually exclusive and may coexist in obese individuals. Furthermore, aging contributes to a natural rise in adipocyte number, highlighting age as an important factor in the pathogenesis of obesity in dogs.

Adipocytes, specialized cells that store lipids, are present in greater numbers in overweight and obese animals. Marques et al. (2020) [14] describe obesity as a low-grade chronic inflammation due to high levels of cytokines and pro-inflammatory proteins secreted by adipocytes in overweight animals. Mendes et al. (2013) [15] distinguish between hypertrophic obesity, which involves hyperstimulation of adipose tissue due to excess body fat typically seen in adults, and hyperplastic obesity, predominantly caused by excessive caloric intake during the growth phase in young animals.

Obesity in dogs is associated with a spectrum of health disorders paralleling those observed in humans. Overweight animals are at increased risk for several conditions, including dyslipidemia, cardiovascular disease [16], and orthopedic disorders [17,18,19]. The most affected systems in obese dogs include the locomotor, respiratory, cardiovascular, endocrine, immune, and integumentary systems. Locomotor problems in obese dogs can result in joint dysfunction, increased susceptibility to fractures, arthritis, ligament ruptures, and exacerbated pain during lameness [20,21].

Endocrine disorders associated with obesity include diabetes mellitus, which can result from the pancreas’s inability to secrete insulin (type 1) or the body’s failure to use insulin effectively (type 2), which can occur through various mechanisms [18,22]. Cardiovascular and respiratory alterations due to fat accumulation can affect heart rhythm and increase ventricular volume as the heart works harder [18]. Tôrres (2009) [23] identifies respiratory diseases exacerbated by obesity, such as tracheal collapse, laryngeal paralysis, and brachycephalic obstructive airway syndrome.

Miyai et al. (2021) [19] also note the association between obesity and an increased incidence of neoplastic diseases, particularly mammary tumors, in adult female dogs. Additionally, they report that excess weight significantly impacts reproductive health by reducing testosterone levels and sperm quality in males and increasing infertility in females.

Obesity leads to elevated triglycerides and cholesterol levels, with notable alterations in lipoprotein profiles [24]. This metabolic derangement is often accompanied by chronic low-grade inflammation, driven by pro-inflammatory adipokines and cytokines secreted by adipocytes [25]. Furthermore, aging contributes to a natural increase in adipocyte number, highlighting age as an important factor in the pathogenesis of obesity in dogs. Sepe et al. (2010) [26] emphasized that the aging process affects the pool and function of adipocyte progenitor cells, leading to impaired adipogenesis, altered fat distribution, and decreased metabolic flexibility. These age-related changes in adipose tissue biology contribute not only to increased fat mass but also to a pro-inflammatory environment that exacerbates obesity-related complications.

These examples highlight the multifaceted nature of obesity and its wide-ranging impacts on canine health. However, they do not encompass the entirety of pathological effects documented in the literature concerning obesity in dogs. This review seeks to provide a comprehensive overview of the current understanding of canine obesity, its contributing factors, and the health complications it entails, thereby informing more effective prevention and treatment strategies in veterinary practice.

3. Factors for Obesity

Obesity is a multifactorial syndrome influenced by genetic, breed-specific, age-related, social, cultural, metabolic, and environmental factors, among others [3,10,19]. Due to the extensive breadth of information on this subject, this section focuses on the factors most frequently discussed in the scientific literature.

Dietary habits are consistently highlighted as major contributors to obesity development. According to Aptekmann et al. (2014) and Miyai et al. (2021) [4,19], the cultural influence of humans is evident in the genesis of canine obesity, often linked to the unregulated provision of treats, high-calorie foods in large quantities and frequency, and table scraps offered by pet owners.

It is important to note that energy requirements naturally vary between breeds, and breed predisposition must be considered. Certain breeds, such as Golden Retrievers, Labrador Retrievers, Cocker Spaniels, Beagles, and Collies, are more prone to obesity [27], whereas German Shepherds, Great Danes, Boxers, and Fox Terriers are reported to be less susceptible [28].

Age and neutering are also significant factors associated with obesity. Excess body weight appears to be particularly problematic in middle-aged dogs. Carciofi (2005) [29] reported that obesity prevalence increases between 5 and 10 years of age, explained by the natural reduction in energy expenditure due to decreased physical activity and metabolic changes. Moreover, neutering exacerbates the risk of obesity, mainly due to hormonal alterations that lower metabolic rates post-surgery. Oliveira et al. (2010) [30] observed that females, in particular, show a higher prevalence of obesity following neutering [18].

Lifestyle factors, largely determined by the conditions provided by pet owners, further influence the risk of obesity. Rodrigues (2008) [31] emphasized that obesity is more prevalent in animals living in apartments or houses without access to outdoor areas due to the limited opportunities for physical exercise compared to dogs that live freely.

Endocrine disorders such as hypercortisolism (Cushing’s syndrome), frequently associated with canine obesity, also play an important role. In addition to polyphagia, hypercortisolism is characterized by clinical signs such as muscle wasting, abdominal distension, lethargy, polydipsia, and polyuria, all of which can contribute to changes in body composition and predispose dogs to weight gain [32,33]. Furthermore, dogs with hypercortisolism often exhibit reduced tolerance to exercise and decreased muscle mass, leading to a reduction in physical activity levels and basal metabolic rate, thereby further promoting the development of obesity.

A sustained positive energy balance, in which caloric intake consistently exceeds energy expenditure, remains the primary driver of obesity in dogs [5]. Although factors such as genetic predisposition, age, neutering, and physical activity levels are important, excessive caloric intake is considered the most significant determinant of weight gain in canine populations [5,9]. Studies have demonstrated that even small daily caloric surpluses can result in considerable weight gain over time; for instance, a daily caloric intake just 1% above maintenance energy requirements can lead to a 25% increase in body weight by middle age [5]. Furthermore, during weight loss programs, obese dogs typically require significant caloric restriction, with energy intakes ranging from 44 to 74 kcal/kg⁰·⁷⁵ per day [9]. These findings underscore the importance of individualized nutritional management based on precise assessments of energy requirements and body composition for each animal [5,9].

Additionally, recent studies have identified genetic mutations that may predispose certain dogs to obesity. Zeng et al. (2014) [34] reported single nucleotide polymorphisms (SNPs) in the melanocortin four receptor (MC4R) gene associated with increased body weight in Beagle dogs. Although the direct effects on appetite and metabolism were not assessed, alterations in the MC4R gene are known to influence hyperphagia and reduced energy metabolism in other mammalian species, suggesting that similar mechanisms may contribute to the development of obesity in dogs [34].

4. Body Condition

4.1. Body Condition Assessment in Dogs

The study of canine body condition dates back to the 1960s, with one of the earliest studies conducted in Sweden by Krook et al. (1960) [35], who classified dogs as obese based on macroscopic observations of fat accumulation. In the 1970s, Mason [36] determined through palpation and visual assessment that 28.0% of 1000 evaluated dogs were overweight and/or obese. Edney and Smith (1986) [37] later observed that 21.4% of a population of 8268 dogs were obese, using a 5-point Body Condition Score (BCS).

In 1997, Laflamme [38] developed a method for assessing body condition in dogs based on inspection and palpation, with a body condition score ranging from 1 to 9, which remains one of the most widely used methods today.

Currently, various methods for evaluating body composition and condition exist, including dual-energy X-ray absorptiometry (DEXA), magnetic resonance imaging, neutron activation analysis, bioelectrical impedance, ultrasonography, hydrodensitometry, computed tomography, body mass indices, and anthropometry. Lower-cost methods are now being integrated into routine veterinary practice [31].

Recognizing overweight and undernutrition in dogs is generally straightforward; however, precise diagnosis requires accurate quantification methods [39]. Thus, there is a need for a reliable, cost-effective, rapid, and accurate method to determine the exact amount of body mass an animal needs to lose or gain during rehabilitation [40]. The following section describes the primary methods currently used for assessing canine body condition.

4.2. Body Weight and Relative Body Weight

Weighing is the most commonly used measure to estimate body condition and nutritional status in small animal clinics [19]. It is a dynamic factor subject to physiological changes [28].

To identify weight gain, the current weight should be compared to previous weights recorded in medical records. Keeping weight records on vaccination cards is crucial, as these provide veterinarians with data to inform prescriptions [41]. For purebred dogs, weights can be compared to breed standards, and the ideal body weight for the animal can be calculated [42].

Relative Body Weight (RBW) represents the ratio between the animal’s current weight and its calculated optimal weight. An RBW of less than 1 indicates underweight, an RBW of 1 or 100% indicates optimal weight, and an RBW greater than 1 indicates overweight. However, this method’s accuracy is challenging due to the vast diversity in weight and body size among dog breeds (

Table 1. Standard Weight of Various Dog Breeds.

Breed	Males (kg)	Females (kg)
Basset Hound	29–34	22–29
Beagle	6–10	6–9
Boxer	25–32	22–27
Chihuahua	0.9–2.7	0.9–2.7
Chow Chow	20–22	18–22
Cocker Spaniel	11–13	9–11
Collie	29–34	22–29
Small Dachshund	3.6–4.5	3.6–4.5
Standard Dachshund	7–10	7–10
Dalmatian	22–29	20–25
Doberman	29–36	25–31
Golden Retriever	29–34	25–29
Siberian Husky	20–27	16–22
Labrador Retriever	29–36	25–31
Maltese	1.8–2.7	1.9–2.7
Standard Poodle	22–27	20–25
Toy Poodle	3.1–4.5	3.1–4.5
Rottweiler	36–43	31–38
Miniature Schnauzer	7–8	5–7
German Shepherd	34–40	31–38
Shetland Sheepdog	7–10	6–8
Shih Tzu	5.4–8	4.5–7
Yorkshire Terrier	1.8–3.1	1.3–2.7

Source: adapted from Rodrigues (2011) [27].

) [20].

4.3. Morphometry

Morphometry evaluates body measurements at various sites based on the premise that basic body proportions relate to the total lean tissue, and any increase in measurements can be explained by fat addition [43,44]. This technique involves combining length measurements, such as head, thorax, and limb lengths, with the animal’s circumference measurements. Equations are then generated to yield a percentage result. The primary limitation of this method is the precision of the dog’s measurements for accurate calculation. Before diagnosing conditions, it is recommended to assess for clinical signs of endocrine disorders and perform complementary tests as necessary [44].

While morphometric measurements are routinely used in humans, there are few studies on their application in dogs [45]. Establishing which body measurements significantly change with weight gain or loss is crucial, as these measurements can be performed by the owner. This allows owners to monitor the effectiveness of obesity treatment protocols, which is essential for successful outcomes [46].

Carciofi (2005) [29] highlights that weight gain or loss directly reflects abdominal circumference measurements, while thoracic circumference measurements are less affected in dogs. They assert that up to three measurements are necessary to estimate body conformation accurately. In his study, Guimarães (2009) [46] considered six anatomical sites for body measurements in animals (

Table 2. Anatomical Sites and Measurement Locations Used in the Morphometric Determination of Dogs.

Anatomical Site	Measurement Location
Withers Height—WH	Between the apex of the scapula and the pad, following the line of the right thoracic limb.
Body Length—BL	From the nape to the base of the tail (last sacral vertebra), following the dorsal line of the animal.
Right Pelvic Limb—RPL	Length between the calcaneal tuberosity and the middle patellar ligament, externally.
Abdominal Circumference—AC	Midpoint between the iliac wing and the last thoracic vertebra.
Chest Circumference—CC	Region of the seventh intercostal space.
Thigh circumference—TC	Midpoint between the patella and the greater trochanter of the femur.

Source: adapted from Guimarães (2009) [39].

): withers height (WH), body length (BL), right pelvic limb length (RPL), abdominal circumference (AC), Chest circumference (CC), and thigh circumference (TC) (Figure 1).

The importance of thigh circumference is underscored by recent findings, which suggest that this measurement is a reliable indicator of muscle mass and can provide valuable insights into the physical condition of the animal [47]. Therefore, relying solely on Body Condition Score (BCS) is not sufficient for a comprehensive assessment, as it does not capture variations in muscle mass and body fat distribution as effectively as morphometric measurements [47]. In this context, the abdominal-to-chest girth ratio (GAB) has been proposed as a complementary tool to improve the objectivity of body condition evaluation. Chun et al. (2019) [48] reported that a GAB value of approximately 1.0 is associated with ideal body condition, whereas values below 0.95 may indicate underweight, and values above 1.05 are often associated with overweight or obesity.

Observations by the authors during nutritional evaluations of working dogs, particularly Belgian Malinois and Dutch Shepherds, revealed that these breeds, due to their natural conformation and athletic build, often present a thoracic circumference greater than the abdominal circumference. This morphological trait results in GAB values frequently below 1.0, even in animals with optimal body condition. These findings highlight the need to interpret morphometric indices such as GAB within the context of breed-specific anatomy and functional fitness to ensure accurate assessment.

According to Burkholder (2000) [7], morphometric measurements can establish the percentage of body fat (%BF) using the following equation: %BF = (−1.7 × RPL_cm) + (0.93 × AC_cm) + 5. Research on body composition in dogs and cats reveals that animals classified as being in optimal body condition possess a body fat percentage between 15% and 20% [38,49].

4.4. Body Mass Index (BMI)

Body Mass Index (BMI) is a critical index that relates body weight to height and can be correlated with mortality due to either obesity or malnutrition [50]. Initially developed for humans, Muller et al. (2008) [39] adapted BMI for use in dogs, proposing the Canine Body Mass Index (CBMI). They suggested that the measurement of the spine combined with the length of the pelvic limb serves as a viable replacement for human height. CBMI also functions as a parameter for evaluating the effectiveness of structured physical activity programs in dogs.

This widely used method is calculated using the following equation: BMI = weight (kg)/withers height² (m²). Two physical measurements are taken with the dog in a standing position, with limbs perpendicular to the ground and head upright. Values between 18.5 and 24.9 kg/m² are considered normal, while values from 25.0 to 29.9 kg/m² indicate overweight, and values ≥30 kg/m² indicate obesity [51].

However, it is important to note that CBMI does not differentiate between lean body mass and fat mass. Therefore, animals with substantial muscle mass may have elevated CBMI values despite having optimal body conditions. This limitation has been observed by the authors during nutritional evaluations of athletic working dogs, where CBMI values did not accurately reflect body fat levels. In such cases, complementary assessment methods are essential for reliable body composition analysis [52].

4.5. Body Condition Score (BCS)

BCS is the most commonly used and easily applicable method in clinical practice today. It involves inspecting and palpating fat in areas such as the ribs, abdomen, neck, tail, and regions of bony prominences where fat accumulates [38,44]. The BCS scale ranges from 1 to 9, where values between 1 and 3 indicate underweight, 4 and 5 indicate ideal condition, 6 and 7 indicate overweight, and 8 and 9 indicate obesity (

Table 3. Body Condition Score and Body Characteristics in Obese Dogs.

Score	Body Condition	Body Characteristics
1	Underfed	Ribs, lumbar vertebrae, pelvic bones, and all bony prominences are visible from a distance. No discernible body fat. Evident loss of muscle mass.
2	Underfed	Ribs, lumbar vertebrae, and pelvic bones are easily visible. No palpable fat. Some other bony prominences may be visible. Minimal muscle mass loss.
3	Underfed	Ribs are easily palpable with no palpable fat. Top of lumbar vertebrae visible. Pelvic bones begin to be visible. Evident waist and abdominal tuck.
4	Ideal	Ribs are easily palpable with minimal fat coverage. Waist observed from above. Evident abdominal tuck.
5	Ideal	Ribs palpable without excessive fat coverage. Retracted abdomen when viewed from the side.
6	Overfed	Ribs palpable with slight excess fat coverage. The waist is visible from above but not prominent. Apparent abdominal tuck.
7	Overfed	Ribs difficult to palpate; heavy fat coverage. Evident fat deposits over the lumbar area and tail base. Absent or only visible waist. Abdominal tuck may be present.
8	Overfed	Ribs are not palpable under thick fat coverage or palpable only with significant pressure. Heavy fat deposits over the lumbar area and tail base. No waist. No abdominal tuck. Abdominal distension may be evident.
9	Obese	Massive fat deposits over the chest, spine, and tail base. Fat deposits on the neck and limbs. Evident abdominal distension.

Adapted from Laflamme (1997) [38].

) [38]. The reliability of this method was demonstrated by Mawby et al. (2004) [52]. BCS allows for a quick and straightforward assessment of the patient’s body condition. Currently, there are two systems used in small animal clinics: the five-point system and the nine-point system, with the nine-point system being the most widely used [53]. BCS determination is performed by palpating the thoracic cage, abdomen, and tail base, assessing the thickness of the subcutaneous adipose tissue. Each score increase above the ideal corresponds to a 10–15% increase in weight, meaning a dog with a BCS of 7 is 20–30% heavier than its ideal weight [34].

An ideal body condition is suggested when the ribs are easily palpable, and the dog has an hourglass shape when viewed from above. Animals with a bulging abdomen from the last rib, evident fat deposits on either side of the tail base, above the hips, and/or in the inguinal region, with a rib cage that is not easily palpable, indicate excess weight [27]. However, BCS alone may not provide a complete picture of an animal’s body composition, as it does not differentiate between lean muscle and fat mass. Therefore, integrating BCS with morphometric measurements is crucial for a comprehensive evaluation of body condition [47].

Owner perception also plays a critical role in the assessment of body condition. Studies have shown that dog owners are more likely to recognize deviations from the ideal body condition compared to cat owners, who often underestimate excess weight in their pets [7]. This discrepancy may be related to differences in human–animal bonding patterns, lifestyle, and typical body conformation between species. As a result, obesity in cats is sometimes underdiagnosed based on owner perception alone, highlighting the need for objective clinical evaluation when determining BCS.

4.6. Dual Energy X-Ray Absorptiometry (DEXA)

A precise diagnosis of canine body condition can be achieved using techniques such as deuterium isotope dilution [54] and dual-energy X-ray absorptiometry (DEXA). These techniques determine lean and fat mass percentages but are expensive and not commonly used in clinical practice.

DEXA was initially developed to measure mineral content but has since been adapted to measure body fat and lean tissue. It employs two different energy levels (70 and 140 kVp) to differentiate tissue types and quantities. DEXA can also establish bone mineral density, bone mineral content, fat mass, and lean mass [55]. These measurements are critical for nutritional research, understanding the pathogenesis of bone diseases, identifying factors that may affect normal musculoskeletal development, and assessing body composition in patients with metabolic, endocrine, and nutritional disorders.

To confirm the reliability of the Body Condition Score (BCS), Brunetto et al. (2011) [54] compared BCS with DEXA and deuterium oxide dilution (D²O). They found a high correlation between the two techniques’ accuracy (r² = 0.92) in evaluating body fat percentage.

Borges (2006) [45] noted that DEXA is precise in estimating body composition in adult cats. Although previously more commonly used in research settings, DEXA has already been standardized for use in dogs, as demonstrated by Toll et al. (1994) [55], supporting its validity as a reliable method for body composition analysis in veterinary practice.

4.7. Ultrasound (USG)

Imaging diagnostic methods can indirectly monitor fat deposit sites. Wilkinson and McEwan (1991) [56] suggested that measuring subcutaneous fat thickness between the third and fifth lumbar vertebrae using ultrasound could predict total body fat in dogs. This method is non-invasive and practical. However, obesity can impair image quality (echogenicity—darkness) due to the increased distance between the transducer and the organ being examined caused by subcutaneous and intra-abdominal fat deposits [57].

A pioneering study on canine subcutaneous fat measurement using ultrasound was conducted by Wilkinson and McEwan (1991) [56]. They considered the relationship between subcutaneous fat observed via ultrasound and histologically evaluated subcutaneous fat to determine total body fat in dogs. The study concluded that total body fat could be successfully predicted from measurements taken from the lower back and lumbar region, suggesting that ultrasound can safely and reliably measure total body fat in dogs.

However, a study by Carvalho (2015) [58] reported that BCS, morphometric measurements, and CBMI strongly correlate, indicating their reliability in assessing body condition in dogs, with consistent results among them. In contrast, ultrasound did not yield significant results as expected. Therefore, the author concluded that each animal should be individually assessed to apply the most convenient technique.

4.8. Bioimpedance (BIC)

Bioimpedance has proven useful in both humans and animals for measuring parameters such as blood flow and body composition (known as bioimpedance analysis—BIA) [59]. Bioimpedance (BIC) evaluates body composition by measuring electrical conductivity differences in tissues. Resistance (R) and reactance (Xc) measurements form the equation that determines the result [60]. BIC estimates the amounts of water and fat present and, with the help of equations, determines the percentage of lean mass (LM) [61].

4.9. Direct Inspection and Palpation

The most practical and widely used method in most cases is a simple physical examination through inspection and palpation. Dog ribs should be easily palpable. When viewed dorsally, dogs should have an hourglass shape. Loss of the central narrowing (waist), a bulging abdomen from the last rib, visible fat deposits on either side of the tail base, above the hips, and/or in the inguinal region, and a rib cage that is not easily palpable indicate obesity [13].

5. Conclusions

Canine obesity, a prevalent and multifaceted condition, poses significant challenges in veterinary practice due to its detrimental impact on animal health and quality of life. A comprehensive understanding of its etiology, encompassing genetic, breed-specific, age-related, lifestyle, dietary, hormonal, and owner-related factors, is crucial for developing effective prevention and management strategies.

Accurate and early diagnosis, facilitated by various assessment methods such as BCS, CBMI, RBW, body fat percentage estimation, and direct inspection and palpation, is vital for addressing obesity in dogs. This review underscores the importance of a holistic approach, integrating multiple assessment techniques to provide a comprehensive evaluation of body condition and inform individualized intervention plans.

Future research should focus on refining existing assessment methodologies and exploring novel approaches to enhance the accuracy and practicality of body condition evaluations. Moreover, continued efforts to educate pet owners on the significance of proper nutrition, regular physical activity, and responsible feeding practices are essential for mitigating the incidence of obesity in companion animals. By fostering a deeper understanding of canine obesity and its multifactorial nature, veterinary professionals can better safeguard the health and well-being of dogs, ultimately contributing to their longevity and quality of life.