Obesity in animals has become a critical veterinary health challenge across the UK, affecting a substantial proportion of companion dogs and cats. Unlike humans, pets cannot control their own diet, making obesity primarily a management issue requiring veterinary intervention and owner commitment. Treatment centres on controlled caloric restriction through veterinary-formulated diets, gradual increases in physical activity tailored to individual fitness levels, and behavioural modification to address inappropriate feeding practices. Whilst no veterinary medicines are currently authorised in the UK specifically for animal weight loss, addressing underlying endocrine disorders such as hypothyroidism can support weight management. Successful treatment requires structured monitoring, owner education, and long-term maintenance strategies to prevent weight regain and reduce obesity-related health complications.
Summary: Obesity in animals is treated primarily through controlled caloric restriction using veterinary-formulated diets, gradual increases in physical activity, and behavioural modification, with no veterinary medicines currently authorised in the UK specifically for weight loss.
- Target weight loss rates are 1–2% of body weight per week for dogs and 0.5–1% per week for cats to avoid complications such as hepatic lipidosis.
- Veterinary weight management diets provide reduced calories, increased protein to preserve muscle mass, and enhanced fibre for satiety.
- Body condition scoring (BCS) using the validated 9-point scale is the gold standard for assessing adiposity in companion animals.
- No veterinary medicines are currently authorised in the UK for animal weight loss; treatment focuses on diet and lifestyle modification.
- Regular fortnightly weigh-ins during active weight loss and ongoing monitoring are essential to adjust treatment and prevent weight regain.
- Underlying endocrine disorders such as hypothyroidism or diabetes mellitus must be identified and treated to support effective weight management.
Table of Contents
- Understanding Obesity in Animals: Causes and Health Risks
- Diagnosing Obesity in Pets: Assessment and Body Condition Scoring
- Treatment Options for Animal Obesity: Diet and Weight Management
- Exercise and Behavioural Strategies for Overweight Pets
- Veterinary Medicines and Interventions for Animal Obesity
- Monitoring Progress and Long-Term Weight Maintenance in Animals
- Frequently Asked Questions
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Understanding Obesity in Animals: Causes and Health Risks
Obesity in companion animals has become one of the most prevalent health concerns in veterinary medicine. Recent UK surveys, including the PDSA PAW Report, indicate that a substantial proportion of dogs and cats are overweight or obese. This condition is defined as an accumulation of excessive body fat that impairs health, function, and quality of life. Unlike humans, animals cannot make independent dietary choices, meaning obesity in pets is largely a consequence of management decisions made by their owners.
Primary causes of animal obesity include:
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Excessive caloric intake – overfeeding, high-calorie treats, and table scraps
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Insufficient physical activity – sedentary lifestyle and lack of regular exercise
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Neutering – altered metabolism and reduced energy requirements post-surgery
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Breed predisposition – certain breeds (Labrador Retrievers, Cocker Spaniels, Beagles) show genetic susceptibility
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Age-related factors – decreased metabolic rate in senior animals
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Endocrine disorders – hypothyroidism (dogs), hyperadrenocorticism (Cushing's disease), and diabetes mellitus
The health consequences of obesity are substantial and well-documented. Overweight animals face significantly increased risks of diabetes mellitus (particularly type-2-like diabetes in cats), osteoarthritis and joint disease, cardiorespiratory impairment (reduced respiratory function and exercise tolerance), anaesthetic risk, and reduced quality of life. Evidence is emerging for associations with certain cancers and urinary tract conditions, including feline lower urinary tract disease (FLUTD) and urinary incontinence in spayed bitches. Research in Labrador Retrievers demonstrates that maintaining lean body condition throughout life may extend longevity compared to overweight counterparts. The mechanical stress of excess weight on joints accelerates degenerative changes, whilst adipose tissue functions as an active endocrine organ, secreting pro-inflammatory cytokines that contribute to systemic inflammation. Additionally, obesity complicates anaesthetic management and surgical procedures, increases heat intolerance, and reduces exercise tolerance, thereby diminishing overall quality of life.
When to seek urgent veterinary care:
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Cats refusing food for more than 24–48 hours (risk of hepatic lipidosis)
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Difficulty breathing or respiratory distress
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Collapse or severe lethargy
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Suspected urinary obstruction in male cats (straining, vocalising, no urine production)
Early recognition and intervention are essential to prevent these serious complications and support long-term health.
Diagnosing Obesity in Pets: Assessment and Body Condition Scoring
Accurate diagnosis of obesity requires systematic assessment rather than relying solely on body weight, as ideal weight varies considerably between breeds, body frames, and individual animals. Veterinary professionals employ body condition scoring (BCS) systems as the gold standard for evaluating adiposity. The most widely used is the validated 9-point BCS scale developed by the World Small Animal Veterinary Association (WSAVA), which assesses fat coverage over specific anatomical landmarks. Muscle condition scoring (MCS) is also valuable to detect sarcopenic obesity, where muscle mass is lost despite excess fat.
Using the 9-point BCS system, animals are scored as follows:
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1–3: Underweight (ribs, spine, and pelvic bones prominently visible)
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4–5: Ideal weight (ribs palpable with slight fat covering, visible waist, abdominal tuck present)
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6–7: Overweight (ribs difficult to palpate, waist barely visible, abdominal fat present)
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8–9: Obese (ribs not palpable under heavy fat, no waist, prominent abdominal distension)
A comprehensive obesity assessment includes visual evaluation from above and the side, palpation of the ribcage, spine, and tail base, and morphometric measurements such as body weight trends over time. Veterinary surgeons should document the animal's current weight, calculate the percentage above ideal body weight, and establish a target weight. An animal is generally considered overweight when body weight exceeds ideal by 10–20%, and obese when exceeding 20%. Both BCS and weight trends should be used together for accurate assessment.
During the diagnostic consultation, veterinary surgeons should obtain a detailed history including dietary intake (type, quantity, frequency of meals and treats), exercise patterns, previous weight loss attempts, and any concurrent medical conditions. Laboratory investigations may be warranted to exclude underlying endocrine disorders. In dogs, thyroid function tests (total T4, TSH) help identify hypothyroidism, whilst testing for hyperadrenocorticism (Cushing's disease) may be indicated based on clinical signs (polydipsia, polyuria, pot-bellied appearance, skin changes). In cats, fasting glucose and fructosamine levels help assess diabetes mellitus risk. Baseline blood tests help identify metabolic contributors to weight gain and inform treatment planning.
WSAVA BCS and MCS charts are freely available and provide standardised visual and palpation guides for dogs and cats.
Treatment Options for Animal Obesity: Diet and Weight Management
Dietary modification forms the cornerstone of obesity treatment in animals, with the primary objective being controlled caloric restriction whilst maintaining adequate nutrition. Weight loss should be gradual and sustainable, typically targeting a reduction of 1–2% of body weight per week for dogs and 0.5–1% per week for cats. Rapid weight loss, particularly in cats, can precipitate hepatic lipidosis, a potentially fatal condition.
Veterinary weight management diets are specifically formulated to provide:
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Reduced caloric density – fewer calories per unit volume
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Increased protein content – preserves lean muscle mass during weight loss
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Enhanced fibre levels – promotes satiety and reduces begging behaviour
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Optimal micronutrient balance – ensures nutritional adequacy despite caloric restriction
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L-carnitine supplementation – included in some veterinary diets; evidence for benefit varies; follow veterinary advice
Calculating daily energy requirements involves determining the animal's resting energy requirement (RER) using the formula: RER (kcal/day) = 70 × (ideal body weight in kg)^0.75. For weight loss, typical starting allowances are approximately 0.8 × RER of ideal body weight for dogs and 0.8–1.0 × RER of ideal body weight for cats, with adjustments based on individual response to achieve target weekly loss rates. Adequate dietary protein is essential to preserve lean body mass. Portion control is essential; owners should use digital kitchen scales to weigh food in grams rather than estimating quantities or using measuring cups, which are less accurate.
Feeding strategies that support weight loss include dividing the daily ration into multiple small meals to reduce hunger, using puzzle feeders or slow-feed bowls to prolong eating time, eliminating all table scraps and high-calorie treats, and substituting low-calorie alternatives. For dogs, safe treat options include small amounts of raw vegetables such as carrots or green beans; however, owners must avoid toxic foods including grapes, raisins, onions, and garlic. Vegetables are generally not appropriate treats for cats. Introduce new foods gradually to avoid gastrointestinal upset. All family members and visitors must adhere to the feeding plan to prevent inadvertent caloric supplementation.
Regular weigh-ins, ideally fortnightly initially, allow for dietary adjustments and maintain owner motivation. If weight loss plateaus for three consecutive weigh-ins despite reported compliance, further caloric reduction of 10–15% may be necessary, though this should be undertaken under veterinary supervision to ensure nutritional adequacy and to monitor cats closely for signs of anorexia or hepatic lipidosis.
Exercise and Behavioural Strategies for Overweight Pets
Whilst dietary restriction is the primary driver of weight loss, increased physical activity plays a crucial supporting role by enhancing caloric expenditure, preserving lean muscle mass, improving cardiovascular fitness, and providing mental stimulation. Exercise programmes must be tailored to the individual animal's current fitness level, any concurrent orthopaedic or cardiac conditions, and species-specific preferences. Veterinary advice should be sought before starting exercise programmes in animals with pre-existing cardiorespiratory or orthopaedic disease.
For dogs, a graduated exercise plan should begin conservatively, particularly in severely obese or previously sedentary animals. Initial activities might include short, frequent walks of 10–15 minutes, two to three times daily, gradually increasing duration and intensity as fitness improves. Low-impact exercises such as swimming or hydrotherapy are particularly valuable for animals with concurrent osteoarthritis, as water buoyancy reduces joint stress whilst providing resistance. Hydrotherapy should be undertaken at facilities with qualified personnel, such as those registered with the National Association of Registered Canine Hydrotherapists (NARCH). Interactive play sessions, retrieval games, and agility training (once appropriate fitness is achieved) add variety and strengthen the human-animal bond.
Safety considerations include avoiding exercise in hot weather, particularly for brachycephalic breeds (e.g., Bulldogs, Pugs) at high risk of heat-related respiratory distress; monitoring for signs of fatigue, distress, or lameness; and tailoring intensity to individual tolerance. Seek veterinary or physiotherapy advice for animals with osteoarthritis or cardiac disease.
Cats present unique challenges, as they are less amenable to structured exercise routines. Strategies include:
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Environmental enrichment – vertical climbing structures, cat trees, and perches
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Interactive play – feather wands, motorised toys, and puzzle feeders for 10–15 minutes, two to three times daily
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Laser pointer play – if used, always end sessions with a tangible toy the cat can 'catch' to prevent frustration
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Food puzzles – encouraging foraging behaviour and physical activity during feeding
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Outdoor access – where safe and appropriate, supervised garden access or secure catios
Behavioural modification is equally important. Owners must recognise that food is often used inappropriately to express affection or alleviate guilt. Education should emphasise alternative bonding activities such as grooming, play, and training. Addressing attention-seeking behaviours that are rewarded with food requires consistency and patience. For animals exhibiting food-motivated anxiety or begging, environmental management such as removing the pet from the room during human mealtimes may be necessary. Positive reinforcement training can redirect food-seeking behaviours towards desirable activities, strengthening the owner-pet relationship whilst supporting weight management goals.
Veterinary Medicines and Interventions for Animal Obesity
Pharmacological interventions for animal obesity are extremely limited, and medication should only be considered as an adjunct to dietary and lifestyle modifications, never as a standalone treatment. Currently, there is no veterinary medicinal product authorised in the United Kingdom specifically for weight loss in dogs or cats. Mitratapide (Yarvitan), previously authorised in the European Union for canine obesity, has been withdrawn from the market. Dirlotapide (Slentrol), a microsomal triglyceride transfer protein (MTP) inhibitor licensed in some other jurisdictions, is not available in the UK.
MTP inhibitors work by reducing the assembly of chylomicrons in the intestinal mucosa, thereby decreasing dietary fat absorption, and by promoting satiety through gastrointestinal signalling. When previously available, common adverse effects of such agents included vomiting, diarrhoea, and lethargy, and careful dose titration and monitoring were required.
UK regulatory context: In the absence of an authorised veterinary medicine for a specific condition, veterinary surgeons may prescribe under the Veterinary Medicines Directorate (VMD) Prescribing Cascade, which permits the use of other authorised veterinary or human medicines in a defined legal hierarchy. However, owners must not use human weight-loss medicines (such as GLP-1 receptor agonists or other anti-obesity drugs) in pets unless specifically directed by a veterinary surgeon and in accordance with the Cascade. Inappropriate use of human medicines in animals can cause serious harm.
Pharmacovigilance: Suspected adverse reactions to veterinary medicines should be reported to the VMD via gov.uk/report-veterinary-medicine-problem. If a human experiences a side effect from an animal medicine, this should be reported via the MHRA Yellow Card Scheme.
For animals with underlying endocrine disorders contributing to obesity, treating the primary condition is essential. Levothyroxine supplementation for hypothyroid dogs can restore normal metabolic rate and facilitate weight loss when combined with appropriate dietary management. Similarly, managing hyperadrenocorticism or diabetes mellitus addresses hormonal imbalances that promote weight gain and impair weight loss efforts.
Surgical interventions such as bariatric surgery are not established practices in veterinary medicine, primarily due to ethical considerations, anaesthetic risks in obese patients, and the availability of effective non-surgical alternatives. In exceptional cases of extreme obesity where medical management has failed and quality of life is severely compromised, referral to an RCVS Recognised Specialist in Veterinary Nutrition, Behaviour, or Physiotherapy may be appropriate.
Veterinary professionals should counsel owners that there is no "quick fix" for animal obesity. Sustainable weight loss requires commitment to long-term dietary and lifestyle changes, with veterinary supervision to ensure safety and efficacy.
Monitoring Progress and Long-Term Weight Maintenance in Animals
Successful obesity treatment extends beyond achieving target weight to establishing sustainable long-term weight maintenance, which requires ongoing monitoring, owner education, and periodic reassessment. Structured follow-up protocols significantly improve outcomes and reduce the risk of weight regain, which can occur in a substantial proportion of animals following completion of a weight loss programme if long-term support is not maintained.
Regular monitoring should include:
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Fortnightly weigh-ins during active weight loss phase
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Body condition scoring at each visit to assess fat distribution changes
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Dietary compliance review – discussing challenges and problem-solving barriers
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Exercise activity assessment – ensuring the physical activity plan remains appropriate
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Photographic documentation – visual records help owners appreciate gradual changes
Weight loss progress should be plotted graphically, allowing identification of plateaus that may require dietary adjustment. If weight loss stalls for three consecutive weigh-ins despite reported compliance, caloric intake should be reduced by 10–15%, or exercise increased if feasible. Conversely, if weight loss exceeds target rates, particularly in cats, caloric intake should be increased slightly to prevent complications such as hepatic lipidosis. Monitor cats closely for signs of anorexia or rapid weight loss and seek veterinary advice promptly if concerns arise.
Once target weight is achieved, the transition to maintenance feeding requires careful calculation of energy requirements to prevent regain whilst avoiding further loss. Maintenance calories typically range from 1.0–1.4 × RER of ideal body weight, though individual variation necessitates ongoing adjustment based on body condition monitoring to maintain BCS 4–5/9. Factors such as neuter status, activity level, and individual metabolism influence maintenance requirements. Some animals may require continued feeding of weight management diets at increased portions, whilst others can transition to standard adult maintenance diets with strict portion control.
Long-term success strategies include:
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Monthly weigh-ins for the first six months post-target, then quarterly thereafter
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Continued treat restriction – treats should not exceed 10% of daily calories
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Sustained exercise routines – maintaining activity levels achieved during weight loss
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Owner support – some veterinary practices offer group sessions or individual consultations for motivation
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Annual health assessments – monitoring for obesity-related complications and metabolic changes
Owners should be advised to contact their veterinary surgeon promptly if weight increases by more than 5% above target, as early intervention prevents full relapse. Celebrating milestones and acknowledging owner commitment reinforces positive behaviours and strengthens the therapeutic relationship, ultimately supporting lifelong weight management and improved animal welfare.
Key resources for veterinary professionals and owners include the WSAVA Global Nutrition Toolkit, BSAVA manuals on clinical nutrition, PDSA and RSPCA guidance on pet health and exercise, and referral pathways to RCVS Recognised Specialists and accredited providers such as NARCH-registered hydrotherapy centres.
Frequently Asked Questions
How do vets treat obesity in dogs and cats?
Vets treat obesity in animals primarily through controlled caloric restriction using veterinary-formulated weight management diets, combined with gradual increases in physical activity and behavioural modification. Treatment plans are individualised based on body condition scoring, target weight calculations, and any underlying health conditions such as hypothyroidism or diabetes.
Are there any medicines available to help my pet lose weight?
Currently, there are no veterinary medicines authorised in the UK specifically for weight loss in dogs or cats. Treatment relies on dietary management and lifestyle changes, though underlying endocrine disorders such as hypothyroidism can be treated with appropriate medication to support weight loss efforts.
How quickly should my overweight pet lose weight safely?
Dogs should lose 1–2% of their body weight per week, whilst cats should lose 0.5–1% per week to avoid serious complications. Rapid weight loss, particularly in cats, can cause hepatic lipidosis, a potentially fatal liver condition, so gradual, veterinary-supervised weight loss is essential.
What is the difference between obesity treatment in dogs versus cats?
Dogs typically tolerate more structured exercise programmes such as walks and hydrotherapy, whilst cats require environmental enrichment and interactive play sessions. Cats also have stricter weight loss rate limits (0.5–1% weekly) due to their higher risk of hepatic lipidosis, and they are obligate carnivores requiring higher dietary protein levels during weight loss.
Can I use human weight-loss drugs like Ozempic for my obese pet?
No, you must not use human weight-loss medicines in pets unless specifically prescribed by a veterinary surgeon under the Prescribing Cascade. Inappropriate use of human medicines in animals can cause serious harm, and there are no GLP-1 receptor agonists or similar drugs authorised for veterinary use in the UK.
How do I stop my pet from regaining weight after reaching their target?
Long-term weight maintenance requires calculating appropriate maintenance calories (typically 1.0–1.4 × RER of ideal body weight), continuing strict portion control and treat restriction, maintaining regular exercise routines, and scheduling monthly weigh-ins for the first six months, then quarterly thereafter. Early intervention if weight increases by more than 5% above target prevents full relapse.
The health-related content published on this site is based on credible scientific sources and is periodically reviewed to ensure accuracy and relevance. Although we aim to reflect the most current medical knowledge, the material is meant for general education and awareness only.
The information on this site is not a substitute for professional medical advice. For any health concerns, please speak with a qualified medical professional. By using this information, you acknowledge responsibility for any decisions made and understand we are not liable for any consequences that may result.
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