As dogs become more like family members in many households, better quality of veterinary care and safer living environments have resulted in pets living longer. Veterinary professionals are responsible for ensuring that their clients receive the best care possible for their pets as they grow into mature, older dogs. Monitoring dogs' health status is an important part of being able to offer guidance and professional suggestions for owners as they maintain a long, healthy quality of life for their dogs.
For pets, much like for people, ageing brings with it physiologic changes. Some changes are obvious: whitening of hair, a general decline in body coat and condition, and failing senses such as sight or hearing. Changes that are less obvious may involve the digestive tract, immune system, kidneys, and other organs (Laflamme, 2005).
Ageing dogs are a common population seen in veterinary practices in developed countries. In 2012, it was estimated that more than 43 million US households owned a dog. Approximately 33% of dogs were 6 to 10 years of age and almost 15% were older than 11 years of age (Larsen and Farcas, 2014). In Australia and the UK, 33% and 23% of households, respectively, owned dogs in 2010 (Australian Companion Animal Council, 2010).
In dogs, the ageing process is influenced not only by breed, genetics, and the environment, but also by nutrition (Laflamme, 2005). When dogs begin to transition from adult to senior or geriatric, it is important that their nutrition is monitored by the veterinary healthcare team so that they maintain health and a high quality of life.
A dog's lifespan varies depending on its breed and size. The Senior Care Guidelines Task Force of the American Animal Hospital Association (AAHA) considers a dog to be senior when it is in the last 25% of its predicted lifespan based on species and breed (Larsen and Farcus, 2014).
Small breed dogs may be considered geriatric at 12–14 years, whereas large and giant breed dogs may be considered geriatric at 7–9 years. It is important that when dogs begin to transition from mature to geriatric that their nutritional status is monitored to maintain a high quality of life.
Patient evaluation
The AAHA and the World Small Animal Veterinary Association (WSAVA, 2011) recommend that nutritional assessment guidelines be followed in order for all pets to have a good quality and quantity of life. To begin a nutritional assessment, it is important to obtain a thorough medical history, nutritional history, and a physical examination in order to be able to effectively evaluate the patient (Baldwin et al, 2010; WSAVA, 2011).
Medical history
Medical history should include vaccination history, heartworm and flea prevention methods, and any prior diseases, treatments, or daily medications (Laflamme, 2005).
Nutritional history
Nutritional history includes a detailed assessment of the patient, including the following:
In general, inactive animals or those that are overweight should be receiving lower calorie foods; however, these animals might also need an increased nutrient-to-calorie ratio. It is also important to know how much of what is being offered is eaten since what is fed does not always indicate how much the dog is eating. In addition, veterinary professionals should determine from the owner if the dog is fed any treats or human food, if it is eating appropriate amounts of a balanced diet, if dietary supplements or vitamins are being given, and if there has been any recent weight gain or loss. It is also important to ask the client if any food or treats are used to give medications. All this information is important when making caloric recommendations (Laflamme, 2005).
Physical examination
The physical examination includes evaluating the following:
| 5-pt scale | 9-pt scale | % body fat |
|---|---|---|
| 3 | 4 | 15–19 |
| 5 | 20–24 | |
| 4 | 6 | 25–29 |
| 7 | 30–34 | |
| 5 | 8 | 35–39 |
| 9 | 40–45+ |
It is important that the entire veterinary staff is consistent with using the same BCS system (Table 1).
Nutritional-related abnormalities of the coat and skin can include dry, easily plucked fur; and thin, dry, or scaly skin (Baldwin et al, 2010). Regarding muscle condition, muscle loss can be of greater concern in animals with acute and chronic disease, which laboratory tests can help identify.
Laboratory tests
With the client's consent, it is important to do a complete geriatric evaluation once a year (Laflamme, 2005). Part of this evaluation includes a laboratory examination with a complete blood cell count (CBC), blood chemistry profile, thyroid panel, and urinalysis. Findings during laboratory evaluations that may be indicative of nutritional deficits that might be resolved with nutritional intervention are anaemia, low albumin, low potassium, increased serum urea nitrogen, and increased triglycerides, glucose, or cholesterol. These laboratory results could also indicate early signs of renal or liver disease. The thyroid panel could provide an explanation for undetermined weight gain or loss (Laflamme, 2005).
Importance of nutrition in ageing dogs
Ageing is not a disease; however, morbidity increases due to normal changes, making the animal more vulnerable to disease. The three leading, non-accidental causes of death in dogs are cancer, kidney disease, and heart disease (Debraekeleer et al, 2010). However, other conditions that may shorten life expectancy are endocrine disorders, periodontal disease, cognitive dysfunction, and obesity. Nutrition is an important aspect of geriatric care, and the overall feeding goals for mature adult dogs are to optimise quality and longevity of life by minimising risk and severity of disease (Debraekeleer et al, 2010).
Ageing is characterised by progressive and usually irreversible change, and its rate is determined by intrinsic and extrinsic factors, one of which is nutrition. Nutritional interventions in combination with mental stimulation can halt and sometimes even reverse the ageing process.
Minimal nutritional requirements of mature dogs are similar to those of young adult dogs. However, for mature dogs, the upper range of some nutrients should be reduced compared with upper ranges for young adults (Debraekeleer et al, 2010).
In a pivotal study evaluating the impact of bodyweight on lifespan, 48 Labrador puppies were followed for 14 years. When the puppies were 8 weeks old, they were assigned to a control or a lean-fed group. All dogs were fed the same commercially prepared, nutritionally balanced diet during the study. The control group was allowed to eat an unlimited amount for 15 minutes, and dogs in the lean-fed group were fed 25% less than the amount eaten by the other group. Study findings showed that the median lifespan was increased by 15% (approximately 2 years) in the lean-fed dogs, compared with the control dogs. The lean-fed group weighed less, had a lower percent of body fat, and maintained their lean body mass as they aged. This study also showed slowed signs of ageing in the lean-fed compared with the control group (Kealy et al, 2002).
Nutritional factor recommendations
The Association of American Feed Control Officials (AAFCO) and the European Pet Food Industry Federation (FEDIAF) make recommendations for both mature dogs and dogs with disease processes. These recommendations take into account the five basic nutrients — water, energy, fat, fibre, and protein — and are calculated on a dry matter (DM) basis. In order to help maintain a healthy mature dog and to provide proper nutrition for helping to prevent disease, these recommended factors must be met in accordance with each individual dog along with other important nutritional management considerations.
Water
Mature dogs are prone to dehydration due to possible renal disease and medications, which will be determined by bloodwork and a complete medical history (Debraekeleer et al, 2010).
Energy
To calculate the resting energy requirement (RER), the following equation is used:
RER = (bodyweight (kg)0.75× 70) × LSF
where LSF is life stage factor (Table 2). The energy amount should be modified accordingly if a dog loses or gains weight when fed at the recommended levels. Very old dogs are often underweight and thus may have inadequate energy intake and need a higher caloric intake; likewise, active dogs may require a higher caloric intake to meet energy needs. A starting place for energy needs for older dogs, regardless of neuter status, is (bodyweight (kg)0.75 × 70) × 1.4. If the dog loses or gains weight, this calculation should be modified using the LSF chart (Table 2) to achieve accurate results for the individual dog (Debraekeleer et al, 2010).
| Life stage | Factor |
|---|---|
| Adult intact | 1.8 |
| Neutered | 1.6 |
| Senior | 1.4–1.6 |
| Obese prone | 1.2–1.4 |
| Weight loss | 1.0–1.2 |
| Growth | 2.0–3.0 |
| Gestation | 1.8–3.5 |
| Lactation | 4.0–8.0 |
Fat
Low-fat diets help to prevent obesity in healthy, mature dogs. However, very old dogs have a tendency to lose weight. Therefore, increased fat content of food and subsequent increased energy might be necessary to improve protein efficiency. For people, increasing fat content generally improves foods' palatability; for dogs, increasing fat content of food to increase energy intake enables a good balance in preventing obesity and providing sufficient caloric intake. Recommended fat levels for mature dogs are between 7–15% DM (Table 3) (Debraekeleer et al, 2010).
| Nutrient | DM % |
|---|---|
| Calcium | 0.4–0.8 |
| Sodium | 0.15–0.4 |
| Phosphorus | 0.3–0.7 |
| Protein | 15–23 |
| Fibre | 2.0 |
| Fat | 7–15 |
Fibre
Mature dogs may be prone to constipation, and may benefit from increased fibre intake; however, fibre can lower the caloric density of foods, so the volume of food may need to increase to maintain adequate energy intake. Recommended crude fibre is at least 2% of DM (Table 3) (Debraekeleer et al, 2010).
Protein
The amount of protein required in a healthy, mature dog's diet has been a controversial topic. With all life stages, healthy dogs should receive enough protein and energy to avoid protein-energy malnutrition. Geriatric dogs are often underweight and may have significant muscle wasting. Providing high quality proteins in increased amounts may help maintain lean mass. Although high protein intake has not been shown to contribute to the development of kidney disease, if kidney function is impaired, protein may play a role in progression of renal disease, and kidney function should be monitored closely (Debraekeleer et al, 2010).
In the case of dogs with kidney disease, providing protein sources of high biologic value with a balanced amino acid profile is important to meet the body's needs without burdening the kidneys with excessive amounts of protein (Forrester et al, 2010). Foods containing 15–23% DM protein provide sufficient protein for healthy mature dogs (Table 3) (Debraekeleer et al, 2010).
Phosphorus
Research has shown that in dogs with advanced renal disease, progression is slower and the severity of disease is reduced when phosphorus levels in foods are decreased, thereby improving dogs' survival time. The minimum recommendation of phosphorus levels in food for mature dogs is 0.3% DM (Jacob et al, 2002), with a range of 0.3–0.7% DM (Table 3) (Debraekeleer 2010).
Sodium and chloride
Dogs have no need for high levels of sodium and chloride. Some ingredients high in sodium chloride are fish, eggs, and poultry by-product. High sodium chloride intake may be harmful in dogs with diseases that have a hypertensive component, such as obesity, chronic renal disease, and some endocrinopathies. These diseases are frequently seen in mature dogs. The recommended sodium requirement is 0.15–0.4% DM (Table 3). Although chloride requirements for dogs have not been established, a reasonable recommendation for chloride level is usually 1.5 times that of the sodium requirement (Debraekeleer et al, 2010).
Calcium
If a mature dog is fed a complete and well-balanced diet appropriate for its lifestage, calcium is usually not deficient; foods with 0.4–0.8% DM calcium are recommended (Table 3). The calcium-to-phosphorus ratio should be in a range from 1.1:1 to 1.8:1 (Baldwin et al, 2010).
Disease processes and old-age nutrition
Certain disease processes that affect ageing dogs might require nutritional management to help improve quality of life.
Cognitive dysfunction
The primary source of diagnosis for cognitive dysfunction syndrome (CDS) is behavioural signs reported by pet owners. These changes may be personality or mood changes or inability of the pet to recognise previously learned behaviour. However, disease of other organ systems can also affect behaviour (Christi et al, 2010). Nutritional management of CDS may include nutrients and compounds such as antioxidants and long-chain omega-3 polyunsaturated fatty acids (PUFAs), which appear to have beneficial effects on cognitive dysfunction, oxidative damage, and the immune system.
Combined with environmental enrichment, antioxidants have been reported to improve clinical signs related to recognition, sleep patterns, social interaction, house soiling, and owner-perceived behaviour in dogs. In one study, improved agility and recognition were seen in dogs fed a diet enriched with an antioxidant blend (vitamin C, vitamin E, carnitine, lipoic acid, glutathione, and a variety of fruit and vegetables) compared with dogs fed a control diet (Larson and Farcas, 2014).
Besides antioxidants, supplementation with longchain omega-3 PUFAs could be beneficial for brain ageing. A PUFA concentration of 0.3 to > 1% DM is recommended. Foods selected should contain nutrient levels that protect against free radical damage and improve learning ability and alertness of older pets (Christi et al, 2010).
Endocrine disorders
Endocrine disorders can cause weight gain or loss, along with other symptoms, in older dogs; therefore, it is important to know if thyroid hormone levels are increased or decreased, and whether medication is needed to control thyroid function in order to help control weight (Zicker et al, 2010).
Periodontal disease
Periodontal disease can affect a dog's ability to eat properly. Making sure that the dog's oral cavity is clean and healthy and no pain is detected will help the dog to maintain a healthy mouth. It is important that a yearly oral examination be performed and, if needed, a yearly professional prophylaxis is carried out. The prophylaxis is usually done under general anaesthesia, and so the health status of the dog will determine if anaesthesia can be tolerated. A well-balanced diet formulated especially for tartar control can help prevent further periodontal disease, and this strategy will help enable a dog to eat pain-free (Logan et al, 2010).
Degenerative joint disease
Fish oil omega-3 fatty acids have been recommended for management of several diseases, including degenerative joint disease (Lenox and Bauer, 2013).
There are a few commercial diets available that contain high concentrations of the anti-inflammatory omega-3 fatty acids eicosapentaenoic (EPA) and docosahexaenoic acid (DHA). These are used in treatment of joint disease; target dosage ranges for EPA and DPA are 50 to 220 mg/kg. Lower doses are used to lower serum triglyceride concentrations, and higher doses are used for inflammatory disease such as degenerative joint disease (Lenox and Bauer, 2013).
Cardiovascular disease
Heart failure is a condition of inadequate output and insufficient delivery of nutrients relative to tissue metabolic needs. Chronic mitral valvular disease is one of the most commonly acquired cardiac abnormalities in dogs. Key nutrition factors that should be evaluated in a patient with congestive heart disease (CHD) are sodium, chloride, taurine, L-carnitine, phosphorus, potassium, and magnesium.
While assessing the nutritional status of patients with cardiovascular disease, overall body condition is an important indicator (Roudebush and Keene, 2010).
Obesity causes cardiovascular changes that can complicate the management of cardiovascular disease; however, weight loss is a far more common problem after the onset of heart failure. Cachexia is severe wasting of the patient and often is an additional risk factor for heart failure. Nutritional factor recommendations for proper management of cardiovascular disease are on a DM basis and are as follows:
These factors also should be taken into consideration when ACE inhibitors are used, especially when in combination with diuretics (Roudebush and Keene, 2010).
Renal disease
Chronic kidney disease (CKD) is the most common disease affecting the kidneys in dogs. It is usually recognised by reduced kidney function or the presence of kidney damage, and these are determined by laboratory evaluation and ultrasound. The goals of managing patients with CKD are to control clinical signs, to minimise electrolyte imbalances, and to support with adequate nutrition. Commercially prepared ‘kidney’ diets are usually formulated with less protein, phosphorus, and sodium than typical diets, and have increased fat and increased omega-3 fatty acids (Forrester et al, 2010).
Liver disease
One of the most challenging diseases is hepatobiliary disease, which involves failure of the liver, the second largest organ of the body. The liver plays a key role in food digestion and nutrient metabolism. Because the liver has tremendous storage capacity, as well as functional reserve and regenerative capabilities, hepatobiliary disease must be severe before clinical signs typically occur. Without appropriate laboratory evaluation, liver disease is often overlooked. Nutritional management of hepatobiliary disease includes maintaining normal metabolic processes, managing support for hepatocellular repair, decreasing further damage, and correcting electrolyte disturbances. Nutritional management of hepatobiliary disease is beneficial only when done in conjunction with proper medical and surgical management of the specific hepatobiliary disease. Consideration should be given to maintaining proper protein and fat levels in the diet to manage the hepatobiliary disease that is diagnosed (Meyer et al, 2010).
Feeding protocols
Twice a day feeding is a recommended protocol to apply to all mature/older dogs; free-choice feeding should not be considered for obese-prone dogs but may be acceptable if the food is being measured daily or if other disease processes necessitate free-choice feeding.
One important take-away message is that pet food that has been approved by the regulatory agencies AAFCO or FEDIAF will have a label assuring proper nutrient level and adequate caloric intake for specific physiological factors, age, and particular diseases, if applicable, of the dog (Baldwin et al, 2010).
Veterinary nurse's role
Veterinary technicians and nurses play an important role in monitoring patients from the time they are puppies through to their senior years by helping assure that nutrition is maintained for a long, healthy life.
The veterinary nurse's role in helping the owner to achieve his or her goals of having a healthy older dog begins the minute the patient enters the clinic for the first time. This starts with the veterinary technician obtaining a thorough medical history and a complete nutritional history in order to make recommendations of the proper amount to be fed based on the patient's breed, age, and disease process(es).
Diagnosis of disease is for the veterinarian to determine. The veterinary technician's responsibility is to: relay the history to the veterinarian; educate, teach and encourage clients; do follow-up consultations; advise clients about foods, potential advantages, risks, and concerns; and monitor whether there are any dietary changes that need to be made or discussed.
Conclusion
Canine nutrition for a healthy old age can be a challenge; however, good nutrition must begin as a young pup and continue as the dog matures. Before making nutritional recommendations for the maturing dog, a thorough physical examination and nutritional evaluation will help determine what factors need to be considered. Evaluations of the breed, age and disease process of the individual dog are key factors. Determining the proper diet for each dog, and making sure that the diet meets recommended nutrient requirements will help to assure a long, healthy and high-quality life for the old-age dog. Frequent communication and follow up with the client is important.