Fat content in ZIWI recipes
Page 3: Research on fat tolerance in dogs
What do ketogenic diets tell us about fat tolerance in dogs?
In the last few decades ketogenic diets have been studied as an adjuvant to cancer therapy in both animal studies and human case reports (Allen et al., 2014). The majority of animal studies have yielded evidence for an anti-tumour effect of the ketogenic diet, either through slower tumour growth or through longer overall survival times in the treated animals (Klement, 2017).
A ketogenic diet is typically composed of at least 75% fat, with a maximum 10% of energy from carbohydrate sources. The diet typically adheres to a ketogenic ratio of about 2:1. The ketogenic ratio is defined as the weight percentage of fat in the diet divided by the combined weight percentage of protein and carbohydrate (Klement, 2017).
An interesting project was conducted in the US which recruited dogs that had been diagnosed with cancer (prior to the study commencement). Human doctors and some veterinarians formed a flagship program called KetoPet in 2014 in order to test the effect of ketogenic diets on canine cancer patients. The researchers recruited dogs from kill shelters in Texas that were diagnosed with naturally occurring cancer(s) (Mettapets, 2018).
Dietary treatment for these dogs included a raw food ketogenic diet, at a 2:1 – 4:1 ratio titrated to keep the dog at lean but healthy weight. The diet consisted of 30% protein – either raw beef or chicken breast, with 70% fat which comprised of either MCT powder (medium chain triglyceride supplement), cream, butter, coconut cream or other fats cycled for variety. The diet included vegetables added for fibre, probiotics, vitamins and minerals. Glucose and ketones were monitored daily, ultrasound was conducted at 30 and 60 days, and overall condition, appearance and blood work was monitored. Overall, the results were promising, as 50 percent of dogs that completed the program showed no evidence of disease many months longer than they were prognosed to survive.
Of relevance to this discussion, none of the dogs involved in the KetoPet study developed pancreatitis. Some dogs in the study did develop changes on ultrasound consistent with fatty liver during the 120 days they were fed the high fat diet, however no dog developed clinical signs associated with liver disease. After the dogs were transitioned to the maintenance phase these ultrasound changes resolved. Thus, it is not clear whether the fat deposition in the liver were clinically relevant.
The fat percentage of the KetoPet diet was VERY high, as a fresh diet – much higher than any ZIWI recipe. As stated – the fat content of ZIWI Peak recipes are below the NRC safe upper limit.
Benefits of a high fat diet for active dogs
Active dogs in particular can benefit from high protein, high fat diets. Breeds that are used for work or endurance sports have high levels of activity and therefore have an increased daily caloric requirement. Using a calorie dense food in these cases is helpful, as dogs do not need to consume vast amounts of food to achieve these caloric goals, which can be four to five times greater than a dog with average activity levels (Loftus et. al., 2014). A high calorie, high protein, and high fat diet like ZIWI Peak is an ideal source of fuel for these dogs.
The source of this energy for high-performance active dogs is just as important as the caloric requirement. Many studies recommend that the composition of the diet should be low carbohydrate, high in bioavailable protein, and high in fat. Kronfeld demonstrated that endurance athlete dogs receiving greater than approximately 30–40 % of their metabolisable energy (ME) as a carbohydrate source can develop signs of ‘tying up’, coprophagy and hypoglycaemia during periods of intense endurance exercise (Kronfeld, 1973). These issues were observed to resolve when the carbohydrate percentage of the diet was reduced. It has therefore been recommended that the diet for canine athletes should limit carbohydrate content to 0-22% of ME energy (Hinchcliff et. al. 1997). Kronfeld and colleagues therefore suggest that dietary carbohydrates are not necessary in the composition of a high-performance endurance dogs’ diet (Kronfeld, 1977).
Additionally, high fat and high protein diets can result in physiological changes. In one study, dogs on a high protein and high fat diet maintained higher serum concentrations of albumin, calcium, magnesium, and non-esterified fatty acids (NEFA) during the racing season compared to dogs fed on diets with higher proportions of carbohydrates contributing to their metabolisable energy (Kronfeld et. al., 1977). The dogs on the high fat and high protein diet showed the greatest increase in red cell count, haemoglobin concentration, and packed cell volume during training (Kronfeld et. al., 1977). The higher energy density and digestibility of the carbohydrate-free, high-fat diet was advantageous for prolonged strenuous exercise regarding metabolic responses in training. (Kronfeld et. al., 1977).
A separate study using high fat and high protein diets for endurance dogs resulted in higher serum concentrations of cholesterol, glucose, lactic acid, NEFA and ketones (Hammel et. al. 1977). Hammel deduced that an enhanced ability to utilise fat offers an advantage in a dog subjected to prolonged strenuous exercise in which fatty acid oxidation accounts for most of the oxygen consumption.
Furthermore, throughout the endurance race, the muscle glycogen in dogs will increase, which indicates that they have a compensatory mechanism that results in reduced muscle glycogen depletion after the first bout of activity (Mackenzie et. al., 2008).
The aforementioned studies have typically been performed with sled dogs, however interesting research with working dogs such as Beagles, Pointers, and Labradors used for scent work also shows improvement in performance when consuming a low carbohydrate diet (Downey et. al., 1980).
A study compared the hunting performance of working English Pointers when fed two different dog foods. Diet B was a standard adult pet food, and Diet A was a performance food that was higher in fat and protein. There was a 10% increase in metabolised energy from fat in Diet A compared to Diet B. The results were statistically significant and showed that dogs fed Diet A maintained or gained weight and body condition throughout the hunting season, while dogs fed Diet B lost body weight and body condition (Davenport et. al., 2001). Dogs fed Diet A demonstrated superior hunting performance, as dogs fed on the lower fat food had significantly less finds per hour of hunting (Davenport et. al., 2001).
Research with scent work Beagles supports the use of high fat and high protein diets, as it was shown that stamina improved for Beagles on treadmills when feeding higher fat diets with approximately 69% metabolizable energy as fat compared to diets of 27% ME fat (Downey et. al., 1980).
Many studies have suggested a link between fat intake and olfaction performance, which could be a factor in Davenport’s study on Pointers achieving better finds per hour on a high fat diet. Another study on working English Pointers demonstrated that polyunsaturated fatty acids improved or maintained the efficiency of olfaction (Altom et. al., 2003). It is suggested that polyunsaturated fatty acids might positively affect olfaction by altering the olfactory bulb cellular constitution, which enhances neuronal signalling (Ober et. al., 2016).
In theory, a high fat diet is very efficient thermodynamically, as there is a reduced need for gluconeogenesis from protein as a source of energy during exercise, which is less efficient than fat or carbohydrates (Ober et. Al., 2016). As previously mentioned, fat as a source of energy is superior to carbohydrates, as a diet high in carbohydrates can result in signs of ‘tying up’, coprophagy and hypoglycaemia during periods of intense endurance exercise, resolving when carbohydrates were reduced (Kronfeld, 1973).
The ZIWI Peak recipes offer a source of highly bioavailable protein and fat that could appropriately support high-performance endurance dogs during intense periods of activity and also throughout their recovery.
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