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Inspired Vet Article – Fat-sensitive conditions in the dog

An article by Jessica-Anne Berlyn, Veterinary Technical Manager at Purina, BVSc MRCVS.

Jessica-Anne Berlyn qualified as a veterinary surgeon from the University of Pretoria in sunny South Africa. She has worked in the UK as a small animal veterinary surgeon in clinical practice since then and now works as a Veterinary Technical Advisor at Purina. Her areas of interest are feline medicine and nutrition. When she is not working, she enjoys open water swimming and travelling.

Fat is a calorific nutrient essential for life. It provides energy, is essential for fat-soluble vitamin absorption, modulates inflammation, and acts as a precursor to eicosanoids and prostaglandins. Fat serves a structural role as a component of cell membranes, promotes healthy growth and development, and affects skin and coat health.1 Fats and their component fatty acids are highly important for normal metabolic functions in the dog, but there are certain disease processes which can be exacerbated by high levels of fat.

Figure 1: Digestion and absorption of MCTs & LCTs 3    Courtesy of Purina Institute.

Composition of fats

Fats (lipids) are composed of triglycerides, which in turn are composed of three fatty acids joined to a glycerol backbone. Fatty acids are hydrocarbon chains, and the number of carbon molecules dictates how they are digested in the body. 2 Fatty acids can be classified into 3 categories: short-chain (containing < 6 carbons), medium-chain (containing 6 to 12 carbons), or long-chain (containing > 12 carbons).

The length of the chain influences how the fat is metabolised and these differences can be exploited in the management of some diseases. For example, medium-chain triglycerides can be beneficial in patients with disorders of lipid digestion or absorption because they are absorbed differently to long-chain fatty acids. 3, 4  (See Figure 1)

Omega-6 and omega-3 fatty acids are polyunsaturated long-chain fatty acids necessary for physiologic growth and function, and are considered essential dietary fatty acids for mammals. Essential fatty acids must be consumed in the diet as mammals are unable to endogenously produce them. 5

Essential fatty acid deficiency could be seen in animals consuming unbalanced diets deficient in essential fatty acids regardless of total fat content, or ultra–low-fat diets, where not supplemented. Deficiency in omega-3- fatty acids results in neurological impairments. Deficiency in omega-6-fatty acids manifests in skin disorders such as alopecia and scaling, reproductive abnormalities and poor growth. 5

Incorporating a proportion of medium-chain-triglycerides (MCTs) in the diet has several benefits:

  • MCTs are more easily digested and more rapidly absorbed in the small intestinal lumen without stimulating cholecystokinin secretion or relying on pancreatic lipase and bile acids for absorption.6,7  
  • MCT can serve as an easily digestible source of energy in diets where long-chain fatty acids (LCFAs) need to be restricted.3

We shall now discuss fat-sensitive conditions in the dog. A summary table is provided, Table 1.

Table 1. Summary of fat-sensitive conditions and dietary fat recommendations. ME refers to Metabolizable Energy, with the %’s referring to the recommendation for the proportion of total calories that comes from fat in that diet.

Acute vomiting or diarrhoea

Animals experiencing acute vomiting and/or diarrhoea should be fed a fat limited diet whilst they are unwell. Fat slows gastric transit time, which may exacerbate vomiting and increase the risk of aspiration. Maldigestion of fat can exacerbate diarrhoea.

Protein-losing enteropathy (PLE)

PLE is a disease syndrome characterized by excessive loss of plasma proteins, particularly albumin, into the gastrointestinal tract. Patients have a severe negative protein and energy balance. Diseases most commonly associated with PLE include intestinal lymphangiectasia, severe chronic enteropathy and intestinal lymphoma.8

Dietary goals for managing the patient with PLE are fat restriction, whilst providing sufficient energy and protein for essential nutritional support. Fat should be restricted to <20% ME regardless of underlying cause. Limiting dietary fat will decrease lymph flow, reduce lymphatic vessel distension and minimize protein loss.

Dogs with PLE may be cachectic. Since low-fat diets are lower in calories, dogs experiencing severe weight loss may benefit from a diet containing medium-chain fatty acids (MCFAs) as an alternative energy source.6,7 It is important to limit the quantity of long-chain triglycerides (LCTs) as they contribute to increased lymph flow and subsequent protein loss. 9

Lymphangiectasia

Intestinal lymphangiectasia is a type of protein-losing enteropathy characterised by dilatation of the intestinal lymphatic vessels in the gastrointestinal tract. This results in leakage of the lymphatic contents into the intestinal submucosa, lamina propria, and lumen.10

Lymphangiectasia has primary and secondary causes. Primary lymphangiectasia may be congenital, but is generally idiopathic. More commonly, lymphangiectasia manifests as a secondary disorder to another disease. Inflammation, infection, and neoplasia may cause lymphatic obstruction.11

Management of PLE includes immunosuppressive drugs, low-fat or hypoallergenic therapeutic diets, oncotic support, and nutritional supplementation of deficient vitamins and minerals, especially cobalamin, calcium and magnesium.12

Dietary interventions include primarily highly digestible, fat restricted diets.13 Low-fat to ultra-low fat diets reduce intestinal lymph flow, decrease lacteal distention, and thereby minimize protein loss. MCFAs can provide an alternative energy source less likely to contribute to lymphatic congestion.

Hyperlipidaemia

Hyperlipidaemia occurs as a disturbance of lipid metabolism that results in elevated blood lipids, particularly triglycerides, cholesterol or both. Primary hyperlipidaemia can be familial in predisposed breeds such as Miniature Schnauzers. Secondary hyperlipidaemias are associated with underlying primary diseases including protein-losing nephropathy, endocrine disorders such as unregulated diabetes, certain drugs and foods.

The therapeutic goal is to reduce the level of serum triglyceridaemia to eliminate clinical signs and maintain serum triglycerides within normal range.14 The mainstay of treatment is a fat restricted (<20% ME) nutritionally balanced diet, with the addition of lipid-reducing drugs, such as statins and fibrates, if there is an inadequate clinical response to dietary modification.14

Supplementation with omega-3 fatty acid-rich fish oil has been shown to reduce triglyceride and cholesterol concentrations in dogs with primary hyperlipidemia.15 Increased soluble dietary fibre may decrease serum cholesterol and/or triglyceride concentrations when added to a low-fat diet.16

Pancreatitis

Pancreatitis is an acute or chronic inflammatory disease of the pancreas. Pancreatitis is a common presentation seen in small animal practice.17 Precipitating factors in dogs include dietary indiscretion, ingestion of high-fat foods, obesity, hypertriglyceridaemia and administration of corticosteroids.

Dietary modification and nutritional support are essential. The goal of dietary management of acute and chronic pancreatitis is to provide a diet that does not contribute to excessive pancreatic stimulation and secretion. The presence of fat in the intestinal lumen stimulates pancreatic enzyme secretion. Reduction of 50% in the metabolizable energy (ME) from fat relative to the current diet is prudent. The extent of dietary fat reduction varies between individuals. A patient with acute pancreatitis, once recovered, may be able to resume a normal diet, however patients with chronic pancreatitis should remain on a low-fat diet.18

Diabetes mellitus

The canine form of diabetes mellitus is typically insulin-deficient (type 1) diabetes, resulting from the destruction of pancreatic beta cells. Other contributing factors include obesity, older pets, metabolic and endocrine diseases (such as hyperadrenocorticism, hypothyroidism, hypertriglyceridemia, and pancreatitis) and genetic predisposition.19,7  The mainstay of treatment for clinical diabetes mellitus is insulin along with dietary modification.20

28% to 40% of dogs with diabetes mellitus show evidence of concurrent acute or chronic pancreatitis. Goals of dietary therapy are to optimize body weight with appropriate protein and carbohydrate levels, fat restriction, and calorie and portion control.7

Obesity

Studies show that overweight or obese pets do not live as long as their leaner counterparts.21,22 Weight loss can be achieved with a balanced, calorie-controlled diet. Dietary fat levels should be reduced to reduce calorie content of the diet, and to manage serum hypercholesterolaemia and hyperlipidaemia if present. Over-restriction of fat should be avoided, however, to prevent deficiency of essential fatty acids. Obesity is a chronic inflammatory disease and animals are more prone to osteoarthritis, so it is important to incorporate EPA and DHA to help modulate inflammation.11

Chronic enteropathy

Chronic enteropathy is defined as a non-specific GI disease characterised by clinical signs lasting 3 weeks or longer for which other causes such as parasites, bacterial infections, cancer and non-GI diseases have been excluded.

The ability of the GI tract to digest food and absorb nutrients, especially protein and fat, may be compromised. A highly digestible and nutritionally balanced diet is crucial. Dietary interventions are made on a trial-and-error basis. Commercial hydrolyzed, limited-ingredient novel protein, gastrointestinal diets and home-prepared diets have all been used successfully in the management of chronic enteropathy.23

Hydrolysed diets, such as Purina ProPlan Veterinary Diets Hypoallergenic (HA), are typically lower in fat, have increased digestibility, and some contain soya and omega 3 EFAs, ingredients known for their immunomodulatory benefits.23

Dietary fat restriction is recommended for dogs with pancreatitis or lymphangiectasia. When fat digestion and absorption are compromised, an increased amount of fat may pass into the colon where it potentially may induce dysbiosis, epithelial cell damage and fluid secretion into the colon.24  Replacing some of the fat with MCTs may be beneficial. Modifying the ratio of dietary omega 3 to omega 6 fatty acids may modulate intestinal inflammation by reducing production of proinflammatory metabolites.25, 26

Exocrine pancreatic insufficiency

EPI is a malabsorptive syndrome characterised by insufficient secretion of digestive enzymes and bicarbonate from the exocrine pancreas. EPI is most commonly caused by damage to the exocrine pancreas through injury or ongoing pancreatitis. Treatment includes administration of pancreatic enzymes, vitamin supplementation and dietary modification.27

The diet should be low residue and highly digestible, with a moderate amount of fat. Previously, fat restriction was favoured, but this has been shown to have no benefit in survival times and also exacerbates malnutrition and deficiencies in fat-soluble vitamins A, D, E and K.28 Novel protein or hypoallergenic diets have been found to be effective in some patients.27

In summary, fat-sensitive conditions of the dog require a tailored nutritional approach.It is helpful to question the owner about the fat level of the previously fed diet to help guide choice of fat levels in any new diet.

Specific dietary recommendations can help clients in the transition to an appropriate diet. This will help them to avoid selection of an inappropriate food. In general, many canned foods are higher in fat than their dry equivalents and it is important to check individual product fat levels when recommending a specific food. Utilising commercial fat-restricted diets is an effective way to provide dietary fat restriction. Where a home-made recipe is required, it is best to consult a board-certified veterinary nutritionist.

References:

  1. National Research Council. Fats and fatty acids. Nutrient Requirements of Dogs and Cats. Washington, DC: The National Academies Press, 2006, pp 81-110.
  2. The Editors of Encyclopaedia Britannica. “fatty acid”. Encyclopedia Britannica, 28 Jul. 2025, https://www.britannica.com/science/fatty-acid. Accessed 13 August 2025.
  3. Purina Institute. Hot Topic: Medium-Chain-Triglycerides in Pet Food. https://www.purinainstitute.com/sites/default/files/2024-02/HOT-TOPIC-Medium-Chain-Triglycerides-in-PetFood.pdf. [Accessed 10 August 2025].
  4. Bach AC, Babayan VK. Medium-chain triglycerides: an update. American Journal of Clinical Nutrition. 1982;36:950–962.
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  6. Purina Institute. Intestinal Lymphangiectasia in Dogs. https://www.purinainstitute.com/centresquare/therapeutic-nutrition/canine-intestinal-lymphangiectasia. [Accessed 12 August 2025].
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  8. Dossin, O., & Lavoué, R. (2011). Protein-losing enteropathies in dogs. Veterinary Clinics of North America: Small Animal Practice, 41(2), 399─418. doi: 10.1016/j.cvsm.2011.02.002 
  9. Purina Institute. Protein-Losing Enteropathy in Dogs. https://www.purinainstitute.com/centresquare/therapeutic-nutrition/protein-losing-enteropathy-in-dogs. [Accessed 5 August 2025].
  10. Louvet A, Denis B. Ultrasonographic diagnosis: Smallbowel lymphangiectasia in a dog. Vet Radiol Ultrasound 2004;45:565–567
  11. Melzer KJ, Sellon RK. Canine Intestinal Lymphangiectasia. Compendium Continuing Education for Veterinarians. 2002 Dec; 24(12):953-961.
  12.  Okanishi, H., Yoshioka, R., Kagawa, Y. and Watari, T. (2014), The Clinical Efficacy of Dietary Fat Restriction in Treatment of Dogs with Intestinal Lymphangiectasia. J Vet Intern Med, 28: 809-817. https://doi.org/10.1111/jvim.12327
  13.  Elliott, K. F., Rand, J. S., Fleeman, L. M., Morton, J. M., Litster, A. L., Biourge, V. C., & Markwell, P. J. (2012). A diet lower in digestible carbohydrate results in lower postprandial glucose concentrations compared with a traditional canine diabetes diet and an adult maintenance diet in healthy dogs. Research in Veterinary Science, 93(1), 288─295. doi: 10.1016/j.rvsc.2011.07.032
  14. Purina Institute. Hyperlipidaemia in dogs. https://www.purinainstitute.com/centresquare/therapeutic-nutrition/hyperlipidemia-in-dogs [Accessed 21 August 2025].
  15. de Albuquerque, P., De Marco, V., Vendramini, T. H. A., Amaral, A. R., Catanozi, S., Santana, K. G., Nunes, V. S., Nakandakare, E. R., & Brunetto, M. A. (2021). Supplementation of omega-3 and dietary factors can influence the cholesterolemia and triglyceridemia in hyperlipidemic Schnauzer dogs: A preliminary report. PLoS ONE, 16(10), e0258058. doi: 10.1371/journal.pone.0258058
  16. Hoenig, M., Laflamme, D., Klaser, D. A., Singer, M. J., & Ferguson, D. C. (2001). Glucose tolerance and lipid profiles in dogs fed different fiber diets. Veterinary Therapeutics, 2(2), 160─169.
  17. Watson, P. (2012). Chronic pancreatitis in dogs. Topics in Companion Animal Medicine, 27(3), 133─139. doi: 10.1053/j.tcam.2012.04.006
  18. Xenoulis, P. G., Suchodolski, J. S., & Steiner, J. M. (2008). Chronic pancreatitis in dogs and cats. Compendium: Continuing Education for Veterinarians, 30(3), 166─181
  19. Nguyen, P., Dumon, H., Biourge, V., & Pouteau, E. (1998). Glycemic and insulinemic responses after ingestion of commercial foods in healthy dogs: Influence of food composition. Journal of Nutrition, 128(12 Suppl), 2654S─2658S. doi: 10.1093/jn/128.12.2654S
  20. Behrend, E., Holford, A., Lathan, P., Rucinsky, R., Schulman, R. (2018). 2018 AAHA diabetes management guidelines for dogs and cats. Journal of the American Animal Hospital Association, 54(1), 1─21. doi: 10.5326/JAAHA-MS-6822
  21. Simpson, K. W., & Jergens, A. E. (2011). Pitfalls and progress in the diagnosis and management of canine inflammatory bowel disease. Veterinary Clinics of North America: Small Animal Practice, 41(2), 381–398.
  22.  Penell, J. C., Morgan, D. M., Watson, P., Carmichael, S., & Adams, V. J. (2019). Body weight at 10 years of age and change in body composition between 8 and 10 years of age were related to survival in a longitudinal study of 39 Labrador retriever dogs. Acta Veterinaria Scandinavica, 61(1), 42.
  23. Aarti Kathrani. Dietary and Nutritional Approaches to the Management of Chronic Enteropathy in Dogs and Cats, Veterinary Clinics of North America: Small Animal Practice, Volume 51, Issue 1, 2021, Pages 123-136.
  24. B.S. Ramakrishna, M. Mathan, V.I. Mathan. Alteration of colonic absorption by long-chain unsaturated fatty acids. Influence of hydroxylation and degree of unsaturation. Scand J Gastroenterol, 29 (1994), pp. 54-58.
  25. Cave, N. (2012). Nutritional management of gastrointestinal diseases. In A. J. Fascetti & S. J. Delaney (Eds.), Applied veterinary clinical nutrition (pp. 175─220). John Wiley & Sons.
  26. Ontsouka, C. E., Burgener, I. A., Luckschander-Zeller, N., Blum, J. W., & Albrecht, C. (2012). Fish-meal diet enriched with omega-3 PUFA and treatment of canine chronic enteropathies. European Journal of Lipid Science and Technology, 114(4), 412─422. doi: 10.1002/ejlt.201100343
  27. Cridge H, Williams DA, Barko PC. Exocrine pancreatic insufficiency in dogs and cats. J Am Vet Med Assoc. 2023 Nov 9;262(2):246-255. doi: 10.2460/javma.23.09.0505. PMID: 37944252.
  28. Batchelor DJ, Noble PJ, Taylor RH, Cripps PJ, German AJ. Prognostic factors in canine exocrine pancreatic insufficiency: prolonged survival is likely if clinical remission is achieved. J Vet Intern Med. 2007;21(1):54-60. doi:10.1892/0891-6640(2007)21[54:pficep]2.0.co;2

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