Lipids are water-insoluble molecules that have many crucial functions in dogs. There are a variety of different lipids, but the only lipids that are routinely quantified in dogs are triglycerides and cholesterol. Hyperlipidemia refers to a state of abnormally increased blood concentrations of triglycerides, cholesterol or both. One indication for low-fat dietary intake in dogs with gastrointestinal disease is the management of dogs with hypertriglyceridemia with GI disease presumed to be due to or related to hypertriglyceridemia. The second indication is a group of dogs that have a normal serum triglyceride concentration, but have GI disorders resulting in difficulty to digest and/or absorb normal amounts of fat in pet food or dogs with lymphatic abnormalities. Hypertriglyceridemia is very common in dogs.1 In one recent study, 611 routine chemistry profiles in dogs performed at a private veterinary laboratory in Italy were evaluated and 33 dogs (5.4 percent) showed hypertriglyceridemia.1 Certain breeds have been identified as being much more commonly affected by hypertriglyceridemia. In a recent study of 192 healthy miniature schnauzers, 63 (32.8 percent) had hypertriglyceridemia.2 Definitive differentiation between primary or secondary hypertriglyceridemia is sometimes difficult, but is based on exclusion of known or suspected risk factors of secondary hypertriglyceridemia, such as diabetes mellitus, obesity or pancreatitis.3 Also, primary hypertriglyceridemia is often associated with a higher breed-related frequency, as described in miniature schnauzers in the U.S.2 The clinical relevance of hypertriglyceridemia in dogs is due to its complications. By far the most important consequence of hypertriglyceridemia in dogs is pancreatitis. In a recent study, the risk of pancreatitis was shown to be about five-fold higher in miniature schnauzers with severe hypertriglyceridemia (above 10.17 mmol/l or 900 mg/dl) than in control dogs.4 There is still some debate as to whether hypertriglyceridemia causes pancreatitis, pancreatitis causes hypertriglyceridemia, or both are caused by the same pathogenetic mechanism without one of them causing the other. However, in a recent study, miniature schnauzers with a previous history of pancreatitis had significantly higher serum triglyceride concentrations than miniature schnauzers without such history.5 Pancreatitis is of great clinical significance because an acute episode can be associated with systemic complications and death, and chronic disease leads to destruction of exocrine and endocrine pancreatic tissue that can lead to exocrine pancreatic insufficiency and/or diabetes mellitus.6 Generally, treatment of hypertriglyceridemia is recommended when serum triglyceride concentrations are above 5.65 mmol/l (500 mg/dl), though there is little scientific evidence for this cut-off value.3 The primary therapeutic approach for treatment of hypertriglyceridemia in dogs is feeding a low fat food (generally less than 20 g of fat/1000 kcal).3 In a recent study, miniature schnauzers with hypertriglyceridemia were successfully managed by dietary change to a low-fat food alone.7 This study showed that while many dogs continued to have serum triglyceride concentrations above the upper limit of the reference range, none of them had serum triglyceride concentrations that were above 500 mg/dl after the dietary change.7 Also, interestingly, the lipoprotein profile of the dogs changed, more closely resembling the lipoprotein profile of healthy dogs. A more recent study showed similar results in dogs with mild to moderate hypertriglyceridemia.8 Serum triglyceride concentrations should be rechecked after withholding food for at least 12 hours approximately three to four weeks after changing the pet food. The digestion of dietary fat is more complex than the digestion of proteins or carbohydrates and it can easily be compromised. Therefore, dogs with a wide variety of GI problems can show maldigestion and/or malabsorption of fat. Decreasing the fat content in the pet food may improve clinical signs in these patients. Essentially, any severe gastroenteritis, including inflammatory bowel disease, with or without protein-losing enteropathy, can lead to fat malabsorption. Even though patients do not have hypertriglyceridemia, they cannot appropriately deal with the normal amount of fat in the pet food and require the feeding of a low-fat food and the avoidance of fat-containing treats. Many pet foods on the market have a moderately decreased fat content, but only a few have a severely decreased fat content. Also, because these conditions can be complex, these patients may also benefit from prebiotics, probiotics, antibiotics, or anti-inflammatory or immunosuppressive agents. In summary, low fat pet foods can play a crucial role in the management of dogs with hypertriglyceridemia and secondary GI disease or in dogs without hypertriglyceridemia but having primary GI disease. Dr. Steiner, Ph.D., Dipl. ACVIM, Dipl. ECVIM-CA, is an associate professor in the Department of Small Animal Medicine and Surgery at Texas A&M University and director of the GI Laboratory at the university. He is involved in a wide variety of research in small animal gastroenterology. This Education Series article was underwritten by Hill’s Pet Nutrition of Topeka, Kan. REFERENCES 1. Comazzi S, Pieralisi C, Bertazzolo W. Haematological and biochemical abnormalities in canine blood: frequency and associations in 1022 samples. J Sm Anim Pract 2004;45:343-349. 2. Xenoulis PG, Suchodolski JS, Levinski MD, et al. Investigation of hypertriglyceridemia in healthy miniature schnauzers. J Vet Intern Med 2007;21:1224-1230. 3. Xenoulis PG, Steiner JM. Lipid metabolism and hyperlipidemia in dogs. Vet J 2010;183:12-21. 4. Xenoulis PG, Suchodolski JS, Ruaux CG, et al. Association between serum triglyceride and canine pancreatic lipase immunoreactivity (cPLI) concentrations in Miniature Schnauzers. J Vet Int Med 2006;20:750-751. 5. Xenoulis PG, Levinski MD, Suchodolski JS, et al. Serum triglyceride concentrations in Miniature Schnauzers with and without a history of probable pancreatitis. J Vet Intern Med 2011;25:20-25. 6. Steiner JM. Exocrine pancreas. In: Steiner JM. ed. Small Animal Gastroenterology. Hannover: Schlütersche-Verlagsgesellschaft mbH,2008;283-306. 7. Xenoulis PG, Suchodoiski JS, Steinep JM. Effect of a low-fat diet on serum triglyceride, cholesterol, and Spec cPL concentrations in Miniature Schnauzers with hypertriglyceridemia. J Vet Int Med 2011;25:20-25. 8. Unpublished data. Hill’s Pet Nutrition.
