This column is the second and final part to our discussion of hepatic lipidosis. In the previous column (June) the disease itself was described and characterized based on field case surveys and research models. Diagnostic tools for recognizing potential risk (rapid fat mobilization measured as non-esterified fatty acids [NEFA]) and disease presence (elevated liver enzymes) were described. It was emphasized that although elevated liver enzymes were indicative of liver dysfunction, hepatic lipidosis is not the only disease condition that could induce these changes in liver function parameters. Liver biopsy, to visualize or measure the amount of fat, is needed for definitive diagnosis. In this column approach to therapy for an animal diagnosed with of hepatic lipidosis will be addressed. As with all diseases, emphasis will be placed on discussing feeding management practices useful in minimizing risk for hepatic lipidosis in your animals.
In the previously described feed restriction trial to induce hepatic lipidosis,¹ animals were returned to normal feeding amounts when initial signs of hepatic lipidosis were observed and fatty infiltration of liver biopsy specimens were documented, which was between 13 and 21 days from the start of feed restriction. When affected llamas were returned to normal feed, body weight increased, blood values gradually changed toward normal, and fat disappeared from the liver (based further biopsy samples). Time frame observed for improvement in liver fat content was between 5 and 12 days from the time of refeeding. This was a significant finding in that it showed that the condition is reversible when normal levels of nutrients and calories are consumed. It must be remembered that the severity of fatty infiltration observed in this study was much less than clinical cases, suggesting a potentially longer period of time required for recovery.
With deficient energy intake being a hallmark factor in initiating hepatic lipidosis, therapy must be focused on increasing energy intake. This is accomplished by stimulating feed intake. Offering a variety of browse material and fresh grass clippings has been beneficial to stimulating intake. Blackberry leaves are particularly appealing to camelids. Injections of B-vitamins as well as some pain relief medications can also stimulate intake.
If more aggressive oral supplementation is required, liquid consistency gruel can be mixed and administered via tube if feasible. Soaking alfalfa pellets in hot water and mixing in calf electrolytes, calcium propionate, propylene glycol and other ingredients can provide a nice workable mixture to provide energy sources and fermentable material. Camelids are obligate nasal breathers, so indwelling tubes through the nasal passages to the stomach are not practical. If oral tubing results in extreme stress to the animal, this may not be a viable pathway for support. Transfaunation (administering rumen contents from another animal) can be used to repopulate the microbial fauna and restimulate fermentation. Collected rumen fluid from cattle, sheep or goats can be used in llamas or alpacas.
In more severe cases, intensive supportive care and dietary management, including parenteral (i.e., intravenous) nutrition, must be used.² Work with your veterinarian to transfaunate the fermentation vat and administer therapeutic nutritional support (glucose and amino acid solutions). Given the concern on insulin resistance, administration of an appropriate dose of insulin in conjunction with glucose therapy is warranted. You should never administer insulin without concurrent glucose therapy; otherwise you may induce low blood glucose. Be aware that prognosis is always guarded in these more severe cases, even with aggressive nutritional support. All sick camelids should be considered at risk for developing hepatic lipidosis, especially those with anorexia or metabolic demands of pregnancy and lactation. Close monitoring of intake in sick animals is absolutely critical to prevent deaths.
Disease Prevention - Nutritional Management
The key to treating and preventing this disease is early recognition and aggressive nutritional support. Prevention is based on ensuring adequate energy and protein intake, especially in pregnant and lactating females through the feeding of good quality forage and appropriate supplementation. New feeding recommendations for llamas and alpacas have just been published by the National Research Council (NRC).³ Forage testing is the only true way to know the quality of forage being fed. Most cases of hepatic lipidosis are associated with the feeding of mature grass forages (< 9% crude protein; >60% neutral detergent fiber [NDF]). Given their innate selective feeding behaviors, adding some alfalfa or clover forage to grass forage can facilitate the ability of llamas and alpacas to consume a high quality diet. Grain supplements with some protein will be required to support lactation, though the amount and composition required will vary by production level and forage quality.
Lactating dams have the highest nutrient requirements and should be fed the best-quality forages and potentially supplemented with a grain product containing energy and protein sources. Based NRC recommendations,3 dietary composition for lactating animals should contain: 60 to 75% total digestible nutrients (TDN), 12-14% crude protein, 0.45-0.62% calcium, and 0.32-0.45% phosphorus. Pregnant females during the last 3 months of pregnancy require moderate to high quality forages with supplement for additional mineral and vitamin needs. Dietary composition for late pregnant animals should contain: 55 to 70% TDN, 10-12% crude protein, 0.45-0.56% calcium, and 0.28-0.33% phosphorus. From these recommendations, mature grass hay has no place in these diets as it will reduce intake and dietary energy and protein content without excessive grain supplementation.
Disease Prevention - Monitoring
Body weight determination
Many llama enterprises have scales in which body weight can be measured. Given the strong association between significant weight loss and hepatic lipidosis, one can use routine (monthly or bimonthly) body weight determinations to assess potential risk. Body weight loss exceeding 15% over a short (1-2 weeks) period of time is a high risk factor for this disease. One needs historical information to interpret current body weight and change over time. Pregnant animals should gain approximately 10 to 15% of their body weight over the last three months of pregnancy to account for fetal growth. Lactating animals will be expected to lose body weight in support of lactation. This weight loss will vary by individuals and amount of milk produced. Typical weight loss should be less than 10% of body weight following birthing. Excessive weight loss in early lactation is an indicator of inadequate dietary amounts or quality and can predispose to hepatic lipidosis problems.
Body condition scoring
By far, the single best and simplest method of evaluating your nutritional program is body condition scoring. Body condition scoring is a method that subjectively grades animals by amount of subcutaneous fat stores into defined "fatness" categories. A 5-point system covering physical states of emaciated (1), thin (2), average (3), fat (4), and obese (5) has been developed (Figure 1).4 As with sheep, to properly body condition score a llama or alpaca one needs to palpate through the fiber coat to feel over boney structures for thickness of tissue and fat cover. Key areas to assess are the loin area just behind the ribs and in front of the pelvis. Within this area you want to evaluate fat presence between the boney projections from the vertebrae extending upward (dorsal spinous process) and laterally (transverse process or "short ribs") from the spinal column (see pictures in figure). In this same area you want to determine how much of a shelf is formed by the transverse processes. This area behind the ribs and below the spine is termed the paralumbar fossa. In thin animals the body wall in this area will be sucked in with the short ribs forming an obvious shelf. In fatter animals, the body wall will project out and the short ribs will be hard to identify. Additionally, one should visualize the degree of fatness in the brisket (chest) and inguinal areas.
Figure 1. Body condition scoring chart for llamas and alpacas (from Van Saun, R. Feeding the Alpaca. In: The Complete Alpaca, 2nd ed., Hoffman, E. (ed.), Boony-Doon Press: Santa Cruz, CA, 2006). Refer to text for description of evaluation sites.
The ideal body condition is 3.0, having a moderate amount of body fat. Although some individuals will maintain lower or higher body condition score and remain healthy, this is just inherent individual differences in metabolism. Body condition scores 2.0 and below or 4.0 and above are considered abnormal and represent extremely thin or fat animals, respectively. Most animals other than those in late pregnancy or lactation should maintain a body condition score between 2.5 and 3.25. Late pregnant animals should have slightly higher body condition (3.25-3.5) to have reserves to support impending lactation. Lactating animals will lose body condition rapidly as they produce milk. Lactating animals should not lose more than 0.5-0.75 condition scores. A loss in body condition implies the consumed intake of feed is deficient in energy, protein, or both. Important times to assess body condition score would be during early to mid pregnancy, early to mid lactation, and periodically (4-6 times per year) to other animals of the herd to assess energy status.
Besides evaluating an animal's physical attributes relative to health and disease, analysis of blood is often used to determine presence of disease. Nutrition can influence many physiologic and metabolic body functions, thus a number of blood parameters can be used within a defined framework for evaluating nutritional status. These are two different objectives in using blood analysis and require different animals to be selected. Blood metabolite analysis in unhealthy animals is best used to help in disease diagnosis. To best assess nutritional status using blood metabolites, one should sample only healthy animals so as not to have confounding effects of disease on blood parameters. Based on what has been described for hepatic lipidosis, blood measures of NEFA and protein (urea nitrogen, albumin, total protein) could be used to assess potential risk in healthy looking animals. Liver function enzymes and beta-hydroxybutyrate are best suited to disease diagnosis.
The importance of forage quality to a nutrition program cannot be overemphasized. Forage quality is best tested by chemical measures for moisture, crude protein, and neutral and acid detergent fiber by a certified laboratory. Feed laboratories in your area can be found through the National Forage Testing Association (www.foragetesting.org). It is important to obtain a representative sample of the entire amount of forage to be fed using a forage sampling device. Visual assessment is based on identifying properties of maturity (i.e., stem thickness, flowers, seed heads), leaf-to-stem ratio, and foreign object presence. In addition to the chemical measures for quality, one should have macro- and micromineral content determined. This would allow one to best determine the need for additional supplements and evaluate which supplements best match their forage.
Feed testing results will be in the form of a report listing nutrient content for the given sample. Generally laboratories will report nutrient content on an as fed (wet weight) basis and a dry matter (water excluded) basis. Dry matter nutrient content will always be the larger number as it represents the amount of nutrient in the sample without the water weight. In comparing nutrient content across feeds, one should use only dry matter values as feeds vary tremendously in their moisture content. Additional information about forage testing can be obtained from agronomy specialists with agricultural universities or extension personnel.
- Tornquist, SJ, Cebra, CK, Van Saun, RJ, Smith, BB. Metabolic changes and induction of hepatic lipidosis during feed restriction in llamas. Am J Vet Res 2001;62(7):1081-1087.
- Van Saun, RJ. Callihan, B, Tornquist, SJ. Nutritional support for treatment of hepatic lipidosis in a llama. J Am Vet Med Assoc 2000;217(10):1531- 1535.
- National Research Council. Nutrient Requirements of Small Ruminants, National Academy Press: Washington, DC, 2007.
- Van Saun, RJ. Feeding the Alpaca. pp. 179-229, In: The Complete Alpaca, 2nd ed., Hoffman, E. (ed.), Boony-Doon Press: Santa Cruz, CA, 2006.