illustre de multiples cas d'augmentation de l'entreposage hepatique 'a partir de regimes alimentaires et de supplements mineraux courants. Can Vet J 1999; 40: ...
Subclinical
copper
accumulation in llamas
Dusty M. Weaver, Jeff W. Tyler, Richard S. Marion, Stan W. Casteel, Christina M. Loiacono, James R. Turk Abstract A 9-year-old, intact male llama with mild ataxia and generalized malaise of 1 month's duration was euthanized following clinical evaluation. Excessive liver copper concentrations were found in the llama and also in clinically normal herdmates. This case documents multiple animals with increased hepatic stores from standard diets and mineral supplements.
Resume
Accumulations subcliniques de cuivre chez des lamas. Un lama male entier de 9 ans 1 mois a ete euthanasie 'a la suite d'une evaluation clinique. Des concentrations excessives de cuivre au niveau de foie ont ete trouvees chez ce lama ainsi que chez les autres membres cliniquement normaux de troupeau. Cette observation illustre de multiples cas d'augmentation de l'entreposage hepatique 'a partir de regimes alimentaires et de supplements mineraux courants.
presentant une ataxie legere et un malaise generalise depuis
(Traduit par docteur Andre Blouin) Can Vet J 1999; 40: 422-424
A9-year-old,
intact male llama was presented for the evaluation of mild ataxia and general malaise of 1 month's duration. The llama was pastured alone. Diet consisted of a commercial llama feed, ad libitum pasture, and a 50/50 mixture of 2 mineral supplements given free choice. Vaccinations against Clostridium perfringens types C and D and C. tetani were current. All llamas on the farm were dewormed monthly with ivermectin as a prophylactic measure for parelaphostrongylosis. For 1 wk prior to admission, the llama had a decreased feed and water intake. On physical examination, the llama was depressed, sternally recumbent, and unable to stand. Other abnormalities observed included depressed biceps brachii, triceps brachii, patellar, and tibialis cranialis reflexes. Deep pain perception was present, but withdrawal response was slow. The llama was 10% dehydrated, based on decreased skin turgor and dry mucous membranes. A 7 cm x 18 cm decubital ulcer with a 3.5-cm cavitation was present over the sternum. Abnormalities present on initial blood analysis included hypoalbuminemia (27 g/L; reference range 29-50 g/L) (1), and an increased serum gamma glutamyl transferase (GGT) (51 U/L; reference range 3-28 U/L) (1) activity. A large bony callus underlying the decubital ulcer was evident on radiographs of the sternum. Maintenance fluids (0.9% sodium chloride at 3 mL/kg body weight (BW)/h, IV), sodium ampicillin (11 mg/kg BW, q8h, IV), and ceftiofur sodium (4.4 mg/kg BW, ql2h, IV) were administered. Modest improvement was noted in the llama's demeanor and appetite. Over the next 7 d, the llama remained recumbent. When lifted, the llama resisted bearing weight on any limb. On day 10, the llama stood unassisted for short periods of time. When Department of Veterinary Medicine and Surgery (Weaver, Tyler, Marion); Department of Veterinary Pathobiology (Casteel, Loiacono, Turk), College of Veterinary Medicine, University of Missouri, Columbia, Missouri 65211 USA. Address correspondence and reprint requests to Dr. D.M. Weaver. 422
standing, the pastern joints were hyperextended. Despite mild improvement, the owner elected to have the llama euthanized. With the exception of the decubital ulcer, no gross lesions were observed at necropsy. Histologic examination of the liver by using a hematoxylin and eosin stain demonstrated a diffuse mild increase in hepatocyte cytoplasmic granularity. Rubeanic acid staining showed copper-containing granules in the cytoplasm of hepatocytes in the periportal regions. There was mild diffuse congestion of the central veins and surrounding sinusoids. Rubeanic acid staining for copper-positive granules was negative in the kidney (2,3). Skeletal muscle obtained from the hind limbs contained patchy areas of interstitial hemorrhage and mild to moderate myofiber degeneration with loss of striation and cellular outline. No microscopic lesions were present in the brain, spinal cord, lung, heart, intestine, kidney, spleen, or sciatic nerve. The skeletal muscle changes were thought to be a result of prolonged recumbency. No definitive cause for the llama's illness was identified. The histopathologic changes in the liver were suggestive of excessive copper accumulation. Toxicologic analysis supported this conclusion. Copper concentration in the liver was 327 ppm wet weight (reference range 25 to 100 ppm, > 250 ppm toxic) (4). A tentative diagnosis of copper toxicosis was made based on the elevated liver copper concentrations, which was supported by the histopathologic changes in the liver. Liver and serum samples were obtained from 5 randomly chosen animals on the farm to assess herd (n = 20 mature animals) copper status. (Table 1) Samples of the feed and 2 mineral supplements were submitted for analysis. Liver samples were obtained from each llama by 4 sequential percutaneous biopsies by using a 14 gauge true cut biopsy needle. Each biopsy sample weighed approximately 10 mg. Observed serum copper concentrations were within a narrow range 0.53 ppm to 0.60 ppm (reference range, 0.4-0.9 ppm) (4). Liver copper concentrations ranged from 132 ppm to 442 ppm wet weight. Serum biochemical analysis demonstrated increased Can Vet J Volume 40, June 1999
Table 1. Liver and serum copper concentrations and serum sorbitol dehydrogenase, gamma glutamyl transferase, and aspartate aminotransferase activities in a llama with apparent copper toxicosis and in 5 clinically normal herdmates Normal range
Clinical case Normal herdmates 1 2 3 4 5
Liver Cu2+ (ppm) 30-100 (> 250 toxic)
Serum Cu2+ (ppm) 0.4-0.9
327 132 442 197 208 235
GGT (U/L) 3-28
SDH (U/L) 0-15
148
51 0.53 0.54 0.54 0.60 0.55
54 58 74 71 49
AST (U/L) 128-450
2.1 1.2 0.8 1.9 1.0
151 161 174 165 186
Cu2+ - copper; SDH - serum sorbitol dehydrogenase; GGT - gamma glutamyl transferase; AST - aspartate aminotransferase; ppm - parts per million
GGT activity (49-74 U/L; reference range 3-28 U/L) (1) in all of the llamas. Sorbitol dehydrogenase (SDH) activity (0.8-2.1 U/L; reference range, 0-15 U/L) (1) and aspartate aminotransferase (AST) activity (148-186 U/L; reference range, 128-450 U/L) (1) were normal in all of the animals. Simple linear regression was used to determine whether serum copper, GGT, SDH, and AST activities could be used to determine liver copper status. None of the examined dependent variables were significantly associated with liver copper concentration
(P>0.10). Copper content of the 2 mineral supplements was 46 ppm and 280 ppm with copper to molybdenum ratios of 28:1 and 79:1, respectively (5:1 to 10:1 recommended) (5). The commercial feed had a copper content of 27 ppm and a copper to molybdenum ratio of 3.5: 1. The copper to molybdenum ratio of the commercial feed was slightly lower than the recommended level (5). It was impossible to determine the exact copper intake of these animals in a natural setting, because they had access to both mineral supplements and pasture. Copper is required for the proper function of several enzyme systems. It is also necessary for the incorporation of iron into the heme moiety. While copper toxicosis has been recognized in llamas, it is better documented and understood in other ruminants (6-9). Excess dietary copper is stored in the liver. When the liver's storage capacity has been exceeded, a large amount of free copper is released into the circulatory system. Excessive copper in the serum interacts with membrane sulfhydryl groups, leading to membrane lipid peroxidation and subsequent red blood cell lysis (10). In the dog, copper accumulation without toxicosis has been linked liver injury and an increased incidence of both acute and chronic hepatitis, and cirrhosis (11). In domestic livestock, chronic copper accumulation is often asymptomatic. Decreased weight gains and chronic weight loss have been seen in sheep on elevated dietary copper (12). In calves, decreases in average daily gain and feed efficiency and low packed cell volume have been documented (13). Once the liver's storage capacity has been exceeded, an acute hemolytic crisis occurs (6,12). This is often preceded by a stressful event such as shipping, lactation, or illness. Weakness, anemia, pallor, and jaundice are the most common clinical signs Can Vet J Volume 40, June 1999
observed with hemolysis. Many of these animals die within 1 to 3 d after the onset of clinical signs. In sheep, elevations in liver enzymes may be observed shortly prior to the hemolytic crisis (12). Otherwise, there are often no hematologic abnormalities to implicate impending copper toxicosis. Serum copper levels remain normal until the final stages, when the liver begins to liberate large quantities of copper. Copper toxicosis in the llama appears to follow the pattern seen in other domestic livestock, except for the absence of the acute hemolytic crisis and the subsequent associated clinical signs. In one report, copper intoxication was diagnosed as the cause of death in 4 llamas housed at a zoo (7). All 4 showed acute onset of inappetence and depression. Increased serum AST, GGT, and lactate dehydrogenase activities were present in all animals within 48 h of death. Copper toxicosis was diagnosed, based on elevated copper concentrations in serum (4.3-5.7 ,g/mL) and liver (847-1700 ppm, dry weight) and the presence of acute hepatic necrosis. In another reported outbreak of copper toxicosis, 20 llamas dying of copper toxicosis showed anorexia, staggering, recumbency, and respiratory distress (9). In these animals, liver copper ranged from 260 to 351 ppm wet weight. The only serum copper reported was 2.19 pg/mL. Diagnosis of copper poisoning was made, based on an elevated serum and liver copper concentrations. Hepatic necrosis and an elevated feed copper to molybdenum ratio were also considered as diagnostic criteria. Hemolysis was not observed in either of these outbreaks. In both cases a commercial pelleted feed was found to be the source of excessive copper. Copper to molybdenum ratios in the feed were 16.6:1 and 225:1, respectively. While this llama did not fully satisfy the diagnostic criteria for copper toxicosis, it does demonstrate that chronic accumulation in an otherwise asymptomatic camelid may occur. This is important, because diagnosis of copper toxicosis in the llama does not appear to demonstrate hemolysis, which is the hallmark clinical sign in other livestock species. It is also important to realize that asymptomatic accumulation occurs, because the increases in liver enzymes that have been documented in cases of copper toxicosis appear to be terminal events. Historically, far more attention has been paid to the potential and problems associated with copper 423
deficiency in llamas, as opposed to excess (1,5). For that reason, it may be overlooked as a potential problem in making feeding recommendations or in the investigation of illnesses or deaths. Many commercial feeds available for llamas contain added copper. A copper to molybdenum ratio between 5:1 and 10:1 has been recommended for llama diets (5). In both previously reported cases of copper toxicosis (7,9), the copper to molybdenum ratios of the diets that the animals had access to were in excess of 10: 1. In this case, the mineral supplements far exceeded recommended copper to molybdenum ratios. Liver and serum copper concentrations in the reported cases (7,9) were also similar to those of the animal in this case and several of its clinically normal herdmates. Liver copper and GGT activity were elevated in all of the clinically normal herd mates that were sampled, but serum copper, SDH, and AST activities were not. It may be that elevations in hepatic enzymes and serum copper levels are terminal events and can not be used as accurate indicators of liver copper status. The consistent increase in GGT activity may suggest that this enzyme is a better indicator of copper accumulation. However, this magnitude of increase is not uncommon in clinically normal llamas. The role of GGT requires more critical evaluation. It is important to recognize that chronic copper accumulation does occur in llamas fed diets containing copper concentrations that are considered harmless in other species, such as cattle and horses.
The potential for copper accumulation and subsequent toxicosis should be considered when evaluating South American camelids for chronic ill-thrift and when making nutritional decisions. cvi
References 1. Fowler ME. Medicine and Surgery of South American Camelids. Ames: Iowa State Univ Pr, 1989: 266. 2. Sheehan H. The Theory and Practice of Histotechnology, 2nd ed. St. Louis: CV Mosby, 1980: 229-230. 3. Rolfe DS, Twedt DC. Copper associated hepatopathies in dogs. Vet Clin North Am Small Anim Pract 1995; 25(2): 399-415. 4. Puls R. Mineral Levels in Animal Health, 2nd ed. British Columbia: Sherpa International, 1994: 96. 5. Pugh DG. Copper nutrition in llamas. Llamas-Intl Camelid J 1993; 7(2): 77-79. 6. Bostwick JL. Copper toxicosis in sheep. J Am Vet Med Assoc 1982; 180: 386-387. 7. Junge RE, Thomburg L. Copper poisoning in four llamas. J Am Vet Med Assoc 1989; 195: 987-989. 8. Perrin DJ, Schiefer HB, Blakley BR. Chronic copper toxicity in a dairy herd. Can Vet J 1990; 31: 629-632. 9. Mullaney TP, Slanker MR, Fitzgerald SD, Elliott MW, Braselton WE, Main KE. Copper toxicosis in llamas [abstract]. Proc Am Assoc Vet Lab Diag 1996: 36. 10. Hochstein P, Kumar KS, Forman SJ. Mechanisms of copper toxicity in red cells. Prog Clin Biol Res 1978; 21: 669-681 11. Ettinger SJ, Feldman EC. Textbook of Veterinary Internal Medicine. Philadelphia: WB Saunders, 1995: 1332. 12. Radostits OM, Blood DC, Gay CC. Veterinary Medicine, 8th ed. Philadelphia: Balliere Tindall, 1994: 1495-1499. 13. Jenkins KJ, Hidiroglou M. Tolerance of the calf for excess copper in milk replacer. J Dairy Sci 1989; 72: 150-156.
COMPTE RENDU DE LIVRE
BOOK REVIEW
941--v Hendrix CM. Diagnostic Veterinary Parasitology. Mosby, St. Louis, Missouri, 1998, 323 pp. ISBN 0-8151-8544-8, $49.95 US. This book highlights diagnosis in veterinary parasitology and is dedicated to the technician and veterinary student, as well as the practitioner. Much useful information is provided, mostly that which cannot be found rapidly anywhere else. There are 17 chapters. The first chapter presents a brief discussion on some terms used in parasitology. Each succeeding chapter deals with a different group of parasites: protozoans, trematodes, cestodes, nematodes, acanthocephalans, arthropods, leeches, and pentastomes. Each group is described in detail, with special emphasis being placed on morphology, uniqueness of life cycle, and the important parasites within the group. In the 16th chapter, the author presents the routine diagnostic parasitologic procedures encountered in any veterinary practice. The last chapter presents 14 zoonoses that are amongst the most important known today and were probably selected because of their high prevalence and their danger for human health. 424
Searching for precise information can, however, be time consuming. The presentation varies from a nomenclature to a host-species order, according to the number of parasites found in a group, which results in a confusing, nonconstant presentation. The studied hosts are the domestic animals (ruminants, horses, swine), common pets (dogs, cats), rodents (rabbits, mice, rats, hamsters, gerbils, Guinea pigs), aviary birds, and other domestic fowls, fishes, and reptiles. The information is presented in a less schematic way than one would expect from this type of books. As suggested in the author's prelude, the book is intended to be used mainly as a course reference in contrast to the standard laboratory guides. Many black and white photos complete the given information. In conclusion, I believe that this book is a valuable complement to the laboratory guides that are normally used in every serious diagnostic laboratory. Reviewed by Alain Villeneuve, DMV, PhD, Faculte' de medecine ve'te'rinaire, Universite de Montreal, 3200 Sicotte, P.O. Box 5000, St-Hyacinthe, Quebec J2S 7C6. Can Vet J Volume 40, June 1999
