Medicine and Surgery of Camelids
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Medicine and Surgery of Camelids Third Edition COPYRIGHTED MATERIAL 1 General Biology and Evolution The domesticated camelids of the world have had a The classifi cation of SACs has been controversial. signifi cant impact on Old and New World cultures. One system classifi es the guanaco, llama, and alpaca Populations of camels and South American camelids within the genus Lama and vicu ñ a as a single species (SACs), also called New World camelids, declined in in the genus Vicugna. Another system classifi es all the latter part of the nineteenth and early twentieth SACs within the genus Lama. Others classify the llama centuries. Governments neglected them as being an and alpaca as subspecies of L. guanicoe guanicoe . Recent unimportant component of the life of indigenous DNA studies have determined that llamas and guana- people and tried to replace them with other domestic cos are appropriately species of Lama , and that the animals. Only in the last few decades have these alpaca and vicu ñ a belong in the genus Vicugna . 12 animals been recognized as a valuable resource and The family Camelidae was previously designated as efforts made to research their unique physiology and an infraorder, Tylopoda, under the suborder Ruminan- adaptation to hostile environments. 1,4 tia, 18,23,26 but the most authoritative and current classifi - cation gives Tylopoda suborder status. 8,10,17,22,25,28,29,30 TAXONOMY Some modern taxonomists have deleted the suborder Linnaeus placed the llama, alpaca, and Old World designation and use only family names. This book will camels in a single genus, Camelus, in 1758. Other tax- follow the classifi cation for camelids as listed in Table onomists proposed separate genus status for SACs in 1.1 . the early nineteenth century, but none of this work Collectively, llamas, alpacas, guanacos, and vicu ñ as was accepted by the International Commission on are called South American camelids or New World Zoological Nomenclature. The genus name Auchenia camelids (NWC), although the term “ auquenidae ” is was proposed by Illiger for SACs in 1811 and is fre- often found in older South American literature. Both quently seen in print even today in the South Ameri- camels and SACs are included in the term “ camelid. ” can literature. However, Auchenia had been applied Alpacas and llamas exist only as domestic species. earlier to a genus of insects and thus was not a valid Guanacos and vicu ñ as are wild species. It is generally name for any other animal. In 1827, Lesson published accepted that the alpaca shares some characteristics an acceptable paper classifying the New World Cam- with the vicu ñ a, e.g., incisor teeth with an open pulp elidae in the genus Lama. In 1924, Miller assigned the cavity and continuous eruption into adulthood. vicu ñ a to a separate genus, Vicugna. 13,14,17 The systematic classifi cation of Old World camels GENERAL BIOLOGY has never been controversial. The one - humped camel The karyotype of all camelids is 2n = 74. All SACs (dromedary) is named Camelus dromedarius (Figure 1.1 ) have produced fertile hybrids. Dromedary and Bac- and the two - humped camel (Bactrian) C. bactrianus trian camels also produce fertile crosses. 9 In Israel a (Figure 1.2 ). Recently there has been acceptance of a cross between an alpaca male and a dromedary female third species of camel, the wild Bactrian camel of Mon- by artifi cial insemination produced a stillborn full - golia, Camelus bactrianus ferus 12,14,21 (Figure 1.3 ). term fetus. In the United Arab Emirates scientists have succeeded in producing four living OWC and NWC Medicine and Surgery of Camelids, Third Edition by Murray E. Fowler offspring (two males, two females). It has yet to be © 2010 Blackwell Publishing, Ltd. determined if the hybrids are fertile. See Chapter 22 3 4 Chapter 1 Table 1.1. Classifi cation of camelids and other artiodactylids. Class — Mammalia Order — Artiodactyla Suborder — Suiformes — Hippos, swine, peccaries Suborder — Tylopoda — Camelids Old World genus and species Camelus dromedarius — Dromedary camel C. bactrianus — Bactrian camel C. bactrianus ferris — Wild bactrian camel New World genera and species Lama glama — Llama L. guanicoe — Guanaco Vicugna pacos — Alpaca V. vicugna — Vicuna Figure 1.1. Dromedary camel. V. vicugna mensalis (Peruvian) V. vicugna vicugna (Argentine) Suborder — Ruminatia — Cattle, sheep, goats, water buffalo, giraffes, deer, antelopes, bison for illustrations (Dr. J. Skidmore, personal communica- tion, Dubai, United Arab Emirates, April 2009). Despite size differences, the anatomy of all species of camelids is similar. SACs have similar behavioral patterns (Chapter 3 ). 26 The camels completed Pleisto- cene evolution in a semidesert environment in south- ern Asia, the Middle East, and North Africa and developed sophisticated adaptations for dealing with heat and dehydration (Chapter 9 ). The SACs became adapted to South American habitats, especially the high altitude lands of the Andes. Figure 1.2. Bactrian camel. Camelids have a complex, three - compartmented stomach. Gastric digestion is similar to, but not analo- gous with, ruminant digestion. The two suborders separated from each other 65 million years ago when primordial species were simple stomached. Both groups used fi brous forage and developed similar foregut fermentation systems by parallel evolution (Chapter 13 ). Camelids regurgitate and rechew ingested forage, as do ruminants, but are more effi - cient than ruminants in extracting protein and energy from poor quality forages (Chapter 2 ). It is important to understand that camelids are not ruminants, pseudo - ruminants, or modifi ed ruminants. See Table 1.2 for other differences between camelids and ruminants.5 SACs establish communal dung piles, and in large herds there may be multiple dung piles, as animals in a herd segregate themselves into smaller units. Llamas and alpacas that have been imported into the United States following extended quarantine are more likely to urinate and defecate at random. Camels defecate at Figure 1.3. Wild Bactrian camel from the Gobi Desert in random. Feces are pelleted in both groups and used Mongolia. Used by permission from George B. Schaller, for fuel by people who share their habitat. Camelids Wildlife Conservation Society. have a unique reproductive cycle (Chapter 17 ). General Biology and Evolution 5 Table 1.2. Differences between South American camelids and ruminants. South American camelids Ruminants Evolution Evolutionary pathways diverged 40 million years ago Evolutionary pathways diverged 40 million years ago Blood Red blood cells elliptical and small (6.5 μ ); predominant RBCs round and larger (10 μ ); predominant WBC is white blood cell is neutrophil; leukocytes up to 22,000 lymphocyte; leukocytes up to 12,000 Foot Foot has toenails and soft pad. Second and third Foot has hooves and sole. Second and third phalanges are phalanges are horizontal. nearly vertical Digestive system Foregut fermenter, with regurgitation, rechewing and Same (parallel evolution) reswallowing Stomach — 3 compartments, resistant to bloat Stomach — 4 compartments, susceptible to bloat Dental formula — I 1/3, C 1/1, PM 1 – 2/1 – 2, Dental formula — I 0/3, C 0/1, PM 3/3, M 3/3 × 2 = 32 M 3/3 × 2 = 28 – 32 a Reproduction Induced ovulator Spontaneous ovulation No estrous cycle Estrous cycle Follicular wave cycle No follicular wave cycle Copulation in the prone position Copulation in standing position Placenta diffuse Placenta cotyledonary Epidermal membrane surrounding fetus No epidermal membrane on fetus Cartilaginous projection on tip of penis No cartilaginous projection on tip of penis Ejaculation prolonged Ejaculation short and intense Respiratory system Soft palate elongated; primarily a nasal breather Soft palate short; nasal or oral breather Urinary system Kidney smooth and elliptical Kidney smooth or lobed Suburethral diverticulum in female at external urethral No suburethral diverticulum orifi ce Dorsal urethral recess in male at junction of pelvic and Dorsal urethral recess in some species penile urethra Parasites Unique lice and coccidia; share some gastrointestinal Unique lice and coccidia; share GI nematodes nematodes with cattle, sheep, and goats Infectious diseases Minimally susceptible to tuberculosis; no known natural Highly susceptible to tuberculosis, bovine brucellosis, and bovine brucellosis; mild susceptibility to foot - and - foot - and - mouth disease mouth disease; rare clinical disease with other bovine and ovine viral diseases a I = incisors, C = canines, PM = premolars, M = molars. the Incas used them as pack animals. 11 All guanaco SOUTH AMERICAN CAMELIDS subspecies share uniform coloration, with a dark The guanaco (Figure 1.4 ) has the broadest distribu- brown upper body, neck, and limbs; whitish fi ber on tion, both historically and currently, of the four SACs. the underside of the neck and belly; and a grayish to Four geographic subspecies of guanaco have been black face. described, 6 ranging from sea level in Tierra del Fuego Vicu ñ a distribution is limited to the puna (Quechua at the southernmost tip of South America to 4,600 m for highland) life zone of the Andes (elevation 4,200 to in the Andes. The northernmost populations exist at 4,800 m). 4,6,26 The vicu ñ a (Figures 1.5 , 1.6 ) is the small- latitude 8 ° south in Peru. 3,11 Guanacos live in both est of the SACs and has the fi nest fi ber coat. It has a migratory and sedentary groups. 4 Captive - born gua- cinnamon - colored coat, white underparts, a pale cin- nacos may be tamed and handled similarly to llamas; namon face, and a bib of white hair on the chest. There 6 Chapter 1 Figure 1.6. Argentine vicu ñ a (short bib hair). Figure 1.4. Guanaco. Figure 1.7. Heavily fi bered huacaya alpaca. Figure 1.5. Peruvian vicu ñ a (long bib hair). ance of Corriedale sheep wool. 6,16,19 The coat of suri alpacas consists of long fi bers with no crimp that hang are two geographic subspecies of vicu ñ a: the Peruvian, down alongside the body in ringlets.