Appendix 40 FMD and camelids: International relevance of current research U. Wernery Central Veterinary Research Laboratory, P.O. Box 597, Dubai, U.A.E. Key words: Tylopoda, camelids, FMD Abstract Camelids regurgitate and re-chew their food and thus technically ruminate. In strict taxonomic terms, however, they are not recognized as belonging to the suborder Ruminantia. They belong to the suborder Tylopoda. Numerous differences in anatomy and physiology justify a separate classification of tylopods from ruminants. Many reports show that New World Camelids (NWC) and Old World Camelids (OWC) possess a low susceptibility to foot and mouth disease (FMD), and do not appear to be long-term carriers of the foot and mouth disease virus (FMDV). Recent preliminary results from Dubai have shown that two dromedaries infected subepidermolingually with FMD serotype 0 did not develop any clinical signs and failed to develop any lesions at the inoculation site. Infectious FMDV or FMDV RNA were not isolated and the two dromedaries failed to seroconvert. It would, therefore, appear appropriate for OIE to refine the definition of NWC and OWC by clearly stating that these animal species are not members of the suborder Ruminantia. Furthermore, these recent results suggest that dromedaries (and most probably all camelid species), which are listed in the OIE Code chapter as being susceptible to FMD similar to cattle, sheep, goats and pigs, are much less susceptible or non-susceptible to FMD. Therefore, the importance of FMD in camelids should be reassessed. The Central Veterinary Research Laboratory (CVRL) in Dubai, U.A.E., offers to become a reference laboratory for OWC. For more than a decade, CVRL has published in excess of 150 scientific papers and three reference books on camel diseases. Classification, population and distribution Although camelids ruminate, they are not modified ruminants in a taxonomic sense. A separate evolutionary history of 35 – 40 million years divides tylopods from ruminants. Camelidae belong to the suborder Tylopoda (Fowler, 1997; Table 1). Numerous anatomical and physiological differences justify the separate classification of Tylopoda from Ruminantia. The most important differences are shown in Table 2 and some are explained in several figures. The camelid stomach system differs from that of ruminants. There are only three distinct forestomachs compared to four in ruminants. In camelids they are called compartments (C) 1, 2 and 3. The rumen equivalent is C1, which possesses cranial and caudal glandular sacs. These were once considered to represent the water store of the animal; however they mainly function as absorption and fermentation areas as well as zones of enzymatic secretion (Wilson, 1989). The second, much smaller compartment C2 is the reticulum equivalent, and the eolongated C3 is the combined omasum/abomasun equivalent, which might best be referred to as the tubular stomach due to its length. Compartments 1 and 2 are lined with non-papillary smooth epithelium (Figure 1). In camelids, the motility patterns are markedly different compared with ruminants. Another distinguished feature of all Camelidae is the unique structure of their feet (Fig. 2). The padded feet act like snowshoes allowing them to walk over soft, loose sand without sinking. Camelids walk on thick pads consisting primarily of fat. They possess two digits, and their second and third phalanges are horizontal. The reproductive physiology of camelids is of particular interest. Camels mate in a crouching position (Fig. 3) and while mating the bull exteriorises its “doula” (Fig. 4), a bright pink inflatable sac, to attract females. Camels are induced ovulators. Their gestation period lasted 13 months. A slippery surface of a third membrane surrounding the fetus eases its birth (Figure 5). Latest osteological investigations on postcranial skeletons of Camelus dromedarius and C. bactrianus have shown that they derived from two different ancestors. Approximately twenty million OWC exist, of which two million are Bactrians (Table 3). There are four different species of NWC which inhabit the high altitudes in South America. The estimated population of NWC is shown in Table 4. Llamas and alpacas were domesticated 7.000 years ago; the dromedary and the Bactrian around 5.000 years ago. Guanacos and vicuñcas are wild and there are few wild Bactrians which roam in the Chinese and Gobi desert. There are no wild dromedaries anymore. The distribution of OWC is shown in Figure 6.
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