Schmallenberg virus

Background

Between August and October 2011, outbreaks of disease in adult cattle that included mild to moderate fever, reduced milk yield, loss of appetite, loss of body condition and diarrhoea were reported in both the Netherlands and Germany. Testing for common causes proved negative.

From December 2011, abortion and stillbirths associated with foetal abnormalities, affecting mainly sheep but also cattle and goats, were identified in the Netherlands, Germany and Belgium.

A new virus was identified in November 2011 as the cause of both conditions. This was named ‘Schmallenberg virus’ (SBV) after the German town where the virus was first identified.

In early 2012, the first cases were suspected in the south and east of England. In these initial cases, the disease was diagnosed following the testing of deformed lambs. Since then, the disease has been diagnosed across a large area of Southern and central England, in affected lambs and calves.

Schmallenberg virus is in the Simbu serogroup of the Orthobunyavirus group. This group of viruses includes many different viruses which occur in Asia, Africa and Australia, but have not previously been identified in Europe.

As this is a newly identified virus there are still aspects of the disease that remain unknown at this point until more research has been done.

The disease is widely distributed in Europe. The annual sheep and goat Brucella survey offered AHVLA scientists an opportunity to conduct additional surveillance for Schmallenberg virus on sheep in counties where infection had not been detected. Tests on samples collected during the sheep and goat Brucella survey indicated that Schmallenberg virus had spread during the 2012 active midge season to cover previously unaffected areas, including parts of northern England and Wales.

Currently we know that the virus can infect and cause disease in sheep, cattle and goats. We would also recommend that keepers of exotic or wild ruminants, such as the camelid (alpacas, llamas) and cervid families (deer) are vigilant.

Transmission

Orthobunyaviruses are typically primarily spread by biting insect vectors, such as midges and mosquitoes, although the routes of Schmallenberg virus transmission have not yet been confirmed. The potential for direct transmission (i.e. direct from one animal to another) is therefore, as yet, unknown.

If biting insect vectors are the major route of transmission, significant spread is believed less likely during the winter period when biting insects are usually much less active.

Research work suggests that live infected animals have virus in their blood stream for two to five days, when biting insects may acquire the virus which they can then transmit to another susceptible animal during blood-feeding.

It is believed Schmallenberg virus was circulating widely in sheep and cattle in the Netherlands and in a part of western Germany between August and October 2011.

It is likely that initial introduction of the virus to the UK resulted from wind-blown insect vectors originating in Europe.

Ruminants in the south, south west and east of England and imported ruminants and their offspring, are currently at the highest risk of showing signs of the disease, which at this time would be manifest particularly as birth of offspring with deformities or neurological signs. Other regions including the midlands and south Wales were at medium risk of midge incursion during the summer and autumn 2011 and therefore farmers in these areas are also requested to be vigilant for Schmallenberg virus associated problems in their livestock.

AHVLA has identified SBV infection in deformed lambs and calves in every month since January 2012. This suggests that some limited transmission, probably via native GB midges, has continued throughout the less active vector season. Therefore, this may potentially provide a reservoir from which new cases occur in 2012.

As the virus can localise in the tissues of foetuses, it is uncertain as to whether there was any potential for live actively infectious lambs, calves and goat kids to have been born in the spring, which could contribute to the spread of the infection this year.

Clinical signs and post mortem findings

Two clinical presentations have been observed due to Schmallenberg virus infection.

Adult animals
In adult cows the acute infection resulted in diarrhoea, fever, a reduction in milk yield, with a full and rapid recovery over several days.

Affected herds had outbreaks of disease lasting two to three weeks, but the possibility of a different epidemiological presentation occurring should be considered. In other species this stage of the disease has not been noted. Clinical signs have not been reported in adult or growing sheep, although there is anecdotal evidence of milk drop in milking sheep in Netherlands.

Newborn animals and foetuses 
The second presentation of the disease is associated with abnormalities in animals born alive or dead at term or aborted following infection of the dam, affecting mainly sheep but also cattle and goats. Malformations observed to date include bent limbs and fixed joints (arthrogryposis), twisted neck or spine, a domed appearance to the skull, short lower jaw and brain deformities (spaces filled with fluid in cerebral hemispheres, abnormally small parts such as cerebellum and brainstem) and marked damage to the spinal cord.  Some animals are born with a normal outer appearance but have nervous signs such as a ‘dummy’ presentation or blindness, ataxia, recumbency, an inability to suck and sometimes convulsions. The foetal deformities vary depending on when infection occurred during pregnancy.

It is important to note that field evidence from England and Europe has shown that many animals have been infected with Schmallenberg virus without any clinical signs being detected. Typically, the impact in most affected herds or flocks has been low, although a small number of farms have reported more significant losses. Other related orthobunyavirusesstimulate a strong immune response, which protects infected animals from subsequent ill effects. This means that they do not usually give birth to further deformed offspring. It is expected that Schmallenberg virus will behave in a similar manner, although there is inevitable uncertainty as this is a new disease.

Risk to humans

A Europe-wide risk assessment has concluded that Schmallenberg virus is very unlikely to cause illness in people. No human cases have been detected in any country, and the most closely related viruses only cause animal disease. A risk assessment produced jointly by the European Centre for Disease Prevention and Control (ECDC), the Robert Koch Institute (RKI), Germany, and the National Institute of Public Health and the Environment (RIVM), Netherlands, concluded that “it is very unlikely that SBV poses a risk to humans”. Please see the Health Protection Agency website for more information.

Farmers and veterinary surgeons are advised to take sensible hygiene precautions when working with livestock and abortion material. Although several members of the group of related viruses can affect humans, the ability to do so is thought to be due to a gene sequence which is not present in Schmallenberg virus.

Pregnant women should not have contact with sheep and goats at lambing/kidding time due to risks of exposure to other disease causing organisms.

Information for visitors to farms

Visitors to farms are advised to adopt the usual hygiene precautions for farm visits, such as washing of hands after touching animals and particularly before eating. Pregnant women are potentially at risk of acquiring a range of infectious diseases from animals, and should follow existing Defra guidance that advises them to avoid close contact with animals (including sheep, cows and goats) that are giving birth. This includes:

• avoiding contact with newborn or aborted lambs, calves or kids
• avoiding handling clothing or boots that may have come into contact with these animals
• ensuring that partners take appropriate hygiene precautions

Diagnosis

Disease suspected in newborn animals or foetusesThis is not a notifiable disease, it is advisable for farmers to consult their veterinary surgeon if they encounter cases of ruminant new borns or foetuses which are stillborn, show malformations or are showing nervous disease and you suspect Schmallenberg virus infection. Veterinary surgeons may contact their AHVLA/SAC laboratory if they require advice on sampling for diagnosis.

Acute disease suspected in adult cattleIf acute Schmallenberg infection is suspected, your veterinary surgeon may contact the local AHVLA/SAC laboratory for advice on sampling for diagnosis. This will usually involve taking EDTA blood samples for detection of the virus at the time of clinical signs, and clotted blood samples for the detection of the virus at the time of clinical signs, and clotted blood samples for detection of antibody in the acute phase of disease, and again 2-3 weeks later, to demonstrate seroconversion.

Advice for veterinary surgeons

• Suspect cases in foetuses or newborn animals will be sampled for histopathological, serological and virological examinations as appropriate.  Confirmation of infection is currently by detection of virus sequences using real time PCR on tissues.
• An indirect ELISA test for antibodies to Schmallenberg Virus (SBV) is available for use in cattle, sheep and goats. This test has been validated by AHVLA. A positive result indicates previous exposure but will not determine when this occurred. This test is available on a commercial basis at a cost of £6.20 per sample, and a turnaround time of 7 days.
• If cases occur outside laboratory working hours, please keep samples and carcasses chilled until they can be submitted for testing.

Treatment and control

On 21 May 2013 the Veterinary Medicines Directorate (VMD) licensed the veterinary pharmaceutical company MSD Animal Health to provide a vaccine for Schmallenberg virus. The vaccine, ‘Bovilis SBV’, should be available for use across the UK in summer 2013. Farmers are advised to speak to their veterinary surgeon if they wish to make use of, or find out more about, the vaccine.

Malformations affecting lambs and calves exposed to the virus in pregnancy may lead to birthing difficulties. Excessive force must not be used during the birthing process as this may risk injury to both the dam and offspring. Farmers should contact their veterinary surgeon in those cases which cannot be delivered naturally.

It is important that strict hygiene measures are carried out during assisted lambings and calvings.

Embryotomy (dissection and removal of a foetus that cannot be delivered naturally) should only be carried out on dead foetuses by operators competent to carry out the procedure. It should never be used to remove a live foetus.

AHVLA Regional Laboratories have reported severe abnormalities in some live born lambs and calves. They are visibly distressed and unlikely to survive or thrive long term. You should consider as soon as possible, and in liaison with your private veterinary surgeon as required, if any offspring deformities are likely to result in any immediate or long term welfare problems during rearing. Euthanasia may be required in severely affected lambs and calves and additional support and care may be required during the rearing period for less severely affected newborns. You should also consider whether any abnormalities will affect the animals’ intended future use and fitness for transport in the long term.

Since SBV is not a notifiable disease there are no movement restrictions. Current knowledge suggests that acutely infected animals carry the virus during this period of viaraemia.

Control of midges is unlikely to be effective given that they are very widespread, and appear to be very effective at spreading SBV.

From Defra Website.

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Elephant Anatomy and Biology

Skeletal system

Because of the large body size of the elephants,, the skeleton must be very large and strong to support the body weight. The whole skeleton weight is approximately 16.5 percent of body weight.

Figure 1. Skeleton of the elephant, Elephas maximus (a) and Loxodonta africana (b) 
(modified from Redmond I., 1997)

Axial skeleton

1. Skull

The elephant skull is large but light weight because of the pneumatic bone which has air cavities making it appear like a honey comb or sponge on cut section.. Pneumatization of the bones of the skull occurs the elephant is 3-4 year old. The big skull allows strong attachment of muscles supporting the movements of the trunk, ear and jaw, and houses various organs especially the brain, eyes, ears, tusks, and upper part of respiratory and digestive tracts. The largest cavity in the skull contains the brain. Molar teeth are in the maxillary and mandiblar bones and the tusks alveolar sockets of the maxillary bones. The skull structure is not different between genders but the skulls of young elephants are more dorally ventrally flattened than those of adult elephants.

Figure 2. (Left) Air cavities in the cranium (Right) The elephant skull (Asian elephant) (modified from Redmond I., 1997)

2. Vertebrae

The vertebral column of the Asian elephants are divided into basic five regions, cervical (7), thoracic (19-20), lumbar (4-5), sacral (4-5) and coccygial or caudal (24-33), the parentheses is a numbers of each region. The vertebral column is a curved linear, arch-like structure in Asian elephants, but is more nearly a straight horizontal line in African elephants. The movement of elephant vertebrae is limited because of fixed and tightened vertebral junctions.

3. Ribs

The numberof ribs is 19-20 pairs depending on the subspecies for the Asian elephants, and 21 pairs for African elephants. The first six pairs of ribs are sternal ribs, the next nine pairs are asternal ribs and last four or so pair of ribs are true floating ribs in the Asian elephants.

4. Sternum

These flat cartilages and bones lay in the pectoral position and serve as points of attachment for ribs and pectoral muscles, whileprotecting the organs in the thoracic cavity.

Appendicular skeleton

The elephant appendicular skeleton includes the fore or thoracic limbs and hind or pelvic limbs. The both are arranged in an almost vertical position under the body, similar to apillar or leg of a table rather than being in the angular position seen in many other quadraped mammals The legs are built to support great weight. The marrow cavities are lacking in the elephant long bones but there iss a network of the dense cancellous bone which contain hemopoietic cells responsible for manufacturing blood cells. This structure makes the bones stronger and better able to withstand pressure than if they contained a marrow cavity.. A special structure in the plantar region of the foot to increase support for the massive weight and gaits of the elephant is called the cushion pad. The plantar surface of the elephant foot is covered with thick keratin layer. Elephants can walk, run and swim, however they do not trot, canter, gallop and jump. Normally an elephant gait involves lifing two feet on one side of the body together while the two feet on the other side remain on the ground (a rack gait). .The speed of elephant gaits varies from slow to quite fast, and elephants can outrun most humans.. Elephants can remain standing for long periods because of the position of bones and limbs.

Figure 3. (Left) Elephant carpal bone (modified from Shoshani J., 1992) (Right) Structure of an elephant foot (modified from Redmond I., 1997)

Muscular system

Muscular structures of an elephant are large, including muscle fibers, tendons and ligaments. There are three types of muscle, voluntary (skeletal) and involuntary ( smooth and cardiac), as is the case in all mammals. Their function effects the movements of the bones, when stimulated by signals from nerve fibers. The muscles are nourished by their vascular supply.

Trunk

The elephant trunk is an interesting organ.It is composed of muscles, vessels, nerves, fat and other connective tissues, and skin. The trunk evolved from fused muscles of nose, upper lip and cheeks. It contains no bone or cartilage, although cartilage is found around the nostrils and at the base of the trunk. The muscles are include superficial and internal muscles. The total number of a muscles is approximately 150,000.. Superficial muscles run longitudinally along the dorsal, ventral and lateral aspects of the trunk. The internal muscles are deep to the superficial mucles and include radial muscles and transverse muscles. The two nostrils are separated by a membranous septum and are connected to openings in the frontal aspect of the cranium. The functions of the trunk include feeding, watering, dusting, smelling, touching, communicating (touch and sound promoter), defense and others. The trunk of an adult Asian elephant can hold about 10 liters of water.

Figure 4. The structure of elephant trunk (modified from Redmond I., 1997)

Integument system

Skin

The skin of elephant is not equally thick at all locations of the body. The thin skin is 1.8 millimeters, found in the ear, around the mouth and anus. The thicker skin is found on the head, back and buttock. This skin can be 2.5-3.5 centimeters or more thick. The skin is a highly sensitive organ with a rich nerve supply. Like other mammals, the skin is composed of two major layers (dermis and epidermis), which include glands and hair follicles. The color of skin is darker (brown or reddish) in African elephants and lighter in Asian elephants (gray). The Asian elephants have localized areas of depigmentation on their forehead, neck, ears and forelimbs. Normally the skin is covered with dust, soil or mud for prevent insect bites, ultraviolet radiation damage and moisture loss.

Hair

Hair can found of a body of baby and young elephant, especially on the head and back. Adult elephants, have less hair than young elephants and African elephants have less hair than Asian elephants. Hairs concentrate around eyes, mouth, chin, the ear opening and the end of the tail. Hair color varies from brownish, to brown, black, gray or white. Nail and plantar pad The structure of elephant nails is similar to other mammals. Elephants stand on the plantar surface of their foot with the cushioned pad supporting the heavy weight. The nails grow about 1 centimeter per month. The plantar surface of the foot is covered with keratinized layer, called the keratinized sole, which is approximately 4-12 millimeters thick and grows at a rate of 0.5-1 centimeters per month. Sweat gland The elephants lack of sweat glands over most of their body, and cannot use them for thermoregulation. Some sweat glands may be seen in coronet line of the toenail. The ears are used as the primary means of thermoregulation dispersing heat through radiation and with the assist of flapping the ears to move air to increase the efficiency of the radiator. Temporal or musth gland An adapted sebaceous gland is located midway between eye and ear on the temple on both sides of the head. Its opening or orifice can be visualized with the unaided eye. The glands are covered with skin that is 2 or more cm thick.. The glands produce chemical substances important in elephant reproduction. The secretion is oily and smells foul when secreted through the glands opening. Elephants in musth areaggressive, especially males. Females in musth are normally not aggressive.

Figure 5. (Left) The temporal or musth gland structures(modified from Shoshani J., 1992), and microscopic structure (x 40) (Right) The opening of temporal

Respiratory system

The respiratory tract of elephants is comprised of the conducting portion (external nares, nasal tubes, internal nares, pharynx, larynx and trachea) and the respiratory portion (bronchi, bronchioles, alveolar duct and alveolar sac in lung). Sound is produced from larynx. The lungs are attached to the thoracic walls and diaphragm, oblitherating the potential pleural space normally maintained in negative pressure to assist breathing in other mammals. . Unlike most other mammals, elephants rely on intercostals and diaphragmatic muscle movement alone to inflate and deflate the lungs. If there is an impediment in the muscular excersion of the key muscles in respiration for the elephant, the resulting dyspnea is severe. For example, long periods of sternal recumbency increase abdominal pressure thereby limiting diaphragm motion. Elephants poorly tolerate sternal recumbency and assume lateral recumbency when they lay down. This can be observed at times when elephants sleep.

Gastrointestinal system

Elephants are herbivoroussingle stomached or monogastric animals. The major alimentary structures are similar to those of the horse. Elephants lack a gall bladder and rely on hind gut fermentation of fecal matter in their large cecum using bacterial symbiosis. The elephant digestive tract consists of (from oral to aboral) the mouth, pharynx, esophagus, stomach, small and large intestine, cecum, rectum and anus. Accessory organs such as molar teeth, tongue, salivary gland, liver and pancreas completethe system. The digestive system of elephant is not very efficient at absorption of nutrients. Elephants digest and absorb only about 44 percent of what they eat. The consumption of an adult Asian elephant is approximately 150-200 kilograms of food (10 percent of body weight) and 200 liters of water per day, although larger amounts of food may be required in some circumstances.

Mouth

The opening of the mouth of the elephant is smaller relative to body size compared to many other mammals . The oral cavity has molar teeth, a tongue, and openings of the salivary ducts and salivary glands. The mouth is connected to the pharynx and the upper respiratory tract. The strong mandibular movement and coordination of teeth and tongue function are important in generating the horizontal grinding action of mastication of elephants.

Molar teeth

The dental formula of adult elephants for both species is I 1/0 C0/0 PM 3/3 M 3/3, with a total number of 26 teeth,The two upper incisors are the tusks. The average weight of the teeth of elephants is approximately 5 kilograms. New born elephants have 2-3 teeth in each jaw quadrant, these teeth develop in the fetus and can be observed in jaw within a few months after the birth. Elephants have 6 sets of molar teeth during their life span but they cannot hold all 6 sets at one time. The molar teeth are shed periodically. They move foreword in the jaw to displace old and worn teeth that fragment and usually fall out on their own and are swallowed. The structure of the teeth of elephants is complex and very much like the structure of the teeth of other mammals,.They are comprised of cementum, enamel, dentin, a pulp cavity and pulp tissue that includes odontoblasts, odontocytes, vessels and nerves. All elephantteeth are held together by cementumwhich forms the foundation for the projections on the occlusal surfaces of the molars which are covered with light or white enamel. These ridges contrast with the grooves where the darker colored dentin is seen.. The shape of projections on molar occulsal surfaces can be used to identify theelephant species. Molar projections are lozenge shaped in African elephants and loop shaped in Asian elephants.

Figure 6. The molar teeth of an Asian elephant

Tusks

Elephant tusks are the upper incisor teeth. The elephant tusk is a hypsodont tooth capable of growing through out the life of the elephant (elephant molar teeth are brachydont teeth). The deciduous tusks can found in new born elephants. The permanent tusks are observed in 2-3 year old elephants. Tusks normally grow about 15-18 centimeters per year. The structure of tusk is similar to that of a tooth except that enamel is only found on milk tusks. Elephant tusks have a unique characteristic refered to as the checered pattern (a net liked pattern) which can be seen in the cross section of the tusk. About 1/3 of the tusk length lies in the alvelolar socket of the maxillary bone. The sulcus is approximately the the length between the eye and the tusk sulcus. The pulp of the tusk extends about 2/3 of the tusk length, (see the figure 8). The position of the pulp is important for properly trimming the tusk.

Figure 7. The longitudinal section of an elephant head and tusk, a tusk (a), pulp (b), internal nare (c), air cavities (d), brain cavity (e) and molar teeth (f) (modified from GrÖning K, 1999)

Figure 8.The measuement useful for estimating the leghth of the pulp cavity in the elpehant (modified from Robinsom and Schmidt, 1986)

Esophagus

The esophagus extends from the pharynx to the stomach running in close relation to the trachea. Its structure is that of a musculomembranous tube, formed primarily by the tracheoesorphagial muscle. The esophageal mucosa has numerous mucous glands which secrete mucus to lubricate the food bolus as it passes through the esophagus.

Stomach

The elephant stomachis cylindrical and approximately 75-90 centimeters in long in adult elephants. The capacity of adult elephant stomach is between 30 and70 litters.

Intestine, cecum and rectum

The length of small intestine of adult elephants is about 66 to74 feet. The intestines are divided into the duodenum (approximately 1.5 feet long), jejunum (approximately 11 feet long) and the ileum. The large intestine of an adult elephant is approximately 38-43 feet long divided into a 20 to 22 foot long colon followed by a 12 to 14 foot rectum the terminating at a muscular anus under the tail. The cecum is 5 to 7 feet long, located coming off of the junction of the ileum and the colon. It is a major site of fermentation in the elephant. The capacity of the small intestines of an adult elephant is approximately 135 liters and the large intestines and caecum hold approximately 480liters of matter.

Liver and pancreas

Although the elephants lack the gall bladder, bile is secreted and passes to the small intestine throughmultiple ducts. The bile functions to enhance lipid digestion and absorption in the intestine. Pancreatic secretions function to facilitate protein and carbohydrate digestion along with secretions from the glands in intestinal wall.

Circulatory, hemopoetic and lymphatic systems

Heart

The elephant heart is large ( about 12-21 kilograms). It is apple shaped with double ventricular apices. Large sinuses moderate the high blood pressure from cardiac contraction to prevent damage of peripheral blood vessels. These sinuses can found in both sides of the temporal area, along the trachea, sternum, axillae and inguinal areas. The vasculature of elephants is thicker walled and stronger than found in most other mammals.

Blood

The blood components of the elephant are similar to other mammals, except that the blood cells are larger.

Lymph and lymphoid organs

The thymus, tonsils, lymph nodes and spleen are the lymphoid organs of the elephant. The lymphatic system plays an important role in the elephant immune response.

Nervous system

The elephant nervous system is comprised of a brain, spinal cord and peripheral nerves. The brain to body size ratio is smaller than other mammals. The brains of male elephants weigh between 4.2-4.5 kilograms and the brains of female elephants weigh bewteen 3.6-4.2 kilograms. Although the elephants have a small brain to body size ratio, they are one of the most intelligent animals, with a highly complex and developed pattern of gyri and sulci. No intelligence difference has been observed between male and female elephants. The spinal cord of the elephant has two enlargements referred to as the cervical and lumbar enlargements. These enlargements contain numberous nerve cells that function in control of the limbs. ,

Urinary system

This system is comprised of bilateral kidneys, and ureters, a urinary bladder, urethra and urethal opening. Like the ox, elephant kidney s are multilobar. An elephant kidney has 5-7 lobules. The urinary bladder capacity of an adult elephant is isapproximtely 6-18 liters. Normal elephants urinate 10-15 times per day.

Reproductive system

Male

The testes are located inside the abdominal cavity. They are tennis ball sized structures just posterior to the kidneysThe elephant penis is the muscular type similar to that of horses and humans. The length of penis is about 2 meters, and it is S-shaped. The other organs involved in the male elephant reproductive system are the seminal vesicles, the sperm storage organ, and prostate gland, the ampullae and the bulbourethral glands.

Figure 9. The male elephant reproductive system (modified from Hildebrandt et al., 2006)

Female

Like a cow or mare, the female elephant has bilateral uterine horns. The ovaries are located behind the kidneys. The genital canal is 68-88 centimeters long and consists of a vagina, vaginal os and vestibule. The vulva position is between the inguinal regions, ventrally, which is different from most other mammals which have the vaginal oss located perineally under the tail. The clitoris lays in the vulva and is about 40 centimeters long, about the same length as thevulva. The two mammary glands are located pectorally between the forelegs. The placenta of the elephant is zonary. The gestation period of the elephant is very long, about 17-22 months. A male calf has a longer gestation period,( average 21-24 month) compared to a female calf (17-23 months).

Figure 10. The female elephant reproductive system (modified from Hildebrandt et al., 2006)

Special sense organs

Eye

The structure of elephant eye is similar for both species. The elephant does not have a lacrimal apparatus, but the hardarian gland can observed closeto the third eyelid. The gland secretion plays theimportant role of preventing drying of the eye. The third eyelid is well developed and strong to protect the globe of the eye . The ppupil and iris are circular shaped and colors of iris vary between greenish-brown and blue. The visual ability of elephants is limited because of the eye, ear and trunk locations and the limited mobility of the eye..

Ear

The ear of the elephant is a second highly sensitive organ The elephant can hear at 12,000 Hertz in the upper limit, compared tobats (80,000 Hertz), dogs (40,000 Hertz) and humans (20,000 Hertz). On the other hand, elephants can hear and produce sound which has a long wave length, 14-16 Hertz, below the hearling range of the human ear (20 Hertz). Therefore elephant communication is not entirely audible to humans. They can communicate to other elephants at a great distance using these ultrasonic wavelengths.. The functions of the ear include acoustic detection, balance, thermoregulation and information transfer. The constriction and dilatation of blood vessels in the elephant ear are controlled by signals from nerves, which are sensitive to temperature. We can estimate an elephants age from the ear fold, which progresses in size with age.

Nose (trunk)

The nose or trunk is the smelling organ of the elephants, and is associated with the special sensory organ called the vomeronasal organ located on the palate of the mouth. The vomeronasal organ structure consists of two small pits connected by numerous nerve endings which transmit smelling sensation to the brain. The vomeronasal organ is a highly sensitive organ for smell. When elephants want to detect an odor, they raising and wave their trunk in the air to better inhale the smell. They can find and locate water sources about 50 kilometers away, and can detect the reproductive status of the other elephants from a long distance, especially males detecting female elephants in estrous.

Figure 11. The opening of a vomeronasal organ of the elephant

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