Veterinary Parasitology: The Practical Veterinarian

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Veterinary Anaesthesia, 10th Edition

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Handbook of Avian Medicine

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Large Animal Internal Medicine (National Veterinary Medical Series)

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A Colour Handbook of Small Animal Emergency and Critical Care Medicine

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O. Lynne Nelson - Small Animal Cardiology

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Pathologic Basis of Veterinary Disease

Pathologic B
asis of Veterinary Disease
Publisher: Mosby; 4 edition (August 21, 2006) | ISBN: 0323028705 | Pages: 1488 | Djvu | 352,75 MB




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Arlene Coulson, Noreen Lewis, “An Atlas of Interpretative Radiographic Anatomy of the Dog

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Casting animals

Precautions before casting:
  1. Fast an animal for up to 12 hours before casting. If the animal has a full stomach, it may rupture during casting.
  2. There should be sufficient labor available to complete the manoeuvre in the shortest time with the least distress to the animal. It is necessary to have a reliable person at the animal's head in order to control it. Depending upon the size of the animal that must be cast, either two or three persons are needed to pull on the rope.
  3. The site for casting should be chosen carefully. The best choice is a well=grassed field where there is sufficient space and no objects which could cause injury. In bad weather a barn is suitable. There should be plenty of clean straw put down to make the animal's fall as comfortable as possible.
  4. A strong webbing halter or head collar must be used. There must not be a bit in the horse's mouth and any twitch that has been used in adjusting ropes must be removed.
  5. Any operations on the feet necessitate the removal of shoes. This is particularly necessary if hobbles are to be used in casting.
Casting Cattle and Buffaloes:
Methods of casting animals (Courtesy: geutenberg.org)
Cattle and buffaloes are cast for a variety of reasons: surgical operations, trimming of feet, and better control at a difficult calving. The most common and efficient method of cassting cattle and buffaloes is Reuff's method. 
Reuff's method of casting cattle and buffaloes minimized the chances of injuring either the animal or people attending it. A running noose is made at one end of a 10 m long rope and passed around the base of the horns. In the case of polled animals, the noose can be placed around the neck. A half hitch is made around the neck, the second around the heart girth, and passed back and looped around the animal just behind the hip bones. A steady pull on the free end will cause the animal to collapse slowly. It is advisable to cast the animal on soft grass or a bed of hay or straw.
An alternative method is shown in figure, in which middle of the rope is placed over the neck and the ends passed between the front legs. They cross under the brisket, are passed upward and crossed over the back and then downwards past the flanks and between the hind legs. Traction on the free ends will then cause the animal to collapse. The ropes must cross under the brisket (Not on the throat), or the animal will not go down.
One great advantage of the latter method is that, because there are no knots involved, it is easier to remove the rope when you are finished with the animal. With Reuff's method, the rope tends to stay in a better position. This is an advantage when casting wild or excited cattle because the rope can be put on in the crush. The animal is then let out of the crush and the process of casting can begin.
Casting is not recommended for pregnant animals because of the possibility of abortion. It can also result in bloat, pneumonia, or displacement of the abomasum.


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Reproduction In Farm Animals: Female Reproductive System



Reproduction In Farm Animals: Female Reproductive System





Female Reproductive Tract - Cow (Courtesy: fao.org)
The female not only contributes the female sex cell (ovum) but also provides the necessary environment in which the new individual is nourished during the early days of its life. These functions are performed by the primary and secondary organs of the reproductive system. A pair of ovaries are the primary organs of reproduction and produce not only ova but also the hormones required for the normal sexual behavior of females. The secondary organs of reproduction are a pair of oviducts (Fallopian tubes), the uterus, the cervix, the vagina, and the vulva. The mammary glands are also considered an accessory sex organ as they are closely related to the completion of reproduction by the nourishment of the young one.
The development of the reproductive organs starts before birth during the embryonic stage, but they remain quiescent. After birth, the reproductive organs develop gradually until the female attains a specific weight at a certain age when she becomes sexually mature, i.e. capable of producing viable gametes. The age at which a female becomes sexually mature is called puberty.
(a) Ovaries: The cow or buffalo has two ovaries situated on either side of the medial line, deep in the pelvic cavity almost at the border of the abdominal cavity. The right and left ovaries are connected with the uterine cornua of each side by tortuous Fallopian tubes. The ovaries of the buffalo are irregularly oval or spherical in shape and variable in size, while the ovaries of the cow are usually ovoid or spheroidal. The size and weight of active ovaries change frequently due to the formation of Graffian follicles and corpora lutea. A functional ovary develops from outer germinal epithelium from which the Graafian follicle develops.
The ovaries are the primary organs of reproduction because they produce not only the egg cells (ova) but also the sex hormones essential for female sexual activities. Willingness to mate (libido), ovulation, and many processes related to development, maintenance, and delivery of the calf are regulated by the female sex hormones. Hormone production in the ovaries is primarily controlled by the gonadotropic hormones of the pituitary gland. Under the stimulation of the pituitary hormones, the ovaries produce a follicular stimulating hormone (FSH), which is an estrogenic substance. Estrogens induce the psychic manifestations of estrus (heat). They also bring about glands of the cervix to secrete, and promote development of the mammary duct system. The characteristics behavior of the female and the secondary sex characteristics of the female are largely due to the influence of estrogens.
When ovulation takes place, the ruptured cells form the corpus luteum. The corpus luteum becomes a temporary endocrine organ under the influence of the luteinizing hormone  (LH) of the anterior pituitray. The corpus luteum secretes a hormone called progestrone which prepares the endometrium for the implantation of fertilized ovum and the maintenance of pregnancy. Progestrone also prevents ripening of additional follicles and ovulation, thus preventing the occurrence and manifestation of heat. It also stimulates the growth of the alveoli of the mammary glands and depresses the production of luteinizing hormone by the pituitary. The corpus luteum also produces another hormone known as relaxin, which causes decalcification of the pelvis. This results in the relaxation of the birth canal during parturition.
(b) Tubular Genitalia:
The tubular genitalia consist of the oviducts or Fallopian tubes, the uterus, the cervix, the vagina, and the vulva.
Oviduct or Fallopian tube. The oviduct is a tortuous, tubular structure of muscular and epithelial tissues. It reaches from the ovaries to the tapered end of the uterine horn. In cattle of different ages, the oviduct varies in length from 20 - 35 cm, while the length of the oviduct in buffalo varies from 20 - 25 cm. On the basis of diameter and internal structure, the oviduct consists of three parts: the isthmus or narrow portion which adjoins the uterine horns; the ampulla, which is slightly wider; and the infundibulum, which opens into the peritoneal cavity.
Uterus. The uterus consists of a body and two "horns". It is a muscular and irregularly tubular organ, the size of which increases during successive pregnancies. In heifers, it is situated 25 - 40 cm from the vulvular opening, just anterior to the cervix.
Cervix. The cervix or the neck of the uterus is a small muscular tube which extends from the uterus to the vagina. The muscular wall of the cervix is thick and its mucosa contain a large number of mucus-secreting cells. The mucosa form thick folds; opposite folds tend to overlap, forming a spiral passageway through the cervix. This makes possible the tight closure of the cervix with a cervical plug that is formed during pregnancy. This structure and secretions from the mucus secreting cells protect the uterus from microorganisms commonly present in the vagina. The cervical muscles relax during estrus and at the time of parturition. At parturition the cervix dilates, allowing the calf and fetal membranes to be expelled.
Vagina. The thin but elastic-walled tubular connection of the cervix with the vulva is called the vagina. It is a common passage for the reproductive and the urinary tract. The epithelial lining of the vagina undergoes changes during the estrus cycle. During natural breeding, semen is deposited in the vagina near the cervix.
Vulva. The external opening of the female genitalia is called the vulva. It includes the clitoris and the vestibule. The clitoris is a structure of erectile tissue (homologous with the male penis) located just inside the lower junction of the vulvular lips. The external opening of the reproductive tract of the cow lies just below the anus. It is about 12 cm long and has a wide, rounded dorsal angle and a narrow ventral angle. The thick labia majora are covered with fine hair.
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Reproductive cycle in farm animals

Reproduction in female is a complicated process, and normal reproduction ivolves synchronization of many functions. It is subject to many adverse effects at certain stages. Different aspects of reproduction in cows and buffaloes along with the physiological mechanisms involved are discussed in the following paragraphs.
Puberty or sexual maturity
Puberty is defined as the age at which reproduction becomes possible. In the female this is usually considered to be the age of first estrus. Puberty occurs before full mature body size is attained. The average age at puberty in cows is average 34 months and in buffaloes is 38 months. In cross breeds, the age at puberty is 9 - 18 months.

Trait
Species
Sahiwal CowHolstein CowBuffaloSheepGoatHorse
Age at first service (days)1030-1052596-6281137-1151195195495
Gestation Period (days)282282310144-151146-152340
Dry Period (days)298-191


Service Period (days)154-221144215


Calving interval (days)500426520


Length of estrus cycle (days)21212116-1720-2121
Duration of estrus (hours)171717-2422-3624-484-8 Days
Post-estrus time ovulation (hours)10-1110-1118-4524-3024-361-2 Days
Best time to BreedLate estrus or shortly after EstrusLate estrus or shortly after Estrus
Middle of Estrus
Every other day beginning 2nd day of Estrus
Fertile life of sperm in the female genital tract (hours)30-4830-48
30-48
72-120
Fertile life of ovum (hours)20-2420-24N/A10-25N/A6-8

The onset of puberty depends upon a change in the balance between the output ofgonadotropins from the gonads and growth hormones secreted by the anterior pituitary gland. The pituitary gland is located in a bony depression at the base of the brain. It consists of two distinct parts, known as the anterior (front) and the posterior (rear) pituitary glands. The pituitary is controlled by certain physiological functions involving the gonads and the anterior pituitary gland, and is influenced by several environmental (season, temperature, nutrition) and genetic factors.
Breeding season
The term breeding season refers to the period of time during the year when females of a species come into estrus. Most species of wild animals have a definite breeding season which is initiated at a time when environmental conditions are conducive to the survival, growth, and development of the young one after birth. For example, the gestation period in sheep and goats is 144 - 152 days, and the breeding season in these species starts in fall so that the young are born in spring. In cattle, where pregnancy on average lasts for nine months, the female breeding season occurs in the early summer so that the calves are born in the spring when the temperature is optimum for the growth of the newborn. Green fodder and forages are also available, which support sufficient milk production by the dams.
Domestication of farm animals has resulted in some variation of breeding season. Due to the intervention of modern production techniques, farm animals are now capable of breeding throughout the year. Among the farm animals, cows and buffaloes are polyestrous, showing diestrous cycles throughout the year. Mares, ewes, and does are seasonally poly estrous, showing diestrous cycles during a definite breeding season. The breeding season of ewes and does is confined largely to fall and winter. In Indian sub continent, buffaloes breed from October to December, when day length is decreasing. The stimulus for the initiation of reproduction during certain seasons results from the action of light, via the eye and optic nerve, on the pituitary gland. This stimulus causes the pituitary to release gonadotropic hormones, which activate the functioning of the gonads. One of the limiting factors influencing the productivity of the buffalo is the seasonality of breeding, which may be due to either anestrus or silent estrus during the hot, dry months of summer.
Estrus Cycle
Estrus occurs in non-pregnant females in characteristic rhythmic cycles. The interval between two consecutive estrus periods is known as the estrus cycle. The estrus cycle in farm animals is characterized by cyclic changes in the morphology of the reproductive organs as well as in the behavior of the animals.
The estrus cycle is divided into four different phases; these are known as proestrus, estrus, metestrus and diestrus. 
Proestrus is the phase of estrus in which the reproductive system is beginning preparation for the release of the mature ovum from the ovary. Estrus is defined as that phase of the cycle when females are receptive to coitus. Metestrus is the short transitional stage following ovulation in which the effects of estrogen are declining. The recently ruptured follicle is reorganized, and the secretion of progesterone is rising. During this phase, the uterus gets prepared for the implantation of the embryo. If pregnancy does not occur, the reproductive tract goes into a period of rest called diestrus. In cows and buffaloes the estrus cycle averages 21 days in length. Sheep and goats usually have a shorter estrus cycle ranging from 16 - 21 days.
Signs of estrus are somewhat similar in females of different species. In cows and buffaloes, estrus is characterized by the manifestation of heat. The cows may bawl frequently, become very active and restless, or mount other females and remain mounted. The vulva swells and the vestibule may be come deep-red. The swelling subsides with the end of estrus. There is marked discharge of clear, viscid mucus secreted by the cervix from the vulva. The excessive secretion at estrus acts as a lubricant during copulation.
Ovulation: Ovulation may be defined as the discharge of the ova from the Graafian follicle. Ova develop from germ cells in the ovaries. Numerous germ cells are present in the ovaries at birth, but few of the follicles surrounding them mature to rupture and shed ova. Follicles grow under the influence of the follicle stimulating hormone (FSH). The layers of follicular tissue become thinner with growth, the follicle rupturees and ova are released. This process is stimulated by the luteinizing hormone (LH). The released ova are swept by muscular and ciliary movements into the oviduct towards the uterus. If mating or articficial insermination takes place, spermatozoa and ova meet in the oviduct.
Esturs and ovulation are more or less synchronized in females to increase the chances of fertilization, the union of an ovum with a spermatozon. Synchronization of ovulation and insemination is essential because the life of the ovum once it is shed and that of the spermatozoa in the female reproductive tract is limited to a few hours.
Gestation: Gestation is the process that begins with the fertilization of the ovum by the sperm and terminates with the birth of a young one. The period of gestation varies considerably among species of farm animals. The average gestation period of cattle is 282 days, buffaloes 310 days, and sheep and goat 151 days. Generally, male calves are carried one day longer than female calves.
Parturition: Parturition is the physiological mechanism that enables the uterus to expel fetus after a certain period of development and nourishment. The process is called "foaling" in mares, "calving" in cows and buffaloes, "lambing" in ewes, and "kidding" in goats.
Signs of Parturition. The dam shows a number of signs of approaching parturition, which are usually divided in to following four stages.
(a) Preliminary stage: This stage may last for hours or even days. The ligaments in the pelvic region and around the tail head begin to relax and sink a few days before calving. The dam exhibits difficulty in movement. The external genitalia are swollen, enlarged, and flabby, and strings of mucous are seen. The mammary glands are enlarged and become tender. A clear, waxy fluid oozes out of the teats when pressure is applied.
(b) Dilation of the cervix: This stage merges with preliminary stage. Uneasiness increases and the animal may lie down and get up frequently. Frequency of micturition (urination) increases. At this time the cervix is fully dialted, and the next stage follows without any appreciable break in the sequence of events.
(c) Expulsion of the fetus: This staage begins with the fetus entering the dilaated cervix and the birth canal. During this time, uterine contractions occur at about two-minute intervals and the amnion is not ruptureed. There is a rush of fluid from the uterus when the water bag rupturees, and the animal appears relieved. Normally, the forefeet, with the muzzle lying behind and over them, appear at the vulva. The young one is expelled from the fetal membranes by a forceful and painful effort by the mother.
(d) Expulsion of membranes: The expulsion of the fetal membranes is commonly known as the delivery of the afterbirth. COntinued contractions of the uterus disjoin the fetal cotyledons, and the placenta is expelled within half an hour to eight hours after partuirition.
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Veterinary Vaccines and Diagnostics, Volume 41

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Veterinary Laboratory Medicine

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Veterinary Virology, Third Edition





Veterinary Virology, Third Edition 
Publisher: Academic Press | | edition 1999 | PDF | 641 pages | 70.5 mb

Completely rewritten, this edition has expanded coverage of zoonotic viruses and the diseases they cause, and viruses and viral diseases of laboratory animals, poultry, fish, and wildlife. The concept of new emerging and reemerging viral diseases reflects the new perspective this concept has brought to veterinary and zoonotic and related fields. Part I presents fundamentalof virology related to animal infection and disease. Part II details the properties and clinical features of the viruses that afflict animals and describes their treatment and control.


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Handbook of Veterinary Neurology

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Applied Pharmacology for Veterinary Technicians 4th Edition

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