eChapters

Introduction
India has been making steady progress in the livestock sector with significant rise of meat, egg and milk production and a sustained annual growth rate of more than 5%. This growth trajectory is anticipated to accelerate further due to rising middle-class incomes combined with high income elasticity of demand for livestock products. However, despite having huge livestock resource, protein deficiency in rural India remains widespread. Recent data shows that two third of the Indian households are deficient in protein intake1. Looking at the growth potential in the sector, Govt. of India has put special focus on this sector and have undertaken many initiatives to boost animal health productivity and to increase farmer’s income. However, a major limiting factor in profitable livestock production in India is the high prevalence of infectious diseases. These livestock diseases cause great socioeconomic impact and are often exacerbated by inadequate biosecurity measures both in intensive and open production systems. Consequently, the use of antimicrobials for disease treatment has become an essential aspect of livestock management. Antibiotics usage in Animal Healthcare Antibiotics are an essential part of therapeutic management of infectious diseases in both farm and companion animals, ensuring better animal health and life; thereby also assures healthy food from the animal sources. In India a wide range of antibiotics are available in the veterinary practice viz. Penicillin, Semi-synthetic penicillin like Ampicillin, Amoxycillin, Aminoglycosides like Streptomycin, Gentamicin, Neomycin; Tetracycline, Kanamycin, Erythromycin; Fluoroquinolones like Enrofloxacin, Norfloxacin, Ciprofloxacin,

Introduction
Aquaculture is one of the sunrise sectors contributing a significant quantity to the global supply of fish for human consumption. Fish is a superior source of highquality animal protein and highly digestible energy. Disease problems in farmed fishes are one of the main barriers, resulting in significant financial losses up to a tune of US$2.48 B, 14.95% of the annual aquaculture production value in Indian aquaculture. In the aquatic environment, bacteria are quite prevalent and the majority of bacterial pathogens are found in the water’s natural flora. They only spread illness when poor husbandry practices, inadequate nutrition, and unfavourable environmental circumstances contribute to fish stress. Pathogenic bacteria, including Aeromonas spp, Escherichia coli, Staphylococcus spp, Salmonella spp., Shigella spp., Yersinia enterocolitica, Clostridium botulinum, Plesiomonas shigelloides, and Listeria monocytogenes, can be either naturally present in fish or introduced to them during handling, processing, and storage. Antimicrobial resistance (AMR) in Indian aquaculture presents a multifaceted and growing challenge at the intersection of public health, environmental sustainability, and food security. As aquaculture expands to meet rising global demands for protein, the sector has increasingly relied on antimicrobials to prevent and treat bacterial infections. However, due to some indiscriminate and unregulated use of these agents as well as the householdsewage, hospital effluents, contamination from agricultural wastes andinadequately treated urban waters that enter the aquaculture through drains and rivers,creates strong selective pressure and accelerate the development and dissemination of resistant pathogens in aquatic environments posing a serious threat not only to farmed fish but also to human health through environmental contamination and the broader food chain. Resistant bacteria and resistance genes can spread through water systems, biofilms, and aquaculture products, creating reservoirs that contribute to the broader One Health AMR crisis. Food borne pathogens (Aeromonas spp., Vibrio spp., and Streptococcus spp.) from aquatic animals were found resistant to antimicrobial agents that are relevant for therapeutic usage in human clinical settings. E. coliwas found to be resistant as a sign of possible human and terrestrial animal effects. Distinguishing resistance that has been selected in different sectors is extremely difficult and caution is needed while trying to attribute the source of antibiotic resistance in bacteria in the aquatic environment. Understanding the drivers, mechanisms, and impacts of AMR in aquaculture is essential for developing effective mitigation strategies and sustainable management practices that safeguard both aquatic and human health.

Introduction
Antimicrobial resistance (AMR) is regarded as a silent pandemic that is responsible for causing the majorityof deaths every year and has become a major healthcare challenge and a significant public health issue. It has been reported that AMR alone has caused more fatalities than road accidents and cancer. It is among the top ten global health threats and has been recognized as a part of the multisector One Health approach. It has been predicted that by the year 2050, the burden of AMR will decrease the gross domestic product (GDP) by 2 to 3.5%, causing a loss of USD100 trillion to the world, with the annual death rate reaching 10 million. India faces one of the world’s highest antimicrobial resistance (AMR) rates, driven by high antibiotic consumption in humans, widespread non-prescription use, and unregulated application in livestock, aquaculture, and agriculture. Surveillance data show alarming resistance in major pathogens E. coli and Klebsiella,which now exhibit very low susceptibility to key antibiotics such as cefotaxime, ciprofloxacin, and carbapenems. Factors exacerbating the burden include inadequate infection prevention, limited laboratory capacity, poor enforcement of regulations, environmental contamination from pharmaceutical and hospital waste, and low public awareness. The combined impact threatens public health, food safety, and the economy. In general terms, AMR is defined as the ability of the microorganisms to withstand the action of an antimicrobial agent,i.e. Antibacterial agents, antifungal agents, potentially toxic metals, and disinfectants. AMR is known to be a natural process that occurs over time due to genetic changes in the pathogens under selective pressure, where a pathogen undergoes mutations and is often linked to indiscriminate use of antimicrobial agents.
Indefinite and improper use of antimicrobial agentshas been a major factor in the emergence of AMR. AMR affects both animals and humans alike, and resistant pathogens pose a challenge in treating infections. One of the crucial factors responsible for AMR is theenvironment, which is regarded as both a vehicle for spreading AMR microbes as well is a culprit of AMR pollutants, which severely impact the ecosystems. AMR is a multifaceted problem and to control it effectively, meticulous measures have been implemented for monitoring and surveillance of AMR in clinical settings, in both human and veterinary fields. However, the environmental surveillance dealing with the environmental AMR has yet to be established. The implementation of comprehensive monitoring of AMR in environment will vastly improve our understanding of the various dissemination routes and propagation of the resistant microbes in environment and their role in spreading AMR. In this chapter, we will discuss the environmental spread of AMR, drivers of AMR in the environment, factors influencing AMR, challenges faced, measures to tackle AMR, and future trends in curbing the burden of AMR.

Introduction
Antimicrobial resistance (AMR) is a global concern that poses a significant threat to contemporary healthcare systems, potentially hindering the management and treatment of various diseases. Microorganisms can act as reservoirs for AMR across various ecological niches; thus, a “one health” proposal is essential for coordinating a multisectoral strategy aimed at investigating and tackling this alarming issue. This method seems to be an effective strategy for addressing and alleviating the challenges posed by AMR; however, it demands the collaborative efforts and assets that are consistently and efficiently executed by health practitioners. Horses have been pivotal in human history; they have served in wars, provided transportation, and even aided in mining operations. In contemporary society, horses are significant as sport animals and in therapeutic settings involving animals. Given these close interactions between humans and equines, it becomes essential to effectively identify infectious diseases and antimicrobial resistance (AMR) impacting both species, particularly in instances of highly contagious diseases. Resistant bacteria represent a significant threat to the health of both equines and humans. Horses may obtain resistant bacteria through several avenues, such as interaction with other animals, exposure to contaminated materials, or to antibiotic uses. The responsible utilization of antibiotics and the implementation of antimicrobial stewardship programs are essential in reducing the transmission of antimicrobial resistance (AMR) within equine populations. A variety of zoonotic pathogens that exhibit resistance to antibiotics has been identified in equines. This includes Extended-Spectrum Beta-Lactamases (ESBL) which produces E. coli, Methicillin-Resistant Staphylococcus Aureus (MRSA), and Multidrug-Resistant (MDR) Salmonella. Horses can develop AMR through various channels like:

AMR has been prevalent in almost all European countries from past decades. A 2021-2022 report published by the European Food Safety Authority (EFSA) and the European Centre for Disease Prevention and Control (ECDC) on AMR in zoonotic and indicator bacteria from humans, animals and food origin reported vast differences in antimicrobials resistance levels among the European countries, with comparatively higher AMR percentages in the southern and eastern parts of Europe (ECDC, 2022, 2023). The resistance levels ranged from very high for tetracyclines, sulfonamides and ampicillin, moderate for ciprofloxacin to low levels for third-generation cephalosporins (cefotaxime and ceftazidime) in human cases infected with Salmonella spp. in 2022 (ECDC, 2023). The trends are dynamic and over a decade of 2013 2022, the human isolates from 12 and 15 countries reported a statistically significant reduction in tetracycline and ampicillin resistance, particularly for S. typhimurium (ECDC, 2023). The ciprofloxacin and cefotaxime combination, a highest priority critically important antimicrobials (CIA), had very low and rare resistance levels for Salmonella isolates of humans and animal and their derived meat.

Livestock species wise variation was also observed in the resistance pattern in imported meat, being higher in poultry meat isolates compared to pig or cattle meat for Escherichia coli (ECDC, 2023). High to extremely high levels of f luoroquinolone resistance from Campylobacter jejuni and C. coli of both human and animal origin isolates exist, due to which the fluoroquinolones can no more be used as a treatment option for human Campylobacter infections (ECDC 2023). The combined occurrence of erythromycin resistance and ciprofloxacin in Campylobacter spp is considered of high public health importance, and the report mentioned that the combined resistance for these antimicrobials was higher in C. coli compared to C. jejuni from food-producing animals and humans. However, while the ciprofloxacin resistance showed an increase in over 13 study countries, seven countries reported reduced erythromycin resistance for C. jejuni. Overall, resistance to conventional antimicrobials was frequent in Campylobacter and Salmonella from humans and animals. Increasing trend in resistance to one of two CIA for treatment in humans has been observed in poultry-originated Salmonella serovars and Campylobacter while combined resistance was is low in few Salmonella serovars and C. coli isolates from humans and animals in some countries (ECDC, 2023).

Introduction
 Antibiotic therapy is one of the mainapproaches of modern medicine used tofight bacterial diseases worldwide.Antibiotics comprise of any natural, synthetic, or semi-synthetic substances which interfereswith the growth and development of microbes or have killing effect onmicrobes, specifically bacteria. The availability of these antibiotics for treating various bacterial infectious diseases significantly improved the quality of life of humans as well as animals.The period from1930s to 1960s is considered as the ‘golden era’ of antibiotics during whichmost of the antibiotics available today werediscovered. Antibiotics, once known as the magic bullets of modern-day medicine, are now an “endangered species” facing the danger of extinction due to the worldwide emergence of antibiotic resistance (ABR)/antimicrobial resistance (AMR) among microbes. In general, AMR is the capacity of a microbes (bacteria, fungi, and viruses) to resist the growthinhibitory or killing activity of an antimicrobial beyond its normal susceptibility by altering their physiologyor genetic makeup. AMR has emerged as one of the most critical and complicated global public health threat due to its multi-faceted nature.World Health Organization (WHO) has declared AMR as one of the top 10 global public health threats. The emergence of AMR is closely related to the extensive use and misuse of existingantibiotics in the human and animal fields without properguidelines as well as failure to developor discover new antibiotics. AMR leads to a significant health burden worldwide as it is estimated that bacterial AMR alone attributesto 1.14 million deaths globally in the year 2021 and if left unchecked, it may contribute to 10 million deaths annually by 2050.This prediction was recently updated with the data from 2019 and reported that the deaths of 4.95 million people were related to drug-resistant bacterial infections and 1.27 million deaths were directly attributable to AMR.In addition to the health burden, AMR also increases the healthcare costs and imposes significant indirect economic burdens.Increasing reports of treatment failures in patients with infections caused by multi-, extensive-, and pan-drugresistant bacteriahave been documented in literature from different part of the world. Antibiotics once normally used to treat bacterial infections are no longer effective, and it becomes vital to use “reserve” or “last resort” antimicrobials that are often more expensive. Furthermore, WHO has also emphasized that AMR not only makes infections harder to treat but also jeopardizes ancillary medical procedures such as surgeries and cancer treatments. Food may act as a carrier for the transfer of antimicrobialresistant bacteria (AMRB) and antimicrobial resistance genes (ARGs) to humans.Many scientific reports establish a link between the extensive use of antibiotics duringagricultural production and the increase in AMRamong human pathogens, in which food is one of thepossible transmission routes. Antibiotics are regularly added to feed as additives in intensive animal production systems at sub-therapeutic doses to stimulate growth, improve feed efficiency and avoid infections. The extensive use of antibiotics in human treatment, animal therapy and agricultural use as growth promoters are further causes of bacterial resistance to antibiotics. In recent years, the prevalence of AMR among microorganisms isolated from animal source foods (milk, meat, eggs etc) has increased. The increasing demand for quality animal protein has driven intensive farming, leading to increased antimicrobial usage. In the year 2020, global antimicrobial consumption in food-producing animals was estimated around 99,502 tonnes.Antibiotics are commonly used prophylactically infoodproducing animals and it is projected that by 2030 such usewill increase by approximately 67% globally.Despite efforts to reduce antibiotic use, many countries still rely heavily on antimicrobials for growth promotion and disease prevention. The Food and Drug Administration (FDA) has emphasized the need for better monitoring of antimicrobial use in animals. The emergence and spread of AMR in the food chain is considered as a multisectoral issue, because (i) antibiotics are widely used in livestock production systems (cattle, poultry etc), (ii) AMRB and ARGs can easily spread at each stage of the food production chain, and (iii) these AMRB can cause infections in humans.Thus, the emergence of AMR along the food chain is a major

AMR is undoubtedly the most serious challenge ever faced by the world health community because of its multifaceted complex nature and its overwhelming impact over the human and veterinary communities. Livestock sector is no exception to have the serious and devastating impact from the emergence and spread of AMR. Because of a steady shift towards intensive farming and increased stocking density there has been increase occurrence of infectious diseases. Growing world population, rapid urbanization, and deforestation, shrinkage of grazing land all aided to this process. This leads to increased usage of antimicrobials in food animals – cause of concern for the scientific community as AMU is known the single most important driver of AMR.

Introduction

Antimicrobials, viz. antibiotics, antivirals, antifungals and anthelmintics are substances widely used to prevent and treat infections in humans, fish & prawn, livestock animals, and crops. In a situation where microorganisms such as bacteria, viruses, parasites or fungi become resistant to antimicrobial treatments to which they were previously susceptible, it is apprehended that antimicrobial resistance in the microbes has evolved. In fact, antibiotic resistant bacteria evade the effects of antibiotics and multiply in their own way leading to severe health consequences in human and animals. The menace is such that antimicrobial resistance (AMR) hinders treatment modalities targeted for infectious diseases. The hazards of antimicrobial resistance is frequently observed in various pathogenic and non-pathogenic organisms, viz. Salmonella spp., Campylobacter spp., Yersinia sp., E. coli serotype O157:H7, enterococci, Pasteurella sp., Actinobacillus sp. with varying severity (McEwen and Fedorka-Cray, 2002). Microorganisms that develop resistance to commonly used antimicrobials are referred to as superbugs. Globally it is a matter of great concern that it spreads rapidly and threatening the ability to treat common infectious diseases, resulting in prolonged illness, disability and death. Without any effective antimicrobial agent, treatment of infectious diseases, many medical procedures like cancer therapy, diabetes management, organ transplantation, and major surgery will not be possible. The microbes showing resistance to multiple antimicrobials are commonly known as multidrug resistance (MDR) organisms (Magiorakos et al., 2012).

Antimicrobial Resistance abbreviated as AMR is defined as the process by which microorganisms like bacteria, fungi, viruses, and parasites change over a period and become resistant to a drug to which they were earlier susceptible to. This makes the medicines ineffective for treatment overtime, thus making infections difficult to treat thereby increasing the risk of spread of diseases caused by them and severe illness which may lead to death. This in turn necessitates the need for development of newer antibiotics. However, there has been a sharp decline in the development and manufacture of new antibiotics in the recent years resulting in development of only few antibiotics in the past two decades. The increase in emergence of antibiotic resistance concurrent with decline in development of newer antibiotics poses a serious threat to health of both humans and animals. Every year about 700,000 deaths have been reported to occur due to resistant infections and this rate is likely to increase further with estimated infections due to resistant pathogens expected to reach over 50 million globally by 2050 (O’Neill, 2016). The worrisome trends of increasing antimicrobial resistance across the globe poses a serious threat to both animal and human health as AMR not only increases the morbidity and mortality rates but also increases the economic burden on health care (Zhu et al., 2022). This presents an extremely grave situation as the supply of new antibiotics is inadequate to cope with the increase of AMR pathogens. The unnecessary use of antibiotics globally especially in the livestock sector as growth promoter further helps in selective enrichment of AMR pathogens which further increases health risks. It is well known that resistant pathogenic and commensal bacteria can persist and spread within and between premises despite zero antimicrobial drug use. This may be explained due to maintenance, replication, and further dissemination of resistance genes by horizontal transfer of genes via natural ecosystem and can occur either by conjugation, transformation and transduction; and these mechanisms can rapidly spread AMR genes among microbial community in natural environment and human microbiome, where these resistant bacterial species may be selected due to presence of antimicrobial drugs (Zhu et al., 2022). The physical transfer of bacteria via movement of animals, workers, and equipment and ineffective cleaning and disinfection may also be responsible for increasing the AMR pathogens in the natural environments.

Introduction to Antibiotic Discovery

Antibiotics are the drugs that are used to treat illnesses caused by bacteria in humans and animals. These act by killing or inhibiting the growth and multiplication of bacteria. Antibiotics were considered as “magic bullets” that selectively kills microbes responsible for disease causation, but at the same time would not affect the host (Zaman et al., 2017).

Louis Pasteur in 1877, first discovered the properties of antibacterial compounds with the inhibition of anthrax by saprophytic bacteria. In 1928, Alexander Fleming observed that the growth of Staphylococcus aureus in petri dishes was inhibited by substances produced by the fungus Penicillium chrysogenum, which led to the discovery of the first antibiotic, penicillin (Aminov, 2017). Selman Waksman, discovered multiple antibiotics from filamentous actinomycetes living in the soil and defined an antibiotic as “a compound made by a microbe to destroy other microbes”. Following the discovery of Penicillin, various antimicrobial compounds such as sulphonamides, aminoglycosides, tetracyclines, lipopeptides, oxazolidinones, glycopeptides, streptogramins, and quinolones were discovered in the “Golden era” of antibiotics during the period from the 1940s to the 1960s and most of the antibiotics still in current use were discovered during that period (Salam et al., 2023). Millions of metric tons of newer classes of antibiotics have been produced in last 60 years since its inception.

Appendix 1 : Syllabus (For the Degree of Bachelor Of Veterinary Science And Animal Husbandry (B.V.Sc. & A.H.)

Introduction

Statistics generally refers to information about an activity or a process that is expressed in quantitate as well as qualitative traits. The quantitative research process is well structured whereas the qualitative one is fairly unstructured. It depends upon how a piece of information have been collected and analyzed. A good researchers need to have both types of skill. This article highlights about the operational procedure, about methods, procedures and techniques that are used in analysis of climate related data.

Parameter vs Statistic

When a data is collected with survey of all the individuals (like in a census) and analysed for certain values, it is called a parameter. But when, we guess the same value with a random sample and interpret for whole population it is called a statistic. Environmental parameters are: mean, variance, correlation, regression, heritability, repeatability etc. Again, there are two types of variables: quantitative and qualitative. Quantitative variables can take any value in a specified range. So, they are of continuous type. But qualitative variables are very few types ( 2 ,3 or 4 types) and they are of discrete type. Body weight is an example of quantitative variable whereas, comb type is a qualitative variable.

Good livestock welfare practices demands thorough understanding of the basic nature of the animal. The science of understanding the details of animal behaviour is known as Ethology.  Knowledge about the behaviour of the species being reared proved as an important tool for implementing animal welfare in practical husbandry practices. Now a day’s global community is also advocating for the better livestock welfare standards. Exploiting animal’s natural behaviour could certainly prevent unnecessary sufferings related to handling and restraining during routine farm activities. On the one hand this ensures physical and mental welfare of livestock, while on the other hand improvement in the production is guaranteed. Without involving heavy investment behavioural knowledge based management interventions can bring paradigm shift in welfare status of farm. Therefore, behavioural studies are of great importance in increasing our understanding and appreciation of animals.

Asiatic Elephant (Elephas maximus) is the national heritage animal of India. This particular species now exists in 13 Asian countries including India. As per 2017 census, India is home to an estimated figure of 29,964 elephants that is >60% wild population of the globe. Once distributed across the country, now they are squeezed to 14 states grouped in four regions ie., southern (14,612), north-eastern (10,139), east-central (3,128) and northern regions (2,085). There are 2675 captive elephants across different states under both private and government custody. This largest terrestrial mammal is protected under Seclude I species of Indian Wild Life Protection Act, 1972.

Both central and state Government are implementing short- and long-term programmes for health and well-being of captive as well as free-range elephants. The Central Government has established an ‘Elephant Cell’ at the Wildlife Institute of India (WII), Dehradun to provide technical inputs to the ministry for strengthening the efforts towards conservation of elephants. Add-on, the ‘Project Elephant’ was launched in 1991-92 in the Ministry of Environment, Forests and Climate Change to restore the elephant habitats and reduce their sufferings. Elephant habitats are notified as Elephant Reserves that are basic management units for elephant conservation and managements. A total of 33 Elephant Reserves has been notified in the country. A book titled, ‘Caring for elephants: Managing health and welfare in captivity’ is edited for field officers, veterinary professionals and elephant handlers.

Introduction

Nanotechnology and nanoparticles are increasingly recognized for their potential applications in various aspects of human animal and animal welfare like development of various healthcare or cosmetic products, nano-electronics and techniques for environmental remediation, and many consumer products. Nanoparticles, by definition, are structures that have one dimension in the 1–100 nm range. Nanotechnology involves the application of materials at the nanoscale to new products or processes. Over the past few decades, inorganic nanoparticles, whose structures exhibit significantly novel and improved physical, chemical, and biological properties, phenomena and functionality due to their nanoscale size, have elicited much interest. Nanophasic and nanostructure materials are attracting a great deal of attention because of their potential for achieving specific processes and selectivity, especially in biological and pharmaceutical applications. Nanotechnology has made a new generation industrial revolution by developing product and formulations for medical, agriculture (nano-fertilizers, nano-herbicides, nano-pesticides, recalcitrant contaminants from water, nano-scale carriers, nanosensors), veterinary care, fisheries and aquaculture, detection of nutrient deficiencies, preservation, photocatalysis, nanobarcode, quantum dots etc. It is a rapidly growing industry currently worth billions of U.S. dollars, with many potential benefits to society. Nanotechnology has the environmental applications to protect climate change and environmental pollution as nanocatalyst, light weight nanocomposite materials, nanocoatings, improved renewables and nanosensors.

This fast growing technology is already having a significant commercial impact, which will certainly increase in the future. Because of their widespread application, the commercial nanotechnology industry is predicted to increase significantly to more $3 trillion in few years. While nanotechnologies offer many opportunities for innovation, the use of nanomaterials in food, agriculture and environment has also raised a number of safety, environmental, ethical, policy and regulatory issues.

Surface anatomy of the organs of left side of abdominal cavity

Rumen

Topography of the rumen: The left side of the abdomen in cow is completely occupied by the rumen except for a small area occupied by the reticulum at its cranial end and the spleen on the craniodorsal aspect sandwiched between the dorsal border of rumen and the diaphragm. The rumen lies in contact with the left abdominal wall extending from seventh or eight intercostal space where it touches the diaphragm to the transverse plane of the tuber coxae where it almost touches the pelvic inlet.

Palpation of rumen: The rumen can be palpated in the left flank of the abdomen and is usually palpated in the dorsal third of the flank region. In ruminants, the contraction begins at reticulum and it continues in rumen in succession and hence is considered as ruminoreticular contraction cycle. It begins with double contraction of reticulum followed immediately by the contraction of rumen. The rumen contraction begins in the cranial sac and progresses to the dorsal sac and then to the ventral sac. During the contraction of the ventral sac, the dorsal sac is forced out which appears as a bulging at the paralumbar fossa. After this, there is a pause of 30 seconds and thereafter the second ruminal contraction begins which is usually associated with eructation. The ruminoreticular contraction cycle ends with the end of second ruminal contraction. Following this, the second cycle begins. Thus there are two palpable rumen contractions per minute. This rate of contraction increases to 2.8 contractions per minute during the act of feeding of the animal.

Site for nerve block

Brachial plexus block

The brachial plexus is the key source of nerve supply to the fore limb. Loss of sensation below the elbow is achieved by blocking the nerve roots contributing to this plexus. In ox it is formed by the ventral branches of 6th to 8th cervical and 1st and 2nd thoracic spinal nerves. These nerve roots pass over the lateral aspect of the middle third of the first rib before anastomosing to form the plexus. All these nerve roots can be blocked by injecting anaesthetic solution on these nerves at the middle third of the lateral surface of the first rib. To reach this site, the needle is inserted between the thoracic wall and the medial face of the shoulder at the level of acromion process of the scapula about 12 to 14 cm cranial to it horizontally in the caudal direction.

The blocking of brachial plexus is indicated for operations for reducing the fractures of the bones of fore arm and manus.

Teeth

Estimation of age from appearance of teeth

The teeth are used as a tool for estimation of age of animal. The time of eruption and the stage of wear of incisors are usually considered as parameters for this purpose. The time of eruption of the incisor teeth in ox has been described under the chapter on gross anatomy of head. The eruption time of incisors in other species is described under the chapter on comparative anatomy of head and neck. To differentiate the deciduous teeth from the permanent teeth is important criteria in this process. The deciduous teeth are smaller, their neck is visible just above the gum line and these are usually whitish in colour. The permanent teeth are larger, their crowns are slightly wider and the neck which separates the crown from the root is concealed inside the gums. These are usually yellowish in colour. In ox, all the four incisors (deciduous) are erupted at the age of 4 years.

The permanent teeth start wearing from fifth year onward. The process of wearing commences on mesiolabial side of the masticatory surface. When the entire masticatory surface is in wear, the outer and inner enamel rings are completely separated by yellow dentin and that particular tooth is considered as leveled. In the process of wearing, the gum starts receding and the neck of the tooth is exposed. In ox, usually the wearing begins at I-1 at the age of 6 years, this is followed by I-2 at 7 years, I-3 at 8 years and I-4 at 9 years. Up to the age of 14-15 years usually all incisors fall off but those remained are reduced to small round pegs.

Sites for surgical interventions

Luxation of patella in cattle and horses

The luxation of patella is a condition wherein the patella of the stifle joint (femoropatellar articulation) is locked above the medial ridge of the trochlea of the femur.

Anatomy of femoropatellar articulation of the stifle joint

The stifle joint is a composite joint formed in two parts. One of these is an articulation between the condyles of distal extremity of femur and the condyles of the proximal extremity of tibia (femoro-tibial articulation) and the other is the articulation between the trochlea of the distal extremity of the femur and the articular surface of the patella (femoro-patellar articulation).

The trochlea of the femur consists of two asymmetrical ridges separated by a groove. The medial ridge is more prominent, wider and a little more extended dorsally than the lateral ridge. The two ridges converge ventrally. The articular surface of the patella is more or less quadrilateral or triangular with the base above and apex below. It has a vertical ridge in the middle and it separates the two concave areas of which the medial one is larger than the lateral. The patella is fastened against the trochlea with the help of three types of ligaments. One of these is the capsular ligament which is attached to the periphery of the articular areas of the two segments of the joint. The other one is the medial and lateral collateral ligaments. The third set of ligaments is the patellar (straight) ligaments.

Surface locations for clinical examination on the wall of thorax

Lymph nodes

Prescapular lymph node is palpable as a cylindrical object just cranial to the point of shoulder. Palpation can be performed by putting the base of the hand on the cranial edge of the scapula and pressing forward with fingers. This enables to roll the skin and feel the lymph node flicking underneath the fingers.

Heart

The clinical examination of heart is performed by percussion and auscultation on the thoracic wall.

For percussion of heart, usually the fifth rib is identified opposite the olecranon of a straight vertical limb. Two fields are identified for percussion of heart. (1) The area of absolute cardiac dullness corresponds to the area of contact of the pericardium with the thoracic wall. It gives a flat sound on light percussion. (2) The area of relative cardiac dullness indicates the outline of heart which is covered by the thin margin of lung. It needs somewhat stronger percussion to define this area which is usually difficult in animals. The absolute dullness is used to test the hypertrophy, displacement and pericardial effusion. In ox, the normal area of absolute dullness is explored in the fourth and fifth intercostal spaces. Traumatic pericarditis may result in absolute dullness in these spaces extending above a horizontal line through the shoulder joint. In horse this area is a triangle bounded by the triceps in front, the sternum below and the lung along the line joining these two. On left side of the normal horse, the dullness extends about 7 cm above the olecranon in the fourth intercostal space and about 3 cm above the olecranon in the fifth space. On the right side, the dullness extends about 3 cm above the olecranon in the fifth space only. In dog, the area of absolute dullness extends about 1 to 2 cm above the sternum in the fourth and fifth intercostal spaces in the line with the corresponding costochondral junction.