eChapters

Introduction

Biological fluids refer to any liquid substances found within living organisms that play essential roles in physiological functions. These fluids can include blood, urine, cerebrospinal fluid, saliva, digestive juices, rumen fluid, peritoneal fluid, pleural fluid, pericardial fluid, synovial fluid, amniotic fluid, milk etc.

Collection of biological fluids refers to the process of gathering various types of bodily f luids from animals for scientific study or medical purposes. This collection often involves techniques like blood draws, urine collection, cerebrospinal fluid sampling, saliva collection, etc., depending on the specific fluid and the research or diagnostic needs. These f luids are valuable for understanding the health, metabolism, genetics, and other aspects of animal biology. Collecting and analyzing these biological fluids is crucial for understanding health and disease processes, diagnosing illnesses, monitoring treatment effectiveness, and advancing medical and scientific research.

Bovine
 
1.    PPR    Eye, mouth, rectal swab in PBS on ice, 10 ml blood  in anti-coagulant at height of temperature, Prescapular lymph node, spleen, piece of intestine on ice, lung, liver, spleen, tonsil in 10% neutral formol saline solution.

The tentative diagnosis of viral diseases of livestock can be made by clinical symptoms alone. The clinical diagnosis is substantiated by the laboratory to obtain a precise, correct and prompt diagnosis. The success however depends on the collection of suitable materials in proper transport medium at a particular stage of disease condition and its dispatch to the laboratory in a manner that little or no alterations occurs in the specimen. This would facilitate the isolation and identification of the causative viral agents easily.

Introduction

Colorimetry is a scientific technique widely used across various fields to quantify the concentration of substances based on their color intensity. Colorimetry is a branch of analytical chemistry that focuses on measuring the absorbance or transmission of light by colored solutions. It utilizes the principles of optics and spectroscopy to determine the concentration of a substance in a solution based on its color intensity. This technique relies on the Beer-Lambert law, which states that the absorbance of light by a solution is directly proportional to its concentration and path length.

Principles of Colorimetry

The fundamental principle of colorimetry lies in the interaction of light with matter. When light passes through or is reflected off a substance, certain wavelengths are absorbed, while others are transmitted or reflected. The color we perceive is due to the wavelengths of light that are reflected back to our eyes. In colorimetry, a photometric measurement is made using a colorimeter or spectrophotometer, which quantifies the intensity of light absorbed or transmitted by a sample.

The response of any living cell to a xenobiotic (including antibacterial agent) is significantly affected by the prevailing local environmental conditions. In case of bacterial infection, it may include the presence of other microbes, no matter commensal or pathogenic, or biochemical alterations at that particular site of bacterial infection in host. All these host and bacterial factors play a critical role in the evolutionary responses of bacteria but usually go unconsidered while determining the microbial sensitivity to a particular antibiotic in a clinical setting. These also include the direct and indirect interspecies interactions that can affect the responses of individual bacterial species and surviving microbial communities to a particular antibiotic therapy. These interactions may significantly alter the qualitative and quantitative responses, potential phenotypic changes and the final trajectory of evolution of antimicrobial resistance. Due acknowledgement and plausible interpretation to these interactions may help to reduce the upsurge in AMR and its associated morbidity and fatality and pave path to more proficient clinical success.

The factors participating in drug- microbe interaction can be classified into two broad groups: host factors and microbial factors. The environmental milieu of the interaction is chiefly regulated by the gut microbiota with stressors causing deflections. The gastrointestinal bacteria amend host mental and physiological cadence via microbial metabolites such as butyrate, polyphenolic antioxidants, vitamins, and amines, affecting the overall ready perception and active rebuke to a stimulus. Lifestyle stressors such as fluctuating sleep and erratic eating patterns (western diet) disturb the host circadian system along with the gut microbiome. The overall impact is impaired detoxification (decreased conjugation of bile acids or increased production of hydrogen sulphide), substrate oxidation and energy regulation (reduced butyrate production) in the host affecting the overall health and productivity.

Cellular stains are the colouring compounds used to impart different colours to varied type of cellular components and help in the demonstration of different micro-organisms such as bacteria, viral inclusions, fungal hyphae etc. The staining techniques enhance the contrast of tissue sections at microscopic level including histological, histopathological and cytological grounds. Before applying the special staining techniques on tissue sections few points which should be taken care include:
• Use of appropriate volume, concentration and type of fixative for preservation of tissue samples.
• Use of fixative with better compatibility as per the nature of tissues to be preserved.
• The tissue sections collected should not be very thick (5 mm approximately).
• Staining solutions should be immediately prepared where so ever required.
• Tissues must be sectioned with an ideal thickness between 4-6 microns.
Different types of stains routinely used to demonstrate varied type of cellular components and microorganisms:
Grocott’s Methenamine Silver (GMS) Staining Method
The fungal hyphae can be better demonstrated with Grocott’s Methenamine Silver stain (GMS). The basis for colouration of fungus is entirely based upon the oxidation of chromic acid forming aldehyde from the cell wall constituents of fungus and thereby reducing the silver-hexamine complex. The silverhexamine complex leads to the reduction of nascent Ag ions and leading the blackening of fungus in tissue sections.

Horse

The visceral branches of the abdominal aorta are the coeliac, cranial mesenteric, renal, caudal mesenteric and testicular or ovarian.

The coeliac artery in horse is shorter than that in ox. It arises from ventral surface of the aorta and reaches the dorsal surface of the pancreas where it divides into three branches, the left gastric, hepatic and splenic.

The left gastric artery passes ventrally and cranially in the gastrophrenic ligament, gives off pancreatic and oesophageal branches and divides dorsal and caudal to the cardia into parietal and visceral branches. The parietal branch crosses the lesser curvature of the stomach just to the right of the cardia and ramifies on its parietal surface. The visceral branch is distributed in the similar manner on the visceral surface of the stomach. A long but narrow oesophageal branch arises from the parietal branch of the left gastric, passes cranially through the hiatus oesophageus and enters the thoracic cavity dorsal to the oesophagus and anastomoses with the oesophageal branch of broncho-oesophageal artery.

The hepatic artery is larger than the left gastric. It passes dorsal to the pancreas and reaches medial to the portal vein, divides into right and left branches from which the terminal branches enter the liver through portal fissure. Its collateral branches are the pancreatic, right gastric and the gastroduodenal arteries. The gastroduodenal artery further divides into right gastroepiploic and the cranial pancreaticoduodenal arteries.

Horse

The shoulder joint of horse has same features as those of ox. However, this joint in horse exhibits greater degree of mobility.

The elbow joint of horse is almost similar to that of ox except that there is only one interosseous ligament in horse against two in ox.

The carpal joint of horse has only minor differences from that of ox. The special feature of the joint in horse is that it has two additional ligaments, the superior check ligament and the inferior check ligament. The superior check ligament starts from the rough elevation on the distal third of the caudal surface, close to the medial border of the radius and is inserted to the tendon of superficial digital flexor above the carpus. The inferior check ligament is the continuation of the caudal (palmer) capsular ligament of the carpus. It joins the tendon of deep digital flexor at about midway on the palmer surface of the metacarpus. The check ligaments assist the tendons of flexor muscles of the digits after severe exertion to keep then tight and prevent flexion.

Horse

Articulations of bones of skull

Most of the joints of the bones of skull are sutures similar to those in ox. However, in the adult horse many of the sutures are effaced. The ossification of the cartilage between the basilar part of the occipital and the sphenoid occurs quite earlier. The fusion of the mandibular symphysis takes place at about second to third month after birth. The temporomandibular articulation has an additional ligament which consists of elastic tissue. It connects the post-glenoid process to the caudal border of the ramys of the mandible.

Hyoidean articulations

In the hyoidean articulations, there is only one intercornual articulation in horse instead of the proximal and distal cornual articulations appearing in the ox. The middle cornu is generally lodged in the articulation between the great and small cornu.

Horse

The hip joint has an additional ligament called the pubio-femoral ligament. It arises from the prepubic tendon, passes dorsally and laterally and then caudally and lodges into the subpubic (pubio-femoral) groove, penetrates the capsular ligament, passes through the acetabular notch and is inserted into the fovea capitis behind the round ligament on the head of femur. This ligament is peculiar to solipeds and it prevents the side kicking. The absence of this ligament in ruminants allows them abduction freely and that is how the ruminants can kick sideways. As against this, the equines can kick only back way. The other difference about the hip joint in horse is that the cotyloid ligament is narrower because of the deeper acetabulum.

The stifle joint of horse in general resembles that of ox except that the middle patellar ligament is not so prominent as that in ox.

The tibio-fibular articulation in horse is a diarthrosis and an amphiarthrosis. The diarthrosis is formed between the lateral condyle of tibia and the head of the fibula. It has intimate capsular ligament. The amphiarthrosis is formed between the shafts of the tibia and the fibula. The shafts of the two bones are binded by the proximal and distal interosseous ligaments.

The hock joint of horse has minor differences with those of ox owing to the difference in the number of tarsal bones and their arrangement. The synovial membrane is supported everywhere except at the dorsomedial (craniomedial) aspect where it bulges out in the cases of bog-spavin. If there is a distension of tarsal sheath, it bulges out as two rounded swellings on either sides of the tendon of deep digital flexor. The movements at the hock joint are very limited.

Horse

The arteries of fore limb of horse are more or less similar in their course and distribution. However, there are some special features in respect of some of these arteries as described below.

The brachial artery descends vertically on the medial aspect of humerus to its distal extremity, crosses it obliquely and descends along the joint capsule and medial lateral ligament of elbow joint, gives off common interosseous artery at the proximal third of the forearm and then continues distally as median artery.

The median artery descends along the caudomedial aspect of the radius covered by flexor carpi radialis muscle and divides just proximal to medial condyle into radial and collateral ulnar (ulnar) arteries.

The collateral ulnar artery is smaller of the two terminal branches of median artery. It descends along the cranial surface of radius under cover of the extensor carpi radialis and terminates a little above the carpus by anastomosing with a branch of radial artery.

Arteries

Horse

The common carotid artery in horse has a similar origin, course and distribution as that in ox except that it has no relation with the internal jugular vein since this vein is absent in horse. Each common carotid artery at its termination in front of the digastricus gives out internal carotid artery in horse in addition to the occipital and pharyngeal arteries given off by the common carotid artery in ox.

The internal carotid artery which is absent in ox is present in horse. It is considered as chief source of blood for the brain in horse. It passes over the guttural pouch and enters the cranial cavity through the foramen lacerum and gains the cavernous sinus. The internal carotid arteries of the opposite sides are connected by a large transverse branch called the intercarotid artery that lies behind the pituitary gland (further course of this artery will be described with the blood supply of the brain in horse).

The external carotid artery which is a direct continuation of the common carotid artery after its termination in front of the digastricus muscle is related to guttural pouch during its course along with other structures described in ox.

Horse

The arteries of the hind limb of horse have in general similar architecture as that of ox except the special features mentioned below.

The deep circumflex iliac artery which is a branch of the external iliac artery in ox has a variable origin in horse. It may originate directly from the aorta or the common iliac trunk just prior to the origin of the external iliac artery. The prepubic and deep femoral arteries arise either by a common trunk or separately from the femoral artery. The obturator artery is a well developed independent branch of the femoral artery in horse as against its origin as a branch of deep femoral artery in ox. The saphenous artery is a small branch of femoral artery and it supplies the skin on the medial aspect of the thigh and leg. The popliteal artery terminates by its division into cranial and caudal tibial arteries at a lower level in horse than that in ox. The caudal tibial artery is larger and longer in horse than that in ox. From the proximal plantar arch extend four caudal metatarsal arteries instead of four, two of them are superficial and the other two deep branches. The large metatarsal artery descends along the groove between the large and lateral small metatarsal bone and divides just above the fetlock into lateral and medial digital arteries. Each digital artery divides at the middle of the wing of the third phalanx into preplantar and plantar digital arteries. The preplantar digital arteries supply the sensitive laminae of the sole. The plantar digital arteries of the opposite sides form anastomosis. Small laminar branches from the anastomosis form the circumflex artery of the toe which supplies branches to the sole.

Arteries of thorax

Horse

The bronchial and oesophageal arteries in horse have a common trunk of origin as broncho-oesophageal artery. It arises from the convexity of aortic arch, passes ventrally and caudally on the right side of the aorta and divides into bronchial and oesophageal arteries. The oesophageal artery passes caudally in the caudal mediastinum along the dorsal face of oesophagus and supplies branches to oesophagus, caudal mediastinal lymph nodes and pleura and anastomoses with the pleuro-oesophageal branch of the gastric artery.

The intercostal arteries are eighteen pairs in number. The first pair arises from the superior artery, the next three pairs come from subcostal artery and the remaining four arise from the thoracic aorta.

The phrenic arteries are not variable in origin as in the ox. They are small and are two to three in number. They arise on the ventral face of the aorta while it passes through the hiatus aorticus and enter the crura of the diaphragm.

The rest of the arterial branches of thorax in horse are similar to those in ox.

Stomach

Horse

The stomach of horse is a simple stomach. It is ‘J’ shaped sac with its right part very much shorter than the left part. It is situated in the dorsal part of the abdominal cavity behind the diaphragm and liver mainly to the left of the median line. The parietal surface faces craniad and dorsad and to the left. It is related to the diaphragm and liver. The visceral surface faces caudad and ventrad and to the right. It is related to the small intestine and colon. Its lesser curvature is short and the greater curvature is extensive. The left extremity is called the saccus caecus. It lies ventral to the sixteenth or seventeenth rib. It is related to pancreas and terminal part of greater colon caudally and to the base of the spleen laterally. The right extremity is the pylorus. It is smaller and is continued by duodenum. The stomach is fastened by several ligaments which include the gastro-phrenic ligament, the gastro- pancreatic ligament, the greater omentum, the lesser omentum and the gastro-splenic ligament. The capacity of the equine stomach is about 8 to 15 liters.

The wall of the stomach consists of four coats, the serous, muscular, submucous and the mucous. The mucous membrane is clearly divided into two parts by sinuous ridge called the margo plicatus. The part which is towards the left extremity is nonglandular while that towards the right extremity is glandular.

Horse

The ovaries in mare are bean shaped and much larger than those of cow. Each is about 7 to 8 cm long and about 3 to 4 cm thick. It weighs about 70 to 80 gm. These are situated in the sublumbar region under the fourth or fifth lumbar vertebra. They are usually in contact with the roof of the abdomen. The average distance of ovaries from the vulvar orifice is about 50 to 55 cm in the average sized mare. The notch on the free border leads to a depression, the ovulation fossa where ovulation occurs.

The uterine tubes are shorter and more flexuous in mare than those in cow. Each is about 20 to 30 cm long. At its ovarian end it is wider with a diameter of about 4 to 8 mm and becomes narrower at its uterine end with a diameter of about 2 to 3 mm.

The uterus in mare is situated partly in abdomen and partly in pelvis. The horns of the uterus are usually pressed against the sublumbar muscles by the intestine. When moderately distended they are about 25 cm long. The junction of the uterine horns with the body of the uterus is abrupt. The average length of the body is about 18 to 20 cm and its diameter is about 10 cm when moderately distended. The cervix is about 5.0 to 7.5 cm in length and 3.5 to 4.0 cm in diameter. The cervical canal is straight. The mucous membrane of the uterus has no cotyledons.

The vagina in mare is shorter than that in cow. It measures about 15 to 20 cm in length and 10 to 12 cm in diameter when slightly distended. Most of the vagina is retroperitoneal.

Horse

In addition to the common articulations of vertebrae, the lumbar region of horse has two special articulations, the inter-transverse articulations and lumbosacral articulations.

The intertransverse articulations are bilateral joints formed between the transverse processes of the fourth and fifth and between the fifth and sixth lumbar vertebrae. The articular surfaces of these joints are the oval facets on the transverse processes of these vertebrae, the cranial ones being concave while the caudal ones the convex. These are synovial joints (diarthrodial). The capsule of the joint is reinforced ventrally.

The lumbosacral articulations are diarthrodial joints formed between the transverse processes of the sixth lumbar vertebra and the wings of the sacrum. These joints are similar to the intertransverse articulations.

The sacroiliac articulation of the pelvis is similar to that of ox. However, the sacrosciatic ligament is broader. Its lateral surface is related to middle gluteus, biceps femoris and semitendinosus muscles.

Horse

Lymph nodes of the wall of abdomen and pelvis

The lumbar aortic lymph nodes extend from kidneys to the deep circumflex iliac vessels. These are not clearly distinguishable from the cranial and caudal mesenteric, renal, testicular or ovarian, uterine and iliac lymph nodes.

The internal iliac lymph nodes are placed at about the origin of the iliac arteries. The external iliac lymph nodes are several small nodes situated in the triangular space between the cranial and caudal branches of the circumflex iliac artery.

The deep (internal) inguinal lymph node is not abdominal in position. It is not situated at the pelvic brim. It is one of the group of the lymph nodes of the hind limb.

The superficial (external) inguinal lymph nodes are on either side of the penis and in front of the superficial inguinal ring in male and above the mammary glands as the supramammary lymph nodes in female.

The prefemoral lymph nodes are about a dozen small glands arranged in an elongated mass placed on the medial aspect of the cranial border of tensor fasciae lata and on the caudal branch of circumflex iliac artery.

Horse

The testicles in horse are oval in form and they are comparatively smaller in size than those in ox. The long axis of the testicles is parallel to the body of the animal and hence the attached border of the testicle is dorsal while its free border is ventral in position inside the scrotum. The testicle of the stallion is about 10 to 12 cm long, 5 cm wide and about 6 to 7 cm thick. It weighs about 225 to 300 gm. The size of the left and right testicle varies and the left testicle is often larger than the right one.

The epididymis is adhered to the attached (dorsal) border of the testicle. The rest of the features of epididymis in horse are similar to those of ox.

The vas deferens of horse right from its origin from the tail of epididymis to its course up to the dorsal surface of the bladder it has a uniform diameter of about 6 mm. Thereafter, it forms a fusiform enlargement, the ampulla of the vas deferens and beyond the ampulla the duct abruptly reduces in size. The ampulla is about 15 to 20 cm long and its diameter is about 2 cm. The genital fold is wider and hence the two ducts apart from each other. The vas deferens and the duct of seminal vesicle open in a common ejaculatory orifice on each side of the colliculus seminalis.

Horse

The muscles of lumbar spine in horse are more or less similar to those of ox. Of the sublumbar muscles, the psoas minor lies under the bodies of the lumbar and last three thoracic vertebrae. It arises from dorsal ends of sixteenth and seventeenth ribs and eighteenth thoracic vertebra and the first five lumbar vertebrae.

The psoas major arises from dorsal ends of last two ribs and the ventral faces of the transverse processes of the lumbar vertebrae. It is much wider than that of ox and covers the quadratus lumborum entirely.

The origin of iliacus muscle is limited to sacrum and ilium only. It has no lumbar origin and it is not so intimately united with psoas major muscle.

The quadratus lumborum is less developed.

The intertransversarii lumborum is absent between the fifth and sixth lumbar transverse processes.

The muscles of abdominal wall in horse do not have any striking differences, except that the obliquus abdominis externus is thicker and more extensive. The muscular portion of this muscle reaches the external angle of ilium and as high as lumbar transverse processes.