Veterinary Clinics of North America Food Animal Practice

Published by WB Saunders
Print ISSN: 0749-0720
A flexible dairy database program, Dairy Comp 305, is described to illustrate how a dairy database can support the decisions of a dairy producer and provide data for veterinarians to plan their production management programs.
Although underrepresented compared with infectious diseases, calves' surgical abdomen diseases and abdominal surgery are a part of daily veterinary practice. Clinical presentations may differ from adult cattle and change rapidly. The decision whether to perform abdominal surgery or refer the animal has to take into consideration the condition and its prognosis for the calf. This article discusses clinical presentation of calves and focuses on specific situations with a detailed description of the surgical techniques, atresia coli, and umbilical remnants infection.
In many patients, abdominal ultrasonography is an excellent diagnostic and prognostic tool. It aids in deciding whether the animal should undergo surgical or medical treatment or be slaughtered. This is particularly true in cattle with traumatic reticuloperitonitis (in combination with radiography of the reticulum) or with a tentative diagnosis of left or right displacement of the abomasum. Ultrasound also is an excellent aid for identification of ileus of the small and large intestine, liver abscesses, cholestasis, various urinary tract disorders, and the different forms of ascites.
Although abdominal emergencies may compose a large proportion of emergency situations for the rural practitioner or bovine specialist, these cases occur under widely different conditions and across a broad range of production settings. These unique conditions create a situation that is ripe for the attending veterinarian to forget to obtain important signalment, history, and physical examination data. Because many of these disorders can progress rapidly to an irreparable state, the attending veterinarian must methodically acquire this data if he or she is to formulate an accurate differential or definitive diagnosis, rational diagnostic plan, and effective therapeutic plan in a timely and orderly manner. In this article, the investigators review the salient signalment, historical data, physical examination findings, and important ancillary diagnostic tests for the most common abdominal emergencies of cattle.
This article describes the signs, hematologic alterations, and methods of diagnosis of digestive disorders that may be treated surgically. The necessity for surgical intervention is analyzed, based on clinical experience and current knowledge. The prognosis for surgical correction of common digestive problems and prognostic indicators for abomasal volvulus are described. Decision analysis for digestive surgery is reviewed, with examples for abomasal displacement and volvulus. Preoperative preparation for abdominal surgery--including facilities, equipment, supportive therapy, and distinction between elective and emergency surgery--is discussed briefly. The four most common surgical approaches for abdominal surgery are reviewed, and their indications noted.
Farm animals exhibit abnormalities of sexual, maternal, and other social behaviors as well as many stereotyped behaviors. The types and incidence of these abnormal behaviors may depend on the species, its diet, and the environmental conditions under which it is normally maintained. An understanding of the causes of various abnormal behavior patterns will enable the producer and veterinarian to better manage populations of livestock and improve their well-being.
The veterinarian is in a unique position to assist and improve the profitability of producers by educating clients on proper intervention and delivery techniques. This paper describes some procedures for intervention, evaluation, and management of dystocia by mutation, forced extraction, and fetotomy. In addition, a brief summary of the factors influencing dystocia is presented. When these techniques are used properly, losses due to dystocia are minimized.
Bull fertility depends partially on the quality of the spermatozoa (i.e., different spermatozoa defects) produced in the ejaculate, emphasizing the importance of the interpretation of the spermeogram results. This article discusses the production of normal and abnormal spermatozoa and the influence that spermatozoa defects may have on bull fertility.
Several congenital developmental anomalies are not listed in this review because they have no proposed cause. It is the author's hope that this article will serve practicing veterinarians and the swine industry by being an informative guide for stimulating independent thought toward diagnosing congenital diseases. Remember that the cause may have exerted its effects weeks or months before being observed. A detailed history of the dam as well as the rest of the herd is important. If possible, a history of neighboring herds should also be examined for similar problems. Either conduct a thorough necropsy with appropriate tissues submitted for diagnostic analysis, or send representative pigs to a diagnostic center for a complete evaluation. If chromosome evaluation is desired, contact the evaluating laboratory for submission procedures. Breeding records should be evaluated for intragenerational frequencies and intergenerational patterns typical of genetic transmission. When evaluating pedigrees, the frequent occurrence of an individual is not proof of its involvement. The frequency of occurrence in the diseased population must be significantly greater than it is in a random population of pigs. Dr. H.W. Leipold, in the pathology department at the Kansas State University College of Veterinary Medicine, maintains an extensive database of congenital anomalies in domestic animals. I recommend that he be contacted in all cases of undiagnosed or unusual cases of congenital disease. He possibly can help with a definitive diagnosis and your contact will help expand this important central database of congenital diseases.
The essential steps in embryology of the genitalia and its sexual differentiation, are briefly reviewed. The major intersex states in domestic ruminants and pigs are briefly considered. Major attention is directed to anomalies of the reproductive organs of mature female and male animals that are likely to compromise fertility. Emphasis is placed on clinical and pathologic findings and on occurrence and pathogenesis of recorded defects.
Congenital abnormalities of genetic and environmental causes constitute a striking proportion of the afflictions seen in goats. These include a variety of malformations and metabolic diseases that could occur in all breeds but tend to exhibit predisposition in some breeds of goats. Genetic abnormalities for which the carrier state is detectable with the aid of enzymes and surface protein markers can be eliminated from goat populations, whereas common polygenic disorders including udder problems in does and gynecomastia in bucks are more difficult to eradicate because the mutant genes responsible for these traits generally do not declare themselves until inbreeding brings together a critical concentration of liability genes to create a crisis. A substantial reduction of common abnormalities in this species, such as intersexuality in dairy breeds, abortion in Angora breed, and arthritis in the Pygmy breed, will require a change in breeders' preference and selection practice. In making these changes, however, the beneficial traits will have to be balanced against the undesirable effects of the selected mutant genes (pleiotropy), which hold the key to success or failure of a breed under domestication.
Many of these malformations are reported sporadically, but a few are common, and several have important clinical implications. One example is schistosomus reflexus, which is always a challenge for veteran clinicians and often baffling to inexperienced obstetricians. The recent finding that early palpation of the amniotic vesicle can cause intestinal atresia in calves is extremely significant for dairy practitioners. Finally, there is the ethical question in breeding animals--repairing defects that are thought to be genetic, such as atresia ani, scrotal hernia, and umbilical hernia.
A careful physical examination of a cow or heifer suspected of having an ovarian problem often results in a specific diagnosis (e.g., freemartinism) or a workable list of differentials. When the diagnosis is uncertain, techniques such as rapid progesterone assays, ultrasonographic imaging, ova or embryo recovery, and cytogenetic evaluation can provide critical information for a well-based diagnosis and prognosis. Despite the wide array of problems that can afflict the bovine ovary, cystic ovaries probably are the most commonly diagnosed and treated ovarian abnormality. Cysts have a variable life span and sometimes occurs together with a CL. Hormonal therapy with either GnRH followed by PG approximately 9 to 14 days later, or GnRH alone, followed by good heat detection is the treatment of choice for cows with cysts. Other conditions associated with ovarian dyfunction and infertility include adhesions, developmental anomalies, and tumors. The life span of a CL in the cow can be shortened unintentionally by attempting to correct other problems (e.g., multiple injections of oxytocin for milk let-down), or lengthened by uterine pathology (e.g., pyometra, or uterus unicornis). The administration of GnRH or hCG to improve ovarian function and pregnancy rates in cows may be beneficial in selected herds.
This article reviews three disorders associated with multiple asymmetric cranial nerve deficits in ruminants: encephalitic listeriosis,otitis media/interna, and pituitary abscess syndrome. Emphasis is placed on encephalitic listeriosis, an infectious disease of the brainstem and cranial nerves caused by Listeria monocytogenes. The epidemiology, pathophysiology, clinical manifestations, diagnosis,and treatment of encephalitic listeriosis are reviewed, and differences between cattle and small ruminants are noted. Physical and neurologic examination findings that distinguish otitis media/interna and pituitary abscess syndrome from encephalitic listeriosis are highlighted.
It must be remembered that viral infections and maternal nutritional deficiencies can and do cause congenital skin diseases and must be included in a complete differential diagnosis list. These disorders are covered adequately in most current texts on infectious and nutritional diseases and therefore are not described here. When an hereditary, congenital skin disease is suspected, biopsy specimens should be submitted for diagnosis. Many breed associations have control programs for these types of diseases and only with veterinary and producer cooperation will these programs be successful.
The increase in number of food-producing animals each year implies that even small prevalences of congenital anomalies in these ruminant species are still reflected in a significant number of affected animals born each year. It takes a specific investigation to show the true incidence of such congenital abnormalities. This article discusses recent research into several conditions to demonstrate the opportunities that exist for investigating such conditions both from a genetic and an environmental perspective.
The normal development of the horn capsule (epidermis), with its dermal support (corium), is described. Abnormalities of horn growth may be caused by changes in blood flow (laminitis), the biomechanics of weight bearing, heritable developmental conditions, and other changes of unknown cause.
The heritability and diagnosis of congenital abnormalities in food animals have been reviewed from the viewpoint of practitioners, clinicians, and researchers. At least 632 putative mutant genes have been cataloged and listed according to the principal body system affected and mode of inheritance (see Tables 1 and 2). Implications of recent advances in genetic methodology are noted.
Chromosome abnormalities have been described in food animals since 1964. Some are self-limiting because they cause sterility or other developmental defects incompatible with normal growth and development, making them unacceptable for production systems. Others, however, cause no discernible phenotypic abnormalities but, in breeding animals, result in increased levels of embryonic mortality and reduced litter size. Although the extent of loss of reproductive efficiency is not entirely understood at this time, care must be exercised in recommending animals carrying a chromosome abnormality to be used as breeding stock. This is of particular concern if animals are to be used extensively in artificial insemination programs.
Abnormalities of the tubular reproductive tract are responsible for decreased fertility in the cow. Typically, these are related to congenital defects such as segmental aplasia or to acquired conditions resulting from infections or trauma caused during breeding or parturition. Infection of the tubular tract may result in vaginitis, cervicitis, metritis, endometritis, pyometra, or salpingitis. Trauma to the tract may result in urovagina, pneumovagina, or prolapse of the vagina or uterus. Retained placenta may result in metritis. Potentially, all of these conditions, unless properly treated, may result in reduced fertility or, in the extreme, sterility. Judicial and properly timed use of antibiotics and ecbolic agents should return the tract to proper function with little or no reduction in fertility. Some conditions, such as prolapse, retained placenta, and pneumovagina, may call for manual or surgical intervention for successful resolution.
This article discusses the different methods used for the correction of left displaced abomasum. The advantages, disadvantages, and success rates of each technique are reviewed. The most common complications are described, and the economics of repeat surgery after a failed left displaced abomasum repair are examined. This article also addresses the need for anesthesia when dehorning and tail docking dairy cattle. The justifications for routine use of these two procedures are discussed, mainly from an animal welfare standpoint.
Abomasal hypomotility is a prerequisite for abomasal displacement in cattle and is present immediately after surgical correction of left displaced abomasum or abomasal volvulus. Hypocalcemia, hypokalemia, and hyperinsulinemia should be corrected in cattle suspected to have abomasal hypomotility. The most effective prokinetic for calves and adult cattle suspected to have abomasal hypomotility is erythromycin.
This article reviews the current knowledge on the pathophysiology of abomasal ulcer formation and abomasal tympany in calves. The development of ulcers and bloat has been attributed to many factors, including coarse feed, environmental stress, vitamin and mineral deficiencies, and bacterial infections. This article discusses various factors thought to play a role in the development of these abomasal conditions in calves.
To reduce the potential drawbacks associated with laparotomy techniques for correction and fixation of left displaced abomasums (LDA), minimally invasive techniques have been developed. This chapter reviews the toggle pin suture (TPS) and the laparoscopic abomasopexy procedures used in the field for correction and fixation of the abomasum for correction of left-displacement of the abomasum in dairy cows. The importance of case selection cannot be overestimated. By combining laparoscopy with the principle of the TPS procedure, the lack of visual control associated with the TPS procedure is eliminated, while the advantage of the speed of completion and minimal invasiveness provided by both procedures are maintained. Successful LDA treatment includes not only early detection and treatment of the LDA, but also the prevention of secondary ketosis and aggressive treatment of concurrent disease.
Results of studies on metabolic variables that exist prior to the diagnosis of displaced abomasum (DA) indicate that subclinical ketosis is a risk factor for DA. Serum aspartate aminotransferase activity, serum and milk betahydroxybutyric acid concentrations, and milk fat-to-protein ratios were often elevated before the diagnosis of DA, and these variables may be used to predict DA. Prevention of subclinical ketosis may prevent DA.
Intensive management of cattle has resulted in an increased incidence of abomasal disorders. Many of these disorders require surgical intervention for the best outcome. This article reviews the anatomy and physiology of the abomasum, abomasal disorders that may be treated by surgery, and the advantages and disadvantages of various surgical approaches to those disorders.
The abomasum is the "true stomach" of the ruminant and contains glandular mucosa for production and secretion of digestive juices. The three forestomach compartments (reticulum, omasum, and rumen) are comprised of nonglandtilar mucosa and serve as chambers for microbial digestion and fluid absorption only. Being the only stomach compartment that produces and secretes digestive juices, its function is very important to the ruminant. Dysfunction of the abomasum can be divided broadly into diseases that alter abomasal outflow and those that result in loss of abomasal wall integrity (Fig. 1). Dysfunction of the abomasum can result in very severe metabolic consequences.
This article summarizes control measures for the most common causes of abortion in North America, New Zealand, the United Kingdom, and Europe. When dealing with an abortion outbreak in a flock or herd, diagnostic investigation is critical to assuring that any future control measures are effective and worthwhile. Biosecurity is an important consideration for any abortion control program, and should be promoted regardless of whether an abortion problem exists in the flock. Many of the infectious agents that cause abortion in small ruminants are also zoonotic pathogens, and producers should be educated to avoid risk to themselves and their families.
A multitude of in utero infections may cause abortion, stillbirths, or the birth of weak calves (see Table 1). Because the diagnostic success for determining the cause of abortions may be low (25%-40%), it is important that more knowledge about the causes and differential diagnoses is gained, and proper samples are collected and submitted. Use of an abortion diagnosis kit enables multiple samples to be analyzed and increases the likelihood of making a diagnosis. The immune response is suppressed during pregnancy. In part, this can be controlled by proper nutrition and appropriately timed vaccination programs.
Successful abortion diagnosis in ruminants involves input from the producer, practitioner, and diagnostician. Unfortunately, despite best efforts, many investigations still result in a diagnosis of idiopathic abortion. If this diagnosis is made after a complete and systematic investigation of appropriate and reasonably preserved samples, some comfort can be taken that practitioners and diagnosticians did their best for the benefit of the producer. As new diagnostic technology is developed for abortion diseases, hopefully this best will only get better.
This article provides a review of the major infectious diseases responsible for bovine abortion and fetal loss. Parameters necessary for disease recognition and diagnosis are emphasized.
Stillbirths, mummies, abortions, and early embryonic death have a substantial impact on the profitability of a farm in both endemic and epidemic conditions. Fetal death is highly dependent on stage of gestation. Implantation occurs around day 14 postmating in sows, and fetal death of an entire litter at this time usually results in a regular return to service. If more than four embryos remain alive, the sow may go on to farrow normally. If fetal death occurs after implantation but before calcification (around 35 days gestation), the sow will either return to estrus at an irregular interval or will farrow a normal litter of reduced size. Although fetuses are normally resorbed prior to calcification, fetal death after that stage of development leads to mummification. Abortions are more directly related to maternal control of pregnancy than fetal failure. Stillbirths are those pigs that appear normal at birth but have lungs that do not float in water. Causes of fetal death can be divided into infectious and noninfectious categories. Infectious causes perhaps are overemphasized but are certainly important in epidemic situations. Some infectious causes of fetal death are primarily systemic maternal pathogens, whereas others may attack the fetus and/or placenta, directly such as PPV, PEV, PRV, SIRS virus, and Leptospira sp. Several other infectious agents have been associated with fetal death. Noninfectious causes of stillborns, mummies, abortions, and early embryonic death are most common in endemic situations. Most stillbirths are due to difficulty at or around parturition, primarily extended duration causing fetal anoxia. Environmental factors such as increased ambient temperature and seasonal infertility affect death rates, as do specific individual sow characteristics, nutritional factors, and toxicities. The causes of stillborns, mummies, abortions, and early embryonic death are often difficult to ascertain, but the potential rewards make investigation efforts worthwhile.
Swellings of the umbilical stalk, with or without herniation, are common findings in calves. Differentiation of involved structures is helpful in deciding the surgical approach and type of anesthesia required. This article deals with clinical signs, diagnostic procedures, and surgical techniques used to repair problems related to the umbilical stalk.
Liver abscesses in feedlot cattle result from aggressive grain-feeding programs and are influenced by a number of dietary and management factors. They have a major economic impact on the feedlot industry because of liver condemnation and reduced animal performance and carcass yield. Ruminal lesions resulting from acidosis usually are accepted as the predisposing factors. Generally, control of liver abscesses in feedlot cattle has depended on the use of tylosin, which reduces abscess incidence by 40% to 70%. However, new methods and products for liver abscess control are needed. Corn milling by-products that are less fermentable may aide in the quest for cattle production techniques that lead to lower usage of antimicrobials. A vaccine is also commercially available.
Sheep producers throughout the United States have begun using accelerated lambing programs to enlarge their net income by increasing the number of lambs produced per ewe per year. These new intensive systems have produced some unique problems and concerns. This article attempts to educate the veterinarian as to the justification for these programs. Areas in which veterinary intervention can greatly influence the success or failure of these new accelerated lambing systems are identified. Selection of ewe type, ultrasound pregnancy diagnosis, ram evaluation, specific flock health concerns, and critical ewe nutrition are discussed.
Dairy practice demands fair compensation for services rendered. If practitioners shortchange themselves when setting fees, they will have to shortchange their employees by paying less than adequate wages. Newly graduating practitioners must be told the realities of practice economics so that consequences of unrealistic expectations are not suffered. Employers must attempt to structure practice opportunities for new associates by establishing workable standards for buying into the practice as well as equitable means for retirement from practice.
Accurate, specific diagnosis of bovine neurologic disease is both possible and necessary in practice settings. The requirements for accurate diagnosis are a knowledge of the pathogenesis and epizootiology of the bovine neurologic diseases as described in this issue and a systematic approach to clinical examinations including accurate history taking, careful physical examination, neurologic examination, and inspection of the environment. Support for an accurate diagnosis can be obtained by use of the clinical pathology laboratory and, in herd problems, necropsy. The value of a precise diagnosis in bovine neurologic disease lies in the avoidance of costly, inappropriate therapy, the restriction of transmission of zoonotic disease, avoidance of ineffective treatment, more efficient salvage of affected individuals, and cost-efficient implementation of appropriate preventive measures as well as a sense of professional satisfaction in overcoming a challenging and difficult diagnostic problem.
Diagnosis and treatment of traumatic conditions of the hip joint in cattle remain a challenge for the veterinarian. This article is intended to give an overview of the most common orthopedic problems of the bovine coxofemoral joint, diagnostic procedures, and treatment options.
Mortality from digestive diseases in feedlot cattle is second only to that from respiratory diseases. Acidosis is a major digestive disorder and is likely to continue because of ongoing attempts to improve the efficiency of beef production by feeding more grain and less roughage. Subacute acidosis is the most prevalent form of acidosis in feedlots but is difficult to diagnose because of the absence of overt clinical signs. Control of acidosis is achieved largely by sound nutritional management. No single strategy or solution exists; however, an effective management strategy should factor in dietary formulation, a consistent feeding program, prudent bunk management, use of nonstarch by-products, and feed additives to minimize pen-to-pen and animal-to-animal variations in feed intake.
In neonatal calves metabolic acidosis is a common sequela to diarrhea-induced dehydration and endotoxemia in the aftermath of gram-negative bacterial infections. Without treatment, metabolic acidosis is a prime factor in the death of many of these calves. This article begins with a general discussion about the causes and recognition of metabolic acidosis. The remaining sections detail the subjective and objective methods available to assess the severity of acidosis and treatment options for this metabolic condition.
Metabolic acidosis is one of the prime factors responsible for the death of many diarrheic calves. This article begins with a general discussion about the recognition of metabolic acidosis. The remaining sections detail the utilization of certain subjective and objective methods to assess the severity of acidosis as well as the approach to treatment of this metabolic condition.
Dairy cows visit a state of negative energy balance (NEB) as they transition from late gestation to early lactation. At the individual level, there are several metabolic adaptations to manage NEB, including mobilization of nonesterified fatty acids (NEFA) from body fat reserves and glucose sparing for lactogenesis. Based on current pen-level feeding and management practices, strategies to minimize excessive NEB in both the individual and herd should focus on herd-level testing and management. This article reviews strategies for testing and monitoring of excessive NEB at the herd level through individual testing of 2 energy markers: NEFA and β-hydroxybutyrate.
Acquired spinal cord diseases in ruminants result most commonly from infectious, traumatic, metabolic/nutritional, or toxic causes and rarely from neoplasia. Clinical signs of spinal cord disease depend on the neuroanatomic location of the lesion. Acquired spinal cord diseases including vertebral osteomyelitis/spinal abscess, cauda-equina disease, enzootic ataxia, lymphosarcoma,polyradiculoneuritis, and degenerative myeloencephalopathy are discussed. Acquired peripheral nerve disease in cattle most often is a result of injury, and most commonly only one limb is involved. Peripheral nerve injuries frequently occur secondary to myopathy in recumbent adult cattle. In small ruminants, peripheral nerve injury seems less common, most likely due to their smaller size,but may occur from predator wounds or iatrogenically following intramuscular drug administration. Injury to the brachial plexus and radial, suprascapular, sciatic, femoral, and obturator nerves is discussed.
Dairy practice often requires substantial time commitments. Those veterinarians with families may find that if they do not actively budget some time for spouse and children, the family unit may suffer. A successful practice and meaningful family life are both possible if the doctor or doctors involved are willing to work for their achievement.
Quinolizidine and piperidine alkaloid teratogens from Lupinus, Conium, and Nicotiana genera have been identified as causes of birth defects in livestock induced by poisonous plants. Many defects now known to be related to poisonous plant ingestion were once thought to have a genetic origin. This supposition delayed diagnosis, reporting, and understanding of such birth defects, because breeders and producers feared the news would make it difficult to sell breeding stock. Defects caused by quinolizidine and piperidine teratogens include cleft palate and contracture-type skeletal defects such as arthrogryposis, scoliosis, torticollis, and kyphosis. Teratogens have been identified, differences in susceptibility to teratogenic compounds among livestock species have been elucidated, periods of gestation when specific types of birth defects occur have been determined, and information about mechanism of action has been developed.
This article discusses the cause and pathophysiology of peracute and acute mastitis. The pharmaceutic and pharmacologic properties of potential therapeutic agents, the interaction between the cow and the drug, and some practical aspects of using these drugs are reviewed.
Ketosis and fatty liver occur when physiologic mechanisms for the adaptation to negative energy balance fail. Failure of hepatic gluconeogenesis to supply adequate glucose for lactation and body needs may be one cause of ketosis; however, poor feedback control of nonesterified fatty acid release from adipose tissue is another likely cause of ketosis and fatty liver. The types of ketosis resulting from these two metabolic lesions may require different therapeutic and prophylactic approaches.
Top-cited authors
Thomas Herdt
  • Michigan State University
S. M. Mcguirk
  • University of Wisconsin–Madison
Garrett R. Oetzel
  • University of Wisconsin–Madison
David E Anderson
  • University of Tennessee
Jesse Goff
  • Iowa State University