49. Bovine Medicine and Management

CHAPTER 49. Bovine Medicine and Management

William Raphael and Daniel L. Grooms




HUSBANDRY






I. Nutrition




A. All ruminants have special capacity to ferment fiber in the forestomachs to produce propionic, acetic, and butyric acids


B. Fiber measured as acid detergent fraction or neutral detergent fraction (ADF + hemicellulose)




1. Dairy: Ensiled feeds, corn silage and alfalfa haylage, predominate


2. Beef: As above for feedlots, pasture for cow-calf operations


C. Propionic acid is gluconeogenic in the liver


D. Acetic and butyric acids are lipogenic in adipose and the udder


E. Bacterial fermentation of soluble sugars and starch can occur rapidly and lead to overgrowth in Lactobacilli spp. and Streptococcus bovis, with rumen pH decreasing to less than 5.0


F. Butyric and propionic acids important for rumen pilli growth


G. Fermentation chamber is also a source and starch of protein




1. Bacterial death and passage out of forestomachs represent an excellent quality and an efficient source of protein for the ruminant


2. Energy and protein are fed to maximize rumen microbial protein synthesis of this manner, then extra protein requirements (e.g., lactating dairy cow) are met by feeding rumen-protected protein, which is absorbed in the intestinal tract and not consumed by rumen microbes


H. Calcium




1. Metabolism can be manipulated by feeding chloride or sulfate salts to diet so that it is close to neutral in electrical charge


2. Effect is easily monitored by measuring urine pH


3. Desired urine pH = 5.5 to 6.5


4. Normal bovine urine pH = 8.0


5. Numerous mechanisms, one of which involves parathyroid hormone (PTH) receptor shape change, resulting in more efficient bone calcium mobilization at commencement of lactogenesis, and hence prevention of hypocalcemia (milk fever)


6. Typically implemented for 2 to 3 weeks prepartum in dairy cattle


I. Energy balance




1. Body condition scoring


2. Five-point scale (dairy)-Subjective measure


J. Metabolic profile testing




1. Random selection of an appropriate number of cows to get representative metabolic profile of the entire group in that particular stage of the production cycle


2. Nonesterified fatty acids, β-hydroxybutyric acid




a. Quantify energy balance


b. Commonly measured in cows close to calving


c. Correlate with dietary composition, preparation, delivery, and consumption, and all variables affecting these


3. Urea, albumin




a. Quantify protein metabolism


b. Commonly measured in cows prebreeding, urea often in milk


c. At high concentrations, urea is thought to negatively affect fertility


4. Micronutrients (e.g., vitamin E, selenium) to diagnose deficiency or toxicity



L. Gossypol toxicity




1. Possible when excessive quantities of whole cottonseed or meal are consumed


2. Clinical signs vary. Gastrointestinal (GI) mucosal hemorrhage and necrosis, cardiac and skeletal muscle and hepatic necrosis can occur. Male infertility (compromised spermatogenesis, proximal droplets, recoverable) is the most common effect


3. Feed less than 6 to 8 lb/day to lactating cows, avoid in bulls


M. Sodium toxicity




1. Most common in calves, when water has been withheld, and most common in winter in cold climates when water sources have frozen and milk replacer may be fed at high concentrations


2. Pathophysiology: Hypernatremia, acute intravascular hemolysis, cerebral edema


3. Clinical signs present shortly after water ingestion




a. Blindness, hyperexcitation, recumbency, coma


b. Hemoglobinuria, hemoglobinemia, anemia


4. Treatment: Grave prognosis. Involves slow dilution of serum sodium with decreasing (toward normal) concentrations of sodium containing intravenous (IV) solutions


II. Housing




A. Ventilation




1. Determinant of respiratory health


2. Removes exhaled microbes and water and volatized chemical irritants (NH 3) from animals’ environment


3. Concentration of upper respiratory tract flora in inspired air increases in poorly ventilated environments, resulting in deeper colonization of the respiratory tract


4. Can be achieved without motorized equipment. e.g., open eaves, ridges, side and end walls


B. Flooring




1. Always concrete


2. Determinant of hoof health


3. Excessive hoof wear from concrete can exist. Also determined by distances cows are walking and presence of other abrasive material (e.g., bedding material)


4. Interdigital dermatitides transmitted from unsanitary walking surfaces


C. Bedding




1. Sand is superior in comfort and sanitation


2. Represents challenges in manure removal because it is nonmiscible


3. Many mattress styles are alternatives to sand




a. Less day-to-day maintenance is required than sand stalls


b. Can be uncomfortable for cows, leading to hygromas and pressure lesions over bony prominences


D. Stray voltage




1. Rare but possible cause for ill thrift. Occasionally legitimately diagnosed as cause of behavioral changes (e.g., feeding, milking, moving behaviors). Common misdiagnosis of many metabolic and infectious diseases


2. Caused by low voltage electric shock, which may not be detectable to producer


3. Sources include distribution network and farmstead wiring


4. Prevented by maintaining electrical systems to best possible standards


E. Electrocution




1. Sources are usually lightning strike, fallen transmission line, or barn short


2. Pathophysiology: Nervous shock, nervous tissue necrosis, burns (from contact point to ground), fractures (possibly because of sudden, profound muscle contraction)


3. Clinical signs: Sudden death with skin burns, or bone fractures, temporary unconsciousness with residual depression, blindness, ataxia, skin sloughing


MANAGEMENT






I. Dairy




A. Products are milk, beef, and replacement heifers


B. Milk production measured as daily cow average (lb) or cow lactation average (standardized to first 305 days of lactation and adjusted for age, season, and region [305 ME])


C. Goal is to calve annually


D. Calves are weaned from dam at birth and from milk (or milk replacer) at approximately 8 weeks of age


E. Goal is for first calving at 23 to 24 months of age, conceiving at 14 to 15 months and 850 lb body weight, 51 inches tall at withers


F. Predominant breed is the Holstein. Other common breeds in the United States include Jersey, Ayrshire, Guernsey, Brown Swiss, and Milking Shorthorn.


G. Recombinant bovine somatotropoin (rBST) administered in some regions of the United States, although a large drop in consumer demand for milk produced this way occurred in 2007/2008.




1. Administered from 57 days after calving


2. Approximately 10-lb increase in daily milk production


3. Safe to animals and consumers


H. First breeding not usually before 60 days after calving (days in milk)


I. Hormonal reproductive synchronization commonly used




1. Ovsynch, gonadotropin-releasing hormone (GnRH) day 0, prostaglandin F 2α (PGF 2α) day 7, GnRH day 9, artificial insemination (AI) day 10


2. G6G/Ovsynch preceded by GnRH by 6 days, and PGF 2α by 8 days


3. Presynch, Ovsynch preceded by PGF 2α by 12 and 26 days



K. Longevity: Two to three lactations


L. Vaccination




1. Leptospirosis, especially Leptospira borgpetersenii serovar hardjo (type: hardjo-bovis), at young age


2. Respiratory viruses (bovine viral diarrhea [BVD] types 1 and 2, bovine respiratory syncytial virus [BRSV], infectious bovine rhinotracheitis [IBR], parainfluenza-3 [PI-3], around time of weaning and then annually


3. Clostridial diseases


4. Escherichia coli bacterins, aid in prevention of coliform mastitis


5. Miscellaneous others


M. Parasite control




1. Internal parasites cause disease in young cattle. Housed cattle are at decreased risk than grazing cattle, but parasitism still occurs




a. Eimeria spp., weaning to 8 months


b. Helminths ( Ostertagia ostertagi, Trichostrongylus spp., Cooperia spp., Nematodirus spp.), weaning to first calving


c. Control by selective deworming, rotational grazing (if appropriate), and monitoring of fecal egg counts for detection of anthelmintic resistance


d. All internal parasitism can be controlled by reducing egg burdens in the animals’ environment, with sound management practices such as regular bedding and barn cleaning


2. Lice cause pruritis and alopecia in winter months and can contribute to transmission of ringworm. Treat with late fall, early winter endectocide


II. Beef




A. Industry segments




1. Seed stock: The segment of the industry that specializes in breeding cattle with high genetic merit for sale to the commercial cow-calf industry


2. Commercial cow-calf: The segment of the industry that focuses primarily on reproducing cattle for food supply


3. Stocker-backgrounder: The segment of the industry that takes weaned calves destined for food supply and adds lean weight to them using low cost feeds such as pasture


4. Feedlot: The segment of the industry that fattens cattle destined for food supply using primarily high concentrate diets


B. Beef life cycle




1. Breeding: Cows are bred during a limited period, often 60 to 90 days


2. Calving: Typically timed to coincide with a period when high-quality feeds are readily available to support milk production for newborn calves


3. Weaning: Typically 4 to 6 months of age. Weaned calves are destined to become either breeding herd replacements (heifers or bulls) or to be fed out for slaughter


4. Stocker-backgrounder-feedlot: These animals are not used for breeding and enter the fed cattle segment of the beef industry, a terminal enterprise


C. Performance parameters




1. Expected progeny differences: An estimate of the genetic value of an animal as a parent


2. Birth weight


3. Weaning weight: Adjusted to 205 days of age


4. Yearling weight


5. Pregnancy rate: Number of cows pregnant over the number of cows bred


6. Calving percentage: Number of calves born over the number of cows bred


7. Weaning percentage: Number of calves weaned over the number of cows bred


8. Average daily gain


9. Feed conversion efficiency: Pounds of feed per pound of gain


10. Body condition score: Subjective evaluation of the body condition of cows. Used to manage nutritional programs. Beef scale is 1 to 9; 1 is thin or underconditioned, and 9 is fat or overconditioned


11. Percent Choice: Percent of feedlot cattle that were graded as Choice or higher at slaughter using the USDA Carcass Quality Grade Standards.


D. Cow calf industry





2. Calving: Calves born in barns, in calving pens and dry lots, or on pasture


3. Passive immunity is derived from colostrum which is ingested by nursing cows


4. Cows raise calves until weaning




a. Cows fed (most commonly) pasture


b. Calf growth is dependent on nutrients derived primarily from milk


c. Calves may be offered supplementary grain (creep feed)


5. Weaning: Calves weaned 4 to 6 months after birth; raised separate from cows


E. Seed stock industry




1. Management is similar to cow-calf industry


2. More attention is focused on specific matings to produce genetically superior replacement animals


F. Stocker-backgrounder




1. Stocker or backgrounding operations take recently weaned calves and prepare them for the feedlot


2. Goal is to put on weight gain, primarily in the form of structure (muscle and bone) using low cost feeds such as grass or grass-based silage


3. Post-weaning health issues such as bovine respiratory disease (BRD) is managed


4. Cattle are sorted and packaged into larger and uniform groups that are desirable to the feedlot


5. Health protocols




a. Vaccination against common cattle pathogens including:




(1) IBR


(2) Bovine viral diarrhea virus (BVDV)


(3) BRSV


(4) PI-3


(5) Mannheimia haemolytica and Pasteurella multocida


(6) Histophilus somnus


(7) Clostridial spp.


b. Internal and external parasites


c. Castration and dehorning


G. Feedlot




1. A feedlot or feedyard is the segment of the beef industry used for finishing cattle before slaughter


2. Cattle are typically fed high-concentrate diets to encourage the deposition of intramuscular fat


3. Vaccination and parasite control are similar to background cattle


H. Beef quality assurance or beef quality and safety assurance




1. Voluntary industry driven initiative to reduce the risk of quality and safety defects in the product (meat) provided to consumers


2. Aim is to educate all segments of the industry on management strategies to reduce risk of introducing quality or safety defects


3. Components




a. Feedstuffs




(1) Reduce risk of contamination from molds, mycotoxins, or chemicals


(2) Feeding of ruminant derived proteins is strictly prohibited because of the risk of bovine spongiform encephalopathy (BSE) transmission


(3) Only Food and Drug Administration-approved medicated feed additives are used


(4) Extra-label use of feed additives is illegal and strictly prohibited


b. Records: Accurate, complete, and up-to-date records need to be maintained for all procedures performed or products administered to cattle


c. Cattle care and husbandry




(1) Proper cattle handling reduces stress, disease prevalence, carcass bruising, and other quality and safety problems


(2) Facilities should be designed and maintained for easy and safe handling


(3) Clean feeding and watering systems


d. Proper product administration and use




(1) Use of products according to their label directions


(2) Observance of label withdrawal recommendations


(3) Proper administration of products including dosage, route, and location


(4) All injections should be given in the neck


(5) When given the choice, injections should be given subcutaneously (SC)


III. Euthanasia of farm animals




A. Often considered for economic reasons alone


B. American Veterinary Medical Association does not approve all methods (determined by humanity and effectiveness and may be conditional on age or species or specifications of device, such as the gauge of gun). e.g.:




1. Not approved: Exsanguination (by itself), IV solvents or cleaning agents


2. Approved: Gunshot or captive bolt to head


PRODUCTION MEDICINE SKILLS






I. Understand industry software [DairyComp305, Spartan Dairy II, CPM Dairy]


II. Familiarity with common statistical procedures (chi-square, t test) and tools (e.g., statistical process control)


III. Understand financial statements and tools (decision tree analysis) and partial budgets


IV. Understand important risk factors for problems in each management sector





B. Management sector




1. Maternity facility: Cleanliness, colostrum feeding practices, and dystocia management


2. Calf-raising facility: Cleanliness, assessment of passive transfer of immunity, diagnosis and treatment of disease, milk replacer selection and mixing, starter feed consumption, and the weaning process


3. Heifer facility




a. Transition heifers: Diagnosis and treatment of disease, forage consumption, growth, and free stall use


b. Breeding heifers: Heat detection, vaccination status, height and weight


c. Pregnant heifers: Growth, vaccination status, and abortion rates


4. Close-up heifers: Barn cleanliness, incidence of dystocia, labor intervention practices, and height and weight


5. Close-up cows: Barn cleanliness, incidence of dystocia and milk fever, and labor intervention practices


6. Fresh cows: Barn cleanliness; disease diagnosis, treatment, and incidence; and grouping


7. Breeding herd: Heat detection, synchronization practices, and disease incidence


8. Pregnant herd: Body condition and foot-trimming practices


9. Dry cows: Mastitis and abortion incidence, duration of dry period


10. Parlor: Udder preparation, gross milk inspection, milk bacterial (bulk tank) and somatic cell (bulk tank and individual cow) counts, milking speed, vacuum pressure, liner, and other rubber condition, cleaning materials, and procedures


11. Waste removal and processing: Barn scraping, storage capacity, soil P concentrations, and protection of waterways


12. Forage selection: Silage or seed variety, digestibility, drought tolerance, yield


13. Forage harvest and storage: Dry matter content, bunker filling speed, and packing density


14. Feed commodity purchase and storage: Price hedging, measurement and control of shrink


15. Ration formulation, mixing, feeding: Mixing order, time, and effect; feeding time and order; feed placement; and unconscious feed withhold


SURGICAL TECHNIQUES






I. Abomasopexy for left displacement




A. Right flank pyloro-omentopexy, pyloropexy, or omentopexy




1. Technique




a. Mid right flank incision, blunt grid dissection of inner layers is optional


b. Abomasal deflation recommended but optional


c. Retract abomasum using greater curvature or greater omentum. Pexy abomasum at pyloric antrum either into ventral transverse abdominal muscle and peritoneal incisional closure (#3 chromic catgut, tapered needle, simple interrupted pattern, repeated several times) or just caudal to incision. Pexy omentum in next part of closure (#3 chromic catgut, tapered needle, horizontal mattress pattern repeated several times)


2. Complications




a. Infection: Mixed flora, gram-negative anaerobes persist; treat with procaine penicillin G, oxytetracycline


b. Failure to pexy because of peritoneal adhesions


c. Recurrence is rare


B. Left flank abomasopexy




1. Long nonabsorbable suture passed through greater curvature of abomasum, abomasum deflated, then suture ends passed through right paramedian abdomen on straight cutting needles. Assistant required to retrieve needles and suture as they are passed through the body wall, and to tie the sutures externally


2. Not possible to pexy normally positioned abomasa


C. Paramedian abomasopexy




1. Complications: As above plus abomasal fistula at incision site, usually associated with pexying the abomasum into the incisional closure; rarely occurs when sutures are placed parallel to and away from the incision


D. Blind procedures: Toggling, stitching


II. Abomasopexy for right dilatation or torsion




A. Right flank approach. Use caution when incising peritoneum because abomasum encroaches


B. Deflate abomasum. Massage abomasum in clockwise direction (as viewed from behind the cow), then counterclockwise direction (as viewed from right side of the cow), revealing the pylorus


C. Alternatively or during this procedure, identify caudal edge of greater omentum, proceed cranially to find duodenum, then ventrally to locate pylorus. Torsion occurs after flotation of abomasal body dorsally along abdominal wall, then counterclockwise rotation along axis of lesser omentum


D. Prior to pexy (blind procedures are inappropriate, right flank, and ventral approach laparotomies are appropriate), palpate caudal omasum for presence of left gastric artery coursing in a dorsoventral manner, to rule out concurrent omasal torsion



IV. Umbilical herniorrhaphy




A. Abdominal bandaging for 3 to 6 weeks useful for simple hernias with ring less than three fingers width. Simple hernias seldom require surgical correction


B. Surgery indicated if bandaging is unsuccessful or hernial ring is large (5 fingers or greater width) or complicated with adhesions or infection


C. Vest-over pants abdominal closure is useful


V. Rumenotomy




A. Indications




1. Exploratory procedure to investigate chronic bloat


2. To relieve acute frothy bloat


B. Procedure




1. Left flank incision


2. Do not use muscle grid pattern


3. Continuous mattress pexy of rumen to skin will prevent peritoneal cavity contamination by ingesta


4. Utrecht or Cushing rumen closure (#3 chromic catgut, tapered needle) repeated


C. Complications: Postoperative peritonitis, SC abscess


VI. Castration




A. Standing or recumbent, commonly performed without anesthesia or analgesia


B. Open




1. Scrotal incision heals by second intention


2. Hemostasis preferred for greater than approximately 300 lb bodyweight; emasculator or ligation is useful


C. Closed




1. Emasculatome (Burdizzo); Crimps spermatic chord while preserving scrotal vasculature


2. Latex rings or tubing: Some added risk of tetanus


VII. Dehorning




A. No polled dairy breeds


B. Anesthesia: Local block of cornual nerve


C. Variety of methods




1. Caustic paste




a. Less than 2 months of age


b. Difficult to control distribution of paste if calf starts rubbing


2. Thermal cautery




a. Less than 3 months


b. Bloodless, hence less risk of fly strike


3. Barnes dehorner




a. 2 to 8 months


b. Variety of sizes; “scoops” horn; frontal sinus can be exposed


4. Keystone dehorner




a. More than 6 months


b. “Guillotine” like; frontal sinus will be exposed


5. Fetotomy wire




a. Usually reserved for adult cattle with long, hard horns


b. Horn can be removed at any level. Frontal sinus may be exposed


D. Postoperative management: Control of hemorrhage using cautery (heat or clotting aids) or manual retraction of vessels; protection from cold and wet environments, especially if frontal sinus is opened; topical insect repellants


E. Complications: Frontal sinusitis, blood loss anemia


ANESTHESIA




MASTITIS






I. Introduction




A. Often one of the most common diseases on dairy farms, and many cases result in chronic, incurable infections


B. Clinical and subclinical manifestations: Often demanding treatment and management decisions because of the impact on cow health and milk quality


C. Individual cow and bulk tank somatic cell count and bacterial counts are diagnostic. 250,000 cells/mL from individual cow likely indicates infection


D. Presenting complaint may be either clinical or subclinical manifestations


II. Risk factors




A. Environmental pathogens are generally widespread, but some can be point sourced (e.g., E. coli in fecal material, Streptococcus spp. in straw). Environmental organisms contaminate teat skin and enter around the time of milking (when the teat sphincters are open). Hence, udder preparation prior to milking is important


B. Sources of contagious pathogens are primarily other infected cows’ quarters. Parlor equipment and staff serve as fomites. When incidence is high, producers are often alerted by increases in bulk tank milk somatic cell count


C. New infections can also occur because of milking machine malfunction, during the dry period, and in nulliparous heifers


D. Subclinical infections of all causative organisms occur, but more commonly with gram positive and Mycoplasma spp. than gram negative


III. Etiology




A. Environmental: E. coli, Klebsiella spp., coagulase-negative Staphylococci spp., Streptococci spp. except S. agalactiae


B. Contagious: Staphylococcus aureus, Streptococcus agalactiae, Mycoplasma spp.


IV. Physical abnormalities




A. Udder examination is critical (increased size, firmness, asymmetry in quarters, pain, abnormal gross milk appearance, or positive California mastitis test)


B. Abnormal milk precedes abnormal quarter precedes abnormal cow, and the rate of progression can vary markedly depending on the organism and the cow. Milk changes may be serous, purulent, or hemorrhagic, and the udder may be necrotic


C. Cow signs and milk changes are not predictive of organism


D. Gangrenous quarters may indicate infection with some strains of S. aureus, Clostridium spp., and E. coli producing vasoactive, or other, toxins


E. Systemic changes are those of septicemia, toxemia, dehydration, or shock: Prolonged skin tent, sunken eyes, fever (especially in acute stage), decreased or absent appetite, and ruminations, depression, and recumbency


F. Clinical pathology can help prognosticate severe cases by measuring neutropenia and renal function, for example


V. Diagnosis




A. Physical examination and milk culture for clinical cases


B. California mastitis test or milk somatic cell count and milk culture for subclinical cases


VI. Complications: Chronic infection, incurable infection, permanent secretory tissue damage, pneumonia, and other organ sepsis


VII. Treatment and management




A. Microbiological diagnosis is critical




1. Basic microbiological procedures for identification of common pathogens should be understood




a. MacConkey agar is selective for coliforms


b. Staphylococci spp. are catalase positive


c. S. aureus is coagulase positive


2. In herd plans, calculating antimicrobial sensitivity is also prudent


B. Many coliform infections are cleared before or shortly after milk collection, so the use of intramammary antibiotics is questioned




1. Severe cases (with systemic signs) require parenteral broad-spectrum antibiotics on presentation (e.g., oxytetracycline) rather than after microbial diagnosis. Ancillary therapy in severe cases may include IV fluid therapy (lactated Ringer’s solution or normal saline with 0.5% calcium gluconate) and antiinflammatory therapy (flunixin, aspirin, dexamethasone)


2. Antimicrobial therapy can be safely withheld for 24 hours pending clinic or farm microbial diagnosis in cases not exhibiting systemic signs


C. Environmental gram-positive infections causing clinical signs should be treated with the intramammary antibiotics that the herd minimal inhibitory concentration (MIC) survey establishes may be effective


D. Mycoplasma spp. infections are incurable and infected cattle should be removed from the herd


E. Many S. aureus infections are refractory to antimicrobial therapy, especially at label doses


F. S. agalactiae infections respond well to antimicrobial therapy


VIII. Prognosis is variable, from acute fatality, grossly normal milk but persistent infection, to complete return to normal function and clearance of organisms. Many organisms have different prognoses from case to case


MUSCULOSKELETAL SYSTEM DISEASE






I. Digital




A. Introduction




1. Lameness is often one of the most common diseases on dairy farms and most commonly presents in the hindlimb (lateral claw)


2. Many hoof diseases have multifactorial causes


B. Skin disease




1. Footrot




a. Also known as interdigital phlegmon, interdigital necrobacillosis, foul in the foot


b. Opportunistic infection with Fusobacterium necrophorum. Usually seen with poor environments that lead to skin immunocompromise or pathogen buildup, such as wet, muddy conditions. Any conditions that lead to abrasion between claws increase risk of foot rot


c. Pathognomonic fetid smell and necrotic appearance. Also swelling up to fetlock and early fever


d. Parenteral procaine penicillin G, ceftiofur, or oxytetracycline


e. Prevention: Reduce exposure to environments that are constantly wet and/or abbrasive to the interdigital space.


2. Hairy heel warts




a. Also known as digital dermatitis, papillomatous digital dermatitis, foot warts, strawberry warts


b. Cause not well established, but not viral, and probably bacterial of the genus Treponema


c. Often interdigital skin at heel, can be elsewhere around coronary band. Pathognomonic appearance, papillomatous, red when cleaned (similar to surface of strawberry), with long hairs around circumference


d. Respond well to topical or parenteral oxytetracycline


e. Use of oxytetracycline or copper sulfate foot baths can control this disease


f. Innate immunity develops, so more common in nulliparous heifers


g. Contagious disease


3. Interdigital fibroma: A mass of connective tissue that grows in the interdigital space, of largely unknown cause, but theorized to be associated with chronic inflammation Sometimes causes lameness, when surface becomes excoriated or mass bears weight, but often subclinical. Usually multiparous cattle are affected. Treated by excision


C. Hoof disease




1. Laminitis




a. Rarely presents as in horse with acute and severe multi-limb lameness. This form is most commonly seen in feedlot cattle on high-energy rations or in individual cattle when acutely exposed to high-energy diets or follow acute and severe bacterial infection in another organ system


b. Checks in hoof growth or growth of abnormal horn result in secondary diseases, which can present as lameness (e.g., white-line separation, sole abscess, sole ulceration, soft and thin soles, wall cracks, or misshaped hooves, e.g., corkscrew claw)


c. Cause is multifactorial




(1) Rumen fermentation (subacute rumen acidosis)


(2) Toxemia (e.g., metritis, mastitis)


(3) Environmental (e.g., impact trauma from walking surface)


(4) Misshapen hooves (can lead to laminitis and is caused by laminitis)


2. Sole abscess




a. Present with variable separation of white line, which on exploration tracks to a pressurized pocket of purulent material (classic signs), dead space, or potential space between old sole and new sole, into corium, or up the wall, possibly to a point of release (somewhere on coronary band)


b. Cause is multifactorial, as white-line integrity is compromised by many factors




(1) Misshapen hooves


(2) Subclinical laminitis


(3) Physical trauma (e.g., stone penetration)


(4) Physical horn changes (e.g., maceration, bacterial decay)


c. Mixed flora, including gram-negative anaerobes


d. Treated by drainage, physical protection of exposed corium by applying supportive block elevation to contralateral sound claw, and parenteral antibiotic therapy if corium is infected. Most cases have excellent prognosis


e. Severe coriitis rarely ensues but can lead to osteomyelitis, septic arthritis, and tenosynovitis, all surgical conditions with grave prognoses


3. Sole ulcer




a. Also known as Rusterholtz ulcer


b. Pathognomonic location, at corium covering flexor tuberosity of distal phalanx


c. Present with horn erosion at heel-sole junction, which on removal exposes corium, sometimes covered with a granulation bed


d. Cause is multifactorial




(1) Subclinical laminitis, with pedal rotation


(2) Misshapen hooves, causing increased force applied to heel during locomotion


(3) Lack of cushion on walking surface


e. Treatment involves horn removal around ulcer, exposure, and removal of granulation bed and application of supportive block to sound contralateral claw. Guarded prognosis for recovery, fair to good prognosis for functional improvement, provided hoof is reexamined frequently to repeat treatment, and no complications exist


f. Complications include deep digital flexor tenosynovitis and osteomyelitis, retroarticular absessation, surgical conditions with grave prognoses


II. Upper limb




A. Hip luxation




1. Common after adductor muscle trauma in adult cows


2. Ventral or dorsal luxation: Rectal and pelvic examination may locate the displaced femoral head


3. Manual reduction under heavy sedation or preferably anesthesia and muscle relaxation


4. Grave prognosis; poor if reduced within several hours


B. Anterior cruciate rupture




1. Uncommon


2. Anterior drawer sign may be elicited


3. Slaughter or euthanasia is recommended


C. Septic carpitis of cows




1. Common after falls and struggling on cement


2. Begins as skin abrasions and progress to joint involvement


3. Preventive measures include improving concrete traction with straw or sand for recumbent cows and wound care for carpal abrasions. Prophylactic antibiotic use should be considered


4. Once the joint becomes involved, prognosis is grave. Repeated lavage is important, but this is difficult to implement in the field


D. Septic arthritis of calves




1. Common in cases of omphalitis; also enteritis and pneumonia. Can present without other systems affected.


2. Often polyarthritis


3. Mixed flora (e.g., coliforms, gram-negative anaerobes, Streptococci spp., Mycoplasma spp.) can cause arthritis without other signs, most commonly in feedlot cattle


4. Mycoplasma spp.


5. Clinical signs: Swelling, pain, fever, recumbency


6. Prognosis is guarded when treatment initiated in acute stage and a long course of broad-spectrum antibiotics is administered. Prognosis is grave if treatment is initiated in chronic stage. Repeated lavage improves prognosis, but this is difficult to achieve in the field


III. Muscle disease




A. Hypocalcemia (milk fever)




1. Jersey breed very susceptible


2. Clinical signs become more severe as serum calcium concentration falls




a. First, subclinical changes in smooth muscle tone




(1) Uterine involution


(2) Rumen, abomasum contraction


b. Skeletal muscles become increasingly weak, leading to recumbency


c. Signalment is diagnostic: Usually day before, day of, or day after calving; multiparous


3. Cause: Sudden increase in calcium requirements with commencement of lactogenesis


4. Treatment: Calcium gluconate, IV or SC (depending on severity of signs)


5. Prevention: Dietary acidification for the 3 weeks before calving, by feeding anionic salts (e.g., NH 3Cl, MgCl 2, [NH 3] 2SO4, MgSO 4 or HCl treated concentrates), has many endocrine effects, one of several useful ones being improved PTH receptor function


6. Compliance: Monitor urine pH (normal = 8.0, goal = 5.5 to 6.5)


B. Grass tetany




1. Cause: Grazing of forages low in magnesium




a. Usually seen when grazing succulent, immature grasses, or cereal grains. Rare with legumes


b. More common in adult cows (inability to mobilize magnesium from bones)


2. Pathophysiology: Hypomagnesemia


3. Clinical signs: Uncoordinated gait, recumbency, convulsions, coma


4. Treatment and control




a. IV injection of magnesium borogluconate


b. Magnesium supplied on a daily basis when tetany-prone conditions exist


C. Clostridial myonecrosis




1. Often following injections or trauma (including birthing). Spores may become vegetative in muscle after bruising. Generally a disease of young stock (less than 2 years of age). Grave prognosis


2. Clinical signs: Inflammation of muscle bodies, often in gluteal muscles and perineal area, sometimes with SC crepitus and skin discoloration and cooling. Signs of toxemia and shock develop quickly


3. Causes: Clostridium chauvoei, (blackleg) C. septicum (malignant edema), C. sordelli (major), C. novyi type B, C. perfringens type A, C. carnis. (minor)


4. Treatment: Parenteral or local procaine penicillin G; surgical debridement and fenestration; supportive care


5. Prevention: Vaccination

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Apr 6, 2017 | Posted by in GENERAL | Comments Off on 49. Bovine Medicine and Management

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