SUGGESTED VACCINATION SCHEDULE FOR OKLAHOMA COW-CALF HERDS

 Lawrence E. Rice
 Professor, Department of Medicine & Surgery
 Oklahoma State University
 

This is a suggested vaccination schedule that is based on the currently known science of immunology and the art of inducing immunization through administration of vaccines or bacterins.  This presentation will not cite data or give references.  For recent thorough discussions on immunization, readers should refer to articles by Drs. Roth, Ellis, Cullor,Schultz, Hutcheson and West in the 26th Annual Proceedings of the AABP Meeting September 16-19, 1993, pages 3-39.

First some definitions or descriptions of types of immunity need to be discussed.

 1. Native defense mechanisms.  These mechanisms are functional immediately when an infectious agent enters the body even if the animal has not been immunized.  They include many things such as enzymes,tears, saliva, white blood cells, stomach acids and many other factors that may kill bacteria or viruses.  They are most effective when an animal has been properly immunized and some animals genetically have better native defense mechanisms.

 2. Passive immunity.  This is a temporary immunity and comes from some source other than being made by the animal.  The most common and most important kind of passive immunity is the antibodies that newborn animals receive through the mother's colostrum.  They have a finite life which varies between diseases.  In cattle, blackleg colostral antibodies are gone by about 2 months of age while BVD colostral antibodies may last 6 months or longer.  Other examples of passive immunity are tetanus antitoxin that animals or people are given when exposed and gama globulin that people are given when exposed to hepatitis "A" that we hear about sometimes on TV.  An animal cannot develop permanent or acquired immunity through vaccination if passive antibodies are present.

 3. Acquired immunity.  This is permanent or semi-permanent immunity that is developed by the animals immune system when exposed to a disease or properly vaccinated.  It takes at least 1 week and usually 2 weeks following infection or vaccination for the immune system to produce the antibodies that are necessary for protection.  The antibodies produced are specific against that particular organism or disease unlike the native defense mechanisms which may destroy many different organisms.  There are 3 types of acquired immunity.

  a. Humoral immunity.  This is immunity from antibodies that are produced by lymphocytes (white blood cells). These antibodies are circulating in the bloodstream and can attach to the specific infectious agent to inactivate or neutralize the organism so it can be destroyed or removed by some of the native defense mechanisms.  These antibodies are those that most commonly present in colostral antibodies.  Some organisms are resistant to humoral antibodies and must be controlled by cell mediated immunity or secretory immunity.

  b. Cell mediated immunity.  Cell mediated immunity is produced by other types of lymphocytes when an animal is exposed or properly vaccinated.  These lymphocytes specially recognize the disease organism and when later exposed they attack and inactivate the infectious organism.  Cell mediated immunity is important in control of respiratory diseases.  Cell mediated immunity is not as easy to be produced as humoral immunity and is rarely produced by a killed vaccine because the infectious agent usually has to replicate in animal cells to stimulate this system. This is why modified live vaccines are produced.

  c. Mucosal or secretory immunity.  The antibodies responsible for humoral and cell mediated immunity are circulating in the blood stream and it is difficult for these to get to get to the linings of the intestinal tract, mammary gland, respiratory tract and reproductive tract.  Therefore these antibodies are not as effective against calf scours.  Secretory immunity is best produced by the cells lining the organ following natural infection.  (Example:  the intestinal lining following scours.)  Unfortunately the infection is often fatal so there must be artificial means of stimulating this system.  Again modified live vaccines are effective if they attack the lining cells of the organ that produces the secretory antibodies.  If the modified live vaccine can be introduced into the organ, the organ will develop secretory antibodies such as done following vaccination of calves with the intranasal IBR-PI3 vaccine (Infectious Bovine Rhinotracheitis and Parainfluenza-3 viruses).  Fortunately the mammary gland produces secretory antibodies present in colostrum so the newborn has better protection against scours if the colostrum is ingested immediately after birth.

 4. Vaccinate.  The process of inoculating a vaccine into an animal.  Does not imply an immune response has occurred.

 5. Immunize.  The process of vaccinating an animal and the animal responds with a detectable immune response.  Does not imply that the animal is protected from the disease.

 6. Endemic.  A disease that is always present in an area or herd.  i.e. blackleg, anaplasmosis and others in certain areas.

Vaccination failures may occur for a number of reasons including animal factors, vaccine factors and human error.  Examples are: (1) colostral antibodies in young animals preventing development of acquired immunity; (2) improper storage, handling or injection of vaccines; (3) animals incubating or highly stressed at time of vaccination; (4) overwhelming infection too great for vaccine immunity to provide protection; and (5) too long between initial injection and booster injection of killed vaccines.  There are many other factors which along with the above factors are really related to proper planning and design of the vaccination program.

 Occasionally I will quote directly from Dr. Schultz in the 1993 AABP proceedings.  The first is the objectives of immunization:

 "Objectives of Immunization

 1. Produce a good humoral, cellular and local immune response similar to natural infection.

 2. Produce protection against clinical disease and reinfection.

 3. Give protection over several years, preferably a lifetime.

 4. Result in minimal immediate side reactions (e.g. reduced milk production, weight loss, infection of the fetus with abortion, congenital anomalies or persistent infections).

 5. The vaccine can be administered simply in a form acceptable to the producer and practitioner.

 6. Cost and benefits of administration of vaccine should clearly outweigh the cost and risk of natural disease."

Obviously not all vaccines will meet all the above objectives all of the time.  Some cannot be given to pregnant animals, some require booster vaccinations, many do not impart longtime immunity, and some are not cost-effective.  Therefore when selecting a vaccination program one must do a risk assessment to determine the desired vaccines and the time to administer the vaccines.  What is the probability of the animals in question becoming clinically or subclinically ill?  If they are susceptible to infection, will the morbidity, mortality, cost of treatment and loss of production be sufficiently reduced to warrant the cost of vaccines and labor involved.  Remember vaccines do not induce a 100 percent immune response and not all immune responses are protective against disease.  The selection of a vaccine is also part science and part art.  The science enters into the equation when veterinarians keep up with data on immune responses and side effects from newer vaccines.  Also important is management and/or nutritional information that enhance an immunization program.  Art is the application of the known science to a particular situation, herd or environment.

Recent scientific and lay literature has been laden with information on respiratory disease and vaccination programs for prevention and control of respiratory diseases.  The plethora of lay information (and some veterinary articles) have fed the controversy of what kind of vaccine to use and how often to administer the vaccine.  Much misinformation and fear has resulted from relying too much on the art of vaccination rather than the science of immunology.  For the cow-calf producer it certainly has detracted from the concept of herd immunity.

Good cow-calf herd immunity has classically been thought of as preventing clostridial diseases, abortion diseases, calf scours, and respiratory diseases in replacements or if the producer retained ownership, respiratory diseases in stocker and feeder cattle.  Little attention has been given to the effect of cow-calf vaccination programs on the next link of the beef food chain.  In line with the Beef Quality Assurance and Food Safety programs, I think cow-calf veterinarians and cow-calf producers should also start addressing herd immunity as to how it affects food safety (injection site lesions) and feedlot health (morbidity and antibiotic residues).

In selecting vaccines--Modified Live Vaccines (MLV) and Non-Infectious or killed products (NI)--I refer to Table 1 from Dr. Schultz and the following quotation regarding timing of vaccination:

  "One of the most important considerations in designing a vaccination program, after the specific vaccines have been selected, is timing. When should the vaccine be administered?  Incorrect timing of vaccination is the greatest cause for vaccines failing to immunize.  Timing includes such considerations as:  1) the effects of maternal (colostral) antibody on active immunization, 2) the period of time between injection of vaccines that require multiple doses and 3) the age of disease most often occurs 4) age, as it relates to the competence of the immune system."

Table 1.  Facts to Remember About MLV and NI Vaccines
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                                                                  Killed-Inactivated
Modified Live Vaccines (MLV)                  Non-Infectious Vaccines
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1. Provide longer duration and                 1.  Provide short lived systemic 
 complete immunity than                               immunity. 
 (Non-infectious vaccines). 
 
2. Cellular and secretory                          2. Cellular and secretory 
 immunity should be produced.                    immunity poor. 
 
3. Do not require multiple vaccinations     3. Often require re-vaccination 
 for immunologic memory.                            to ensure immunologic memory. 
 
4. Often do not require revaccinating        4. Require multiple vaccinations 
 or require fewer revaccinations                    for active immunity. 
 during life of an animal. 
 

5. Rarely cause hyper- sensitivities,           5. Often cause hypersensitivity 
 but may be virulent for certain                       reactions. 
 individual animals or revert to 
 virulence. 

6. When used on pregnant animals           6. Cannot cause disease even in 
 some abortions will occur.                             immunologically compromised 
          animal. 
 
 
 

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With the above thoughts in mind, I will suggest programs for different herd scenarios.

A. The first and most simple is for a cow herd that is known to have immunity (through exposure or vaccination) to the common viral and bacterial diseases seen in Oklahoma.  In such a herd, outbreaks of disease ordinarily would not be expected and the goal would be to maintain herd immunity (active in yearlings and cows and maternal passive immunity in nursing calves).

 1. At approximately two months of age all calves should be vaccinated for clostridial diseases with an effective bacterin/toxoid making sure products and methods will be used that provide immunity and minimize injection site reactions.  Calves this age (and sometimes younger) have lost passive protection for clostridial diseases and are therefore susceptible to infection.  Calves this age in herds with good maternal immunity will not likely be susceptible to other common diseases.  The passive immunity to IBR, PI3, and especially BVD will still be at high enough levels to interfere with injectable vaccines and may still be protective.  Therefore the clostridium antigens are the only ones I recommend.

 2. At 2 to 4 weeks before weaning, I recommend the following:

  a. The Clostridium bacterin/toxoid of choice.  In most herds no further clostridial vaccinations will be necessary, however, some herds may require annual boosters.

  b. Modified Live Vaccines, IBR, PI3, BVD vaccine.  Five-way Leptospira bacterin may be incorporated if considered necessary in your area.  Remember this herd is known to have immunity to these viruses and administering a MLV vaccine to calves is not threatening to pregnant dams the calves are nursing.  This vaccine is known to provide the quickest and highest humoral response plus produces cellular and secretory antibodies.  (CAUTION:  At weaning some calves may still have passive BVD immunity which could block active immunity.)

  c. A Pasteurella leukotoxoid vaccine which should be boostered in 2-4 weeks (weaning).  Data show such a program significantly reduces respiratory disease and treatment time of respiratory disease after weaning in exposed calves.

  d. Calfhood vaccination of replacement heifers with strain 19 Brucella abortus vaccine.  Vaccination has protected our clean herds and I do not recommend discontinuing this vaccine until we have maintained a Free State status.

 3. At weaning:  booster the Pasteurella leukotoxoid vaccination.

  Some veterinarians recommend boosters of MLV IBR, BVD, PI3 but most revaccinations with a MLV product do not stimulate a secondary response.  The advantage of this booster would be if a previously inhibitive passive immunity had waned, thereby permitting the MLV antigens to stimulate a primary response.

 4. At 1 year of age replacements:

  a. Modified Live Vaccines IBR-BVD with 5-way Leptospira bacterin as a diluent. This vaccination should provide lifelong immunity against IBR-BVD infections.  There will likely be no secondary response if the weaning vaccination provided immunization but this administration is important to permanently protect those that still had BVD passive immunity at weaning.  This is important for protecting the embryo and fetus plus providing colostral antibodies.  The Leptospira immunity is short-lived and must be boostered at least annually.

  b. If Campylobacter (vibriosis) infertility is a possibility the first injection of the bacterin should be administered and reinjected in 2-4 weeks.  This bacterin must be boostered annually.  Remember campylobacterosis is primarily an infertility disease so breeding animals must be protected during the early part of the breeding season.  These bacterins provide short-lived immunity and do not have maximum protective titers at breeding when given in combination with Leptospira bacterin at pregnancy palpation or when the calf if weaned.  To be most effective Campylobacter bacterins should be given prebreeding.  On the other hand, cowherd Leptospira infections primarily involve late term abortions and best protection is provide when the bacterin is administered at pregnancy testing time.  Herds with high degree of exposure to Leptospira abortion may require twice a year vaccination.

 5. At weaning or pregnancy testing time cows should receive annual boosters of:

  a. Five-way Leptospira bacterin.

 6. Cowherd vaccination for stimulation of maternal (colostral) antibodies against calf scours.  K-99 E. coli bacterins administered at least 4 weeks before calving have been shown to be effective in reducing colibaclosis of newborn calves WHEN ADEQUATE colostrum is consumed WITHIN 6 TO 12 HOURS of birth.  The first year (pregnant replacement heifers) of vaccination MUST include two injections 2 to 4 weeks apart.  The second injection should be given at least 4 weeks before calving.  Annual boosters are given 4 to 8 weeks before calving.  Some companies include rota and corona virus vaccines in their products.  Studies of antibody levels in colostrum and newborn calves following adequate nursing would indicate currently available rota-corona vaccines do not stimulate adequate maternal antibody production to be protective for the calf.  However, the K-99 E. coli bacterins are protective and are recommended for herds with colibacillosis infections.  Some companies claim their products stimulate high and long lasting enough antibody titers that the vaccine can be administered to the cow at weaning time thereby eliminating another handling event.  Question your supplier closely regarding this claim.

 The only vaccines I consider imperative in this program are the Clostridial bacterin/toxoids and the IBR-BVD MLV vaccines.  These diseases are endemic and all Oklahoma herds will be exposed at one time or another.  With transportation of infected and incubating cattle being what it is, an unvaccinated closed herd that is protected by quarantine is a myth.  These vaccines are highly effective and inexpensive when used as recommended above.

B. However, many cow-calf herds do not have herd vaccination programs or herd immunity is unknown.  Also some herds calve all year around and vaccinations cannot be performed uniformly at "working time", "weaning time", "before breeding" etc.  In some of these herds a vaccination program is finally initiated when a severe respiratory disease outbreak or an abortion storm occurs.  In these herds the use of modified live viral vaccines is probably too risky to females in different stages of pregnancy.  The administration of MLV vaccines to naive pregnant females runs a high risk of fetal infection and abortion.  In these cases herd immunity must be established through the administration of killed or chemically inactivated MLV vaccines that are safe for pregnant females.  Remember all such products must be administered twice 2 to 4 weeks apart.  One injection will not provide protection and if the injections are given LESS than 2 weeks or GREATER than 4 weeks after the first injection, immunity will be significantly decreased or perhaps nonexistent.  These protocols must be followed precisely.  I prefer the chemically altered modified live IBR PI3 and killed BVD products.  All cattle (cows and calves) are given these vaccines to establish herd immunity.  However to maintain herd immunity with the same products, they must be reinjected on an annual basis because the killed or chemically inactivated MLV vaccines do not impart permanent immunity and cellular immunity is poor.

 If such a herd has a defined calving season/seasons, I initiated herd immunity as prescribed above and continue herd immunity with MLV vaccines as follows:

 1. Two to four weeks before weaning vaccinate calves with the clostridial bacterin/toxoid and the Pasteurella leukotoxoid.  I do not use the MLV IBR, BVD, PI3 vaccine because the dams may be susceptible due to decreasing immunity from previous killed or inactivated vaccines.

 2. At weaning booster the Pasteurella Leuko/toxoid and give IBR, BVD, PI3 modified live vaccine.  This starts these calves towards herd immunity as in known immune herd in "A" above.

 3. After the cows have calved but at least 30 days before breeding give MLV IBR, BVD, PI3 vaccine to cows and replacement heifers.  Within 2 weeks I consider this herd will have good permanent herd immunity and I continue the herd vaccination as noted in "A" above.

 Some producers cannot or choose not to have a defined calving season and I do not feel secure using the modified viral products when there is risk of accidental injection in pregnant cows.  For these producers the recommended "Keep it Simple" procedure is to use a killed or chemically inactivated modified live virus in all cattle annually.  Remember to establish herd immunity all replacements must be vaccinated with these products twice, 2 to 4 weeks apart the first year.

C. Respiratory disease in nursing beef calves.  Recently we have diagnosed more cases of Pasteurellosis pneumonia in nursing beef calves (2 to 4 months of age).  Occasionally IBR virus has also been isolated but not as frequently as Pasteurella species.  Our approach to these has been.

 1. Intranasal IBR, PI3.  Local mucosal immunity is quickly established and interferon is produced with in 24-48 hours which is somewhat effective against all viruses for a short time.

 2. Pasteurella leukotoxoid.  This must be reinjected in 2 weeks for good immunity although two companies now have labels for "one shot" being effective.

  Maternal antibodies for IBR, PI3 and pasteurella are greatly diminished by 6 to 8 weeks of age making these calves susceptible when exposed to sufficient numbers or especially virulent organisms.  In these cases the above vaccines should be immunizing and could be administered at 6 to 8 weeks of age on an annual basis in susceptible herds.  The preweaning or weaning vaccinations should be used as in "A" above except the pasteurella needs to be given only once.

D. Other vaccines.  In some areas Hemophilus somnus bacterin and Bovine Respiratory Syncitial Virus (BRSV) modified live vaccine is recommended. 

 1. The data would indicate that Hemophilus bacterins do not significantly reduce respiratory disease but may reduce the prevalence of thromboembolic meningoencephalitis (TEME).  I do not recommend incorporating Hemophilus bacterin as being cost-effective in most herds.

 2. The inclusion of BRSV vaccine may be helpful in endemic areas, but I do not recommend it's use unless the virus has been identified as a causative factor of respiratory disease.  This vaccine MUST be injected twice 2 to 4 weeks apart to stimulate immunity and adds a significant cost to the IBR, BVD PI3 combination.  This organism is not commonly isolated in this area and I am not certain how much it is involved in producing disease.

 3. Anaplasmosis vaccine.  The only anaplasmosis vaccine available is Ft. Dodge's Anaplaz® and all veterinarians are aware of Neonatal Isoerytholysis (NI) that is caused by incompatible blood type antigens that may be in the vaccine.  NI is caused by certain blood type antibodies that may be present in the cow's colostrum and which cause lysis of the calves' red blood cells after consuming colostrum.  The condition has been minimized by administering the vaccine only to open cows allowing the antibodies to decay and be at minimum level at calving.  Even so, NI was reported not uncommonly until approximately 5 to 10 years ago.  Many veterinarians and producers have been reluctant to use the vaccine.  Approximately 10 years ago the company was able to identify the blood type determinant that stimulated the production of the offending antibodies.  Therefore vaccine is not produced from blood with these blood types.  The occurrence of NI is now quite rare and I have not seen a case in the last 10 years.  In anaplasmosis endemic areas, I recommend vaccination as the most cost-effective means of control.