Vol. 7, No. 2 -- April 1997
Editorial
Heel Warts: Causes, Symptoms, and Treatments
Use of Prostaglandins
Mastitis is Almost Always Caused by Bacteria
Colloidal Silver Not Approved for Treating Animals
Alternatives to Antibiotics – Are They Appropriate for Treating Mastitis?
The winter of 1996-97 has presented challenges, several of which are yet to come. In response to current issues, all producers should have received a series of fact sheets in the mail in early March. For those of you with access to the World Wide Web, additional information has also been put on-line, including not only NDSU generated information, but hot-links to many other sites around the country. Check out the URL: http://www.ext.nodak.edu/. I also have a homepage. Point your browser (Netscape, Explorer) at http:\\www.ag.ndsu.nodak.edu/aginfo/dairy/.
I've provided the following information for your reference this quarter. I've begun with an article familiar to those who made it to Cow College. Hairy heel warts is quickly becoming the nemeses of the Holstein breed. Our discussions proved that many of you have it as well. It's become such a widespread problem, I've included a copy of the discussion by Dr. Barry Steevens to bring you up to date on the seriousness of the disease.
Hope you have a good (low water) spring.
J.W. Schroeder, Extension Specialist-Dairy
A current problem causing lameness in dairy cattle is a wart-like disease called papillomatous digital dermatitis, otherwise known as heel warts. This disease was first reported in the U.S. in the early 1980s in New York. The disease is estimated to now be prevalent in up to 70% of all U.S. dairy herds.
The cause of heel warts is not thoroughly understood, although a spirochete-type anaerobic bacteria has been isolated. One hypothesis is that bacteria causing foot rot may act in conjunction with the spirochete bacteria to cause the wart lesion. Although wet, muddy conditions seem to enhance the spread of the bacteria, heel warts have been found on cows in the desert Southwest, indicating that the spirochete bacteria are highly contagious and thrive and grow both in dry and wet environments.
Wart lesions are usually found at the back of the rear foot near the heel bulb. The uniqueness is that the wart lesions are only seldom observed on the front feet of cattle. Manure on the back of the heel appears to help provide an anaerobic environment for the bacteria to grow and develop. Early lesions are small, round and strawberry-like in appearance. Mature lesions are usually raised with surfaces covered by gray/brown/black frond-like papillary growths, hence a common name "hairy footwart."
The disease appears to affect mostly first and second lactation cows. This would indicate older animals have developed a resistance to the disease. The hind feet are the most often infected. Symptoms include moderate to severe limping, with little or no swelling above the hair line of the foot. Animals with the symptoms seem to experience extreme pain at the site of infection. Decreased feed intake, decreased milk production and loss of body weight can occur, suggesting hairy warts are associated with a bacteria.
Certain antibiotics can provide effective therapeutic response. The most common treatment includes topical application of oxytetracycline on the affected area, with bandaging if the lesion is greatly affecting the cow's mobility. An example of a successful treatment, the foot was cleaned, and oxytetracycline is then applied to the lesion. Treatment was repeated for two or three days in a row. If the lesion was severe, gauze pads soaked with oxytetracycline were placed on the lesion, and the foot bandaged. After five or six days, the bandage was removed. With a normal healing process, the lesion should appear black and scabbed over, indicating healing has taken place. Other treatment products reported to be effective include lincomycin, tetracycline, and spectinomycin.
Footbath solutions that have shown positive results in controlling heel warts include formalin (5% solution), 2-4 g oxytetracycline/liter water, or .2-0.5 g lincomycin/liter of water. The use of antibiotics in footbaths is "off-label," and so it is important to work closely with your veterinarian. Results with footbaths have been variable. For this reason, an alternative method of using a sprayer to treat the surface has been preferred by a number of dairy producers. The successful spraying procedure, as reported by Shearer at Florida in 1997, includes the following steps:
Following this procedure, data from the University of Florida indicated successful healing of 84 out of 86 animals within five days after beginning treatment, and prevented other susceptible animals from becoming infected.
Heel warts are a leading cause of lameness in dairy cattle in the United States. Dairy producers need to be very cautious when purchasing new animals to enter the herd. Maintaining a clean condition of the rear feet of young animals appears to be helpful in minimizing the spread of this disease.
Barry J. Steevens, State Extension Dairy Specialist, and John Underwood, University of Missouri, Animal Sciences Department
Prostaglandins used in a systematic reproduction management program have received much attention. An excellent study conducted in New York with three commercial herds totaling 1624 cows compared two reproductive management scenarios using prostaglandins (PG) with a program based on routine rectal palpation, intrauterine therapies and veterinary intervention. One program was based on the following assumptions: 1) rectal palpation is not sensitive for correctly identifying functional corpus lutea, 2) controlled studies have indicated that uterine infusions may not be beneficial, and 3) heat induced by therapeutic use of PG may cleanse the uterine environment and increase fertility. The second program included the following concepts in addition to those of the first program: 1) PG at a scheduled interval may result in synchronization of heat and improved reproductive efficiency, and 2) a higher pregnancy rate may result from PG administered at 14-days than at the original recommendation of an 11-day interval.
The reproductive program which included a therapeutic injection of PG at 25 to 32 days postpartum (no rectal palpation) and another PG injection just prior to the end of the voluntary waiting period resulted in reproductive performance similar to the program consisting of routine rectal palpation and intrauterine therapies. Pregnancy rate, first service AI rate, first service conception rate, overall conception rate, percentage of cows that became pregnant, and culling rates were not different between these two programs. The second PG program combined the therapeutic PG injection at 25 to 32 days after calving with two PG injections 14 days apart for estrus synchronization and increased early heat detection.
Synchronization injections were given at 39 to 46 and 53 to 60 days postpartum. Injections were given once a week to fit a convenient management schedule. Although no difference in reproductive performance occurred among programs (routine palpation group had 111 days open), partial budgeting indicated that PG treatment costs were $4.46 and $15.61 less per cow for the 2x and 3x PG programs. The increased savings with the 3x PG programs was probably due to higher heat detection efficiency as a result of estrus synchronization, which did reduce days open by six days.
Three new NDSU Extension Service circulars on mastitis are in the works. Lowering of the SCC legal limits and increasing problems brought on by a harsh winter have prompted updates of this information. While the completed series is a couple of months off, news releases and fact sheets were issued in January and February.
Mastitis, an inflammation of the mammary gland, is almost always the result of bacterial infection. Route of infection of the major species of mastitis-causing bacteria is often considered as being either contagious or environmental. This distinction, contagious or environmental, is also very helpful in understanding mastitis control strategies.
Contagious mastitis pathogens are often associated with problems in the milking parlor. Therefore, if bacteria causing mastitis are found to be of the contagious type, the primary focus or strategy should be aimed toward events occurring in the parlor.
Environmental pathogens are as the name implies, bacteria that gain entry to the udder while cattle are away from the parlor or in their environment. This does not mean that environmental pathogens cannot be spread during milking; it implies that the primary focus would be aimed toward evaluation of the area where cows spend time away from the parlor.
Milking equipment can act as a fomite, or an instrument to spread mastitis organisms from cow to cow, or it can damage or irritate the teat end and allow entry of organisms into the udder. Since the route of infection of the mammary gland is through the teat end, numbers of bacteria on the skin and teat openings are important. If no bacteria get through the teat opening, no new mastitis infections will occur. The most obvious source of contamination by the milking machine is the teatcup liners. It has been demonstrated that bacteria placed on the liners at the milking of one infected cow persisted on that same liner for six additional milkings. Milking equipment maintenance is of vital importance to decrease the incidence of new infections and decrease the spread of mastitis in the parlor. Most problems with milking equipment are due to inadequate maintenance, which leads to malfunction. The following are recommendations for maintaining a functional milking system.
Daily:
Monthly:
Every four months:
Every six months:
Evalute the entire milking system every 6 months.
FDA has received reports that products containing colloidal silver are being promoted for treatment of mastitis and other serious disease conditions of dairy cattle, as well as for various conditions of companion animals. For example, FDA's Center for Veterinary Medicine has received reports from the agency's regional milk specialists and state inspectors that colloidal silver products have been found on some dairy farms. Also, recent articles in some farm newspapers and journals promote the use of colloidal silver in treating mastitis and claim that no milk discard is needed.
FDA is not aware of any substantial scientific evidence that supports the safe and effective use of colloidal silver ingredients or silver salts for any animal disease condition. Also, in the October 15, 1996 Federal Register, FDA proposed to establish that all over-the-counter human drug products containing colloidal silver ingredients or silver salts for internal or external use are not generally recognized as safe and effective and are misbranded.
Use of colloidal silver ingredients in food-producing animals constitutes a potentially serious public health concern because of the possibility of residues in milk or meat. According to several scientific publications mentioned in the October 15, 1996 Federal Register proposal, the human consumption of silver may result in argyria -- a permanent ashen-gray or blue discoloration of the skin, conjunctiva, and internal organs.
In addition to the possible human health concerns, use of these products to treat a serious illness in animals (including pets) could potentially endanger the health of the animal by delaying timely, appropriate treatment.
Colloidal silver-containing products have not been approved by FDA for use in any animal species. Promoting the use of colloidal silver for treating animal diseases causes such products to be misbranded veterinary drugs under the Federal Food, Drug, and Cosmetic Act (the Act). Labeling colloidal silver products to treat animals causes such products to be new animal drugs which are adulterated under the Act.
FDA has taken action against colloidal silver products, and is continuing to investigate the promotion and use of colloidal silver products in dairy and other animals. If necessary, FDA will take further appropriate regulator action.
Source: CVM Update, FDA Center for Veterinary Medicine
The use of antibiotics to treat infections is a well established practice on dairy farms. Ideally, antibiotics are used under the guidance of a veterinarian who is knowledgeable of the management practices on the farm. However, even under these conditions, antibiotic treatment may not effectively eliminate all infections. Because of these and other concerns, there has been renewed interest in utilizing alternatives to antibiotic therapies for treating infections.
It has been reported that the most common reason for antibiotic use on the dairy farm is to treat mastitis. In a dairy farm TQM pilot project, the costs associated with treating mastitis were greater than for any other health disorder on dairy farms. These expenses include the cost of the drug treatment and the costs associated with discarded milk. A New York study estimated that mastitis results in a $100 million dollar loss to the New York dairy industry. Therefore, since mastitis is so costly to dairy producers, alternative treatments that can both decrease expenses and increase effectiveness of treatment are actively being investigated.
The most commonly used alternative treatment for clinical cases of mastitis is frequent milk-out and oxytocin administration to assure complete milk removal from the gland. Also, supportive therapies are used when the cow exhibits systemic effects (elevated body temperature, scours, and dehydration). Supportive therapies include anti-inflammatory drugs and fluid therapy. In more severe cases of clinical mastitis, hypertonic saline solutions are administered intravenously to promote water intake and alleviate dehydration. These therapies are used in an extra label manner and should only be used under the guidance of a veterinarian. Unfortunately, there are very few well-controlled studies on the effectiveness of these treatment regimens.
Total farm application of alternative treatments for mastitis have been followed with case studies. A University of Michigan case study measured the success of using alternative therapies for treating clinical mastitis over a two-year period. Oxytocin was successful in many of the acute cases of mastitis in early lactation whereas in alter lactation (greater than 100 days in lactation) there was a trend toward an increase in persistency of infections and an increase in the number of clinical cases. This suggests that studies evaluating the effectiveness of alternative treatments should include stage of lactation as well as other factors associated with milk production.
Future possibilities for treatment or prevention of mastitis have exciting possibilities. Current investigations are ongoing evaluating the possibility of cytokines (proteins produced by the cow) that would aid the cow's immune system in eliminating mammary infections. Certain proteins isolated from microorganisms that have antimicrobial activity may prevent the establishment of pathogens in the mammary gland. Vaccination for Staph. aureus shows promise in reducing the number of cases of clinical mastitis from Staph. aureus organisms. Proper nutrition is necessary for the prevention of disease. Supplementation of Vitamin E and selenium to recommended levels has been shown to reduce the number of clinical cases of mastitis. Finally, new research has demonstrated that heifers can harbor pathogens in the mammary gland and, upon calving, heifers may be a source of pathogen transmission to the herd. It is hoped that new research can provide effective methods to reduce the incidence and severity of mastitis.
Prevention of mastitis is preferred over treatment for mastitis. Not only is prevention more cost effective, prevention can also result in increased milk production and qualifying for quality milk premiums. the mastitis control program should include: attention to the cleanliness of the environment, proper milking procedures, training for all milkers, maintaining milking equipment, utilizing effective dry cow treatment, isolation of new animals in the herd, and a targeted treatment plan for mastitis. The decision to treat mastitis should be based on economics, considering both the value of the cow and the cost of antibiotic treatment.
A targeted treatment plan for mastitis should begin with the identification and elimination of Strep. ag. in the herd. The control of Staph. aureus is next in order of importance. Finally, the decision to treat a clinical case of mastitis can be accomplished with a decision tree that is developed in consultation with the veterinarian to specifically target the needs on an individual farm. Accurate records are an essential component of this plan.
The goal of the targeted treatment plan is to reduce the use of antibiotics and increase the effectiveness of treatment for mastitis.
While alternatives to antibiotics may appear to be the answer to concerns associated with antibiotic use, successful control of this disease must include proper preventative management practices along with targeted antibiotic treatment plans. Presently, prevention of mastitis is our most successful alternative treatment for mastitis.
Clinical Mastitis
Early lactation/Heifer
Late lactation/Relapse
Summarized from S.M. Andrew, University of Connecticut
Vol. 7, No. 2 -- April, 1997
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