IACUC Learning Module - Cattle

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APPENDIX 2:

COMMON DISEASE PROBLEMS OF BEEF CATTLE

CALVES

Diarrhea

• Infectious agent: Several viruses and some bacteria (primarily E. coli).

• Clinical signs: Depression, fever, diarrhea

• Pathogenesis (course of the disease): The infectious agent usually colonizes the small intestine causing the lining of the small intestine to allow more water to pass from the blood into the gut. This increase in water exceeds the ability of the large intestine to reabsorb the water causing the diarrhea. The excess water pulls ions from the blood causing the dehydration and clinical signs.

• Treatment: The primary cause of death is dehydration. Keep the calf from becoming dehydrated by giving fluids with electrolytes added. Usually a self limiting disease, allow the gut to rest and repair itself. Keep milk out of the digestive tract because the intestine cannot digest the lactose. Oral antibiotics are usually not necessary and may make the problem worse.

• Prevention: Sanitation, colostrum, isolation.

Pneumonia

• Infectious agent: Viruses (IBR,PI₃) with secondary bacterial agents (Pasteurella or Corynebacterium).

• Clinical signs: Depression, off feed, thick nasal discharge, increased respiration (usually increased difficultly in breathing out)

• Pathogenesis: Viruses colonize the upper part of the respiratory tract depressing normal host defense systems. Secondary bacteria can then attack the lung tissue.

• Treatment: Antibiotics (determined by sensitivity), non-steroidal anti-inflammatory drugs.

• Prevention: Good housing, reducing stress, good ventilation.

Environmental Stress

GROWING CATTLE

• Infectious agent: Various species of Clostridium bacteria. Found in dirt, manure and bedding.

• Clinical signs: Will vary with the specific organism involved. Often no obvious signs, just rapid death.

• Pathogenesis: Varies, usually the organism invades a wound or is present normally and then undergoes a rapid increase in population numbers. Increased growth produces toxic byproducts that enter the blood stream and attack the liver and kidney. Rapid death is the result.

• Treatment: None

• Prevention: Vaccination

PREGNANT CATTLE

• Causes: The tissue around the birth canal becomes relaxed as the cow starts the last third of gestation, increased pressure in the abdominal cavity will push the vagina or the rectum out. If the tissue is trapped outside the birth canal it will swell and may become infected. In some cases the bladder is also trapped and the animal is unable to urinate. This condition is more common in older cows. Overly fat cattle and cattle on pasture with a high legume concentration are at higher risk.

• Treatment: Epidural anesthetic is usually necessary. Replace the tissue and suture in place. Vaginal sutures must be removed before calving

• Prevention: Remove animals from the breeding herd that develop this condition. Don't allow cows to gain too much weight during the last trimester of pregnancy.

Ketosis/pregnancy toxemia

• Causes: Cows are exposed to low nutrition during the last two months of pregnancy. Cows that are overly fat or are carrying twins are at a higher risk.

• Signs: Affected animals become depressed, stop eating and will often stand off away from the herd. Some animals will have the odor of acetone on their breath. As the condition gets worse, the cow will develop muscle tremors (trembles) and then go down.

• Treatment: IV glucose, B vitamins. Propylene glycol given by oral drench. Any animal that is down should be lifted by a hip hoist 2 or 3 times a day for 15 to 20 minutes. Cows that are in late pregnancy might need calving induced or a C section.

Dystocia

• Breeding management: Cull heifers with small pelvic areas before breeding starts. Use bulls on first calf heifers that will produce small birth weight calves. Expose heifers to the bull so they will start calving 30-45 days before the adult cows. Watch body condition during gestation; heifers must not get overly fat or lose weight.

• Calving management: Develop calving grounds. These should be separate from wintering areas, dry and have some shelter from weather if possible (a wind break will help). Separate first calf heifers from the cows. Surveillance and calving assistance are provided on a 24 hour basis if possible. Restricting the breeding season to 42-60 days will allow personnel to focus their attention to assist in calving for a short, but intense, period. Feeding at night (between 9-11 pm) will cause more animals to start calving during daylight hours. The dam and calf should be moved from the calving area to a separate nursery pasture after the calf has nursed, is up and moving about, and has bonded onto the dam. This generally takes 24-36 hours.

• General indications for calving assistance: The start of calving is indicated by the cow laying down and starting abdominal contractions. The water bag (part of the placenta) appears in the birth canal. The water bag will normally break after 30-60 minutes, and is often followed by a period of restlessness and several position changes. Abdominal contractions become more forceful and the feet appear in the birth canal. Birth is usually completed after 30-60 minutes of hard labor. If the animal has not made any progress after 60-90 minutes, assistance should be given. The appearance of the head alone, the head and one leg, or one leg alone are all indications of an abnormal calf presentation and indicate the need for assistance.

Position of the calf in the uterus after it has been oriented for delivery.

• Guidelines for calving assistance: Comfortably restrain the cow. A squeeze chute will work, but if an animal goes down during a contraction, she may not be able to get up. The best situation is to have a small pen with a head catch. After the animal's head is in the catch, a halter is applied; once the dystocia is corrected and traction is applied to the calf, release the head and allow the cow to lay down in the pen. The basic guidelines are clean and gentle. Keep the area around the birth canal as clean as possible, keep your hands and arms as clean as possible and use lots of lubricant (mild liquid soap is fine). The calf can only come out one of two ways, both front feet followed by the head or both back feet out together. If you are unable to correct the position of the calf to get it coming in one of the above presentations, get veterinary assistance.

  The three most common problems are:

  1. not getting the head to come out with the front feet (head turning back);
  2. having a calf that is too big to be delivered through the birth canal resulting in hip lock; and
  3. a breach in which the tail is the only part of the calf visible at the vulva.

  The presence of any of these problems usually requires veterinary assistance. When pulling a calf, direct the traction down and away from the birth canal, not straight out behind the cow. Do not use excessive traction. If you are unable to deliver a calf with two men pulling on the OB chains or when using a calf puller; the calf is oversized for the birth canal and should be delivered by C-section. After delivering the calf, always make sure that there is not a twin present. This is a good time to check the birth canal for any tears and to put some antibiotic pills in the uterus (neomycin-sulfa works well).

Bruises, lacerations and rupture of the birth canal

• Causes: Calving difficulties, rough handling of the maternal tissues and careless use of obstetrical instruments during delivery of the calf. Injuries occur more often in cows that have been in labor for several hours and when the birth canal is dry and non-lubricated.

• Treatment: Give oxytocin (P.O.P.) immediately to shrink the uterus and control bleeding. Pack the uterus with antibiotics to control infection and give systemic antibiotics (IM or IV). Try to control bleeding with coagulant compounds. Surgical repair may be required if the laceration penetrates completely through the uterine or vaginal wall. Cows with severe blood loss will require treatment to control shock; fluids, steroids, calcium gluconate or blood transfusions.

Uterine Prolapses

• Causes: Difficult birth with injury or irritation of the external birth canal and severe straining. Retained placenta. Loose uterine attachment in the abdominal cavity. There may be an increased prevalence in some families. Poor uterine tone post-calving may be related to low blood Calcium levels. Poor body condition with malnutrition.

• Treatment: An emergency condition; rapid treatment is important. Keep the prolapsed uterus clean and moist. Apply material to pull fluid from the uterine wall: sulfa-urea powder, urea powder, sugar. For replacement epidural anesthesia is often required. Replace the uterus or obtain veterinary aid immediately. When replacing the uterus, all of the organ must be replaced into the abdominal cavity and both horns must be fully everted. Failure to completely evert the uterine horns will cause the animal to continue to strain and prolapse again. Treat the uterus with antibiotics and give systemic antibiotics. Most operators will suture the vulva closed for 3-4 days. Some cows will rupture the uterine artery during the prolapse. If this occurs, the cow will hemorrhage internally, become shocky and die.

• After Effects: No permanent problem if the uterus is quickly replaced. Don't need to automatically cull a cow because of a prolapsed uterus but an injury such as freezing, drying or severe laceration may cause infertility.

Obturator paralysis/downer cow

Obtruator "downer" cow

Causes: Excessive pulling to deliver a calf, pulling a calf straight out from the cow rather than down and backwards or having the calf in the birth canal too long (several hours). Some cows may deliver normally but because of poor footing slip and "split out". Damage, in this case to the pelvis, produces a downer cow.

• Treatment: Steroids must be used to reduce swelling and assist in nerve healing. Cows that are unable to stand should be hoisted 15-20 minutes twice a day. Cows that split out but can stand, should be in a clean dry pen with hobbles, that prevent the legs from splaying out to the sides. IM Vitamin E/Se may help.

Retained Placenta

• Causes: Dystocia, C-sections, fetotomy, twining or abortion will all increase the chance of a retained placenta. Some infectious diseases such as IBR, Brucellosis, listeriosis and leptospirosis will cause abortion and retained placentas. Malnutrition and feed deficiencies, especially low carotene, Vitamin A, Iodine, Selenium and Vitamin E.

• Treatment: Slight manual traction, gently pull on the placenta. If the placenta resists, stop and pack the uterus with boluses or use fluid douches to keep antibiotics in the uterus. Be very careful to use good hygiene when treating the uterus or the problem will become worse. Systemic antibiotics are useful, particularly if the uterus develops an infection (metritis). Prostaglandins may aid in getting the uterus to reduce in size and in releasing the placenta. Make sure the calf is nursing and treat any other problems that may have caused the retained placenta. Oxytocin is useful only in the first 48 hours and may be used to reduce the size of the uterus. If used later than 48 hours, the uterus must be sensitized with estrogen.

Grass tetany

• Clinical signs: Affected cattle will appear restless, stop grazing and have increased activity with an unusual high stepping gait. As the condition progresses the animal falls down, the legs are stiff and convulsions occur. The eyes move in an erratic manner and may roll in the head. The heart rate and body temperature are elevated. Some animals may become very aggressive.

• Treatment: IV Magnesium usually given with Calcium. Treatment is not as effective as with milk fever and many affected animals do not respond.

• Prevention: Supplemental feed (hay) to lactating cows that are grazing lush pasture particularly during cold, wet weather.

Infectious Bovine Rhinotracheitis (IBR)

• Clinical signs: Inflammation of the upper respiratory tract, in some cases there may be an pustular inflammation of the vulva and inflammation of the eye (conjunctivitis). Cows in the last trimester of pregnancy will abort.

• Pathogenesis: Virus is spread from animal to animal by contact or inhalation. The virus attacks the lining of the respiratory tract and then is carried throughout the body. Viral infection of the fetus causes abortion.

• Prevention: Vaccinate. Modified live vaccines are very effective in providing immunity. Intranasal vaccines are very good.

Bovine Viral Diarrhea (BVD)

• Clinical signs: Fever, depression, off feed. Oral lesions, pinpoint lesions that enlarge to 1-2 cm, shallow ulcers and mild diarrhea. Infection of mid trimester pregnancy can lead to mummification or congenital defects. Late term infection leads to abortion or weak calves.

• Prevention: Vaccinate. Vaccination of immunotolerant, persistently infected cattle with an attenuated vaccine can result in persistent infection (mucosal disease).

Leptospirosis

• Clinical signs: Fever, yellow milk, anemia, hemoglobinuria, jaundice. Late term abortion.

• Pathogenesis: Carrier animals shed the organism in their urine. Urine will contaminate feed, water and other animals will ingest the bacteria completing the cycle of infection.

• Prevention: Vaccination with the correct serotype. Current vaccines are unable to provide long term protection so boosters are recommended every six months.

USDA REGULATED DISEASES

• Infectious agent: Brucella bacteria. This bacteria is an obligate intracellular bacteria

• Clinical signs: Often none but may see abortion or weak calves.

• Pathogenesis: Infected cows abort and shed billions of the bacteria. Other cows lick the aborted fetus, placenta or fluid and are infected. The organism is carried to lymph nodes around the udder and uterus. With pregnancy the organism increases dramatically in number, eventually killing the fetus and causing abortion. The organism is also shed in the milk.

• Prevention: Vaccination with Strain 16B abortus. Single vaccination at 2-8 months of age.

Tuberculosis

• Infectious agent: Mycobacterium bovis.

• Clinical signs: Chronic respiratory disease or "poor doer".

• Pathogenesis: Organism lives in lymph nodes in the respiratory tract, udder or digestive tract. The organism is shed in the exhaled air, manure or milk. Cattle and humans are infected by direct contact.

• Prevention: Test and slaughter. All dairy cattle are tested every three years. The test is a measure of cell mediated immunity. A small amount of purified cell wall is injected at the base of the tail. The injection site is examined in 72 hours for sign of swelling (positive).

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