Visit with a Vet: New Tool for Monitoring Blood Calcium Concentrations in Dairy Cattle

Originally published in the Feb. 19, 2014, issue

 

Visit with a Georgia veterinarian in this monthly feature. This edition comes from Dr. John K. Bernard, animal and dairy science professor on the UGA-Tifton campus. 

 

Hypocalcemia, known as milk fever, is a condition of low blood calcium concentration that negatively affects performance and health in dairy cattle. Cows with clinical milk fever are more likely to have other diseases including retained placenta, mastitis, ketosis and left displaced abomasum, or LDA. Though the incidence of milk fever has declined to approximately five percent with improved close-up dry cow nutrition, it is estimated that 50 percent of all dairy cows in the US experience subclinical hypocalcemia. Cows with subclinical hypocalcemia have lower milk yield, decreased reproductive performance and increased odds of ketosis and LDA.

 

Blood sample analysis is the traditional way of evaluating a dairy cow’s calcium status. The sample is analyzed for total calcium concentrations. This is calcium that meets three specifications: bound to plasma protein; in an ionic form associated with low molecular weight compounds; and free ions. Metabolic functions such as muscle contraction, blood clotting and bone formation is supported by the free ion form of calcium.

 

Ionized calcium measures these free calcium ions, which are readily available for the aforementioned metabolic functions. This provides a better estimate of true calcium status. The proportion of total calcium that is ionized is not constant, and changes with lactation stages. Occasionally, some calcium concentrations indicate the cow is not ill, but looking at ionized calcium concentrations confirm she is in a state of clinical hypocalcemia.

 

Ionized calcium concentrations of less than one millimol per liter are considered indicators of subclinical milk fever. Both ionized calcium and magnesium levels can be used to evaluate nutrition in close-up dry and transition cow nutrition, as well as diagnose milk fever and grass tetany that occur around parturition or early lactation.

 

Recently, an electrode-based method was developed for rapid measurement of ionized calcium. This method is both economical and available to researchers and producers, and a unit is located at the University of Georgia Veterinary Diagnostic and Investigational Laboratory in Tifton, Ga.

 

Samples of ionized calcium and magnesium should be collected in a green top (Lithium Heparin) with a separator gel Vacutainer tube, or a “tiger-top” gel-separator tube. The sample should be allowed to clot, centrifuged to separate the plasma or serum from the blood clot and refrigerated immediately. The frozen sample should be packaged with an ice pack and shipped for overnight delivery to the laboratory for analysis. The pH of the sample is measured and used to calculate the final result.

 

Do not remove the cap from the collection tube. Exposing samples to air or long storage can change blood pH, so it is important to collect and transmit and process samples quickly in a laboratory to obtain valid results. 

 

For questions about submitting ionized calcium and magnesium samples, contact Anita Merrill at 229-386-3340.



Visit with a Vet: Animals in the Cold

Originally published in the Jan. 22, 2014, issue

 

Visit with a Georgia veterinarian in this monthly feature. This edition comes from Associate State Veterinarian Dr. Wendy Cuevas-Espelid in Atlanta, Ga.

 

All too often we think animals can withstand a certain amount of cold weather because they have fur and are "animals.” I know my dog is accustomed to air conditioning in the summer and a nice warm house in the winter. What advice can we offer to others that may not consider inclement weather a hazard to our companion animal friends and to livestock?

 

Equine

Horses have become strong family members and are treated as such. They have air-conditioned barns, wear nice blankets during the winter and even the lucky ones receive manicures on a regular basis by a farrier. However, they are not exempt with the elements nature has to offer us.

 

Horses will start growing winter coats when there are fewer than 12 hours of daylight. They remain healthier if they stay outside, and healthy horses can tolerate cold temperatures if they have adequate hay, grain and water.

 

In cold weather, horses require more calories. However, they can get impaction colic if they don’t drink enough water on cold days. To combat that, sprinkle salt in their feed. This, along with Gatorade in their water, will encourage water consumption – just make sure water is always available at feeding time and any ice in it is broken.

 

Occasionally, ice will form on a horse’s back, which actually helps them retain heat. For old, skinny horses, offer adequate shelter or a winter blanket and additional care to help them stay warm.

 

Bovine

Last October approximately 100,000 cattle died due to exposure by an extreme blizzard. This cost the state of South Dakota as much as $1.25 million. Although Georgia does not experience such extreme changes in temperature, recognizing good management of cattle due to intense fluctuations in temperature is always a good idea.

 

Beef cows exposed to cold stress require more energy for maintenance. Cold stress occurs when the wind, temperature and humidity affect bovines’ critical temperature.

 

If a farm has woods, hills or other types of shelter, this can provide some protection against wind. Once a bovine reaches its lowest critical temperature, it begins to shiver, which requires more energy to maintain internal body temperature.

 

Try to reduce mud in and around feeding areas. This can reduce energy stores and internal body temperature, especially for calves.

 

The best and easiest way to manage a winter feeding regime is to know how to monitor cattle’s body conditions. Forage should be tested for its true nutritional composition. If hay doesn’t provide a sufficient amount of energy, then cattle need to be supplemented with another form of energy-dense ration. Keep a mineral supplement, especially with magnesium, in an effort to reduce grass tetany, which can be triggered in cold weather.

 

Canines and felines

As spoiled as our furry friends are, dogs and cats, can suffer from the elements.

 

Small pets, especially young and geriatric ones, should be kept indoors. Long-haired breeds such as Huskies will do better outdoors than short-haired breeds such as Dachshunds. Though there are stylish dog sweaters and raincoats available, be aware that most heat loss occurs from ears, the respiratory tract and foot pads. If there is ice on the ground, wash dogs’ feet with a wash cloth. Rock salt or chemical ice melts can cause foot pads to get chapped and raw, and excessive licking of it can cause digestive problems.

 

Make sure there is plentiful food and water. Pets with pre-existing conditions such as cardiac disease, kidney insufficiency, diabetes and hormone imbalances will have more difficulty regulating body temperatures.

 

Cats will hide anywhere to stay warm, including under the car hood. If you park outdoors, tap your hood to scare away felines that might be hiding there. They can get seriously hurt or killed by moving engine parts.

 

This is just a small amount of information to get us all thinking of how to protect our animals. If there are any issues not addressed, please consult your veterinarian for further advice.

 

Additional questions? Contact the Department’s Animal Industry Division at 404-656-3667.



Visit with a Vet: Feral Swine -- More Than Just a Nuisance

Originally published in the Dec. 25, 2013, issue

 

 

Visit with a Georgia veterinarian in this monthly feature. This edition comes from State Veterinarian Dr. Robert Cobb in Atlanta, Ga.

Free-ranging populations of wild pigs, or feral swine, exist in at least 39 states. Some estimate their numbers to be more than 4 million, with the largest populations located in California, Florida, Hawaii and Texas. Georgia’s large population of feral swine resides mostly in the river swamps of south Georgia, but can be found statewide.

Today’s feral swine population is a combination of escaped or neglected domestic swine, Eurasian wild boar and feral pigs that have been captured and transported for the purpose of starting wild, free-living populations. The intentional movement of trapped feral swine resulted in extensive crossbreeding of feral populations, producing many variations.

Feral swine regularly tear through livestock and game fences; consume animal feed; destroy field crops such as corn, milo, watermelon, peanuts, hay, turf and wheat; and, when given the opportunity, will prey upon young livestock and other small animals.

Moving untested feral swine to new areas or allowing them onto farms with domestic pigs is illegal in Georgia and can have disastrous consequences to the commercial swine industry. Feral swine can be imported into Georgia only by a special permit issued by the state veterinarian. Three feral swine agreements are utilized by the Department in cooperation with the US Department of Agriculture. Individuals wishing to have feral swine facilities must meet strict testing, fencing and reproduction prevention protocols. The feral swine facilities are regularly inspected by the Department to assure compliance with the rules in order to maintain separation of feral swine from domestic herds.

Feral swine are carriers of a number of diseases: swine brucellosis, pseudorabies, leptospirosis, tuberculosis, tularemia, trichinosis, plague, anthrax, African swine fever, classical swine fever  or hog cholera and swine vesicular disease. USDA eradicated hog cholera from the US in 1976.

Though they’ve been eliminated or controlled from US commercial production swine herds, some are still found in Georgia feral swine and can be readily transmitted to humans and other animals:

Brucellosis is a bacterial infectious disease of animals and humans, caused by Brucella bacteria. Swine brucellosis is a reproductive disease, causing abortions in sows and infertility in boars. Infected swine are disease carriers for life and can serve as sources of infection. The only way to remove the disease is to detect infected swine through blood tests and cull the animals. In humans, the disease may mimic severe flu and may cause crippling arthritis or meningitis. Animals and humans are exposed to the swine Brucella bacterium by contact with infected blood, reproductive tissues and fluids from animals during farrowing, abortion or carcass dressing.

Pseudorabies: Viral PRV attacks the central nervous system and is fatal to cattle, horses, goats, sheep, dogs, cats, raccoons, skunks, opossums and small rodents. Though not fatal in swine, it causes abortions and stillbirths. Pseudorabies is caused by a herpesvirus in swine. It is not related to rabies and it does not infect humans. The spread of PRV from feral swine to domestic cattle has also been documented in Florida and Texas. Feral swine are known to break into feed bunks and congregate around areas where supplemental feed is distributed, providing a source of contamination of feed and potential spread of infection through contact with domestic herds.

Parasites: Feral swine are also host to several disease-causing parasites. These parasites include lung worm, kidney worm, thorny-headed worm, ascarid roundworm, hog lice and the parasite that causes trichinosis.

The more feral swine populations increase and expand, the greater the chances that they may transmit diseases to domestic animals, wildlife and humans as well as destroy expensive crops. To minimize the threat feral swine pose to domestic swine operations, farmers should not introduce wild pigs into herds or attempt to market wild-caught pigs. Before transporting breeding swine, perform blood tests according to state and federal guidelines, and blood-test all new stock before adding them to existing herds. Fence out feral swine and do not butcher feral swine on the farm, or feed offal from field-dressed wild hogs to domestic ones.



Visit with a Vet: Six-Year Tuberculosis Test Eliminated

Originally published in the Nov. 27, 2013, issue

 

Visit with a Georgia veterinarian in this monthly feature. This edition comes from State Veterinarian Dr. Robert Cobb in Atlanta, Ga.

In March 2013, I received a request from Georgia Milk Producers, Inc. to conduct a review of Georgia’s Whole Herd Tuberculosis Testing Program. This request was made because of several reasons: it has become increasingly difficult to locate veterinarians who will conduct whole-herd tuberculosis testing; the amount of labor involved; the veterinary fees for the testing; and the considerable financial loss for the dairy owner due to the disruption of the cattle’s daily routine.

In an effort to work with our dairy industry, I consulted with other state veterinarians concerning their state regulations for dairy tuberculosis testing, considered the Bovine Tuberculosis Free status of all 50 states; and determined that most states rely upon import testing and slaughter surveillance. The greatest risk of introduction of bovine tuberculosis comes from imports from Mexico, commingling of cattle with Mexican-origin animals and specific areas in the country where tuberculosis is endemic in the wildlife.

After careful review of slaughter surveillance records, tuberculosis import testing requirements and the fact that Georgia has been Bovine Tuberculosis Free since 1986, I wish to announce the elimination of the required six-year Whole Herd Tuberculosis Test for Georgia dairy producers.  The effective date of the change to Georgia Department of Agriculture Rule 40-13-4-.04 BovineTuberculosis Eradication Requirements is Oct. 7, 2013. 

I wish to emphasize that by eliminating the six-year tuberculosis test, our state and the dairy industry will depend wholly upon import tuberculosis testing and slaughter surveillance as a means of detecting tuberculosis in dairy animals. Individual official identification will greatly aid in disease control and prevention. I encourage all dairy producers to utilize official identification in all their dairy animals. Official metal ear tags can be obtained from the Department. Official electronic tags are encouraged and available at your vendor of choice. 

Although the required six-year tuberculosis herd test has been eliminated, the Department shall conduct tuberculosis tests on any dairy herd suspected of being infected with or exposed to Mycobacterium bovis at such times as deemed necessary by state or federal animal health officials. The Department’s animal health officials reserve the right to supervise and monitor any tuberculosis testing and the associated control and eradication activities.

For questions about the elimination of this tuberculosis testing, or to obtain official identification metal ear tags, contact the Department’s Animal Health Division at 404-656-3667.

Visit with a Vet: Monitoring for Porcine Epidemic Diarrhea Virus to Begin This Month

Originally published in the April 30, 2014, issue

 

Visit with a Georgia veterinarian in this monthly feature. This edition comes from State Veterinarian Dr. Robert Cobb in Atlanta, Ga., and follows up on a previous Visit with a Vet story on Porcine Epidemic Diarrhea virus from the Oct. 30, 2013, issue.

Porcine Epidemic Diarrhea virus is highly contagious in swine.
It has not yet been found in Georgia, but producers are
encouraged to take biosecurity and other measures to prevent
PEDv from making its way to their farms. File photo

The US Department of Agriculture recently announced it will be instituting a monitoring and control program to prevent the spread of Porcine Epidemic Diarrhea virus, a viral disease of swine associated with fever, severe diarrhea and vomiting. Right now, PEDv is considered a production disease, and is not regulated by the World Health Organization or the Department. However, USDA Animal and Plant Health Inspection Service will issue a federal order in May that requires mandatory reporting of all herds diagnosed with PEDv. Herds will be required to identify themselves and provide location information. In addition, animal health laboratories that receive diagnostic samples will be required to provide positive tests and location information to USDA.

The disease is highly contagious and is caused by a coronavirus. PEDv mimics a common pig disease called transmissible gastroenteritis, or TGE, which is also a coronavirus. Only lab tests can tell the difference between the two. PEDv is not a zoonotic disease, meaning it does not affect people. It does not affect other domestic species and is not a food safety concern. 

The disease is most severe in young piglets, but can affect pigs of any age. The disease can cause death and loss of production. Introduction of PEDv into a swine herd with no previous exposure to the virus typically results in acute outbreaks of abortion, severe diarrhea, vomiting, high morbidity – often 100 percent – and variable mortality, as high as 100 percent in pigs younger than 3 weeks of age. The incubation period is short, three to four days, and natural immunity develops. Pregnant sows often abort due to fever; however, older pigs usually recover from the disease within seven to 10 days.

PEDv exists in many parts of the world. The disease is very common in China, Korea and other Asian countries. In May 2013, the disease was first diagnosed and confirmed in the US, in Iowa.  It is unknown how the virus entered the US. There is some concern that feed products, such as porcine plasma products sprayed on pellets in certain rations, was responsible for introduction or spread of the disease. PEDv is not a listed disease of the World Organization for Animal Health, or OIE; is not considered a foreign animal disease in the US; and there are no international or interstate trade restrictions pertaining to PEDv in US swine.

The disease has spread to 28 states and to Canada, causing millions of dollars of damage due to losses from abortions, mortality and poor feed conversion. The number of confirmed cases is more than 5,500. In the Southeast, only Georgia, Florida, Alabama, Louisiana and Arkansas have not had a reported case of PEDv.

There is no specific treatment or commercially available vaccine for the disease. Supportive therapy is useful in the treatment of older animals, and sows that have recovered from the disease pass immunity to their offspring. Recovered animals can shed the virus for up to a month after recovery. 

PEDv can be spread in several ways. The fecal-oral route involves healthy animals ingesting the fecal matter of infected pigs. Fomites, which are inanimate objects such as trailers, chutes, buckets and waterers, clothing, boots and contaminated feed have all been shown to spread the virus as well. The virus is hardy and can survive for long periods of time, especially in cold, damp weather.

A strict biosecurity program is the only way to prevent introduction of the virus. Thorough cleaning and disinfecting of trailers and equipment are essential to keeping the virus out. Be diligent about personnel and visitors, but also consider supplies, feed ingredients, food items, etc. that might be of international origin. To check the origin of a product or ingredients, contact the supplier and request that information. The creation of a “clean crossing line” will help to prevent contaminated personnel or products from entering the farm. 

Additional biosecurity recommendations include thoroughly cleaning and disinfecting anything coming onto the farm; enforcing downtime requirements and maintaining a log of visitors; properly disposing of dead livestock; isolating new animals; continue vet-to-vet discussion about animal health at the herd of origin; and showering into the facility and changing into clean boots and overalls. Veterinarians should also be careful not to transport the virus between herds on their person, equipment or vehicles.

All hog farmers are encouraged to monitor the Department website for news and updates on PEDv.

Some information in this column comes from the National Pork Board, American Association of SwineVeterinarians and USDA-APHIS. For more information on PEDv, visit www.agr.georgia.gov, www.pork.org/pedv or contact the State Veterinarian’s Office at 404-656-3671. Veterinarians can send samples to the two state diagnostic labs for confirmation of PEDv. The Athens lab can be reached at 706-542-5568 and the Tifton lab at 229-386-3340.

Visit with a Vet: Porcine Epidemic Diarrhea Virus

Originally published in the Oct. 30, 2013, issue

 

Visit with a Georgia veterinarian in this monthly feature. This edition comes from Dr. Jeremiah Saliki, director of the Athens, Ga., Veterinary Diagnostic Lab.

 

In April and May 2013, multiple Midwestern American pig farms were simultaneously hit with a disease characterized by diarrhea and vomiting. These symptoms led clinicians and diagnosticians to suspect the coronavirus transmissible gastroenteritis virus, or TGEV, as the cause. Testing fecal samples from sick piglets using standard laboratory techniques failed to confirm these suspicions.

 

However, when the same samples were examined under an electron microscope, coronavirus particles were detected. The unexpected discovery of coronavirus particles that were negative for both US swine coronaviruses – TGEV and porcine respiratory coronavirus – prompted further testing. Tests done at Iowa State University and the Federal Laboratory at Ames were done for exotic coronaviruses, and resulted in the confirmation of porcine epidemic diarrhea virus for the first time in the US.

 

Geographic distribution, transmission and clinical signs

 

Coronaviruses are highly contagious, and the outbreaks in the US spread rapidly. Within six weeks the virus had been confirmed in about 200 hog facilities in 14 states including Arkansas, Iowa, Illinois, Indiana, Kansas, Michigan, Minnesota, Missouri, North Carolina, New York, Ohio, Oklahoma, Pennsylvania and South Dakota.

 

Sporadic outbreaks of porcine epidemic diarrhea were first identified in the United Kingdom in 1971, and this infection has become endemic in most Asian countries since 1982. There was one incursion into Canada in 1980, but it has not been reported in North America since then.

 

The virus is transmitted by the oral-fecal route, with an incubation period of three to four days. Contaminated personnel, equipment, or other fomites may introduce PEDV into a susceptible herd. The disease is difficult to distinguish from TGEV, with the main clinical sign being watery feces that may resemble tufts of wool and have an unpleasant smell. Vomiting may occur and dehydration is a secondary sign.

 

Morbidity and mortality can surpass 90 percent in suckling piglets fewer than 14 days old, but gradually decreases with age. During necropsy, histological examinations – where thin pieces of tissue are mounted on slides and viewed under a microscope – show the small intestine is inflamed with shortened villi, which indicates nutrients are not being properly absorbed, causing diarrhea.

 

Diagnosis

 

The most useful diagnostic specimen is feces or a loop of small intestine. A variety of diagnostic tests, including negative-staining electron microscopy, fluorescent antibody staining, immunohistochemical staining and virus isolation, commonly used for TGEV diagnosis are available in our laboratory for presumptive PEDV diagnosis. However, a test known as polymerase chain reaction is the only technique that can differentiate between TGEV and PEDV. The diagnostic labs in Tifton and Athens, Ga., offer a PCR technique that can detect both viruses, and  a positive result is followed by an additional test – sequencing – for definitive diagnosis.

 

PED and Georgia

 

The rapid spread of PED across the US and its occurrence in neighboring North Carolina raise concern for its possible introduction into Georgia. Fortunately, we are poised to rapidly detect the virus if it was to enter the state. The vigilance of swine practitioners and animal owners is key to detecting its incursion into our state. We recommend that PEDV testing be requested for all cases in which an acute TGEV-like disease is observed with high morbidity.

 

Some information in this column comes from the USDA Porcine Epidemic Diarrhea Technical Note and the 2012 publication “Porcine epidemic diarrhea virus: a comprehensive review of molecular epidemiology, diagnosis, and vaccines.”

Visit with a Vet: BVD Testing at the Georgia Veterinary Diagnostic Laboratories

Originally published in the Sept. 18, 2013, issue

Visit with a Georgia veterinarian in this monthly feature. This edition comes from Drs. Lee Jones, Roberto Palomares, Sree Rajeev, Susan Sanchez, Murray Hines and Jeremiah Saliki of the diagnostic laboratories in Athens and Tifton. 

BVD – one complex disease, one simple sample, one simple strategy!

Bovine viral diarrhea is a significant cause of economic losses to the cattle industry. Clinical signs include reproductive failure, respiratory disease or diarrhea. About 70 percent of infected cattle don’t become sick, but are susceptible to other diseases. Moreover, some animals showing no symptoms are dangerous to the herd as they can be virus carriers, also known as persistently infected animals, or PIs.

PIs are calves infected with certain non-cytopathic strains of BVD in the womb. Although many infected calves die or are culled within six months, some grow into adults. These shed large amounts of the virus in secretions such as saliva, feces, urine and milk throughout their lives, exposing the herd to BVD.

PIs can transmit BVD by direct contact, such as nose-to-nose, or through contaminated veterinary equipment, farm equipment or facilities. To manage BVD, vaccinate all dairy calves at 2 to 3 months old and all beef calves at 4 to 5 months. Add biosecurity procedures to prevent introduction of the disease – isolate and confirm that new animals are BVD-negative; bio-containment to interrupt virus spread; and laboratory testing of samples for BVD presence.

To diagnose a disease such as BVD in an animal or herd, laboratory testing is required. The same is true for whole-herd screening as part of a herd health program.

Diagnosis

When an animal is sick, it is recommended to take eight milliliters of whole blood in EDTA, a combination of a specific acid and a colorless, water-soluble solid typically placed in a purple-topped tube for veterinary purposes. In the case of abortion or death, it is recommended to take samples of lung, spleen, lymph nodes, kidney or the entire fetus.

Herd screening or animal marketing:

To test the herd for PI screening, or to market an animal after confirming it is not BVD-PI, it is recommended to take one ear-notch sample in a screw-capped tube or blood in a red-topped tube. When BVD-free bred heifers are purchased, it is still necessary to test the calf after birth to ensure BVD won’t be accidentally introduced. Diagnostic labs can pool up to 24 ear-notch or blood samples and run one test, called a PCR, to reduce costs per animal, with a turnaround time of two to three business days. If any pool is positive, all members of that pool will be re-tested for BVD using the Antigen Capture ELISA test. This individual animal testing may present an additional cost and turnaround time, but will identify and allow removal of PIs.

Table 1: Testing strategy for PIs. Tests, price and turnaround time of laboratory testing

# of samples received at once	PCR pool size	PCR cost per head	Time to results (PCR)	ACE cost per head	Time to results (ACE)
1-5	NA	NA	NA	$5.00 plus $10 Setup fee	24 hours
5-23	NA	NA	NA	$4.50	24 hours
24 or more	24	$2.5*	2-3 business days	$3.50	24 hours

 

To contact the diagnostic labs, call 706-542-5568 for Athens, 229-386-3340 for Tifton.