Animal Disease Research and Diagnostic Laboratory
Providing high-quality veterinary diagnostic services as a means to promptly and accurately establish causes of animal health problems.
Animal Disease Research and Diagnostic Laboratory News
Pine Needles: Another Possible Threat to Beef Cow Pregnancies
From ĂŰĚŇÓ°Ďń Extension Veterinarian Russ Daly, DVM
Seasoned cow-calf producers know the long list of everything that has to go right for a cow to become pregnant during breeding season. Nutrition, as measured by cow body condition, needs to be right. The number of fertile bulls needs to be sufficient for the number of cows to be bred. Heat waves, dry spells, infectious diseases from the neighbor’s cows over the fence line — the harmful effects of all of these have to be managed so they don’t interfere with the cow’s ability to become pregnant and to maintain that pregnancy.
Cows confirmed pregnant in the fall and winter have, so far, dodged all that adversity. Fortunately, once midgestation is reached (four to five months postbreeding), it’s uncommon for anything bad to happen to that pregnancy; cows that are deemed pregnant at "preg-check" time yet open at calving time are an unusual occurrence. Studies have shown that once gestation hits even 42 days, herd pregnancy loss is only 2% at the most.
Yet, late-term pregnancy loss occasionally happens. Within a given herd, it’s not unusual for a sporadic cow or two to expel her calf prematurely, oftentimes for no discernible reason. In even rarer situations, exposure to a germ or toxin can cause large numbers of pregnancy losses.
Germs such as bovine viral diarrhea virus, infectious bovine rhinotracheitis virus and Neospora caninum are often mentioned as the usual causes of infectious abortion outbreaks. But there’s another interesting cause of pregnancy loss that cattle producers in less mountainous areas maybe haven’t heard of before — ponderosa pine needles.
For at least the past 50 years, consumption of ponderosa pine tree needles (and those from a few other pine tree species) by pregnant cattle has been recognized as a cause of abortions during the last trimester (three months) of gestation. A compound called isocupressic acid in the pine needles causes the problem. Once in the pregnant cow’s system, this chemical interferes with the production of normal hormones like progesterone that help maintain pregnancy.
One might think it unusual for cattle to eat pine tree needles, of all things. For the most part, that’s correct. When these animals have an ample source of more typical, more palatable feed, they usually won’t resort to pine needles as a source of dietary sustenance. It’s during cold winter temperatures and deep snow conditions that cattle start thinking about consuming them. Cows hunkering under trees to avoid wind will encounter fallen needles to chew on (dead needles still contain the chemical). Unfortunately, those winter weather conditions often coincide with the last trimester of gestation when the fetus is most susceptible to the effects of the chemical.
A great number of cattle producers won’t ever have to worry about this potential exposure since ponderosa pines are fairly unusual in their locations. On the other hand, for cattle producers in the Black Hills of South Dakota, for example, where the trees are plentiful, the threat is all around them. Ponderosa pines are also common in other parts of southwestern South Dakota (they’re the namesake of Pine Ridge), northern Nebraska and throughout mountain forests in the western U.S.
There’s no vaccine against pine needle abortion, nor are there preventive medications or antidotes. The only tool at our disposal against the problem is to make sure pregnant cattle don’t have the chance to consume the needles. It’s especially important during winter once snowfall and cold temperatures encourage cows to look to these needles as something to eat. Avoidance doesn’t just apply to the standing trees themselves, but also to brush piles from pine trees and fallen needles on the ground underneath the trees.
Pine needles are just one more pregnancy threat to put on the list for cattle producers to manage. If you’re a cattle producer in areas where the trees are prevalent, it’s certainly something to pay attention to.
Other Stories
Q&A with Dr. Sunil Mor
From South Dakota Searchlight:
Airborne diseases have not been kind to the poultry industry in recent years.
Highly pathogenic avian influenza, which spreads through the air to the lungs of wild and captive birds, has devastated chicken and turkey flocks in waves. The price of eggs has ballooned, then fallen, as the outbreaks have flared up. Last year, the virus jumped from birds to cattle, causing trouble in the dairy industry by way of decreased milk production.
Sunil Mor, Ph.D., of ĂŰĚŇÓ°Ďń thinks a lot about respiratory diseases in animals. Mor leads the virology section of the school’s Animal Disease Research and Diagnostic Laboratory, and has a keen interest in respiratory viruses — especially those with the potential to mutate and infect humans, known as zoonotic diseases.
Mor was recently named the winner of the Bayer-Snoeyenbos New Investigator Award by the American Association of Avian Pathologists, a win based on the work his lab did last year to confirm the presence of a new respiratory poultry disease in the U.S.
New World Screwworm in Livestock
From KELOLAND
According to Russ Daly, ĂŰĚŇÓ°Ďń Extension veterinarian, the New World Screwworm had been in the U.S. in the past, but eradication efforts using sterilized male flies (the females of the species only mate once in their lifecycle) drove the insect out of North America.
But now it is coming back. The NWS has been identified in Mexico and other nations to the south, and Daly speculates that this could be the result of slackening of the use of sterilized males, and perhaps more likely, increased movement of livestock from place to place.
“[The NWS] develops from the fly eggs that are deposited in that animal,” explained Daly. “This particular fly and its eggs, instead of liking the dead tissue (like normal maggots) — it likes the living tissue.”
Daly explained that even something as small as an insect bite on an animal can be enough to attract a fly to lay its eggs.
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Cat Death Losses Due to Highly Pathogenic Avian Influenza in South Dakota
Cat Death Losses Due to Highly Pathogenic Avian Influenza in South Dakota
Veterinarians and laboratory diagnosticians are fielding reports of death losses in cat populations linked to avian influenza infections.
Beginning in 2022, an H5N1 subtype of highly pathogenic avian influenza virus caused death losses in domestic turkeys and chickens in South Dakota and elsewhere in the United States, an outbreak that continues. The highly pathogenic avian influenza virus causes respiratory and multiple organ failure in affected birds, typically appearing as increased numbers of dead birds in large commercial operations, as well as smaller backyard flocks. Deaths in wild birds, typically migrating waterfowl but also other bird species, have been observed at the same time, as well as spillover of the virus into mammals, such as raccoons, foxes, skunks and other species.
In spring 2024, the highly pathogenic avian influenza virus began , causing drops in milk production and other signs of illness. Unlike infections in other species, widespread death losses have not been associated with highly pathogenic avian influenza infections in dairy cows.
About the same time as its emergence in dairy cows, the highly pathogenic avian influenza virus was implicated in deaths of domestic cats in the vicinity of affected farms. Most affected cats showed neurologic signs, such as tremors or seizures, for a short period of time before dying.
Since that time, three cases of substantial death losses in groups of outdoor domestic cats in South Dakota have been described. In each of these cases, there has been no apparent link to dairy cows, other livestock or domestic poultry.
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Changes to Rabies Testing at the South Dakota Animal Disease Research and Diagnostic Laboratory
Please note the following changes to the billing for animal rabies testing specimens sent to the South Dakota Animal Disease Research and Diagnostic Laboratory.
Human Exposure to Wildlife
Effective Sept. 1, 2023, South Dakota Game, Fish and Parks will only pay testing fees for wildlife animal species that have posed a risk of human exposure to rabies. This includes live wildlife species that have bitten, scratched or otherwise exposed a person or persons. In the past, this department had paid testing fees for all wildlife species, regardless of human exposure risk.
Human Exposure to Domestic Animals
The South Dakota Department of Health will continue to pay testing fees for domestic animal species that have posed a risk of human exposure to rabies.
Animal-Only or No Exposure
Animal specimens for rabies testing that have exposed other animals or have not exposed either people or animals will be billed to the submitting clinic, regardless of whether the specimen comes from a wildlife or domestic animal species.
Prior to testing, veterinarians and submitters need to fill out the rabies submission form completely and with appropriate detail about human exposures. Information from this form is used to contact people with possible exposures and ensure they get prompt, appropriate treatment should the specimen test positive for rabies. Supplying sufficient detail on the submission form also ensures that testing fees are appropriately charged.
Please call the Animal Disease Research and Diagnostic Laboratory at 605-688-5171 with questions.
To learn more:
Bovine Viral Diarrhea Virus Persistent Infection, Novel Bosavirus Characterized in Bison through SDSU Work
As part of an investigation of reproductive losses in an American bison herd, faculty and staff at ĂŰĚŇÓ°Ďń's Animal Disease Research and Diagnostic Laboratory characterized for the first time persistent infection with Bovine Viral Diarrhea Virus, as well as a novel bosavirus in bison.
Following reproductive problems in a bison herd during the 2018-19 calving season, investigators collected samples from the breeding herd as well as four animals with failure to thrive. Serology, virus isolation, metagenomic sequencing and pathology was performed.
All 26 animals examined serologically had titers to BVDV Type 1 (range 1:512 to 1:8192, with 17 with titers greater than 1:1000) and BVDV Type 2 (range 1:64 to 1:8192, with seven greater than 1:1000), despite the lack of recent BVDV vaccination. Metagenomic sequencing on pooled nasal swabs and serum identified coinfection of BVDV and bovine bosavirus. The BVDV genome was most similar to the BVDV type 1a vaccine strain Oregon C24V with 92.7% identity in the coding region. Bosavirus was also identified but its clinical significance is unknown.
Pathology examination did not reveal any gross lesions. On histopathology, two BVDV-positive animals had lymphoid depletion in the ileocecal valve lymphoid region. A female PI bison had a decrease in primary follicles in the ovary, and a male PI bison showed evidence of decreased spermatogenesis in the testes.
Serum from these same animals collected two months later remained positive for BVDV and bosavirus, with one animal coinfected with both BVDV and bosavirus. These results suggest that both viruses can persistently infect bison. While the etiological significance of bosavirus infection is unknown, the ability of BVDV to persistently infect bison has implications for BVDV control and eradication programs.
Investigators from SDSU on the project included Angela Pillatzki, Ben Hause and Chris Chase. They can be contacted at 605-688-5171 for more information.
Address:
Animal Disease Research and Diagnostic Laboratory
1550 Medary Ave., Box 2175
ĂŰĚŇÓ°Ďń
Brookings, SD 57007
For all sample drop-offs, please use the entrance off of Medary Avenue.
Telephone: 605-688-5171
Fax: 605-688-6003
Regular Hours: 8 a.m.-5 p.m. Monday through Friday
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Note: Starting April 1, as per the American Association of Veterinary Laboratory Diagnosticians accreditation requirements, full diagnostic laboratory reports will be sent labeled as "preliminary," indicating some results are still pending or "final," where no test results are pending. Previously, for some cases, only the newest results were sent via email or fax.
Thank you for understanding this requirement. If you have any questions, please feel free to contact the laboratory.
