Ontario Animal Health Network (OAHN) Bovine Expert Network Quarterly Producer Report

OAHN Q1 Laboratory Data from the Animal Health Laboratory

Compiled by Dr. Rebecca Egan, AHL

There were 196 bovine pathology submission between February 1st and April 30th 2021.

Salmonella

In total, 255 bovine submissions had bacterial culture performed (non-milk). Salmonella spp. were isolated from 14 submissions this quarter, representing an estimated 7 premises. Salmonella Dublin was the isolate in 6 of these cases, representing 1 premises. The primary finding associated with isolation of S. Dublin was septicemia with concurrent pneumonia and/or enterocolitis. Other isolates included S. Cerro (diarrhea), S. Typhimurium var Copenhagen (enteritis, pneumonia, septicemia), S. Uganda, and S. Muenchen.

Respiratory disease

As seen in previous quarters, pneumonia was the most frequent pathology diagnosis in cattle over 2 months of age (n=21). This quarter, the pneumonia etiologic agents detected in young cattle were Histophilus somni (n=2), BRSV (n=2), Mannheimia hemolytica (n=6), Pastuerella multocida (n=4), Mycoplasma bovis (n=1), and Salmonella Dublin (n=1). A few cases of M. hemolytica or H. somnus pneumonia had concurrent isolation of Pasteurella multocida, Trueperella pyogenes and/or Mycoplasma bovis. Mannheimia haemolytica (n=2) and Bibersteinia trehalosi (n=1) were detected from mature cattle this quarter.

Enteric disease

Enteritis was the most common diagnosis in young calves, and the dominant infectious causes were rotavirus (n=17), cryptosporidium (n=8), and coronavirus (n=14), with concurrent infections identified in several instances. There were three cases of abomasitis/rumenitis, and two of these had secondary mycotic infection (one abomasitis and one rumenitis). In older calves, there were also two cases of coccidiosis, a few cases of abomasal bloat or ulceration, and one case of necrosuppurative glossitis caused by Fusobacterium necophorum.

Neurologic disease

In older calves and adults, there were several cases of polioencephalomalacia (n=5), and lead toxicosis was confirmed in one case. Two cases of Listerial encephalitis were identified as well (one in an older calf and one in an adult).

Abortion

There were 34 submissions for abortion investigations (dairy n=17, beef n=17), and a presumptive or definitive diagnosis was achieved in 14 cases. The infectious causes of abortion identified were bacterial (n=10, including Trueperella pyogenes, Bacillus licheniformis, Streptococcus pluranimalium, Streptococcus lutetiensis), Neospora (n=1), and Bovid herpesvirus-1 (n=1). There were also a few reports of beef herds experiencing increased numbers of stillbirths and/or weak born calves.

Congenital disproportionate dwarfism was confirmed in one instance. Potential etiologies for this condition include genetic chondrodysplasia, nutritional chondrodysplasia (associated with low liver zinc or manganese concentrations), and chondrodysplasia resulting from exposure to plant toxins or toxic levels of vitamin A. The full case report can be accessed at https://www.uoguelph.ca/ahl/congenital-disproportionate-dwarfism-beef-calf

Bovine Viral Diarrhea Virus

A total of 362 PCR tests performed. There were 36 were positive results, and of these there were 12 identified as part of routine herd screening, 22 were part of herd screening for one sheep flock following identification of multiple congenital infections, and 1 was identified in an animal with mucosal disease. Three immunohistochemical tests were performed, with one positive result occurring in a lamb with congenital infection (BVDV type 1 by PCR). For full case details, check out the case report at https://www.uoguelph.ca/ahl/congenital-bvdv-type-1-infection-group-lambs-shaky-situation

Ontario Provincial Abattoir Condemnation Update 2020

During 2020, 124,784 bovines were slaughtered in provincially inspected plants. The condemnation rate for whole bovine carcasses (veal, beef, and cull cow) was 1.01%. The most common reasons for whole carcass condemnation were septicemia, peritonitis, abscess, lymphosarcoma and endocarditis. There was an upward trend of condemnations for septicemia in late 2020 driven by male veal calves. The condemnation rate for partial carcass condemnations (veal, beef, and cull cow) was 16.42% with the primary reasons for condemnation being kidneys nephritis, liver parasitic, and liver abscess.

Preventing Lead Toxicity in Cattle

In 2021 there have been 2 reported cases of lead toxicity in Ontario cattle. Lead is one of the most common toxins in cattle. Cattle are curious and often indiscriminate feeders which puts them at risk for lead toxicosis when they encounter novel, discarded materials. Cattle are attracted to the metal taste and will actively seek it out.

Although lead cases are typically sporadic, they tend to happen in spring when cattle are turned out to pastures that contain a lead source.

Signs of Lead Toxicity

Cattle that have consumed lead have been reported to :

• Die suddenly or are found down
• Be depressed
• Appear blind
• Aimlessly wander, often separate from the herd
• Less commonly vocalize and be excitable

Although cattle of any age are at risk, young milk-fed calves absorb lead more effectively from their gastrointestinal tract, leading to greater susceptibility to lead toxicosis.

Human Health Concerns

Cattle with blood levels above acceptable lead concentrations make them unsafe to enter the food chain.

Some cattle can have elevated lead levels without showing any outward signs of disease, however their meat and milk contain lead levels unsafe for human consumption. For this reason, all cattle exposed to the source of lead must be identified and tested.

Potential Sources of Lead

• Discarded batteries – Improperly discarded lead acid batteries from automobiles and farm machinery are the greatest risk. Batteries that have been exposed to freeze-thaw cycles with damaged cases are easily accessed by cattle and particularly dangerous.
• Lead-based paints – Newer paints are virtually lead-free but older painted surfaces remain a risk. Cattle may lick old outbuildings or other painted surfaces, or consume flaked paint chips. Lead also remains in the ashes from buildings that have burned.
• Discarded engine oil – Although unleaded gas has reduced the risk, old oil spills or dumpsites may still be contaminated.
• Farm machinery – May contain batteries, grease, used oil or filters containing lead.
• Roofing materials, plumbing supplies, lead shot and other waste can contain lead.

Prevention

• Prior to turning out cattle to new pasture or returning to a yard, check for discarded materials that have accumulated since the area was last occupied by livestock
• Dispose of used batteries, paint, and oil properly at local collection stations for hazardous waste
• If batteries are broken open, the soil around the battery will also be contaminated and should be cleaned up

Control

• To protect other cattle from possible lead poisoning, it is critical to identify the lead source and remove access

If you suspect lead toxicity:

-Call your veterinarian. The herd veterinarian will want to investigate the cause of neurological disease or death by blood testing or postmortem, and rule out other causes of neurologic disease such as rabies

-Immediate action is needed to prevent animals with toxic lead levels from entering the food chain

-Lead toxicosis is an immediately notifiable disease in Ontario and your veterinarian will work with the Ontario Ministry of Agriculture, Food and Rural Affairs to human and animal health is protected

Bovine OAHN Team Updates – Welcome to our newest network members!

We welcome Dr. Rebecca Egan, a veterinary anatomic pathologist with the Animal Health Laboratory at the University of Guelph. Rebecca completed her Bachelor of Science Degree in Animal Biology and Doctor of Veterinary Medicine at the University of Guelph. She spent a year working in mixed-animal practice in Southwestern Ontario prior to returning to the department pathobiology where she studied anatomic pathology, carried out research investigating early cellular immune responses in calves experimentally infected with Mycobacterium avium subspecies paratuberculosis, spent time teaching, obtained ACVP board certification, and completed her Doctor of Veterinary Science degree.

Dr. Diego Gomez will be joining the OAHN bovine network on behalf of  Clinical Studies at the Ontario Veterinary College. Dr. Gomez completed a Master of Veterinary Science and Large Animal Internal Medicine Residency at the Atlantic Veterinary College and his PhD in Veterinary Infectious Diseases at the Ontario Veterinary College. Dr. Gomez serves as faculty in the department of Clinical Studies and as a clinician in the Large Animal Health Sciences Centre. His research interests are neonatal calf diarrhea, acid-base disorders and fluid therapy, and microbiota assessment in mammals.

Thank You

A big thanks to network members who have completed their terms with the OAHN bovine network.

Dr. Dan Kenney has provided insight from Clinical Studies on bovine referrals since the network’s inception. We appreciate his time and his contributions to surveillance.

Dr. Andrew Brooks has spent 7 years summarizing and presenting bovine laboratory data  for the bovine network. This is a very time-consuming endeavor and we have appreciated his attention to detail reviewing each case, categorizing submissions, and analyzing the data for our network.