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Moos News

The Latest on Avian Influenza in Cattle

Reports from Texas, Kansas, and Michigan of a “mystery cattle illness” affecting dairy cows has been recently discovered to be a form of Avian Influenza or bird flu. This article will review what Avian Influenza is, what the risk to human health is, what the risk to cattle is, and what steps we can take to manage as much of the risk as we can. More information is being released every day, but this information is accurate to the best of our abilities as of April 2nd, 2024.

Canada, among many other countries across the globe, has been managing an outbreak of Highly Pathogenic Avian Influenza (HPAI) since February of 2022. The virus is a concern as it can cause high rates of illness and death in infected birds, thus the descriptor of “highly pathogenic”. It is spread mainly by waterfowl (e.g. ducks) and migratory birds in their respiratory secretions and droppings via direct contact with infected birds or a heavily contaminated environment (e.g. pond). Though cases of Avian Influenza in non-avian animal species (e.g. dogs, cats) is not common, it is known to occur. Last month, for the first time we are aware of, dairy cows became infected with the virus.

Signs of Avian Influenza in cows:

  • Older (2nd lactation and higher) cows in mid-lactation seem more severely impacted than young or fresh cows

  • Decreased ruminations and feed intake

  • Acute, sudden drop in milk production

  • Milk becomes thick, yellow, almost colostrum-like, but negative on California Mastitis Test

  • Manure becomes firm and tacky

  • Cows may be lethargic, dehydrated, or fevered

  • ~10% of the herd may become affected and illness lasts 10-14 days


If you are concerned about any of the above symptoms, please call the clinic

Investigation into an infected herd in Texas has identified infected pigeons, blackbirds, and grackles as a possible vector for the virus. While we may think of Texas as far away, there are many species of birds who span that distance as part of their migration. With the additional confirmation of Avian Influenza infection in a Michigan dairy herd, the question of geography becomes much less hypothetical.

Another potentially concerning aspect to the Avian Influenza is that humans are also able to contract the virus. This may be quite concerning to hear, but it is important to know that only one human case of Avian Influenza has ever been reported in Canada and the individual was likely infected out of the country. Additionally, there is no evidence that eating fully cooked eggs and meat carries any risk of transmitting Avian Influenza. Birds from infected poultry flocks are depopulated and do not end up in the food chain. Milk from affected dairy cows is being discarded and pasteurization is capable of killing the virus.

This all being said, one of the individuals working on an infected Texas dairy has contracted Avian Influenza. Thankfully, the person is only mildly ill so far, but it emphasizes the importance of being vigilant for signs of illness in your animals and yourself.

Signs of Avian Influenza in humans:

  • Conjunctivitis

    • This appears to be a major symptom to differentiate between Avian Influenza and other flu viruses or similar illnesses

  • Flu-like upper respiratory symptoms (cough, sneeze, runny nose, sore throat, etc.)

  • Fever

  • Muscle and body aches, headaches

  • Fatigue

  • Shortness of breath and difficulty breathing

  • In rare cases, diarrhea, nausea, vomiting, or seizures

Biosecurity – What can we do about it?

With all that we currently know about Avian Influenza, the risk to Canadian cattle is low, but it is important not to become complacent. The issue illustrates just how important it is that we consider risks to one area of animal agriculture as a risk to all areas, and relevant to human wellbeing as well. While stressful, we can use this opportunity to make changes that reduce the risk of acquiring or spreading infectious agents between and on farms.


Biosecurity items that can help:

  • Wash your hands after handling animals and change clothing or wear coveralls when leaving animal housing and entering human housing

  • Limit access of wild birds to food and water sources for cattle

  • Remove nests and access to other tempting structures for roosting

  • Do not consume raw or unpasteurized milk, especially from animals who are displaying any signs of illness

  • Reduce non-essential visitors to the farm, especially those from the United States of America

  • Ensure any visitors are wearing clean clothes and disinfected boots or disposable boot covers

  • Minimize new animal introductions, especially those from the United States of America

  • For animals that are brought in, quarantine them for 21 days and monitor feed and water intake during this period

  • If you have poultry in the same barn or property as your cattle, monitor them for signs of Avian Influenza as follows:

    • Drop in egg production, often with more soft-shelled or shell-less eggs

    • Diarrhea

    • Coughing, gasping for air, or sneezing

    • Nervous signs like tremors or lack of coordination

    • Hock hemorrhages

    • Sudden and high mortality rate

    • Quietness, lack of energy or appetite, or depression

    • Swelling around the head, neck, and eyes

    • Swollen and congested wattles and combs

  • If you find a sick or dead wild bird on your property, you can report the discovery to have the carcass tested or to track bird deaths for Avian Influenza monitoring

    • You can reach out to the Ontario regional centre of the Canadian Wildlife Health Cooperative at 1-866-673-4781

    • There is also an online reporting tool available to report sighting of sick/dead wildlife or arrange the submission of carcasses for testing at

    • Regardless, disposal of dead birds should be done wearing gloves and the carcass buried deep enough as not to be disturbed by other animals, followed by handwashing and the cleaning and disinfection of any tools used


If you have any further concerns about biosecurity or Avian Influenza, please reach out to your herd health veterinarian.


  • Canadian Food Inspection Agency

  • Canadian Wildlife Health Cooperative

  • Dairy Farmers of Ontario

  • Ohio State University’s Buckeye Dairy Network

  • United States Department of Agriculture


Avian Influenza Update 

(CFIA statement – May 3, 2024)

Canada is expanding its surveillance to manage the possible emergence of HPAI in Canada by:

  • Conducting enhanced testing of milk at the retail level to look for viral fragments of HPAI.

  • Facilitating the voluntary testing of cows that are not presenting with clinical signs of HPAI to facilitate enhanced industry biosecurity efforts.

  • Additional import requirements for breeding animals imported from the US to Canada including:

    • lactating dairy cows have tested negative by PCR for HPAI virus at an approved lab within 7 days of export;

    • lactating cows found positive must complete a 60-day waiting period and have been retested with a negative result;

    • lactating dairy cows have not been on a premise where HPAI has been detected during the 60 days immediately proceeding exportation.

Lactating dairy cattle are defined as a cow producing milk, regardless of the volume of milk she is producing. This does not include dairy calves, pregnant heifers, or dairy cows that are dry or no longer producing milk.

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