Animal Health – Influenza

Factsheet - ISSN 1198-712X   -   Copyright King's Printer for Ontario
Agdex#: 400/660
Publication Date: January 2013
Order#: 13-009
Last Reviewed:
Written by: Tim Pasma

Table of Contents

  1. Cause
  2. Clinicial Signs
  3. Treatment
  4. Protection and Management
  5. Transmission to Humans
  6. Reporting

Influenza affects a variety of species and usually causes cough, nasal discharge and fever. The spread of influenza can be prevented through good biosecurity measures and vaccination (Figure 1).


Influenza virus has various subtypes, such as H1N1, H1N2 and H3N2. These subtypes can change over time and, in rare instances, can lead to the development of a new influenza subtype. A new subtype can lead to outbreaks or even a pandemic if there is little or no immunity against the virus.

Clinical Signs

Outbreaks of influenza usually occur suddenly and spread rapidly, although sometimes the disease is extremely mild. Animals such as pigs, horses and dogs will have a poor appetite and experience cough, nasal discharge and fever with signs of muscle stiffness. Animals rarely die from influenza but can be quite sick from the disease and recover after several days.

Group of pigs in a pen

Figure 1. Good biosecurity measures can keep animals healthy.

In chickens and turkeys, the disease is called avian influenza, and the signs range from mild to severe. Signs include a drop in egg production with abnormal-shelled eggs, coughing and sneezing, depression, diarrhea, purple-blue discolouration of combs and wattles, and death.

Influenza usually does not cause disease in wild birds, such as ducks and geese, which are the source of all influenza viruses found in nature.


Animals diagnosed with influenza need supportive care with adequate rest, food, water and bedding or shelter. A veterinarian may prescribe medication to help control secondary infections.

In the event of an outbreak of some types of avian influenza, the Canadian Food Inspection Agency (CFIA) will be called in to investigate and manage the case. To prevent the spread of the disease and protect public health, the birds will be euthanized.

Prevention and Management

Your veterinarian can help you design a biosecurity program with measures including sanitation, quarantine and vaccination that can help prevent the spread of the disease.

Washing your hands and covering your cough are important actions that will help stop the spread of the disease between animals and across species.

Vaccination can help minimize symptoms and reduce the spread of the disease. Repeat vaccinations regularly to help maintain protection against the disease.

Two brown chickens walking outside of a barn

Figure 2. Keep poultry from contact with wild birds.

Keep birds and other animals housed outdoors from contact with wild birds as much as possible (Figure 2).

Transmission to Humans

In rare situations with close contact, influenza can spread between different species, including to and from humans and animals. Preventing the spread of influenza between different species is important, because if an individual is infected with two or more influenza viruses at the same time, the viruses can combine and develop into new influenza strains, possibly leading to new outbreaks or possibly a pandemic.

If you are sick with a cold or flu, stay home and have someone else look after your animals.

Use precautions around animals diagnosed with influenza or other diseases, including wearing gloves and an N-95 respirator mask. Always wash your hands after working with or handling animals.

When handling manure from swine or poultry, or spray washing livestock housing or vehicles, wear an N-95 respirator mask.

Get vaccinated for influenza every year.


Influenza is a notifiable disease in Ontario, and veterinary laboratories in Ontario and veterinarians who use a laboratory outside of Ontario must notify the Ontario Ministry of Agriculture and Food and Ministry of Rural Affairs (OMAF and MRA) in the event of a diagnosis. OMAF and MRA will take actions to monitor the disease and will provide assistance to the CFIA during an outbreak of avian influenza.

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