Only since I started asking specific questions about annual vaccination protocols in the milking herd have I realized how many farms do not routinely vaccinate adult livestock.
Young stock are often vaccinated when it can be combined with other health events like disbudding or weaning, but it seems a significant number of adult animals are not protected for clostridial diseases and leptospirosis — or possibly some producers do not realise that annual boosters are required to maintain ongoing immunity.
Clostridial diseases are the often-fatal result of invasion by toxin-producing bacteria known as Clostridium species, which form spores that can survive in the environment for several years.
Cattle are exposed to these spores in a multitude of ways, including: penetrating wounds, trauma during calving, bruising, stress, parasites including liver fluke, and even phosphorus deficiency.
The bacteria are not contagious between cattle, and not all infected cattle will show signs of disease. Clinically affected animals often present as suddenly unwell, and death can occur rapidly following infection.
In Australia, the main clostridial diseases and their common clinical signs are:
● tetanus — stiff gait, hypersensitivity, convulsions, death;
● blackleg — severe swelling and lameness, dry cracked skin, depression, fever, death;
● malignant oedema — contaminated wound, depression, fever, death;
● pulpy kidney disease — convulsions and death;
● black disease — abdominal pain, depression, death; and
● botulism — paralysed tongue, drooling, anorexia, aggression, weakness, paralysis, death.
Leptospirosis is another bacterial disease affecting many animal species and with numerous strains. The two main strains seen in cattle are Hardjobovis and Pomona.
Infection usually persists in the kidneys and is often spread via urine directly from cow to cow, however pigs and rodents can also transmit the disease to cattle.
Leptospires can survive for long periods in wet soil, stagnant water or effluent. Infection can cause mastitis, abortions, kidney and liver damage in adult cattle and severe disease or death in calves.
Leptospirosis carries the added risk of being transmissible to humans. Contact with urine, foetal membranes or fluids, and aborted or sick calves from affected cows can all result in human infection.
In humans, the bacteria usually enter through cuts or abrasions in the skin or contact with exposed mucus membranes, such as the mouth or eye. A single drop of urine or foetal fluid can be enough to transmit the infection.
Leptospirosis in humans can be a very serious, chronic and even fatal disease. There is currently no routine vaccine available in Australia for humans.
When used appropriately, vaccines such as 7in1 are highly effective against the most common leptospirosis and clostridial strains, and total protection is usually achieved. Animals over six weeks of age must be vaccinated twice, four to six weeks apart.
An annual booster is required to ensure adequate immunity, particularly in high-risk areas. Cost is roughly $2 a dose.
A separate vaccine is required for animals at risk of botulism (mainly seen in cattle fed mixed rations where feed has been spoiled or contaminated, or in phosphorous-deficient cattle prone to chewing carcases and bones).
Consulting your veterinarian will help you determine the best vaccination schedule for your herd.
If you choose not to protect your herd with a 7in1 vaccine, you have a duty of care to notify your staff that they may be at risk of contracting leptospirosis.
Similarly, if you work on a farm in close contact with cattle, you should make yourself aware of the current vaccination status of the herd. If children or elderly family members frequent the dairy, vaccination is really a no-brainer.
The author has no affiliations (financial or otherwise) with any companies producing 7in1 vaccines for market in Australia. She does however have a vested interest in not contracting leptospirosis through her work as a veterinarian on dairy farms.
Lucy is completing her dairy residency with the University of Melbourne. She works as an on-farm veterinarian in Kyabram with Apiam Animal Health, and alongside her partner on his family’s 650-cow dairy farm in Dixie. She is a 2021 Nuffield Scholar supported by Gardiner Dairy Foundation.
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