In both beef and dairy cattle, vaccines are commonly co-administered. A common question we get is how many is too many at any single point in time?

We look at it from two aspects:

1. Will it compromise the effectiveness of the vaccines?
2. Will it compromise the safety of vaccines?

From an efficacy standpoint:

Zoetis, the major vaccine manufacturer and distributor in Australia have conducted formal trials looking at the co-administration of Ultravac 5-in-1 plus Pestigard, and Ultravac 7-in-1 plus Pestigard where the vaccines were administered concurrently but at a distance of 3cm apart on the side of the neck.

After the second dose of vaccine, the study findings showed that:

• Responses to the clostridial components (tetanus, pulpy kidney etc) in both the 7-in-1 plus Pestigard, and the 5-in-1 plus Pestigard group were at least as good as the groups getting 7-in-1 or 5-in-1 alone.
• Responses to the leptospirosis components of the 7-in-1 plus Pestigard group were as good as the group getting 7-in-1 alone.
• Responses to pestivirus was slightly inferior in the groups getting 7-in-1 and 5-in-1 at the same time.

As a result of this study, we now advise that it is preferable to vaccinate with 7-in-1 on the opposite side of the neck to Pestigard where animals must be vaccinated on the same day. In the instance you can't get to the opposite sides of the neck, administer a hand width apart. It would be even better if these vaccines could be separated by at least a week to reduce the likelihood of any interference.

There aren’t formal trials looking at other combinations of vaccines in cattle, so where we have no data our advice is:

• Separate the time of vaccination where possible, and where this is not possible, separate vaccines by giving them on opposite sides of the neck.
• Where a particularly reactive vaccine is given, such as Vibrovax or Silirum, our advice is not to co-administer other vaccines as it is likely to be enough for the animal to deal with the immune response they are mounting to these reactive products on their own.
• It is also a reasonable principle to assume that vaccines with like adjuvants are more likely to be compatible than vaccines with different adjuvants, where a more immunogenic adjuvant (i.e. such as an oil) might dominate in its influence on the animal’s immune system.

While we rarely have reactions reported from co-administered vaccines, we have had guest speakers in Australia talking about their experience with co-administered vaccines in USA. The USA vaccine market is quite different due to a greater number of vaccines available, and a larger proportion of them being modified live vaccines, as opposed to the killed vaccines which dominate the Australian market. So, we need to keep this in mind when comparing the two markets.

In the US, researchers developed an endotoxin risk scoring system, whereby they assigned a score of one to any vaccine containing gram negative bacteria (two for a multivalent clostridial vaccine) and then advised not to co-administer vaccines adding up to score of greater than three at any one time.

In Australia, endotoxic reactions are so uncommon that it’s difficult to tell if this advice carries to Australia, but it’s worth keeping in mind, and where possible, we stick to this rule.

For assistance in designing your vaccination program, please speak with one of the livestock vets at the clinic.

Flies and biting insects can be equally distressing for both horse and owner. Affected horses may be very unsettled, show constant head tossing, biting, stomping or kicking, evasive activity or have a reluctance to eat.

In addition to the irritation and worry, flies can act as vectors for some bacterial diseases and can also spread the parasitic skin condition known as Habronema or “summer sores”. Biting insects such as mosquitoes can carry viruses called arboviruses. Sporadic cases have been suspected in southern Australia, usually coinciding with periods of very high mosquito activity after a high rainfall period. Arbovirus affected horses may present with neurological signs in horses such as wobbling, and sometimes lethargy and joint pain.

How can you reduce the impact of flies and biting insects?

Ensure good paddock and stable hygiene, pick up manure regularly to reduce fly attraction and breeding sites. Eliminate or avoid stagnant water sources as these can be a breeding ground for flying insects such as mosquitoes. Protective rugging and masks may provide your horse some relief.

There are a number of topical insecticide treatments available for livestock - these may not necessarily be safe for use in horses, and veterinary advice should always be sought regarding their use.

Nearly all vertebrate animals host one or more species of the protozoa Eimeria which is the bug responsible for causing coccidiosis. Given this, coccidiosis is a disease which all livestock producers need to be aware of. It causes problems in cattle, sheep, pigs, goats, chickens and goats, to name a few.

Coccidia develop in the intestinal tract, and produce oocysts that pass in the dung onto the pasture. The spores then infect grazing stock. Often the subsequent infection causes no ill effects, or at least no visible effects. 95% of the loss which occurs with coccidiosis is ‘sub-clinical’, meaning the only effect is reduced feed conversion efficiency and reduced weight gain. However, with stress and overcrowding, particularly under damp unhygienic conditions, profuse diarrhoea can occur with blood and mucous in it. This can be accompanied by significant mortality. It is most commonly seen in young stock just before weaning, in feedlots, or other situations where stock are confined at very high stocking rates.

Do you have a coccidiosis problem?
Most stock are infected early in life without showing signs of infection. However, coccidiosis is usually suspected in lambs too young for a worm problem, or when stock are scouring but fail to respond to drenching (unless significant worm burdens are also present).

A quick diagnosis is important to work out a plan.
If you suspect coccidiosis is causing a problem in your stock, get in touch. Faecal floatation is a quick way to determine if large numbers of coccidia are passing through into the faeces. If you have lost animals, there are often tell tail signs (e.g. white spots in the intestines) in the intestines which can raise the alarm.

There are treatments, and preventions which are best discussed on a case-by-case basis.

Heat, light and freezing can destroy the effectiveness of many medications and vaccines.

It is not only the value of these products, but the cost of them not working properly or not working at all, if they have been inactivated.

At our clinic, we take measures to ensure we can be confident with the effectiveness of the products we supply. Steps we use and recommend include:

• Reading the label, so you know the storage conditions that are appropriate.
• Having good quality fridges for storage. Poor-quality fridges will freeze products in certain areas of the fridge. Freezing destroys most vaccines.
• Leaving an air conditioner running in hot weather in medications storage area.
• Monitoring temperatures in fridges and storage areas.
• Keeping products that are light sensitive (this is marked on the label "protect from light") in their original box.
• Using a fridge or esky in vehicles.
• When picking up medications in warm weather, please ask us for an esky if you need it. Also, pick vaccines up as the last job before you got home, and don’t let them sit in the car for extended periods of time.