November Large Animal Newsletter

Welcome to our monthly newsletter, covering the latest large animal care advice and tips‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌

The region continues to be challenged by the weather, and wild wild water. The Local Land Services have Flood Recovery guidelines for livestock that some producers may find helpful: see the link below. Stay safe.

If you are in a position to do so, we are trying to set up a "Pet It Forward". We are also able to be a drop off point for food donations for flood affected people.

Thank you for your understanding as we try to triage the needs of livestock, horses and pets as these times challenge us all, whilst supporting staff whom are also flood affected.

Flood recovery from LLS

Mosquito management reminder

We've had lots of rain- now we await lots of mosquitoes. Lumpy Skin Disease, Japanese Encephalitis and Bovine Ephemeral Fever (BEF) are all viral diseases spread by mosquitos and biting midges. The spread of such diseases is common after intense wet seasons, especially those following several previously dry years. Under these conditions, population numbers of transmitting insects rise, and as a result, a higher proportion of older animals will become infected. Movements of waterbirds can also contribute to disease outbreaks.

Needless to say, this year we can expect mosquito borne viruses to cause serious problems!

Mosquito borne virus prevention strategies

Step ONE- reduce mosquito numbers

Overturn or reduce all pooling water where possible, especially in shady areas. Potholes are a current risk. Try to minimise places that mosquitoes rest near stock- think of the shady bushes that start buzzing when you walk by. Treatment of mosquito pools with larvicide or adulticide to kill mosquitoes can be helpful if water cannot be eliminated.

Stock protective equipment
Wearing light rugs for horses and mosquito/insect repellants can help to reduce the risks of mosquito bites: meaning less disease risk and less skin irritation for your stock! Horse rugs may be permethrin treated for added repellant activity. Stabling and utilising fans to facilitate air movement may help. Use fluorescent lights where possible as mosquitoes are less enticed.

Personal protective equipment

People in farming occupations may be eligible for additional vaccinations, such as Japanese Encephalitis. Talk to your human doctor if this interests you.

Minimising mosquito bites is of high importance for everyone- whether working with stock or just living in the great outdoors. Loose fitting, light coloured clothing can help. DEET mosquito repellant is recommended. Use fluorescent lights in outdoor areas where possible as mosquitoes are less enticed.

Vaccination

Bovine ephemeral fever is best prevented by vaccination. Cattle can be vaccinated from six months of age. Field observations have shown that some vaccinated cattle may still develop mild disease, however the severity and duration of illness are much lower than in unvaccinated cattle. Below is a picture of BEF distribution in Australia. Consideration of vaccination is strongly advised throughout the whole endemic region- this might mean high value stock only, or breeding stock, or everything. Moving cattle from the BEF virus-free area to the infected zone is particularly risky. The highest risk stock are heavier animals and high-value stock such as bulls and ET cows.

Two stone lighter

Equine castration is an essential management procedure. We can prevent the development of unwanted stallion-like behaviour, such as aggression, by removing a colt’s testicles at an appropriate age. Geldings are easier to manage than stallions, they have a more even, calm temperament, and can be mixed with other horses of either gender.

Horses may be castrated for other reasons, including injury, tumours, herniations and infections.

Complications requiring veterinary attention can occur before, during or following the procedure and can be potentially fatal, so many veterinarians will ask the owner of the horse to sign a consent form prior to the surgery as is common with small animals undergoing desexing procedures. Such complications include haemorrhage, intestines escaping through the wound, colic, wound infection, peritonitis and disruption of the penis circulation.

The best time to castrate

The best time to castrate a colt is when both testicles are fully descended. This happens in most colts from one-to-two years of age. We recommend having their vaccinations on track before surgical castration. It is advisable to perform castration as young as possible before stallion characteristics develop, and the blood supply to the testes is less developed. This will lessen the risk of significant blood loss.

Surgical procedure

Your horse will initially be sedated; which we administer directly into the jugular vein in the neck. As the sedative takes effect, we will examine the testicles to ensure both are fully descended. If only one testicle is descended, it may be sitting between the abdomen wall and the scrotum, or it may be inside the abdomen. While partially descended testicles can often be removed in a routine castration operation, a testicle retained in the abdomen will require surgery in a controlled and sterile surgical facility.

If your horse is to be castrated under a general anesthetic, we will determine and administer the appropriate dosage after assessing your horse’s weight and temperament. As the general anaesthetic takes effect, your horse will lose consciousness and collapse onto its side, so this is done in a soft, clean, dry and safe area.

Once anaesthetised, the skin and underlying tissue are cut and the testicles are exposed one at a time. We then use a specialised surgical device called an emasculator, which cuts the spermatic cord as well as the blood supply to the testicle. The device also crushes the artery as it cuts, making it easier to tie off the blood vessel.

The wounds are left open to slowly drain any excess fluid as they heal over one-to-two weeks.

After-care

After the procedure, we will recommend post-surgical pain management. The need for antibiotic cover will depend on the conditions of the surgery. With close monitoring of your horse, you will be able to advise us if any other intervention or treatment is required.

All horses should be closely observed for two-to-three weeks after castration. Some fluid will drain from the surgical wounds for about two weeks after the operation. Initially, this fluid will be blood-stained but should become clear. The area surrounding the wound will also show swelling which may extend along the sheath. This is normal after surgery but should not interfere with urination.

Fluid draining from the wound may collect inside the horse’s legs. This fluid should be carefully cleaned as it can attract flies. The horse may be quite sensitive in this area due to discomfort from the surgery, so care will be required. Cold hosing may be the best option.

Keeping the horse moving after surgery is advisable to assist the wounds to heal and drain. Unmounted mild trotting exercise is recommended, and most horses can return to ridden work after four weeks.

Vaccinating bulls - what's necessary?

Several transmissible diseases can decrease fertility in both dairy and beef herds:

Vibriosis

Vibriosis is a widely known and common disease both throughout beef and dairy herds Australia-wide. It’s highly contagious – one stray animal jumping a fence could cause a herd infection. Vibriosis is asymptomatic in bulls but can reduce reproductive rates in cows and heifers by 30-60%, causing conception delay, irregular oestrus, embryonic mortality and occasional abortion.

Pestivirus and Leptospirosis

Pestivirus and Leptospirosis are both implicated in poor sperm production and reproduction. When a bull contracts pestivirus during joining, it may excrete the virus in its semen. The infection damages sperm production and may result in damaged sperm for several months.

IBR

Infectious Bovine Rhinotracheitis (IBR) is highly contagious and is spread by close contact and aerosol. Routine cattle management practices like weaning, transportation and commingling exacerbate disease spread and severity. Clinical signs include abnormal or rapid breathing, nasal discharge and/or coughing. The herpes virus causing IBR is also associated with penile lesions causing reproductive failure in bulls, and vulva and vaginal lesions in breeding females.

Vaccination recommendations

Considering this we advise vaccination with 7-in-1, Vibrovax, Pestigard and an IBR vaccine. This will also confer immunity to clostridial diseases

Eperythrozoonosis alert as mosquitos come to town

It’s highly likely we’ll see a rise in mosquito-borne diseases after high rainfall throughout winter and spring, which has aided the rise in mosquito populations across the eastern states of Australia.

Eperythrozoonosis (or ‘Epi’) is a bacterial disease affecting sheep and goats, which is most commonly spread by mosquitos.

Here are the key facts you need to know about the disease:

Epi causes anemia in sheep. Bacteria attach to red blood cells and cause them to rupture.
Epi has the potential to cause death in severely-affected sheep, losses of up to 30% have been reported.
Epi can spread mechanically by the transfer of infected red blood cells.
Outbreaks are known to occur within four-to-six weeks after marking, mulesing or shearing.
Affected sheep will be pale, and will lag behind the flock. They become distressed and pant heavily when moved and stagger or collapse if forced to run. Severely affected sheep may die, especially if stressed by yarding and handling.
The signs of Epi mirror barber’s pole worm: anemia and death. However, treatment of the two is very different. Sheep with barber’s pole worm need to be drenched, however, sheep suffering from Epi should not be moved, as mustering may cause extensive losses.
Unfortunately, if a whole mob contracts Epi, there are no practical treatments, you just have to wait it out and try to minimise stressful handling.

If you suspect you may be dealing with Epi, call us for specific advice.

Colostrum testing for calves

Colostrum with high antibody concentrations does the best job of achieving high immunity in newborn calves, so it’s important to estimate the concentration of antibodies in every dosage. This becomes increasingly important with high value calves and high value genetics.

Understanding the results
The optimal threshold value to remember is 22. A reading above 22 estimates the antibody content is 50g per litre.
A value above 22 is good, and we recommend them for first feeding.
Values below 22 are not optimal. Use for second or later feedings.

Tips for getting valid results:

Keep the optic and cover surfaces clean by rinsing after every use and drying with a tissue or soft cloth. Distilled water is the ideal rinse water.
Always avoid a mineral or milk film on the optic surface.
Calibrate regularly by placing a couple of drops of distilled water on the optic surface. The “blue:white” line should be at zero on the scale.
Remember that these readings are not “exact” values. You may need to round to the nearest whole number.

How much colostrum to give calves?

To provide protective immunity, calves require at least 150g of IgG (ideally more than 200g). This equates to three litres of colostrum with a Brix value of more than 22%.

Remember, a Brix value of 22% correlates to colostrum with 50g of IgG in it.

In what timeframe?

Ideally, three litres of first milking colostrum is fed within two hours of birth (and definitely within six hours of birth), and then two litres of colostrum is fed approximately 12 hours later. The sooner it is given, the better the outcome. As calves get hours older, the special portions of the stomach that can take up colostrum get switched 'off'.

Mosquito heaven

At least a few small members of our ecosystem are pleased by the massive amounts of water inundating parts of Australia.

Mosquitoes will breed well in the masses of stagnant water lying around. As a result, the risk of mosquito-borne diseases will be particularly high in many areas of eastern Australia.

Causes

There are now three main mosquito-borne infections of concern: Along with Murray Valley Encephalitis Virus (MVEV) and Kunjin/West Nile Virus (WNV), Japanese Encephalitis (JE) has been added to the list of significant risks to your horse’s health.

Japanese Encephalitis is a notifiable exotic disease in most states. These viruses are uncommon but can cause serious disease. All three affect the nervous system and can be challenging to diagnose. Japanese Encephalitis primarily affects pigs and is transmitted to horses and humans by mosquitos. Humans are considered end hosts as they don’t produce sufficient viral load to infect mosquitoes.

Murry Valley Enchephalitis is endemic to Australia and also affects humans. It tends to cause outbreaks following flooding, so you need to be on alert in the coming months. The natural hosts of this virus are water birds which will also be increasing in numbers after the rains. Surveys carried out in South Australia recently have estimated that around 8% of horses have antibodies to this virus and so have been exposed but do not necessarily show any symptoms.

Kunjin is a strain of West Nile Virus also endemic to parts of Australia. The virus has been detected in two parts of NSW in four foals which all showed neurological signs of infection. In 2011 after unusually wet conditions, there was an outbreak involving about 300 horses in NSW. Kunjin/West Nile Virus has also been known to infect humans.

Signs to watch out for

These viruses primarily affect the nervous system, and symptoms may appear quite similar.

Symptoms of Japanese Encephalitis range from mild to severe, even fatal.

Clinical signs may include fever, jaundice, lethargy, loss of appetite, incoordination, difficulty swallowing, impaired vision, and in rare cases, the horse can become over-excited. The disease may also be subclinical, meaning the horse shows no signs of disease.

Murray Valley Encephalitis may cause facial paralysis, exaggerated movement, incoordination or muscle twitching. More commonly, however, these symptoms come from depression or weakness.

Kunjin causes similar symptoms, but this virus can also cause overreactions to stimuli, blindness and walking in circles.

Often, one or more blood tests are required to definitively diagnose these infections but occasionally the fluid around the spine may need to be sampled and tested for evidence of infection.

In some areas, health and agriculture departments are using sentinel chickens to run surveillance programs to detect the presence of these diseases. These chickens have their blood regularly sampled, and if disease is detected, an alert may be issued to warn the public of the increased risk.

Treatment

Depending on the symptoms each horse experiences, common treatment for these infections may include anti-inflammatory and sedative drugs. Prevention is much easier than treatment, so take precautions to avoid mosquito bites.
Affected horses usually recover in days to weeks but in severe cases, infections can be fatal.

Prevention

See above- minimise risk by protecting horses with rugs, anti-mosquito masks and insecticides, particularly at dawn and dusk when mosquitoes are more active. Try to minimise stagnant water where mosquitoes breed.

Minimising risk with Bullcheck

Pregnancy rates in cattle herds vary from very good to very bad. The poorest results occur when bulls fail during joining. Then, pregnancy rates may drop well below 50% for any given joining period. Bullcheck was created to minimise risk by screening bulls prior to joining to identify issues which are at high risk of causing reproductive failure.

For example, Persistent Frenulum (pictured above), is a condition seen especially in young bulls, where the penis does not fully protrude from the sheath. In most cases, these bulls will not achieve intromission. If the penis cannot enter the heifer or cow, pregnancy becomes exceedingly unlikely. A pre-joining Bullcheck detects this abnormality, preventing a failed joining.

What is a Bullcheck?
Bullcheck is an efficient procedure for screening bulls prior to sale or use.

Developed by the Australian Cattle Veterinarians (ACV), Bullcheck features world-recognised procedures and standards for conducting examinations and for computerising relevant information.

What does it involve?

Typically:

A general physical examination
A reproductive examination (measurement of testicle size, palpation of the testicles and sex glands)
Collection and examination of semen (for sperm motility and morphology)

In addition, a serving ability test or tests for diseases (e.g. vibriosis or trichomonosis) may be included. These additional procedures add value to the Bullcheck exam but are not mandatory.

After testing, bulls are categorised as follows:

Satisfactory: All factors assessed are consistent with ACV standards. No risk factors for reduced fertility are identified.
Unsatisfactory: Some factors assessed are not consistent with ACV standards, e.g. lameness, penile injury or semen morphology defects.
Classification deferred: Although not all factors met ACV standards, the bull may be used under certain conditions, e.g. ’mild post leg - likely to develop arthritis prematurely’.
Not tested: Factor(s) could not be adequately evaluated. A retest is recommended.

In summary
All bulls should undergo Bullcheck one-to-three months prior to mating to optimise herd fertility, genetics and profitability.

This email contains comments of a general nature only and is not intended to be a substitute for professional veterinary advice. It should not be relied on as the basis for whether you do or don't do anything.

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Orange Veterinary Hospital
57 Molong Rd
Orange, NSW 2800

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