South East animal health update
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Local animal disease watch
Bill Johnson, Goulburn Senior district vet
Footrot in sheep and goats
Virulent footrot is a bacterial infection that separates the hoof, causing severe lameness. It lowers productivity and impacts animal welfare. Warmth, moisture, pasture density and sheep pedigree all combine with the strain of footrot bacterium involved to determine the extent of hoof disease.
Virulent footrot was diagnosed in more than 45 flocks in part of our region following a series of seasons favourable to its spread. Eradication of footrot from infected sheep flocks requires planning and commitment by their owners, and in most cases, considerable expense. So it is pleasing to report that with diligent work by producers, assisted and guided by South East Local Land Services staff, the number of known infected flocks has been reduced to eight, with four of these expected to be declared footrot-free in coming weeks. Remarkable progress, especially when some other areas of the state are reporting an increase in footrot cases.
Theileria (pronouonced "Ty-leery-a")
This microscopic parasite invades and destroys red blood cells of cattle. In many areas it is believed to be spread by ticks, although other blood-suckers like biting flies may also play a role. The disease is more common in coastal herds, associated with fever, anaemia, jaundice, abortion and deaths. In recent months, our district vets in coastal areas have commonly found the disease in calves, especially in those herds that have previously experienced symptoms in adult cattle.
Is it foot and mouth disease?
Three recent cases remind us all to be on the lookout for unusual symptoms in our stock, and to have them investigated. All cases involved cattle that drooled saliva and lost weight quickly, two of the symptoms of foot and mouth disease (FMD). When the first case was examined by a vet, she found a large ulcer on the end of the tongue, which again could have been caused by FMD. She also found the rest of the tongue was swollen and rock-hard (so-called Wooden Tongue), caused by a common organism present in soil. It appears the ulceration on the end of the tongue resulted from eating attempts by the cow.
The second case was noticed by astute farm staff during routine handling of cows on a large property. The cow lagged behind the mob, slobbering. When he saw a large, ragged ulcer on the roof of the mouth, the station manager called the local vet who collected samples to exclude FMD. The results were negative. This cow had been foraging amongst blackberry bushes, and probably sustained the injury to her mouth from thorns on a blackberry cane.
The third case involved a yearling steer, grazing amongst rushes on a creek flat. The owner promptly reported the symptoms to a district vet, who found a severe throat infection was interfering with swallowing. All three cattle responded to antibiotic injections.
Early detection of an exotic animal disease will save our livestock industries millions of dollars. With “holiday season” approaching, remember the Emergency Animal Disease Hotline if you have difficulty reporting any unusual symptoms in your livestock to your local district vet. The Hotline is manned 24/7, on 1800 675 888.
Blood-sucking liver fluke have caused symptoms including anaemia, weakness, weight loss and bottle jaw in sheep, cattle and alpacas in the past two months. Fluke require a small fresh water snail to complete their life cycle, so are more likely to affect stock grazing paddocks with slow-flowing creeks, swamps, or over-flowing spring-fed dams. There is more information on diagnosis and treatment of liver fluke below.
Barber's pole worms in sheep and goats
All parts of our region are reporting relatively high worm egg counts in sheep and goats, with barber’s pole worms predominant. Warmth and moisture drive explosive reproduction in these blood-sucking worms, and most areas now have ideal conditions. Young sheep set-stocked in low-lying paddocks are most at risk, but this is a worm that can quickly overwhelm even prime conditioned older sheep. Anaemia, weakness and sudden death would trigger your suspicion. Frequent worm egg counts with culture for worm type help to alert you to a possible problem.
Increasingly, Barber’s pole worms are showing resistance to drenching with abamectin on its own, and many flocks now get little extended benefit from long-acting drenches against this parasite. Check the effectiveness of your drench with a follow-up worm egg count 10-14 days later to stay in front of this serious pest.
Lameness in lambs
Several producers have noticed an increase in the number of lame lambs and hoggets in the past few years. A few lambs may be lame at marking time, but most cases show up by weaning or even later. In some cases, producers are alerted to the problem by the abattoir.
A bacterial infection by an organism widespread in soil (Erysipelas) has been found at autopsy in a large number of arthritis cases. The reason for raising the subject now is that there is a vaccine available to help protect lambs against this form of arthritis, but you need to collect some information on the number of cases in your flock and the ages of lambs affected. You need this basic data to guide your decisions about whether it is worth vaccinating, and whether you vaccinate the ewes to protect the lambs early in life, or vaccinate the lambs themselves at marking and weaning.
With current lamb prices, it doesn’t take too many cases to justify the outlay on vaccine. It is also important to have your vet examine a few affected lambs to determine the type of infection. Remember that it is NOT acceptable to send lambs and sheep hunched up and crippled from arthritis to the saleyards – dispose of them humanely on farm. See the MLA’s guide “Is it fit to load” for more information.
Farm biosecurity plan
Most livestock producers would have received information from Livestock Production Assurance (Integrity Systems Company) on how to complete their farm biosecurity plan. This information package followed a series of information sessions presented by South East Local Land Services across the region. We are still getting frequent enquiries from stock owners about their plan, and most producers are pleased to realise that what they are doing already ticks most of the boxes. If you are having difficulty completing your plan, please give your nearest Local Land Services office a call.
One concern raised at every information session we ran was the coming and going of contractors and employees of the utility companies such as electricity, gas, water and telcos. We are only at the start of this biosecurity process, and we’ll all get better at it over time. It is all about assessing and dealing with risk. The same person who complains about the meter reader probably doesn’t change or even clean their own boots after a visit to the saleyards, so who is the greater risk?
NSW DPI is currently in consultation with the major utility providers to develop a set of guidelines that will be both practical to implement and effective at controlling the major risks posed as they move between properties.
Pale, weak lambs? It's not always Barber's pole worms
Petrea Wait, Monaro district vet
Eperythrozoonosis is a disease which occurs sporadically in sheep and goats in NSW. It is due to infection with the bacterium Mycoplasma ovis (M. ovis), which may cause a range of symptoms including ill thrift, pale gums (due to anaemia), jaundice (yellow gums), dark red urine and/or, in more susceptible animals, death. Losses may be compounded by abattoirs condemning infected carcasses due to jaundice.
The bacterium infects the red blood cells of the animals, prompting the spleen to attempt to clear the infection by destroying the diseased blood cells. It is this excessive destruction of the blood that leads to anaemia, jaundice and death. Disease outbreaks can last for 14-28 days.
Not all infected sheep will show signs of the disease. The immune system of some sheep will effectively fight off the infection and rid the bloodstream of the organism. Other animals’ immune systems will not completely eliminate the organism, but will keep it at such a low level that it does not cause disease. Such animals may stay infected for life but may relapse into clinical disease when stressed, or suffer from recurrent bouts of low-grade anaemia every 2-4 months. These ‘carrier’ animals are the most likely source of infection for other sheep. A reservoir of infection is probably maintained in breeding ewes.
Eperythrozoonosis is spread by the transfer of infected red blood cells from one animal to another. Many outbreaks occur in spring, 4-6 weeks after marking, mulesing or shearing. The disease may also be spread by management procedures such as vaccination (re-using the same needle), ear tagging, bloodsucking insects (e.g. mosquitoes and midges) and flies on wounds.
Antibiotics have been used to control the disease in the past, however, they are not recommended in a flock management situation. Those animals that recover naturally will develop immunity and be resistant to re-infection. The best management plan is not to move infected flocks during an outbreak (for a period of 4-6 weeks) and to make good nutrition and water available. Animals will usually have recovered from the disease after this interval. Vaccines have not proven successful.
Prevention requires good hygiene during marking, mulesing and shearing – keep instruments clean to avoid the transfer of infected red blood cells between animals. Control of biting insects such as flies and mosquitoes by application of a fly treatment is also important. Develop management programs that eliminate the need to yard stock within six weeks of marking/mulesing or shearing. This involves careful consideration of when you time marking/mulesing, shearing and parasite control programs.
Careful paddock feed planning is also important to eliminate the need to move lambs within six weeks of marking/mulesing. Also pay careful attention to nutrition, worm control and trace element supplementation (if required) to limit the severity of the disease.
It is important that the disease is correctly diagnosed as the stress of moving severely anaemic animals can lead to high death rates. Other causes of ill-thrift, anaemia, jaundice and death must also be excluded, including conditions such as infection with Barber’s Pole Worm or liver fluke, copper deficiency or vitamin B12 deficiency. If you suspect M. ovis infection in your flock please contact your local district vet.
Cattle health considerations during dry times
Kate Sawford, Palerang district vet
Seasonal conditions across Palerang have declined over winter and into spring and, while rain is in the forecast, it is unlikely that it will make up for the rain that never came.
Many producers are facing difficult decisions about what to do with stock in the face of dwindling feed and water supplies. With agistment in short supply, the decision boils down to whether to hang onto stock and supplementary feed or sell stock and buy animals back in when conditions improve.
Early weaning of calves is one tool in the kit to manage in the face of low feed availability. Calves can be weaned when the youngest calf is around 12 weeks of age or when the lightest calves weigh 100 kilograms. If you’re going to utilize this strategy make sure early weaned calves have high quality feed that contains more than 11.5MJ ME/kg dry matter and at least 15 percent crude protein. Introduce them to supplementary feed while still on their mothers.
Make sure you have a good long look at breeding animals when deciding which animals to retain in the herd. Now might be a good time to reduce the average age of the cow herd by selling older middle age cows as pregnancy tested in-calf (PTIC) breeders, and getting rid of all cows over 10 years of age. Don’t hang onto anything with poor conformation, unsound feet or legs, damaged teeth, a history of calving difficulty or inability to wean a calf, or poor temperament. Make sure cattle are body condition score 2 at a minimum if they are going to be sold through a saleyard.
Now is not the time to try to save money by cutting corners in your animal health program. Remember that any cow or bull consuming feed on your property that is not doing its job (aka – having a calf or getting cows pregnant) is impacting your bottom line. If you are getting ready to join bulls consider getting an Australian Cattle Veterinarians (ACV) member accredited through the BULLCHECK scheme out to conduct reproductive examinations on bulls prior to joining. Bulls that have passed a BULLCHECK have a high probability of being fertile, which is critical to getting heifers and cows into calf. Cows need to be body condition score 3 to have a high likelihood of getting pregnant, and Angus heifers should weigh 300-330 kg at joining depending on frame size. The last thing a cow-calf producer needs at this stage is to spend time and money feeding mobs of cows only to have them not get pregnant.
If your joining period is earlier in the year and you have just pulled the bulls, consider getting an Australian Cattle Veterinarians (ACV) member accredited through the PREgCHECK scheme out to determine the pregnancy status of your joined cattle. PREgCHECK accredited veterinarians can identify pregnancy as early as 35 days after the end of joining, and determine which heifers or cows got into calf early or late in the joining period. Producers can then use this information as a tool to both tighten the calving interval of various mobs and sell pregnancy tested in calf heifers and cows at a premium. It also enables producers to sell dry heifers and cows sooner rather than later.
Finally, don’t forget the need for worm control and vaccination. Nutritionally compromised cattle are particularly vulnerable to the negative impacts of worms. Now is the time to routinely drench bulls before joining. Consider drenching any other cattle that look like they could be carrying a worm burden (diarrhoea, weight loss, ill thrift, bottle jaw, sudden loss of body condition, or a body condition score of 2 or less). Remember to vaccinate calves at marking and then 4-6 weeks later with a 5-in-1.
This booster 5-in-1 dose is essential prior to supplementary feeding. Bulls should be vaccinated with a 5-in-1 or 7-in-1, Pestigard, and Vibrovax prior to joining. And cows and heifers should have their Pestigard vaccination boosted 2-4 weeks prior to joining. If you have not yet implemented a pestivirus control program contact your local district veterinarian as reproductive losses associated with pestivirus become more costly as feed costs rise.
The DPI has a wealth of information available to producers on the ‘DroughtHub’ section of its website. The DPI also has a Drought Feed Calculator available for free download from the Apple iTunes store or Google Play. It allows for quick comparison and costing of various supplementary feed options that are available locally. Producers are strongly encouraged to make use of feed testing to ensure that purchased feed is fit for purpose. And ensure you obtain a commodity vendor declaration regarding chemical residues for any feed purchased.
Liver fluke - what you need to know
Kate Sawford, Palerang district vet
There have been a number of reports of liver fluke across the region over the past couple of months. Producers have become aware of high burdens of this parasite due to reports from the abattoir, results from WormTests, as well as illness and death in stock.
As with all parasites, the key to control is ‘know thy enemy’.
Adult liver fluke can live in the liver of a number of host species, including sheep, cattle, horses, goats, and alpacas. Adult liver fluke lay eggs that pass through the bile duct, travel through the intestinal tract, and end up in the feces. Under optimal conditions, the eggs hatch in wet areas. The first larval stage invades the intermediate host, the lymnaeid snail, where they develop and multiply. The final larval stage leaves the snail and swims until it encysts on vegetation, which is the infective stage for grazing livestock. This stage can survive for many weeks at temperatures below 20°C – higher temperatures and desiccation will destroy this infective stage in a short time. If ingested, immature fluke are released in the small intestine from which they enter the abdominal cavity and migrate through the liver tissue. Their final destination is the liver bile ducts where they become adult liver fluke for the life cycle to begin again. The time between ingestion and commencement of egg laying in the bile ducts is around eight-ten weeks.
There are three things required for liver fluke infection at the property level:
1) A suitable snail species (the intermediate host)
2) An environment that suits the fluke eggs, snails, and larval fluke, namely springs, slow-moving streams with marshy banks, irrigation channels, and seepages
3) Adult liver fluke in a host species that has access to the suitable environment containing the snail species.
Fluke eggs hatch when mean temperatures increase to above 10°C. In summer it takes approximately 21 days for eggs to develop into the first larval stage, while in spring and autumn this part of the life cycle can take up to 90 days. Adult liver fluke can live for several years and lay over 20,000 eggs per day. Finally, it is important to know that one single first stage larvae that hatches from a liver fluke egg can give rise to up to 4,000 final stage larvae. With this information it is easy to see how a bad year for liver fluke can quickly become very bad.
The intermediate snail host increases their numbers from spring to late autumn. Snails containing intermediate parasite stages can survive in dry mud for a long time, and tolerate low temperatures.
So why issues with liver fluke in Palerang during a dry spring? My theory is that during the warm wet summer and autumn last year, snail numbers increased dramatically due to an increase in suitable habitat, and therefore so did fluke numbers. For producers that missed the most important fluke drench, the April/May drench (after the first frosts) that is effective against all stages of fluke, adult fluke numbers had ample opportunity to accumulate in grazing livestock. Add in the dry spring in the district, creating nutritional stress and encouraging stock to graze in previously marshy areas where there is green pick that also have the potential to be heavily contaminated with the final infective stage and you have pretty much got a perfect storm.
Disease due to liver fluke can present in a number of ways. In acute infection animals may show signs of abdominal pain and become jaundiced prior to death from blood loss. In sheep, these losses can present very similarly to those from acute Barber’s pole worm infection. If infection is less acute, animals may present with jaundice, poor body condition, or pale mucous membranes. Death usually occurs in 8-10 weeks due to severe anemia and liver failure. Most commonly, liver fluke infection is quite chronic. The adult liver fluke in the bile ducts consume blood, causing anemia and chronic liver inflammation. Clinical signs develop slowly, with animals becoming increasingly anemic, pale, and reluctant to travel. Some may have a decreased appetite and develop ‘bottle jaw’, or fluid under the jaw.
Concerned yet? If there is a history of liver fluke on your property you probably should be. In sheep, consider a WormTest and make sure you tick the box to include testing for liver fluke. In cattle, you may be better off looking for antibody to liver fluke in blood samples as looking for liver fluke eggs is generally considered to be less reliable in cattle compared to sheep. Discuss options for testing with your local veterinarian.
If you have liver fluke on your property, consider drenching all stock with a drench that is effective against all stages of the fluke as well as a regular liver fluke control program. And remember that liver fluke control is more than just about reliance on drenching – consider improved drainage, fencing, and grazing management.
For more details on liver fluke and its control refer to the NSW DPI’s excellent primefact titled “Liver fluke disease in sheep and cattle”. Be sure to discuss your strategy with your local veterinarian.
If you have any questions about an animal health or welfare issue please contact your nearest Local Land Services office and ask for your district veterinarian.