South East Local Land Services animal health update February 2022

11 Feb 2022

South East Local Land Services district veterinarians

Your district veterinarian is a source of impartial advice for herd health and welfare concerns on your farm. They provide over the phone advice, property visits and veterinary sampling where required. They work with your private practioner veterinarians, rural resellers and agricultural advisors to provide you with an accurate diagnosis of the cause of disease and treatment and prevention options. The monthly surveillance results share the significant cases seen and reported over the last month.

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Staffing

We are currently recruiting to fill the Cooma and Goulburn district vet positions and we thank producers for their patience while these positions are vacant. We are also short staffed due to COVID-19 restrictions, and staff being directly or indirectly affected. Please ring the office if you have an enquiry and you will be redirected to an available vet on our team. We aim to get back to all enquiries promptly but please allow extra time for us to return your calls and for interstate and export documentation.

SOUTH EAST MONTHLY DISEASE SURVEILLANCE RESULTS

Theileriosis

Theileria continues to dominate as the leading cause of death in young cattle on the coast. Introduced/naïve stock are most at risk and cases have been occurring in locally born calves and introduced cattle. On the tablelands we have had cases occurring where stock have been purchased through the saleyards from the coast. Theilieria Ikeda is a blood-borne parasitic organism transmitted between animals by vectors, mostly ticks but also other biting insects. It causes a breakdown of red blood cells and anaemia which results in ill thrift and extreme lethargy and can, in worse-case scenarios, cause abortion and death. Some people are employing ear tags as an element of protection and these are proving to work in most cases. Using pour on Deltamethrin products to control vector numbers also seems to help in reducing numbers affected in an outbreak.

Bloat – not just an issue on pasture

There has been an ongoing bloat problem in a coastal dairy herd. Whilst most of us associate bloat with white clover at the beginning of spring it is important to remember that there are a number of other situations where bloat can eventuate. In this scenario triticale had been replaced by barley as the main ration in the dairy and was being milled too fine. This, especially when cows ate a double dose if another skipped their meal in the bail, led to rapid digestion and the over-production of rumen gasses and bacteria and consequent bloat. A summary of bloat follows below to remind us of the key points.

Fly Strike

Fly strike continues to be a major issue causing deaths due to the continuing warm wet conditions, ideal for flies and maggots. Remember that even sheep with preventative treatment applied need to be checked frequently for their welfare and treatment in these adverse conditions. Products can fail due to overwhelming challenge, being diluted by rain and resistance issues. Owning sheep this summer comes with an increased level of work and responsibility as a stock owner. The RSPCA are being called frequently for cases of fly strike this summer where owners have failed to act. A summary of preventative and treatment options follows below.

Barbers pole worm causing deaths

Deaths have been seen when sheep and goats have been drenched with a product that the barbers pole worm are resistant to, particularly ‘mectin’ and ‘white’ drenches. With temperatures > 15°c and regular rainfall, conditions are ideal for barber’s pole worm numbers and infections are building quickly. Faecal egg counts (FEC) are rapidly rising, some of these counts are a mixed infection of barber’s pole and scour worms, but as the summer progresses many counts are now 100% barber's pole worm. Faecal egg counts (worm egg counts) are the best way to monitor worm numbers before they cause deaths. Conditions are so ideal for worms we recommend using FECs to monitor your mobs every 4-6 weeks during the summer. There is widespread resistance in Barbers Pole worm to most current anthelmintics. Moxidectin and closantel based products have a useful duration of protection however resistance reduces this period. Zolvix and Startec are newer drenches less likely to have resistance issues. It always good practice to check worm eggs counts after treatment to ensure the treatment has done the job. These can be taken initially 10-14 days after treatment and then 4-6 weekly thereafter. A Barber’s pole vaccine is available from some stores and are a very good option on farms where this parasite is present each year. This can reduce the need for chemical treatment; however, its use requires good attention to timings. If this is contemplated, then seek advice from your district veterinarian.

Photosensitizations in sheep

There have been several reports of swollen ears, faces and heads which have been a result of sheep gazing St John’s wort, Panic species grasses and lucerne. There are many plants that can cause photosensitivity (extra sensitivity to sun burn) by different mechanisms, resulting in swelling and damage to the lips, nose, and ears. In severe cases it will cause death and welfare concerns. The important thing is to be on the watch out for it and to respond quickly should it occur with a phone call to your vet, a move of the sheep off the affected pasture and into shade.

Selenium deficiency in sheep

Bloods taken recently from ewes pre-joining have shown extremely low selenium levels (GHXPX levels 6-12). These low levels are thought to have contributed to a disappointing scanning to lambing percentage, with losses from white muscle disease, and poor growth rates in the lambs with increased susceptibility to internal parasites. Talk to your local vet about getting your sheep tested now to assess the need for long term selenium supplementation.

Foot rot in sheep

Check your sheep now for signs of virulent or benign footrot. Attention to feet now, by culling lame sheep or trimming and foot bathing will result in better joining and better management of the pregnancy and lambing. Continued wet conditions have been very tough on feet, requiring action to manage benign footrot as well as virulent. You must call your district veterinarian if you have concerns that you may have virulent footrot.

Pinkeye in cattle

Increasing reports of this condition are occurring in young cattle as the summer progresses. Pinkeye (infectious bovine kerato-conjunctivitis, or IBK) is a bacterial infection of the eye that causes inflammation and, in severe cases, temporary or permanent blindness. Early signs are excessive lacrimation or tears, cloudiness of the eye, leading to ulcer formation and varying degrees of blindness. Pinkeye can affect up to 80 per cent of a herd and is an important health and welfare issue. Important factors that predispose cattle to infection include close physical contact, hot and dusty conditions, flies and other physical irritation such as grass seed, dust, and thistles. Cattle that are yarded and trucked can be especially vulnerable. Treatment relies on antibiotic eye ointment or injections and eye patches. Your veterinarian should be consulted as early as possible, when signs first appear, to avoid more serious eye damage. Infected cattle should be segregated from non-infected. Steps to prevent infection include avoiding yarding or trucking in the worst periods for flies and dust, and treatment for flies on the cattle using a deltamethrin pour on product, or in the environment. A vaccine is available (Piligard) which can reduce outbreaks and limit the extent and severity of infection depending on the strains of the bacteria that are present. It needs to be administered at least 3-6 weeks before the pink eye season, the timing depending on location and season.

Internal parasites in cattle

The season has been very favorable for transmission of internal parasites and especially noted in rising yearlings. While pasture conditions have also been favorable and therefore there is adequate nutrition, there are still ongoing reports of ill thrift and diarrhea.

Ostertagia (small brown stomach worm) are a likely cause, with both normal cycling parasites and the inhibited stage maturing from the stomach wall. Worms cause damage to the stomach or gut lining, interfering with appetite and nutrient absorption, and can cause diarrhoea. The host animal suffers malnutrition by not eating enough and by having nutrients “stolen” by the parasite. By the time you visually observe the external signs of worms in livestock, such as weight-loss or diarrhoea, much damage has already been done. Before these signs are seen, animals with worms are producing less milk, growth or muscle development and their immunity is suppressed. Faecal egg counts don’t give a good picture of the burdens in older cattle but can be of value in young stock. Instead in cattle we tend to advise strategic routine drenching. Young stock require more frequent drenching. If suspected, it is worth contacting your district veterinarian for advice on treatment options. Paraboss also has plenty of information to help learn about parasite control.

WHAT IS BLOAT AND WHY DOES IT OCCUR

Mark Doyle, District Veterinarian - Bega

What is Bloat?

Bloating occurs when ruminants have impaired ability to eructate (burp) ruminal gases of fermentation, causing these to accumulate and distend the rumen. Bloating can be classified into frothy or free-gas bloat, depending on the mechanism impairing eructation.

Free-gas bloat

Free gas bloat occurs when normal fermentation gases are freely accumulated. Potential causes are irregular feed intake, inhibition of the nerves responsible for ruminal contractions or a physical obstruction (blockage) of the oesophagus.

An irregular feed intake can result from uneven feeding intervals, disease, changing weather, a change in diet or unpalatable feed. Physical obstructions of the oesophagus are generally due to swallowing a large object (e.g. a beetroot or potato) which does not enter the rumen. Damage to the nerves responsible for rumen contractions most commonly results from hardware disease (where a metal or sharp object has been grazed up and is sitting in the rumen causing an infection in the area around it). Grain overload resulting in acidosis can also reduce rumen contractions.

Free-gas bloat has a sporadic incidence, generally affecting individual animals rather than groups, and accounts for the minority of bloating cases.

Frothy bloat

Frothy bloat occurs when eructation is impaired by the development of frothy or foamy ruminal contents. There are two types of frothy bloat: pasture bloat and feedlot bloat. Both, however, result from increased bacterial slime (a by-product of microbial fermentation) which entraps the gas bubbles forming the froth.

Feedlot/grain bloat is caused by feeding high energy rations (grains) with low fibre (roughage). It is important to note that the more finely ground a grain is the higher the risk of it causing feedlot bloat. Very finely ground grains increase bloating risk even when fed at moderate amounts, meaning bloating can occur in non-feedlot settings such as feeding supplementary grains to dairy cattle.
Pasture bloat is caused by grazing legumes in rapidly growing vegetative state. Lucerne and white clover are examples of common legumes which could make a high bloat risk pasture when in a rapidly growing state.

Basic Preventions

Prevention of bloating largely relies on avoiding the high-risk situations. For pasture bloat, avoid grazing legumes such as lucerne and white clover when they are rapidly growing. When feeding grain ensure they are not too finely ground, and the animals are getting enough fibre. In the case of free-gas bloat, hardware disease and physical obstructions of the oesophagus, these are harder to prevent, however, monitoring feeding can prevent grain overload and irregular feeding patterns.

For more detailed prevention and complicated cases, seek further professional advice on grazing and nutrition management.

FLY STRIKE TREATMENT AND PREVENTION

Alexandra Stephens, District Veterinarian - Yass

Minimize fly strike opportunities (wet smelly wool) through shearing, crutching, sheep selection for conformation and wool type, chemical application, and prevention of scours.

Monitor sheep regularly and prevent strike maggots getting back into the soil to pupate.

Purchase quality electric clippers, clip off the area of strike before you apply chemical and place the maggoty wool in a bag to seal and leave in the sun to kill the maggots. Not only does this help to prevent the build of the fly wave it also greatly delays the development of resistance.

Know your chemical treatment options and rotate chemicals and be aware of resistance issues.

Know your chemical groups

Blow fly strike preventative options

Chemicals (by Group)	Product examples	Resistance	Application	Protection period
Ivermectin (Macrocyclic lactone)	Blow fly and lice	No	Jetting/Dip	Up to 12 weeks
Spinosad	Extinosad	No	Jetting/Dip	4-6 weeks
Imidacloprid (Neonicotinoid)	Avenge+fly	No	Spray-on	14 weeks
Cypermethrin (Synthetic pyrethroid)	Vanquish	No	Spray-on	10 weeks
Dicyclanil (Insect Growth Regulator)	Clik, Strikeforce	Yes	Spray-on	11-29 weeks
Cyromazine (Insect Growth Regulator)	Vetrazin, Spartan	Yes	Spray-on /jetting	10-14 weeks

Blow fly strike treatment options (must kill maggots)

Chemicals (by group)	Product examples	Dressing	Protection period	Notes
Spinosad	Extinosad	Yes	4-6 weeks	Use aerosol pack or make up fresh daily
Ivermectin	Blowfly and lice	Yes	Up to 12 weeks	Dilute for treatment
Organophosphate	Diazanon, temphos Strike powder	Yes	No residual protection	O,H and S concerns