Author Archive

Wairarapa Drench Capsule Study

Key points from the famous Wairarapa capsule study

This large scale piece of research (14 separate trials on commercial farms) was going to give us the answers we needed to make better informed decisions on the need (or otherwise) for ewes to be treated with long acting (LA) anthelmintic products pre-lamb. Read More →

Theileria .. Emerging Disease in Cattle

Theileria .. Emerging Disease in Cattle

Theileria.

Theileria has recently been diagnosed on a dairy farm in Takaka. The Tasman has been classed as a moderate risk area for the disease but with warmer weather and an increase in the tick population we will start to see cases on this side of the hill. Since the first reports of anaemia in beef and dairy cattle appeared from Northland in spring 2012 there’s been an increase in reported cases from Northland down to the central North Island and now the top of the south. It can affect both beef and dairy herds.

What is Theileria?

Theileria is a blood parasite that damages red blood cells and causes anaemia in cattle.

What to look out for:

Signs of Theileriosis are those associated with anaemia and include: pale or yellow mucous membranes ie. gums, vulva and whites of the eyes., depression, lethargy, lack of appetite, exercise intolerance, (lagging behind the mob) downer cows that do not respond to treatment and in some instances cattle may collapse and die if stressed or forced to move or run. Pregnant cows may abort and still births are common. In dairy cows a drop in milk production will occur and somatic cell counts may rise.

How do herds/animals get Theileria?

It is passed between animals by ticks. These ticks can be brought in by infected cows moving onto the property or vectors such as dogs or rabbits.

Tick Lifecycle

The tick lifecycle consists of four stages – egg, larva, nymph and adult. Theileria are not transferred from the adult to the egg. However, once hatched if a larva becomes infected with Theileria the tick remains infected through the later nymphal and adult life stages.

Adult ticks are active mainly during early summer, larvae from late summer to early winter, and nymphs mainly in spring. Nymphs will be dormant during winter becoming active as the weather becomes more favourable in the spring.

All stages live at the base of pasture plants. Each stage, apart from eggs, needs to feed on a warm-blooded host to progress to its next life stage. During questing (searching for a host) ticks will climb up plant stems and attach to a passing animal.

Feeding lasts anywhere from 5 to 14 days, longer with older stages and after feeding the larva, nymph or adult tick drops off the host and returns to the bottom of the pasture to mature to the next stage, or to lay eggs if it is an adult tick.

When is it most likely to occur?

Spring and autumn have been the predominant disease periods. This is due to the high levels of stress around calving and drying off, peak milk lactation is also a time of concern.

Contributing factors:

Stock movements, environmental conditions, stress in the herd, concurrent disease, tick populations and prior exposure to the disease are likely contributing factors.

Diagnosis:

A presumptive diagnosis can be made on presentation with pale/yellow membranes and a drop in production are the normal clinical signs. This can be confirmed by a blood test.

Treatment options

The treatment used depends on the severity of clinical signs. Stress is a big factor in the severity of clinical cases. Supportive care and good husbandry around these times will help lessen the impact of the disease.

Establishing once a day milking for affected cows and increased nutrition can speed up recovery and prevent drying off.

The best drug used to treat Theileria is Buparvaquone. This has been used in Australia for some time but has only recently become available in New Zealand. Unfortunately as it has not undergone clinical trials here and because of our stringing export requirements the meat and milk withholding times are long: currently for meat this is 18 months, and for milk 43 days also milk from treated cows must not be fed to bobby calves (OK for replacement calves). Bobby calves born to treated cows must not enter the food or feed chain.

Efficacy of Buparvaquone is good providing use is timely, appropriate and used with other disease management methods.

Previous to the introduction of Buparvaquone high doses of Engemycin had been used to treat clinical cases with some success.

Cows that are very anaemic with a PCV (packed cell volume is a measure of red blood cell loss) around 10% will require a blood transfusion. For this healthy donor cows must be chosen and checked that they are not also affected by Theileria. This can be done on farm in an emergency situation if we have the equipment. Cows given blood transfusions recover quickly and can often return to milking.

Control and prevention options

In areas where Theileria is commonly found (endemic areas) most adult cattle are found to be immune. This disease is mainly a problem in naive herds that have not had any exposure to the disease. With time and controlled levels of exposure most herds will develop a good level of immunity. We cannot completely control the tick population and therefore the spread of the disease but it is possible to greatly lessen the impact.

Young stock:

Calves should be examined closely when they are 6-12 weeks old as this is the time when temperatures are increasing and ticks will be starting to attach to stock.

Stock movement:

Introduced cattle should be examined closely when they arrive on farm, and are starting to settle in over the next few weeks – as this is commonly when stressors are maximal and clinical disease may present.

In districts where Theileria is normally not present, but cattle from Theileria infected areas have been introduced (such as cattle been grazed away or cattle bought in from endemic areas), check home cattle regularly between two and six months after the introductions. If signs of disease are noted, seek veterinary advice as treatment when animals are mildly affected has been most successful.

Avoid importing animals from known affected properties, however where the health status of bought-in stock is unknown, treatment with a registered tick treatment such as Bayticol may be advisable prior to introduction. Bayticol has a nil milk and meat withhold.

Cattle may require treatment every two to three weeks for a few months during summer and autumn, but it must be noted that over-use of tick products can cause resistance within the tick population. Therefore it is important to remember that tick treatments should not be the only method of tick control – each stage of the life cycle of the tick is only on the body for a short period of time. For beef farmers rotational grazing practices may also help control ticks; the use of sheep or deer may act as ‘vacuum cleaners’ to remove ticks from pasture before the introduction of cattle.

Theileria can also spread by way of blood transmission – ie use of a needle or ear taggers on an infected animal being then used on an uninfected animal, or even biting flies. It is therefore very important to disinfect equipment between cattle to help prevent the spread and control flies in sheds and facilities.

 

Please contact us if you have any questions or wish to set up a Theileria control plan for your individual farm.

Sheep and Beef Articles

The following is a list of Articles that might be of interest to you.  Just click on the title and you will be directed to the article:

Pre Lamb Treatments for Ewes

Pre Lamb Treatments for Ewes

Pre Lamb Treatments for Ewes……..

There are not many times of the year that you can influence the production from your sheep flock. One notable time is pre-tupping through ram/ewe selection, and mineral and vaccine choices designed to maximise the conception rates. The other is pre-lambing.

This critical time when the ewe‟s natural immunity relaxes (Peri-parturiant relaxation) and her ability to cope with a parasite challenge is reduced. Choices you make then can have an influence on lamb weights at weaning and ewe weights prior to the next tupping period.

If we assume your feeding is as good as you can make it, ewe treatments pre -lamb come down to a choice of

1. vaccines

  1. anthelmintic treatments
  2. mineral supplements

Vaccines:

Clostridial Vaccines:

At around 30 cents a dose, clostridial vaccination is an inexpensive
insurance. You will be protecting the ewe during a period of susceptibility and the lamb via the ewes colostrum for around 8 weeks. The loss of only one lamb or ewe pays for a lot of protection at today’s pricing. 5 in 1 vaccine does not cover all clostridial cases so consider ULTRAVAC 6 in 1 for a little more protection. 6 in 1 vaccine includes Clostridium sordellii which caused ‘Sudden Death Syndrome’, more recently recognised in NZ.

Pre Lamb Ewe Treatments .. The options ..

Vaccine Suggestions:

  • Sheep are very susceptible to Clostridial diseases so vaccination to prevent them is an inexpensive, but essential pre-lamb activity.
  • Vaccinating the ewes 3 to 4 weeks prior to lambing will provide a good level of protection to the lamb via the colostrum for about 8 weeks. It will also provide long term (1 yr) protection to the ewe.
  • If ewes have NOT been vaccinated before. they should have a “sensitiser‟ at least a month before their pre-lamb “booster‟, which should be timed for 3 to 4 weeks before lambing.
  • Lambs are most susceptible to Pulpy Kidney especially during periods of feed change. Of the clostridial diseases this is the one that a lesser immunity may be only be achieved. You should therefore consider a booster for the lambs at tailing time or at about 8 weeks of age (PK/Anti-tet, if available or an un-selenised 5 in 1) to provide further protection after 8 weeks through to weaning.
  • The strongest and longest vaccine cover is provided with “Nilvax‟ which also includes the anthelmintic, Levamisole. This can be useful as a ‘primer’ dose prior to administering capsules.

• Change needles frequently. Administer under skin behind ear. Store vaccines at fridge temperature at all times.

Other vaccine options available include 5 in 1 vaccines with either or both B12 and Selenium. (see below)

Anthelmintic Treatments:

Oral liquid treatments are probably of very limited value unless your ewes are suffering from a high worm burden throughout the winter. This is unlikely if they are being well fed and being kept in good condition with no other concurrent disease e.g. Johnnes or liver fluke. If you are going to use an oral drench, then a dual or triple action product (Matrix or Switch) should be used.

No treatments (yarding of ewes) to ewes should be given in the last two weeks of gestation, due to the risk of stress related abortion, so the short action of an oral anthelmintic will miss that period of immune suppression or “pre-parturient rise‟ immediately prior to lambing, making them of no value to the lamb and of little value to the ewe.

Injectable anthelmintics may give a benefit as a pre-lamb ewe treatment but to be clear, they do not compare with drench capsule technology and they may pose a
risk to resistance development through the effect of their “tail‟ of
anthelmintic levels in the ewe below therapeutic levels.

Advertising tries to compare a Moxidectin LA (Exodus or
Cydectin) treatment with capsules and gives the impression that they are equally effective for 100 days. This is only true for one parasite, Ostertagia, which is not generally significant in sheep. More significant is the parasite Trichostrongylus against which Moxidectin is effective for a maximum of 42 days. All the rest, and some are very significant such as Nemotidirus, efficacy is for only 1 day! This is pretty much of no use at all, because the benefit will have passed long before lambing and the period of ewe immunity suppression.

In summary only Moxidectin LA will give some sustained benefit; all other injectables such as Eweguard and abamectin (Genesis) injectable will be of questionable benefit to ewe and lamb and can definitely NOT be compared to capsule technology. The main reason for this is the “constant contact‟ of the anthelmintic in the capsule, minimising the effect of the lowered immune response and energy diversion. What this means is the ewe can utilise every blade of grass into either milk production or body condition.

The advantage of injectable anthelmintics is a lower cost per head and ease of application. I addition the likes of Eweguard and Nilvax, they are combined with a 5 in 1 vaccine.

Anthelmintic or Drench Capsules vary in the active ingredient they carry, but all will last for 100 days at therapeutic levels.

If you have parasite resistance issues you need to be aware of your status and select a treatment that you are confident will work. If you are uncertain, then you are safer with a combination product. A premium capsule with combination anthelmintics is BIONIC and this will provide therapeutic levels against all 13 internal sheep parasites for 100 days.

To achieve a production gain (assuming your feeding levels are good) the requirement is to have an anthelmintic in the ewe at lambing time and for a reasonable period after lambing. In the face of a parasite challenge, the ewes energy will not be diverted to the challenge on its immune system, but will be put into maintaining its condition and milk production for lamb growth. The net result is a significant increase in lamb growth (supported by numerous trials) which is the real benefit of using capsules over other treatments and it is what sets them apart from all others.

Capsules provide many benefits:

  1. Increased ewe milk production resulting in better lamb weights at weaning

    (between 4 and 8 kg)

  2. Better ewe weights at weaning (average 5.8kg)
  3. More lambs away at first draft
  4. Increased wool production.
  5. Ewes in better condition at mating (= more fertility)
  6. Less dagging

Yes, they do cost more per head, but numerous trials over the years have shown that with good available feed, production gains as mentioned above will produce an economic return on the cost of the capsule.

In the interests of ‘refugia’ and on the basis of return on outlay, you might consider just treating the more susceptible ewe groups. This would include twins and triplets, hoggets (if mated) and 2-tooths.

In Summary:

  • Drench Capsules are the only product that has been proven to be an “Investment” i.e. “you get a return on your money spent”. (Numerous trials show heavier lambs and most important, heavier ewes going back to the ram after weaning. Often your weaning weights become your tupping weights … this then effects next years lamb crop). In fact all things being equal e.g. feed supply, capsule ewes “stand out‟ in their body condition, milk production, lamb growth and post weaning ewe weights !
  • Other treatments (injection and oral) may be cheaper but; they are only a treatment for the ewe with comparatively minimal long term financial benefit.
  • You need to know your farms resistance status.
  • Trich sp worms are the main worm of concern in Tasman. NOTE: Be careful

    of adverts that say injections last for 100 days. They do, but for only one

    relatively insignificant parasite in ewes !

  • If stock are light, use pre-lamb treatments earlier (4 to 6 weeks pre-lamb)

    compared to ewes in good condition (2 to 3 weeks out).

  • Use a primer drench with Extender SeCo Capsules at the time of capsule

    dosing. (suggest Nilvax or Levimisole Oral or Matrix)

Minerals.

  • Vaccinations give you the opportunity to provide selenium and cobalt (B12) which will raise levels for 4 to 6 weeks.
  • Oral anthelmintics will only provide very short term mineral supplementation, and injectable anthelmintics may contain selenium and cobalt (B12), also lasting 4 to 6 weeks.
  • Drench capsules (BIONIC, EXTENDER SeCo) provide cobalt and selenium by slow release for 100 days.

Additional minerals can be of benefit for lamb survival and there is research to support this. Of note is LSD, originally developed by Vet, Pete Anderson of Blenheim.

Mineral Supplement Suggestions:

  • Most common minerals required by ewes and lambs include: Selenium, Vitamin E, Iodine, Cobalt, Zinc, Chromium and in some cases copper.
  • You tend to pay for what you get. If it is cheap, it will either have very low levels of some elements or they will be a largely unavailable form.
  • LSD is the “Gold Standard‟ and has been well researched. Others with fewer ingredients may be sufficient.
  • Avoid giving two Selenium products at one time due to potential toxicity. Repeated fertiliser applications of Selenium may negate the need to give further supplements. (Exception: LSD can be used with one other form).
  • It always pays to run biannual optigrows of stock classes to know your farm levels of key minerals. (Selenium, Copper and Cobalt).

The Vet Centre, Richmond & Motueka.

Gladstone Road, P.O.Box 3509, Richmond, Nelson.

Phone: 03 5445566 Fax: 03 5445561

BVD (Bovine Viral Diarrhea)

BVD (Bovine Viral Diarrhea)

BVD (Bovine Viral Diarrhea)…….

BVD is probably the most important viral disease of the New Zealand cattle industry. An estimated 90% of New Zealand dairy farms have been exposed to the virus, and BVD costs the dairy industry approximately $50 million per year. BVD is a common but complex disease. The costs are often hidden and difficult to calculate, and the effects of the disease often insidious.

  • If you are living with BVD, you are probably accepting poor performance as normal.
  • Eliminating BVD usually causes expectations of ‘normal’ to rise dramatically!
  • Reproductive effects are responsible for the greatest financial losses.
  • BVD is mainly spread by persistently infected carrier animals.
  • The disease can be diagnosed by testing of blood or bulk milk.
  • When infected bulls come into contact with vulnerable herds, the results can be devastating. Bulls that areuntested and unvaccinated are a danger to the herd.
  • When naïve bulls are introduced to an affected herd and get infected, their semen quality can be reducedfor up to 80 days, thus compromising conception rates.
  • Several options are available for control. The best include vaccination of the herd and elimination ofpersistently infected carrier animals.Transmission

    The BVD virus may be transmitted between animals in one of three ways:

    1. By direct contact between animals (’horizontal’ transmission). The virus can be spread in all body fluids, including saliva, tears, nasal discharge, semen, urine and faeces. Nose-to-nose transmission over boundary fences can occur.
    2. By contact between an animal and the body fluids of an infected animal no
      longer present. For example, calf pens can remain infectious for up to 4 days after PI removal if no disinfection is executed.
    3. By invasion of the foetus when the virus infects a pregnant cow (’vertical’ transmission).

    Effects

    The consequences of viral infection differ, depending on which classes of animals are infected:

    Infection of youngstock, bulls or cows. Infection is temporary, death rates are low and animals recover from infection after an average of 2 weeks, with subsequent immunity to the virus. There may be no signs that an animal is infected at all, but when clinical signs are present they can include diarrhoea, reduced weight gain, reduced appetite, rough coat, immunosuppression with increased susceptibility to other diseases such as pneumonia, temporary infertility (cows and bulls), and reduced milk yield (cows). BVD in youngstock can appear similar to gastrointestinal parasitism.

    Infection of cows in the breeding season. This is the area in which the virus can have particularly devastating effects when it infects cows that have not acquired immunity, either by vaccination or by natural exposure. Clinical signs depend on the stage of gestation of the cow when she encounters the infection, and are listed below.

www.vetent.co.nz

It is important to remember that sometimes a PI will look perfectly normal, and may survive long enough to breed itself. A PI cow will always give birth to a PI calf. A PI bull can have disastrous consequences on fertility in a naïve herd. Bulls must be tested to make sure they are not PIs. They only need to be tested once in their lifetime.

Ideally, PIs should be identified and removed from the herd.

Behaviour of BVD in the Herd

BVD behaves differently in dairy and beef herds, due to their different natures.

In dairy herds, the disease waxes and wanes. A PI carrier is born, and the herd’s immunity declines as the calf is raised away from the main herd. When that PI rejoins the now naïve herd as a replacement, widespread BVD infection occurs. The pattern is a regular cycle of infection every few years.

In beef herds, younger and older animals are kept together, and so PI carriers remain in constant contact with all age groups of the breeding herd — cows, replacements and bulls. The disease remains active and spreading all the time, and losses are ongoing.

Diagnosis

Individual cows can be blood tested (or tissue tested) to see if they have been exposed to the virus and have mounted an immune response (antibody test), or to see whether the virus is present (antigen test). Animals that have been exposed to the virus and that have recovered will be antibody positive. PIs will usually be antibody negative, due to their lack of immune response, but antigen positive due to their inability to clear the virus. Transiently infected animals may be antigen positive due to temporarily circulating virus, and should be retested in 4 weeks, by which time they should be antigen negative but antibody positive, thus distinguishing them from the PIs. Blood samples can be pooled, which makes testing more economical.

Note that if a pregnant bought-in cow tests negative for antigen, it is still necessary to test her calf—she may be carrying a PI calf while being antigen negative herself—the ‘Trojan Cow’.

Bulk milk samples can be tested for antibody, to assess the level of exposure of the herd to the BVD virus, or for antigen, to see if a PI is present in the herd (N.B. for this to be reliable, milk from every cow must be going into the vat).

1. Infection prior to insemination or insemination using infected semen. Reduced conception rates.
2. Infection between 0—45 days gestation. Reduced conception rates; increased empty rates. Early embryonic death causing returns to service which in many cases are at irregular intervals.
3. Infection between 45—125 days gestation. Abortion, mummification or birth of persistently infected calves (see below).
4. Infection between 125 days gestation and term. Calves born with congenital defects, e.g. small eyes, blindness, brain defects. Abortions. Normal-looking calves may be persistently infected or may be born with an active and effective immune response to the virus.

Persistent Infection

When an animal is infected with the BVD virus, whether or not it shows any of the clinical signs listed above, generally it will mount a response, clear the virus within 2 weeks and become immune to it. The length of this immunity is variable. This is known as ‘transient’ infection. However, when unborn calves are infected in the uterus, between 45 and 180 days gestation as described above, they may be born with a persistent BVD infection. Because they are infected before their immune system is mature, they perceive the virus as ‘self’ and become tolerant to it. They never get rid of the virus or develop immunity, and they act as ‘virus factories’, shedding huge amounts of virus (from all their body fluids, but especially from their nasal secretions) all throughout their lives. PIs are much more efficient at spreading BVD virus than transiently infected animals—most BVD is spread within and between herds by PI carriers. Any non-immune animal that comes into contact with a PI is at risk of contracting the infection.

The Persistently Infected or ‘PI’ Animal

PIs are thought to make up about 1% of the New Zealand cattle population. PIs may die before birth. If they survive, they are often unthrifty, poorly grown and stunted, with an increased susceptibility to other diseases such as pneumonia and parasitism.

Sometimes the BVD virus in a PI will mutate. This causes a severe disease in the PI known as mucosal disease. Signs include severe mouth and gastrointestinal ulcers, nasal and eye discharge, weight loss, profuse diarrhoea and eventual death. Mucosal disease is always fatal, and only occurs in PIs, usually at 6-24 months of age.

There is no cure for PIs, and once identified they should be culled immediately before they continue to spread the virus to other cattle.

Options for Control

There is no treatment for BVD, but control is vital. There are a number of options for controlling the virus, ranging from very poor to very good, as listed below.

1. Do nothing

When the herd is exposed to the BVD virus, some cows will suffer from the disease and then become immune, but immunity is unpredictable and some cows will remain susceptible. This is a poor option with negative financial benefits.

2. Closed herd and biosecurity

Each cow, bull and replacement in the herd is individually blood sampled, and PIs are identified and culled. Then absolute biosecurity is maintained to prevent BVD virus getting onto the farm. The disadvantages of this option are that the herd becomes unprotected, since no immunity is generated either by vaccination or by natural exposure, and biosecurity can be very difficult to maintain, leading to great potential for disaster. Common routes of BVD entry include bought-in stock, contact ‘over the fence’ with neighbouring stock, stock brought home from grazing and PI bulls, but BVD has occurred in apparently ‘closed’ herds.

3. Vaccinate only the heifers/replacements prior to breeding

As long as the vaccinated animals receive a booster injection every year, this method will eliminate disease in the long term. However, in the short to medium term, many of the older members of the herd are left naïve and unprotected. PIs will not respond to the vaccine, although their non-PI herdmates will, and so a vaccinated PI carrier will continue to shed virus. This may cause losses in animals that haven’t responded well to the vaccination producing insufficient immune protection to avoid natural infection.

4. Vaccinate the whole herd, including replacements, prior to breeding

This protects all members of the herd, breaking the cycle of infection before exposure by making sure that most herd members are immune before mating starts. Herd members are protected from disease, reproductive losses are minimized and the chances of further PI carriers being born is greatly reduced. Annual booster vaccines are required.

5. Vaccinate the whole herd, including replacements, prior to breeding, and find and cull all PIs

Because the PIs do not respond to the vaccine, they will always produce PI offspring and so maintain BVD in the herd despite whole herd vaccination. In this option, each member of the herd is blood tested to identify, and then remove, any PIs. This option provides rapid and ongoing BVD control and also prevents the birth of any more carrier PI animals. This method is the gold standard. It is reliable and has maximum financial benefits.

Vaccination Programme

Heifers and bought-in replacements are vaccinated prior to their entry to the main herd. The primary vaccine course for all animals is two injections three weeks apart. Heifers should be older than three months when first vaccinated, and should have their booster at least two weeks before their first service. After this, annual boosters are required to maintain immunity.

The main herd has an annual booster vaccine several weeks before the planned start of mating. If the main herd is being vaccinated for the very first time, two injections, three weeks apart, will be required. The second injection should be given at least two weeks before the planned start of mating.

Bulls must not be forgotten. They are prime candidates for bringing BVD onto a farm. They must be blood tested to check if they are PIs, and should have a certificate to prove this. If proven negative, they should be vaccinated as above, and their immunity maintained by annual vaccine boosters.

Hoof Distortions

Hoof Distortions

Negative Plane or Counter Rotation of the Distal Phalanx (Pedal Bone) in Hind Feet.

 

There are many types of subtle equine lameness, often it is more of a ‘discomfort’, but it is uncommon to recognise the symptoms as being linked to the feet. Typically foot problems affect more than one area of the upper body. It is quite common with observant equine owners, trainers, farriers and vets, to see and recognize stiffness in the rear quarters. Frequently horses that are reluctant to move freely are resistant to work and require longer warm up times than one would consider normal.

 

How do we determine if the horse has a negative plane distal phalanx? A negative plane distal phalanx is not always easily observed unless x rays are taken first. However, other injuries or symptoms may become apparent prior to further investigation. All these injuries and conditions are directly related to the condition of a negative plane distal phalanx.

  • Hock pain
  • Stifle pain
  • High suspensory strains
  • Filled legs which go down following work
  • Tight hamstrings or injuries
  • Strains of the suspensory apparatus -­‐ predominately proximal (high)

suspensory desmitis (strains)

  • In front feet, check ligament injuries and mild fore limb lameness
  • Kissing spines
  • Constant back pain and the need for continuous therapeutic treatments,

i.e. chiropractic physiotherapy and acupuncture. In particular sacroiliac injuries or general pain around the area.

The above ailments are some of the most common found in horses with a

Negative Plane Distal Phalanx.

  • The external indicators are that the horse does not land slightly heel first, thus engaging the back parts of the foot on the ground first.
  • The frog is diseased of dysfunctional.
  • The dorsal wall has a domed appearance to it.
    Although this condition is found in the front limbs of horses, I have found a greater incidence in the hind limbs.
  • A line drawn along the line of the coronary band on the hind foot should bisect the front limb just behind the knee. On horses with NPDP syndrome, this line will often bisect the front limb at the elbow or above. (NOTE: Make sure the canon bone of the hind limb is vertical to the ground before assessing)

 

When examining the foot closely from the side (lateral view), there is commonly a crown or arch to the dorsal hoof wall this often corresponds with heels that are very unstable and appear to crumble easily under the weight and movement. Along with what seems to be poor heels, the frog is very large and has descended through the shoe to meet the ground. (Fig 1) With hoof tester examination, a positive response is common in the sole behind the widest part of the foot, through the heels and occasionally over the frog. Regardless of the pain response from the hoof testers (painful or pain free), the discomfort that exists when manipulating the limb, the dorsal wall arch and the prolapsed (enlarged) frog are the main indicators that lead to suspicion of a Negative Plane Distal Phalanx. This, means that the bottom surface of the distal phalanx that is normally elevated slightly more in the rear than in the front (2° -­‐ 5°) or in some cases parallel, is actually closer to the ground in the rear of the bone than in the front.(Fig 1 Normal angle – Fig 2 NPDP syndrome)

 

If your horse has some of the above symptoms, give us a call at The Vet Centre. We may be able to help you.

Laminitis or Founder

Laminitis or Founder

This is a painful condition of the feet resulting from the disruption of normal blood supply to the foot and associated with abrupt changes in diet or overeating (most common), severe colic, severe infections and illness. The signs are often a sudden onset of lameness and reluctance to move, with the front feet being most commonly involved, making the horse take on a characteristic stance with the forelimbs stretched out in front and the horses weight shifted to the hind limbs. It is an urgent condition, and early treatment is required.

Please contact us if you think your horse or pony has this condition.

The sensitive lamini tissue is located between the hoof wall and the pedal bone. This is where the inflammation occurs and if left untreated it will cause a permanent deviation or rotation (X-Ray picture) to the pedal bone. This could result in chronic lameness. This is why early treatment is important.

Early treatment includes intensive pain relief and anti-imflammatories to limit the development of the chain of events that is happening within the hoof

Treatment other than the above involves a close working relationship with a farrier.

In principle, the pedal bone within the hoof has to be supported as this is the bone most effected and the support structures that hold it in place inside the hoof wall.One of the best ways to provide initial support and relief is with Styrafoan blocks. (The sole foam support can be Styrofoam obtained from a builder supplier .. must be the blue one, 50 to 60mm thick and cut to the size of the foot and taped on with duck tape. (don’t use the white polystyrene used in refrigerators) Can also be obtained from Classic Horseshoes Pty Ltd. Each foot requires two blocks. The first is applied and taped in place and weight bearing over the first 24 to 48 hours compresses the block creating a cast 15 to 20mm thick. This foam cast has the area under the descending and rotating pedal bone tip removed, the area being determined by careful hoof tester application. This becomes the zone that must receive no pressure from the foam cast and the area behind and the frog become the only supporting areas.

The second foam bock is then taped onto the first and this will compress down as well. The resultant foam sandwich is taped together and left taped in place. They can be replaced of modified as required and should be left in place 1 to 3 weeks.) The foam pads are only a temporary support to stabilise and support the pedal bone (distal or 3rd phalanx) and support the damaged lamellae.

Digital support shoes need to be applied longer term.Two options include Heart Bar Shoes (HBS) and the Equine Digital support system (EDSS).

Both require lateral XRays to establish positioning of the break over point in relationship to the rotated point on the pedal bone.XRays need to be done with NO shoes attached, just prior to HBS or EDSS (Equine Digital Support System) application.

The important thing about the HBS is that the frog plate should be parallel and 2 to 3 mm above the level of the branches of the shoe. The frog support plate and the shoe should apply even pressure over the entire length of the frog. The toe is rolled to ease breakover of the foot when moving and relieves tension on the laminae. Effectively the HBS is applied to the distal Phalanx, not the entire hoof.

Shoes are best not nailed but screwed and glued as the vibration of nailing can add to damaging already weak laminae and tendon/capsule attachments

Additional forces from contraction of the deep digital flexor tendon can add to the rotation of the pedal bone and laminae separation. This can be controlled with the use of wedges to raise the heels 12 to 18 degrees. This can be best achieved using the Digital support system which is a system of pads, wedges, frog inserts etc and impression material. The heel wedges can be screwed on and off the shoe (wedge rails) as they are all predrilled and can be removed a couple of weeks later when the signs of laminaitis have disappeared (without analgesia)

NOTE: The hoof has to be trimmed first to normalise the position of the pedal bone in the hoof capsule. All applications are best done with NO analgesia (sedation/nerve blocks)so that the horses response can be immediately seen (or not). Any application to the foot may need small adjustments that can show marked responses, often immediately.

Why are X-Rays Essential:

Because the Pedal Bone has shifted inside the Hoof Capsule, we can only determine with X-Ray examination essential things like:

  • Sole depth over the tip of Pedal Bone.
  • The amount of rotation of the pedal bone
  • If the whole Pedal Bone has “sunk”. This is a very serious situation with a poor prognosis.

All these points can be measured accurately with X-Rays and will give the owner valuable information about treatment options and prognosis.

Without X-Rays you are just guessing and putting your horse at risk!

Laminitis is a complex and urgent condition of horses and needs to be treated as a Veterinary Emergency.

Phone 5445566