Genevieve is one of our associates who will attend large animal calls  She is always ready and willing to help our large animal patients.  Genevieve has been with Orange Veterinary Hospital since December 2012 and is also a qualified human physiotherapist. She is conducting physiotherapy on some small animal patients but is also happy to discuss physiotherapy for your performance animals as well.

FOOT ABSCESS AND LAMENESS IN SHEEP

With recent cold weather, rain and good pasture densities there has been increased numbers of farmers dealing with lameness in sheep. The most common cause in this area is foot abscess and interdigital dermatitis. Often there is severe pain and lameness with flow on effects to production - in pregnant ewes there are impacts on ability to feed lambs, become at risk of pregnancy toxaemia whilst rams will have difficulty joining.

Foot abscesses can be present in the heel or toe. Abscesses in the heel develop following bacterial colonisation of damaged interdigital skin. Sheep will present with pain, swelling of the toe and heat above the hoof - If the abscess bursts there may be blood or discharge from the coronary band region (where the hoof and hair meet) as the infection forms a track to the top of the hoof.

Toe abscess may present as acute lameness and occur due to damage of the sensitive layer of the hoof as a result of overgrowth and injury to the toe or changes associated with laminitis. Usually involving the front feet, toe abscesses are identified by identifying pus after paring the affected claw.

Foot abscess and footrot can appear similar in nature and should be carefully identified as footrot is considered a notifiable disease. Call for more information about this.

Control measure include – keeping feet in good condition with regular inspection and paring, avoiding wet, muddy paddocks and yards as well as putting pregnant ewes onto cereal crops which can often predispose to the formation of dermatitis. Preventing ewes (particularly pregnant ewes) from becoming over-fat is also helpful and avoid yarding stock into muddy yards if possible.

10% zinc sulphate foot baths can help to control dermatitis whilst trimming the feet to drain any abscesses will help with resolution of toe abscesses, in some cases antibiotics will be required.

Following on from our diatribe on worms in the previous newsletter, let us expand on the idea of increasing resistance to worm disease by natural means. 

The animals most at risk risk of developing disease due to worms are the naïve and the young.

Lambs frequently fail to develop protective immunity to gastro-intestinal nematodes. This results in direct losses from mortality and decreased production, and indirect costs in the necessity for drenching post weaning.

Lamb weight is a function of birth weight, sex, genetics and growth rate. Nutrition and attention to the demands of the pregnant ewe are vitally important for a robust lamb of adequate birth weight. Diagnosis of twins, for example, by ultrasound  pregnancy testing is an important management tool to help cope with the nutritional demands of the pregnant ewe. For the first 8 weeks of life, lamb growth rate is largely dependent on ewe nutrition and milk yield. After 8 weeks, pasture quality and availability becomes increasingly important.

Under extensive grazing conditions, lambs frequently fail to reach the desirable target weight at weaning. Lambs should be approximately 45% of their adult weight at this time. Light lambs have limited fat reserves which may decrease their immunity to worms. Weaning itself has the potential to delay the development of immunity so it is critically important to wean lambs in adequate condition.

So, in summary, attention to ewe condition and nutrition, and quality of the lamb diet (including the possibility of early supplementation) are important ingredients in worm control on the farm. Limiting access of the naïve population to infected pastures plus these other measures may limit the need for non-strategic anthelmintic use and ultimately prevent the development of resistant worm populations on your farm.

As depicted in the image below, we are very lucky that foot and mouth disease (FMD) is an exotic disease to Australia. However, it is important for all parties involved in livestock production to be aware of the disease and the potential implications of an FMD outbreak. It is predicted that a large 12 month FMD outbreak would cost in the order of AUD $12 Billion to diagnose, manage and eradicate the disease and finally regain our export markets.  Early detection of the disease will reduce the losses that an outbreak would cause.

FMD is typically detected in cattle, causing salivation, lethargy, anorexia, lameness and a drop in milk production. The cow pictured below had vesicles/lesions in the mouth - these clinical signs can be similar to common viral and other diseases in Australia, so it is recommended to have your veterinarian examine all cases presenting in this manner.

FMD affects cloven-hoofed animals (those with divided hooves), including cattle, buffalo, camels, sheep, goats, deer and pigs. It is highly contagious as the virus is excreted in breath, saliva, mucus, milk and faeces. There is no treatment, however most affected animals recover.

It is imperative that everyone is aware of foot and mouth disease and reports any suspect cases.

The transition period is well recognised as a critical time for cow nutrition. However to minimise diseases around calving and for the best lactation and reproductive performance, we cannot neglect the nutrition of cows in late lactation and the dry period. 

Achieve and maintain Body Condition Score (BCS) 4.5 – 5.5 on the 8 scale

BCS is difficult to manipulate in a late pregnancy when the cow and foetus’ needs must be met and intake can be down. BCS changes are best achieved in late lactation when cows can be fed individually in the dairy or can separated into groups according to their needs.

Once a healthy BCS has been achieved, it is important to maintain it through the dry period.

Cows that lose weight in this period have less body reserves to draw on after calving. Cows overfed in this period can experience greater drops in dry matter intake close to calving and develop fatty liver.

Meet nutritional requirements

• Energy approx. 90 – 100 MJ of ME
• Protein >12% CP
• NDF >36%
• Calcium 0.4% diet DM
• Magnesium 0.3% diet DM
• Phosphorous 0.25% diet DM

Develop rumen papillae

Cows eating grain develop papillae (finger like projections) on the internal surface of their rumen. These increase the surface area for absorption of nutrients. In dry cows that are not fed grain, papillae regress and it can take 3 – 6 weeks to reform when grain is reintroduced. Feeding grain throughout the dry period maintains these papillae as well as the rumen flora required to digest carbohydrates. This ensures that cows can absorb and utilise the nutrients provided in the springer diet as well as the early lactation diet, when all available energy will go into milk production.