Monday, May 27, 2019

Tackling obesity

The problem of obesity in equines is not new. However, the increasing number of obese horses and ponies, predominantly in the leisure industry, has now become a globally recognised welfare concern.  

Carrying excess weight places increased stress on the skeletal system of the horse, can limit reproductive performance, adversely affect athletic performance and may lead to an increased risk of laminitis, osteoarthritis, heat intolerance and certain types of colic. 

Dr Pat Harris, a veterinary specialist in equine nutrition from the Equine Studies Group, WALTHAM Centre for Pet nutrition in the UK gave a plenary speech on equine obesity at the 2018 ISES conference in Rome.

Dr Harris reviewed the current research, raised concerns about the growing number of overweight horses worldwide, and gave practical advice to help horse owners and keepers recognise early signs and manage the condition.  

She pointed out that promoting weight loss can be very difficult, especially in certain horses/ponies once they become obese.

So it is very important for all owners/feeders to appreciate why their animal should not be allowed to become obese and to be able to recognise when they are starting to put on weight, so that appropriate management and feeding strategies can be put in place as quickly as possible.

The increase of obesity in domestic horses may not only result from the way they are fed, managed and exercised, but also a result of owners and keepers not being able to recognise when their horses are starting to become overweight. 

In recent years, there may also have been a shift in favour of higher body condition scores. This could be due in part to the number of overweight horses and ponies winning at shows and being seen as the ideal ‘breed standard’.  

Equine obesity can be a very difficult condition to manage. Weight loss programmes are complex and require changes to diet, management and exercise. Ponies can eat up to 1% of their body weight in dry matter in just 3 hrs of turnout at grass, and nearly 5% over 24hrs which means that, in order to encourage weight loss, management changes must often be quite marked. 

“It can be very easy for some animals to gain weight and extremely difficult for them to lose weight, especially when limited facilities are available” Dr Harris points out. “It is, therefore, really important that all involved help support the owner/feeder in their efforts, rather than perhaps making them feel guilty for continuing to have an overweight or obese animal.” 

Managing weight loss involves time and planning on the owner’s part and in practice requires more than just reducing energy (calorie/kilojoule) intake in order to help keep the horse healthy and maintain long-term weight loss. It is vital an appropriately balanced diet is provided throughout – horses must have the correct protein, vitamin and mineral intake to avoid negative health consequences.  

Weight loss programmes also need to consider that horses are trickle feeders and cannot be left for long periods without forage. Useful management steps can include:

  • ·         soaking hay in water before feeding it to reduce sugar and starch content,
  • ·         using small-holed hay nets and slow feeders to slow-down intake,
  • ·         introducing more exercise if the horse or pony is sound
  •        using well-fitted grass muzzles to allow them some access to pasture (after training the horse to wear and use one)
  • ·         removing rugs so they can spend energy keeping themselves warm.

Dr Harris stressed that prevention is better than cure and the need for owner education on the subject is vital. Once horse owners understand the dangers of obesity, they better appreciate the reasons why horses should not be allowed to become obese in the first place, and therefore, recognise the need for them to be able to regularly monitor their horse/pony’s condition.    

Teaching owners to recognise when their horses and ponies are starting to put on weight will mean that necessary changes to management and feeding strategies can be implemented earlier. 

Many owners assess their horse’s weight simply by looking at them or using a weigh tape – neither option will give an accurate record of the horse’s condition or where fat deposits may be accumulating in the body.  

To produce consistent, reliable results when routinely monitoring condition requires both experience and skill. Dr Harris stressed that it would be very helpful for all owners and carers to learn how to assess their horse’s Body Condition Score (BCS) correctly by feeling and palpating the horse as well as observing their appearance.

She outlined how to correctly assess the BCS of several horses using the Henneke System. This 9-point scale uses a combination of visual observation and palpation in six areas of the body: neck, behind the shoulder, withers, ribs, loin/back and tailhead. A numerical value is assigned based on the fat accumulated in all six areas.

Firstly, an initial observation should be taken from both the side and back of the horse from about 2.5m away. This provides a general overview of the body shape and enables the assessor to look for the possible presence or absence of key bony ‘landmarks’ – e.g. the hips or ribs. 

Whilst a visual inspection can give an indication of the BCS, anatomical differences as well as variations in hair coat means that the assessor must run their hands over the different areas of the horse’s body to determine the correct final condition score.  

Palpation of the fat storage sites at the 6 key body areas (neck, withers, shoulder, ribs, back and tailhead) should be performed in a consistent way, for example, starting with the neck and then moving to the tail. Each area is assessed and independently scored against the 9-point scale to take into account individual differences in regional fat deposition. The individual scores for observation and palpations are then added up and divided by 6 to give the final overall score for the animal. 

The final scale ranges from 1-9 with 1 defined as ‘poor’ and 9 as ‘extremely fat’. Both a severely underweight (taken as a BCS of 3 or less) or obese (defined as a BCS of 7 or more out of 9) result are associated with a higher risk of health problems. 

As a guide for leisure horses and ponies, Dr Harris recommended a BCS of 5 tending to 6 towards the end of summer and around 5 tending to 4.5 at the end of winter. It is important for all horse owners to learn to carry out a BCS effectively so that horses at risk can be identified as soon as possible so appropriate changes in nutrition and management can be put in place, and/or veterinary/nutritional advice is sought. 

But Dr Harris says that BCS scoring is only a part of weight management. Especially for some of the more obese animals and at least initially during a weight management programme, it is really important to be aware that the body condition score may not actually reduce despite them losing weight most likely because, at this stage, they lose the ‘invisible’ internal fat first rather than the external fat that we can palpate.  

Therefore, she always recommends regularly measuring and recording belly girth and rump width (taking care the horse is fully comfortable with the procedure). In addition, periodic and accurate body weight measurement (preferably using a calibrated weighbridge at a local veterinary practice), can be extremely helpful to ascertain early on if the management changes are having a positive effect.
She hopes that future advances will help in managing overweight horses and ponies.

 “Looking forward, we are working hard to find ways to identify those animals that are more resistant to losing weight than others so that we can better advise on the optimal weight management programme for an individual animal.” 

“I hope that new techniques will become available that will enable us to quickly and routinely measure the % Body fat in any animal which will not only enable better monitoring, but also the determination of disease risk level according to body fat content.”

Read the conference abstract (see p54):

See Spillers body condition scoring tool based on the Henneke system:

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