The body’s cells age and this can lead to the development of symptoms and even diseases. 

What are the common problems and diseases of older horses?

The aging of the body is reflected in the aging of certain organs and cells. Indeed, aging can lead to a decrease in the functioning of cells or to their non-renewal. This will result in a decrease in the functional capacity of the organs in which these cells play a role. The transition of this aging may be different depending on the organs affected.

The most common disease of the older horse is due to the aging of the joints. This is called arthrosis. Almost all horses are affected by arthrosis. In this case, the joints will lose their functional quality and the horse will become stiff. The cartilage and subchondral bone are the two areas of the joint that will be affected and cause pain when the horse moves.

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Osteoarthritis is a degenerative disease for which there is no definitive treatment. There are different types of treatment, some of which relieve the pain created by the joint inflammation (infiltrations). Other treatments will slow down the onset of osteoarthritis and at the same time relieve the pain: bisphosphonates.

Prevention helps to slow down its development and the appearance of symptoms. Proper foot care, working on quality footing and certain food supplements can help prevent and limit the onset of osteoarthritis.

Kidney failure

Similarly, the kidneys can show a progressive aging process. The cells of the kidneys will find it increasingly difficult to perform their filtration role. This is known as chronic renal failure. The most common symptoms of this disease are progressive weight loss, fatigue and an increase in water consumption and the amount of urine eliminated.

Unfortunately, in cases of chronic renal failure, there is no treatment because the mechanism is not reversible.

Ageing of the eyes

The eyes can also be affected by aging. The crystalline lens is the part of the eye that is most often affected. It will progressively become opaque, leading to a reduction in vision for the horse. This phenomenon is called cataract*.

The horse will not show any obvious symptoms. It will show hesitations in the passages from the shade to the light. At the eye level, a whitening of the deep part of the globe can be observed.

In more advanced cases, an operation to replace the lens may be performed. The appropriateness of performing the operation will depend on the level of damage, the age of the horse and its activity.

Aging can also affect the teeth. This can be characterised by severe and sometimes inappropriate wear of the teeth or even by the teeth falling out. Wear and tear are a normal phenomenon but with advanced age it can be excessive.

Tooth loss is more related to wear of the attachment areas to the jawbone. In both cases this can lead to chewing difficulties which can result in weight loss or even digestive disorders such as colic or oesophageal blockages.

Dental problems can also lead to infections in the teeth or the surrounding sinuses. If the teeth are infected or loosened, it is best to have them removed. The diet should also be adjusted if the horse has a non-functioning dentition. As a preventive measure, regular visits to a specialist to monitor the teeth are necessary. 

In terms of digestion, the digestive tract may be significantly aged. This can result in a decrease in the horse’s digestive capacity. The digestive tract will be less able to digest and process feed.

This deficit will result in weight loss and possibly diarrhoea. In this case, anti-inflammatory treatments such as corticoids can help to de-inflame the mucous membrane of the digestive tract and thus recover some of its functional capacity.

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The diet can also be adapted to promote digestibility and thus slow down weight loss. Diseases in the horse can be caused by specific organ damage. In this case it is not only a question of the cells in the affected organs ageing, but also of a transformation of these cells making them dysfunctional.

Cellular dysfunctions

This is what happens in tumour processes. Different types of tumours can be found in the horse. Their frequency and risk of occurrence increases with age. This is the case, for example, with melanomas*, which increase in size with the age of the horse and can cause digestive problems. Similarly, tumours of the digestive tract are more common in older horses.

They result in digestive disorders such as diarrhoea, signs of colic and often weight loss. Unfortunately, there are no specific treatments for tumour pathology. Surgical interventions can remove some tumours but rarely lead to a complete cure. The introduction of certain drug therapies will slow down the progression and relieve the horse.

Another disease due to degeneration of certain cells that is frequently found in the older horse is Cushing’s syndrome or pars intermedia dysfunction of the pituitary gland.

Affected horses are mainly older than 15 years. In this disease, a gland at the base of the brain will malfunction and cause the production of the hormone ACTH to be disrupted. The overproduction of this hormone will lead to disorders in the rest of the body: fatigue, hypertrichosis*, weight loss, muscle wasting, laminitis, recurrent infections, increased water consumption and urine production.

Clinically, the affected horse will look like a very old horse when it is not yet very old. Diagnosis is made by blood tests which show an abnormally high amount of the hormone ACTH. The treatment then consists of the daily administration of a molecule called pergolide. This is a lifelong treatment.

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In summary, there are two main types of pathology in the older horse. The most frequent are pathologies linked to the aging of certain organs of the body. The most common is osteoarthritis, which affects almost all horses with varying degrees of impact.

Other pathologies are related to the transformation of certain cells, as in the case of tumour processes. Unfortunately, they can be found at any age, but they are more frequent with age. The majority of these diseases do not have a definitive treatment, but treatment is possible to slow down their evolution. Prevention of age-related diseases can slow down their development and ensure that they appear as late as possible in the horse’s life.

Prevention in the older horse

Older horses have similar needs in terms of prevention as other horses. In some respects, they have even greater needs. For the classic issues, it is important to maintain the same protocols as for an adult horse in terms of vaccination and parasite management. Vaccinations and deworming should therefore be maintained even on a retired animal.

Dental maintenance will be an important part of the follow-up as dental problems can be frequent in the ageing horse. Regular foot care is also important, whether it is to clean the lower part of the hoof or to manage horn growth and hoof balance.

Regular weight monitoring is also essential as older horses can tend to have difficulty maintaining a correct weight. If weight is falling, checking teeth and droppings are good first indicators to assess. This will allow the feed to be adapted to make it easier for the horse to chew, and possibly richer and more digestible if the horse has digestive difficulties.

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More generally, older horses may have a more fragile immune system than adult horses of a normal age. It will be necessary to adapt the way of life: blanket or night indoors in cold season, shaded area during periods of high temperature, flat grounds, avoid living with other horses who might be aggressive…

Finally, a regular check-up with your veterinarian will allow the implementation of protocols adapted to your horse as well as a regular follow-up of its health.

Lexicon

Hypertrichosis: excessive development of the quantity of hair and difficulty in losing it during the changes of season.

ACTH: a hormone secreted by the pituitary gland; it is responsible for modulating the secretion of cortisol. An overproduction of ACTH will lead to an overproduction of cortisol secretion.

Cataract: opacification of the lens. It is mainly due to ageing. It leads to a decrease in visual capacity.

Melanoma: a tumour that affects the pigment cells of the skin. In horses, it mainly affects grey horses, but horses of other colours can also be affected.