Ill-thrift in adult farmed deer
Published 27 January 2025
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According to the British Deer Veterinary Association (BDVA) as per 2023 there are approximately 40,000 deer in enclosed premises such as deer parks, zoos or small deer enclosures on campsites, garden centres, petting farms etc. but excluding deer farms.
Voluntary food intake in red deer is known to show seasonal variation – being high in the summer and low in the winter. This often results in corresponding fluctuation in body weight and live weight gain. The periods of greatest nutritional requirements in deer relate to late pregnancy, lactation, and growth, which occur during the spring and early summer months. For male deer, the rut (in Red, Sika, and Fallow deer: September to November) is a period of intense energy usage and reduction in feed intake, with marked body condition loss by the end of the rut.
During the winter months the cumulative effects of a reduced voluntary food intake, provision of feed of inadequate nutrient value, lack of shelter and inadequate fat reserves and body insulation can lead to ill thrift, weight loss, and in extreme cases death. These effects can increase susceptibility to disease and can continue into the times of increased nutritional requirement in the spring and summer.
The following table lists some of the diseases associated with ill-thrift.
1. Diseases associated with ill-thrift
| Disease | Notes |
|---|---|
| Lungworm | Red deer are very susceptible to Dictyocaulus viviparus. Losses are often greater in the winter months due to a failure to build up adequate fat reserves through the summer. Clinical signs include decreased appetite, weight loss, roughened coat and unexpected deaths. Unlike cattle, coughing is not a major problem. Often there may be an underlying cause predisposing the deer to developing a heavier infection. |
| Parasitic gastroenteritis | Deer generally carry low worm burdens when compared to cattle and sheep. Clinical signs are like other ruminants, with loss of weight, poor coat, and soft faeces. Worm egg counts can be unreliable, even in the face of a burden resulting in clinical disease. It is potentially a major problem in reindeer (albeit an unconventional farmed species). |
| Cryptosporidiosis | Infection is through the faecal oral route and more severe in neonatal animals than in adult animals, which tend to be subclinical. Zoonotic. |
| Yersiniosis (Yersinia pseudotuberculosis) | Can be isolated from normal deer faeces but can cause enteritis and death. Often stress related, with animals in poor condition, and accompanies a history of recent transport, dietary changes, or inadequate shelter. |
| Tuberculosis (Mycobacterium bovis) | A notifiable disease and suspected cases should be reported to Animal and Plant Health Agency (APHA). In Great Britain, deer are generally considered a spillover host. |
| Johne’s disease | Nearly always presents as single losses in yearlings after a prolonged period of wasting, with little sign of diarrhoea. |
| Malignant Catarrhal Fever | Has a variable incubation period in deer and can be triggered by nutritional or other stresses leading to outbreaks of disease with death following depression, malaise, dysentery and often blindness. Generally, deer (apart from fallow deer), are highly susceptible, and affected deer often die within a few days of onset of clinical signs. While direct contact with sheep is a more likely transmission pathway, indirect exposure still poses a risk. |
| Copper deficiency | Usually only severe deficiency will present clinically, however relation between clinical signs and liver copper is not always reliable. Recognised as a cause of enzootic ataxia in young adults. Can also result in poor coat quality, ill thrift, broken antlers, and poor fertility. |
| Selenium and/or cobalt deficiency | In common with cattle and sheep, poor coat quality and ill thrift have been associated with low concentrations of selenium and / or cobalt. |
| Chronic Wasting Syndrome | Extensively described in elk and mule deer in the USA. Clinical signs include behavioural alterations, progressive weight loss and death. The disease name can be a misnomer as results in more than just wasting, and wasting does not necessarily mean CWD. Histopathological lesions are similar to those of scrapie and BSE. It has never been recorded in UK deer. |
2. Associated reading
2.1 Handbook
APHA guidance on sample and test selection
2.2 Literature and articles
- Management and diseases of deer: a handbook for the veterinary surgeon, 2nd edition (1994) edited by Tom L. Alexander and David Buxton, published by the British Veterinary Deer Society (BDVS). Email admin@bdva.co.uk for more information.
- The Management of Enclosed and Domesticated Deer (International Husbandry Systems and Diseases) (2022) edited by John Fletcher.
- Monitoring the health and welfare of free‐living deer in deer parks - Green - 2017 - In Practice - Wiley Online Library https://doi.org/10.1136/inp.i6657