Less obvious causes of thin ewes identified
Results of a major study which has shed light on some of the less obvious causes of thin ewes in Irish flocks were shared with those attending the Teagasc National Sheep Conference last week.
Facilitated by the Department of Agriculture, Food and the Marine’s Regional Veterinary Laboratories (RVLs), and supported by Teagasc and industry, Seamus Fagan of the Athlone RVL presented the main findings of the Thin Ewe Scheme.
Providing a background to the study, Seamus Fagan, pictured below, explained that it aimed to identify the underlying causes of thin ewes in some flocks where no obvious reason – either nutritional, illness, dental or parasites – was available.
Additionally, it aimed to quantify the presence of iceberg diseases in Irish flocks. An iceberg disease, he commented, is one where the illness and losses seen in animals is only a small proportion of the true number of infected animals. These diseases, he said, tend to be deceptive, as they are usually well established in a flock by the time the first impact is seen. The five main iceberg disease discussed were: Maedi-Visna Disease; Caseous Lymphadenitis; Ovine Pulmonary Adenomatosis (OPA) or ‘Jaagsiekte’; Pseudotuberculosis (Johnes Disease); and Border Disease.
Presenting the results of the study, as outlined in table 1, he noted that damage caused by worms to the ewe’s digestive tract and dental issues were the biggest culprits identified in the study findings.
Of the 104 ewes examined as part of the study, thinness occurred as a result of parasitic gastroenteritis in 53 ewes or 51% of the animals tested. As these animals had low worm burdens when submitted to the laboratory prior to post mortem, Seamus Fagan concluded that the thinness occurred as a result of parasitic infections in earlier life which caused chronic damage to the intestines, often times leading to a reduced ability to absorb nutrients.
Additionally, dental issues were identified as the cause as to why 17.3% of the ewes presented were thin. Rather than being issues with the front teeth, which can be easily identified through visual examination, he noted that these tended to occur due to the back teeth problems, something not visible in the live animal without a physical examination of the ewe’s jaw to identify any abnormalities.
Table 1: Results of the Thin Ewe Scheme
| Individual diagnoses | Ewes | % | Flocks | % |
|---|---|---|---|---|
| Parasitic gastroenteritis | 53 | 51 | 26 | 43.3 |
| Teeth | 18 | 17.3 | 9 | 15.0 |
| Ovine Pulmonary Adenomatosis (Jaagsiekte) | 7 | 6.7 | 4 | 6.7 |
| Caseous Lymphadenitis | 4 | 3.8 | 3 | 5.0 |
| Johnes | 5 | 4.8 | 5 | 8.3 |
| Metritis | 1 | 1.0 | 1 | 1.7 |
| Abscess | 1 | 1.0 | 1 | 1.7 |
| Lameness | 5 | 4.8 | 4 | 6.7 |
| Tumour | 1 | 1.0 | 1 | 1.7 |
| Pneumonia/lungworm | 5 | 4.8 | 4 | 6.7 |
| Liver fluke | 4 | 3.8 | 2 | 3.3 |
| Total | 104 | 60 |
Additionally, Seamus Fagan featured on an episode of the Teagasc OviCast podcast last October, where he detailed the process of checking teeth, molar problems and other health issues in sheep.
Listen in below:
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Also read: Reducing the number of thin ewes makes management easier