Not all goats that are losing weight, weak and lethargic are suffering from worms, or they may be suffering from worms as well as another disease condition. Goats may become heavily parasitized because they already have a chronic debilitating disease that affects their immune system, or their ability to graze or absorb nutrients.
Goat diseases most likely to be confused with worms are discussed below.
Goats with Johne’s disease do not have the profuse scouring typical of cattle; weight loss is the main clinical sign and intermittent scouring may only occur in the terminal stages. Johne’s disease more commonly affects dairy goats than meat or fibre goats, but all goats are susceptible. Goats can get both the cattle and sheep strains of Johne’s disease, although the cattle strain is more common.
Even if goats are affected, clearly visible signs can be lacking at post-mortem. Tests are needed for confirmation, e.g. histology of the ileo-caecal lymph node. Many goats with Johne’s disease are also heavily infected with worms.
There is no clinical test that can identify Johne’s disease early in the incubation phase and if the goat is under 12 months of age. The incubation period can last many years. More information about Johne’s disease in goats can be found on the Animal Health Australia website.
Goats infected chronically with CAE virus can have wasting and enlarged joints. Sometimes there is also pneumonia and mastitis. There is also a nervous form, but this is very rare. Dairy goats have the highest incidence, but all breeds are susceptible.
As the CAE virus affects the white blood cells, the immunity of goats is severely compromised. This means that goats with CAE are highly likely to have heavy parasite loads.
More information about CAE in goats can be found on the Animal Health Australia website.
Note: goats with Johne’s disease and CAE have lower resistance to worms, and may have high worm burdens.
All goat owners should obtain a goat health statement when purchasing new animals. This document mentions both CAE and Johne’s disease and can be downloaded from the Animal Health Australia farm biosecurity website. It also records recent vaccinations and worm drenches.
Other possible causes of wasting in goats include: