Internal parasites in sheep and goats

Roundworms

The most important roundworms in this region:

• Barber’s pole worm Haemonchus contortus
• Scourworms
  - Black scour worm Trichostrongylus colubriformis
  - Small brown stomach worm Teladorsagia (Ostertagia) circumcincta
  - Thin-necked intestinal worm Nematodirus species (in young sheep)

Less important or only occasionally seen worms:

• Large bowel worm Oesophagostomum venulosum
• Small intestinal worm Cooperia species
• Black scour worm Trichostrongylus vitrinus

Liver fluke

Liver fluke (Fasciola hepatica) is an internal parasite that occurs throughout this region where there are colonies of the intermediate host snail (Austropeplea (Lymnaea) tomentosa). It can affect goats and sheep severely, sometimes causing deaths. The life cycle differs from the simple life cycle of roundworms, so control strategies are different. Liver fluke should be considered if there are cases of anaemia or bottle jaw in goats and sheep that are not associated with barber’s pole worm.

Other worms

Gastro-intestinal parasites of minor importance include stomach fluke and tapeworm.

Faecal egg counts

To help make the decision whether to drench or not, faecal egg counting (FEC) is a valuable tool. We can complete this in the clinic or otherwise send it away to a parasitologist and provide interpretation.

Drench resistance trials can also be completed depending on FEC results. Drench resistance is common in the Central West. Therefore a drench resistance trial carried-out on your flock will provide you with the information to select effective drenches. Using a drench that has low efficacy will further select for resistant worms, and will amount to a significant cost in production losses and contaminated pastures.

We can carry out a trial to assess which drenches will be effective on your property, and discuss drench rotation and parasite management.

Ovine Brucellosis

Ovine brucellosis (OB) is an infectious bacterial disease of sheep caused by Brucella ovis. It is present in many sheep flocks in New South Wales.

OB occurs in all districts, in any sheep breed and causes considerable economic loss in many flocks, through ram wastage, low lamb-marking percentages and extended lambing periods. Brucellosis is still very much a problem in our area. Poor scanning percentages and suspicious testicular lesions should be investigated.

Movement of infected rams is the primary way that OB spreads between properties. This includes introduction of infected rams, but strays are also a major risk. There is the potential for introduced ewes from an infected flock to spread infection, but this is less likely.

Diagnosis is based on the careful manual examination of the scrotal contents, and on the results of a blood test. Eradication of confirmed ovine brucellosis is based on eliminating infection in older rams and preventing the infection of young rams. It is achieved by a combination of manual examination, blood- testing and removal of all infected rams as soon as they are detected. In an infected stud flock, the stud owner should seek advice from their veterinarian on an eradication program

We can provide advice on management of this disease, and oversee an eradication program. We are also able to accredit stud flocks as Brucellosis-free.

Ram/buck Breeding Soundness Exam

It is recommended that testing is completed 3-4 weeks prior to breeding. Rams/bucks that are run as single sires should be tested to protect success at breeding. We can also test sale rams.

Physical exam:

• General health and body condition
• Feet and legs
• Vision
• Defects that may impair ability to breed

Reproductive exam:

• Palpation of scrotum and testicles and the completion of scrotal circumference (adult ram should be more than 33cm and lamb rams more than 30cm)
• Physical exam of penis
• Collection of semen sample

Ram vasectomy

Vasectomy in the ram is a management technique used principally to increase conception rates in a compacted lambing period. Using a vasectomised ‘teaser’ ram is a method of synchronising oestrus to give a peak lambing period over two and half weeks. It can also be used to encourage ewes to cycle a few weeks earlier than the normal breeding season.

Any teaser ram candidate should possess the following: healthy, moderate size, some sexual experience.

We recommend that the operation is carried out well in advance of when you plan to use the ram in case of any rare surgical complications. If you are interested in have a ram vasectomised then please call the clinic.