Common Small Ruminant Parasites and Diseases
By Jeanne Breneman
You can protect your herd (goats) or flock (sheep) from the most common diseases and parasites by practicing excellent animal husbandry, monitoring for parasite infection, and recognizing symptoms of disease. Prevention is less expensive and troubling than treatment.
Quarantine New Animals
Quarantining new animals is something you should always do. Even an animal that appears healthy can spread infection to your other animals, compounding the problem. Quarantine new animals for a minimum of two weeks, even animals that appear to be fine.
Time in quarantine gives symptoms a chance to manifest, revealing previously undiagnosed conditions. It also gives you time to check for GI parasites, deworm as needed, and evaluate the effectiveness of the anthelmintic (dewormer) drugs. If you find that no anthelmintic drug is effective in the new animals, we recommend you consider culling those animals or returning them to the previous owner. Parasite resistance to anthelmintic drugs is a significant problem. Introducing animals that already have resistant parasites would make it much more difficult to keep parasites below disease-causing levels in your herd or flock. For more information about parasite resistance and strategies to help slow it down, see our blog article, The Barber Pole Worm in Sheep and Goats. That article also discusses the importance of using anthelmintic drugs in a targeted manner as part of a larger integrated management approach to parasite control.
While new animals are in quarantine, you can also trim their hooves to help prevent foot rot. If symptoms of foot rot are already present, this also gives you time for treatment.
Your veterinarian is the best resource for information about vaccinations appropriate to your area. Another reason to consult your veterinarian is that some vaccines are approved for sheep but use in goats is considered “off-label”. Dosing guidance can be provided by your veterinarian since it is not provided by the manufacturer.
The recommended vaccines in your area are likely to include CDT (3-way clostridial disease vaccine). This vaccine protects against clostridium perfringens types C and D, plus tetanus. For sheep, 7-way and 8-way clostridial disease vaccines are also available. The additional clostridial diseases the 7-way and 8-way vaccines protect against are uncommon in goats.
Some other vaccines that might be recommended include:
- CLA (Cornybacterium pseudotuberculosis)
- Chlamydia during pregnancy to prevent abortion
- Sore mouth (a skin disease also known as contagious ecthyma or orf)
- Foot rot
If you are raising animals for food, be sure to take withdrawal time (usually 21 days) into consideration. In other words, allow enough time after administration of the vaccine, before slaughter, for the meat to be safe to eat. Your veterinarian can advise you about withdrawal time for specific vaccines.
Overview of Common Internal Parasites
Management of parasites in your animals and on your property can keep their populations from rising to levels that cause disease. See our blog article, The Barber Pole Worm in Sheep and Goats for a discussion of parasite management strategies, with a particular focus on stomach and intestinal worms such as the barber pole worm.
The barber pole worm (Haemonchus contortis), in the Strongyle worm family, is one of the most dangerous of all the parasites affecting sheep and goats. There are other parasitic worms in the Strongyle family, such as Teladorsagia (Brown Stomach Worm) and Trichostrongylus (Bankrupt Worm). Fortunately, controlling the barber pole worm tends to control these other Strongyles as well.
Besides the Strongyles, some other internal parasites to watch out for include coccidia, tapeworm, and meningeal worm.
Coccidia are protozoan parasites that reside in the digestive tract. It is normal for adult sheep and goats to host a small number of coccidia without experiencing any debilitating effects from them. This parasite is most dangerous to kids and lambs because they have not had a chance to develop any immunity. When a goat or sheep is suffering from coccidia infestation, they are said to have coccidiosis, characterized by mild to severe diarrhea, loss of appetite, failure to gain weight, and dehydration. The diarrhea is caused by intestinal tissue damage.
One of the biggest challenges with coccidiosis is that it can range from quite mild with barely noticeable symptoms, to so severe that it causes death within 24 hours. Since coccidiosis is the biggest cause of diarrhea in kids and lambs between three weeks and five months of age, and because it can be so dangerous, it is important to act as soon as you notice diarrhea. It is also possible for animals to have early coccidiosis without diarrhea, so be alert to any indication that an animal is failing to thrive. Diagnosis is based on symptoms and fecal examination. Coccidia eggs in manure look distinctly different from those of other internal parasites.
First, isolate animals with suspected coccidiosis to help prevent it spreading to the rest of your flock or herd. Beef up the sanitation protocols for all your animals, sick or otherwise. This will also help control spread.
Work with your veterinarian to confirm coccidiosis and treat the affected animals. Treatment generally consists of an orally administered coccidiostat (coccidia killer) such as amprolium, plus sulfa drugs to help manage secondary infections. Use of both these treatments for goats is off-label, so be sure to have your veterinarian provide dosing guidance. Also discuss with your veterinarian how to prevent vitamin B1 (thiamine) deficiency, a frequent side effect of amprolium treatment.
Anyone who has dealt with an outbreak of coccidiosis will likely agree that prevention is the way to go! Coccidia eggs are passed to the outside environment in manure, where they mature to an infective life stage. Sheep and goats ingest the infective forms through food and water contaminated by manure. Prevention, therefore, primarily focuses on manure management and keeping food and water clean. For example, you can:
- Feed animals off the ground, away from manure.
- Collect and dispose of manure frequently.
- Make sure the design of your watering system prevents contamination of drinking water and does not leak onto the ground where water puddles can become contaminated with feces.
- Keep housing and feeding areas well ventilated and dry.
Stress is also a factor in coccidia outbreaks. One of the most stressful events for a kid or lamb is weaning, with the emotional stress of separation from the mother plus the physical stress of a change in diet. Anything you can do to reduce this stress helps. Some examples include:
- Provide youngsters with excellent nutrition as they transition to solid food, including providing a vitamin/mineral source.
- Familiarize kids and lambs to their weaning pens in advance of actually weaning them. That prevents the move itself from becoming a compounding stress factor.
- Be sure the weaning pens are safe, clean, and dry. Gates and fence lines should be low to the ground to prevent animals from getting stuck under them.
- Encourage consumption of clean, fresh water. Waterers should be low enough to the ground that weanlings can reach them easily. Some owners add electrolytes to the water for added support.
- Be sure vaccinations are up to date. Before weaning, kids and lambs should receive their CDT vaccine and booster.
The segmented tapeworm lives in the small intestines of sheep and goats. Each segment is a reproductive unit, producing eggs that are released into the external environment when the segment is shed in the animal’s manure. The segments, whether individual or in chains, are visible to the naked eye in manure. The life cycle of the tapeworm includes a period of development inside a pasture mite which lives by the millions in a typical pasture. When a sheep or goat consumes a mite that contains infective stage tapeworm larvae, the parasites mature inside the animal.
Eradication of the mites is probably not feasible. Eradication of the tapeworms is also probably not feasible. The good news is that tapeworm infestation, unless extreme, does not seem to be associated with disease in sheep and goats. Although, as an owner, you might find seeing the worms distasteful.
Whether or not to treat your animals for tapeworms when you see them is a discussion worth having with your veterinarian. The only anthelmintic drug approved in the U.S. for treatment of tapeworms in sheep and goats (albendazole) is one of the drugs to which the barber pole worm tends to develop resistance. Using this drug to combat tapeworms could hamper your efforts to slow parasite resistance on your property. See our blog article, The Barber Pole Worm in Sheep and Goats for more information on parasite resistance.
One possible strategy is to treat once in the spring and optionally, in the fall. You could also limit treatment to young or stressed animals who are more likely to be susceptible to tapeworms.
Meningeal Worm (Parelaphostrongylus tenuis)
The meningeal worm (also called deer worm or brain worm) is common in white tailed deer and does not seem to cause disease in that species. But infected small ruminants can suffer mild to catastrophic paralysis, depending on the area of the brain or spinal cord infected and the abundance of the parasite.
It can be difficult to definitively diagnose meningeal worm infection in a living animal. It can also be difficult and expensive to treat, with treatment not always being successful. Treatment can involve long courses of anthelmintic drugs along with steroids and non-steroidal anti-inflammatories (NSAIDs) as supportive therapies. Part of the problem with treatment is that once the parasites have reached the brain, only drugs that can cross the blood-brain barrier have a chance of being effective. Studies are ongoing. The Cornell University website provides an excellent resource for information on this parasite and the current research and thinking on treatment for sheep and goats: https://blogs.cornell.edu/smallruminantparasites/chemical-treatment-protocols/.
Because the life cycle of the meningeal worm includes a period of larval development in a land snail or slug, ensuring your herd or flock does not have access to wet pasture areas that snails and slugs frequent can help protect your animals. You can also use various measures to deter deer from sharing your pastures. Some examples include deer-proof fencing and the use of guardian dogs.
Overview of Non-Parasite Diseases
Click a disease for a description and information on treatment and prevention.