This fact sheet was developed by students enrolled in Purdue's ANSC 442 Sheep Management course in Spring 2007, as a semester project. These fact sheets provide useful information on various topics related to sheep. View the list of fact sheets.


*COMMON PROBLEMS IN SHEEP*

Bloat

BloatThere are two types of bloat. One type is known as frothy bloat and sometimes commonly referred to as pasture bloat. Another type is known as gas bloat and is sometimes referred to as feed lot bloat. Bloat is normally caused by nutrition problems, such as increased pressure in the rumen due to too many gases being built up. These gases could include carbon dioxide (CO2) and methane gas (CH4). Prevention is the best method in controlling this disease. One method is providing constant grazing instead of feast and famine, as long as the pasture doesn't contain a lot of legumes, which can cause bloat easily. The symptoms of bloat can include the skin on the left side of the animal behind the last rib may appear distended (see picture). Bloated sheep should be treated with great care, due to the condition of their body, and the possibilities of greater damage can occur. These can include collapsed lung due to pressure build-up, blood is pushed out of the body cavities, and can cause a type of acidosis. There are a few different options for treatment, depending on the time of diagnosis. You can use a stomach tube to release pressure of the gas, agitation of the rumen will also release trapped air bubbles, commercial anti-bloat medicines, and in severe cases a rumenotomy can be performed in life-or-death cases by puncturing a hole in the rumen, but will need to be sutured afterwards.


Bluetongue

BluetongueBluetongue is an insect-transmitted disease that is transmitted by biting gnats. It is a viral disease, and other animals cannot directly contract the disease from infected animals. This disease affects domestic ruminants such as sheep, cattle, goats, as well as wild ruminants. These wild ruminants serve as the reservoir for the virus. It is reported that this virus killed 179,000 sheep in 4 months, so it has affected the industry tremendously. Bluetongue is very prevalent in Southwest and Southern parts of the United States . Symptoms of the disease include inflammation, swelling, and hemorrhage of the mucous membranes of the mouth, nose, and tongue. Sheep show clinical signs, where as other domestic ruminants rarely show clinical signs of the disease. There are no known prevention methods. Veterinarians are more aware of the disease and look for symptoms and clinical diseases when doing herd checks. There are two types of viral antigens for bluetongue virus testing. This testing is not very accurate due to low numbers of antibodies correlated to bluetongue viremia. Virus isolation from blood samples is the only soundproof method of detection. There is a vaccine to help with treatment, but only certain serotypes are available with a vaccine. The vaccine comes with adverse side effects and you cannot use the vaccine on pregnant ewes.


Copper Toxicity

Copper toxicity is a big concern for sheep, because it is a required mineral but is also toxic to them as well. This can vary based on breed, age, health status, levels of other minerals in body and in diet, and levels of ionophores in the diet. Copper is found in the feeding supplement for cattle and swine diet. If mixed with or fed to sheep, it can have drastic effects. There are two types of copper toxicosis; acute and chronic. Acute is when a high level is ingested in a short period of time. Chronic is when a low level is ingested over a long period of time, and exceeds the threshold level and escapes into the bloodstream. Excess copper is stored in the liver. Eventually hemolytic crisis occurs due to the destruction of red blood cells. Prevention is key in this disease. There are several key factors in prevention which include no feeding swine or poultry diets to sheep, communicating with your feed suppliers, testing your feed for levels of copper, molybdenum and sulfate, avoidance of pasture that has been treated with swine or poultry manure, and doing post-mortems on dead animals from your flock. The major symptom of copper toxicity is death in your herd. But symptoms may include animals go off feed and become weak, mucous membranes and skin are yellowish-brown, and/or urine will be reddish-brown and hemoglobin will be present. Treatment should involve your veterinarian. Treatment includes feeding or drenching with ammonium molybdenum, sodium sulfate, and penicillamine.

Copper Toxicity

McDill, Lisa. "Bluetongue Virus". Animal Disease Diagnostic Laboratory. 2001. Purdue University . 27 Feb. 2007
http://www.addl.purdue.edu/newsletters/2002/spring/bluetongue.shtml

Neary, Michael. " Preventing Pasture Bloat in Sheep". Purdue University Sheep Extension. 1997. Purdue University . 27 Feb. 2007.
http://ag.ansc.purdue.edu/sheep/articles/pasbloat.html

Schoenian, Susan. "Sheep Diseases A-Z." Sheep 201; A Beginner's Guide to Raising Sheep. 26 Sept. 2006. Maryland Cooperative Extension. 6 Feb. 2007
http://www.sheep101.info/201/diseasesa-z.html

 

Ovine Progressive Pneumonia

Ovine Progressive PneumoniaOvine Progressive Pneumonia, or OPP, is caused by a virus and is prominent in the United States . This type of virus is very similar to Maedi-Visna, a retrovirus found in different parts of the world. A study found that 26% of sheep in the United States are infected with OPP, but the prevalence of the virus is largely dependent on flock management, the strain of the virus, and the genetics/breed of sheep. In fact, sheep and goats seem to be the only species that can naturally contract the OPP virus. Breeds which have been found to be highly susceptible to the OPP virus in the United States include Border Leicester, Finnsheep, Finn-crosses, Corriedales, Dorsets , and North Country Cheviots. Texel sheep are only susceptible in Europe , and the Ile de France has even been shown to be resistant to infection and disease. This suggests a difference between the pathological potency of the OPP virus rather than just the genotype of the sheep.

Ovine Progressive PneumoniaTransmission of OPP is mainly by ingesting contaminated milk/colostrum, like if a lamb receives milk from an infected ewe. Respiratory fluids, like from coughing, can also be transmitted between closely confined sheep. Signs and symptoms of OPP can begin to be noticed around two years of age or older because the disease progresses very slowly. Unfortunately, once signs are spotted, it is often too late to fix the problem. Two common signs are weight loss and lethargy when required to exercise more than usual. Breathing becomes very laborious and difficult for the sheep. OPP can be diagnosed by the presence of the virus or antibodies in the blood. A perfect diagnosis can only be made during necropsy, where the lung is covered in large lesions and discolored to grayish-blue. There are currently two different tests that can be used to detect the virus in live animals: Agar Gel Immunodiffusion Test (AGID) or the Enzyme Linked Immunosorbent Assay (ELISA) test. AGID is able to detect circulating antibodies in the blood, but it should only be tested after six months of age, once the colostrum-derived antibodies are no longer present. The ELISA test is more sensitive than AGID as it can detect OPP only two weeks after infection. There is no treatment for such a virus. There are, however, two methods to prevent future exposure of OPP. One method of prevention would be to remove lambs from infected mothers before they have the chance to nurse from them. This is the start of an OPP-free flock and should never come in contact with infected sheep. The second method would be to test and remove all infected sheep and lambs that test positive for OPP.


*More information on OPP and the Maedi visna virus:
http://www.extension.umn.edu/distribution/livestocksystems/DI5750.html
This information was used with permission from: Neil Anderson, Copyright Coordinator, University of Minnesota Extension

Pictures were used with permission from: Dr. Paula I. Menzies , Associate Professor, Department of Population Medicine, Ontario Veterinary College pmenzies@uoguelph.ca

 

Scrapie

ScrapieScrapie is a disease that severely affects the nervous system of sheeps and goats. This disease is fatal and degenerative. It is just one of the several diseases classified under the transmissible spongiform encephalopathies (TSE) and can cause significant production losses in a flock. Scrapie can be spread when female animals are sold from infected flocks to other flocks. Because of this hazard, the export of breeding stock, semen, and embryos to other countries is prohibited. Scrapie is caused by a minuscule virus that has not been completely characterized. So far, we know that disease is caused by a prion, or an abnormal form of a cellular protein. Also, the cause, or agent, is a virus with unusual characteristics. Finally, the agent is a virino, a tiny piece of DNA that acts like a virus. Unfortunately, the scrapie agent is unaffected by heat and sterilization processes. There is also no detectable immune response in sheep and goats.

ScrapieScrapie is mainly spread from a mother to her offspring or through contact with placental fluids. Signs of the disease usually do not appear until 2-5 years after the animal is infected, and by then death is inevitable. These signs and symptoms mainly include behavioral changes, tremors, rubbing, and uncoordinated movements due to the damage of nerve cells. An infected animal may not show signs until stimulated by noise or excessive movement, in which then they tend to tremble and fall down. The signs can be confused with the symptoms of other diseases such as ovine progressive pneumonia (OPP), rabies, and toxins.

Due to the large concern of scrapie, an eradication program has been initiated by USDA. This program includes testing animals for scrapie, following genetic lines of scrapie-infected sheep, and how to preserve breeding stock if there is a disease breakout.


*Want more information? Check out this website:
http://www.aphis.usda.gov/lpa/pubs/fsheet_faq_notice/fs_ahscrapie.html

Pictures and information were used with permission from Diane L. Sutton, National Scrapie Program Coordinator, National Center for Animal Health Programs USDA, APHIS, VS. E-mail: Diane.L.Sutton@aphis.usda.gov

 

Tetanus **

TetanusTetanus is a common, fatal disease in sheep and goats caused by a bacterium known as Clostridium tetani. The spores of this bacterium can be found in feces, they produce a powerful toxin in open wounds, and are not affected or destroyed by disinfectants. Most often, tetanus is caused by infection of an open wound. Because sheep undergo several maintenance procedures, such as castration, ear-marking, tail-docking, dehorning and debudding, sheep are highly at risk for contracting tetanus. Dog bites or deep scratches can also be "homes" for the bacteria. Incubation of Clostridium tetani is between 3 days and 3 weeks. During this time, the bacteria multiply and generate this powerful toxin. This toxin then affects the nerves around the site of injury/wound, travels to the spinal cord and brain, and ultimately causes uncontrollable muscle spasms. Consequently, signs and symptoms of tetanus infection include muscle stiffness and spasms, bloat, panic, uncoordinated walking and movements, and/or the inability to eat and drink. Death is inevitable, about 3-4 days after symptoms appear. Many sheep in a flock can be found dead without having shown any signs of the disease.

Thankfully, the risk of contracting tetanus can be prevented through cleanliness and vaccinations, such as tetanus anti-toxin and penicillin. Treatment, once the animal is already sick, can be very expensive and not very effective; this is why prevention is extremely important. The correct vaccinations are given twice around 4 weeks apart. An annual booster is recommended. A single vaccine will do little to build long lasting immunity in the lamb; therefore, it is important that the animal is fully vaccinated and protected before any type of surgical procedure.

For more information, please see the following website by Ross Newman: http://www2.dpi.qld.gov.au/sheep/8584.html

** If this information is to be used for any other purpose, please contact Dr. Mike Neary (mneary@purdue.edu) and the Department of Primary Industries and Fisheries, GPO Box 46, BRISBANE QUEENSLAND AUSTRALIA 4001, Ph: 61 (0)7 3239 3116 , Fax: 61 (0)7 3239 3504

Information was referenced from "Livestock Health: Tetanus in sheep and goats" by Ross Newman, DPI&F (http://www2.dpi.qld.gov.au/sheep/8584.html).

Information for this Educational Fact Sheet has been used with permission from: Dr Allen Hibberd, Project Officer - Information and Communication Services, Department of Primary Industries and Fisheries, Brisbane Queensland Australia; e-mail: allen.hibberd@dpi.qld.gov.

 

Ovine Infectious Keratoconjunctivitis:

Ovine Infectious Keratoconjunctivitis, or OIKC, has the common name Pink Eye. This disease affects sheep of all ages, but is more prominent in ewes than in lambs and lasts approximately three weeks. The causes of the disease are the organisms Chlamydia psittaci and Mycoplasma conjunctiviae. Many other bacteria may also be involved in a secondary role of causing the disease. The disease spreads rapidly when sheep are in close contact and because of this there is high incidence during winter months. Sheep that appear to have recovered from the disease may still carry the causative organisms for several months and may be a source of re-infection of other animals. The first symptom of the disease is tear staining from the corner of one or both eyes. As the disease continues the cornea of the eye becomes cloudy and blood vessels can be seen clearly at the edges of the eye. There is some discharge from the corners of the eyes that becomes thicker and pus-like as the disease worsens. When both eyes are severely affected sheep may become temporarily blind. In most cases with treatment, healing will occur over several weeks, eventually leaving only a slight corneal scar. Treatment involves using the topical application of aureomycin as an ointment to the corners of the eye along with use of antibiotics. Prevention of this disease would involve carefully monitoring sheep that are being kept in close contact with other sheep. There is no vaccination for this disease.

Sheep with healthy eye

A sheep with a healthy eye

Source: Pagie Leffel

A sheep with Ovine Infectious Keratoconjunctivitis or Pink Eye

Source:Neil Sargison, Nadis
(www.nadis.org.uk/pinkeye_1.html)

Sheep with Ovine Infectious Keratoconjunctivitis or Pink Eye

*More information on Ovine Infectious Keratoconjunctivitis available at:
http://www.nadis.org.uk/Pink%20Eye%20in%20Sheep/PINKEY_1.HTM

Information was referenced from Neil Sargison, Nadis (http://www.nadis.org.uk/Pink%20Eye%20in%20Sheep/PINKEY_1.HTM).

 

Flystrike

Flystrike is the infestation of living tissue with blowfly maggots. Sheep are the most commonly affected species out of all domestic livestock. Flystrike primarily affects wool breeds because it is the dirty wool that attracts the blowflies. Wounds, foot rot, and sweat are other factors that may attract blowflies and increase the incidence of flystrike. The Southwest of England and Australia have annual occurrences of blowfly strike due to the warm and humid summer weather. In the first stage of the disease, the larvae penetrate through the wool into the skin of the sheep and secrete enzymes that liquefy the tissue. As the larvae develop, they cause secondary bacterial infection and attract other blowflies to the wound. It is the toxins sent by the animal's own decomposing tissue that cause death in the animal. Flystrike is a preventable disease and can be prevented by any of the following methods: Shearing regularly before summer, docking tails, removing dags which are sections of wool containing feces, and using insecticides. Insecticide application can be in the form of plunge dipping, hand jetting, pour-ons, or vaccination. Treatment of flystrike should be done immediately by clipping only access to the wound (to prevent sunburn) and applying insecticidal organophosphate. Massaging the wound may be necessary to make sure the insecticide gets to the infected tissue.

A sheep infested with blowfly maggots in the first stage

 

Source: Neil Sargison, Nadis
(http://www.nadis.org.uk/Fly%20Strike/FLYSTR_1.HTM)

A sheep infested with blowfly maggots in the first stage

 

 


*Want more information on Flystrike? Check this out:
http://www.nadis.org.uk/Fly%20Strike/FLYSTR_1.HTM
www.sheep101.info/201/diseasesa-z.html

Information was referenced from Neil Sargison, Nadis (http://www.nadis.org.uk/Fly%20Strike/FLYSTR_1.HTM) and www.sheep101.info/201/diseasesa-z.html.

 

Lactic Acidosis

Lactic acidosis has the common names ruminal acidosis, grain overload, carbohydrate engorgement, rumen impaction, and grain poisoning. Lactic acidosis is an acute disease caused by excess consumption of concentrates or grain, that are high in carbohydrates.. Ingestion of toxic amounts of highly fermentable carbohydrates is followed by a two to six hour change in the microbial population within the rumen. The bacteria Streptococcus bovis increases which results in the overproduction of large quantities of lactic acid. (p. 178-179, Merck) The symptoms are that the animal will act restless and depressed. The animal may appear to have abdominal pain of various strengths, indigestion, dehydration, and incoordination. Prevention of this disease is to keep proper feeding management practices. Feeds, especially grains high in carbohydrates, must be switched gradually to allow the rumen microbes to adjust properly. The treatment includes drenching affected animals with antacids such as carmalax, bicarbonate soda, or products containing magnesium carbonate or magnesium hydroxide.

*Want more information on Lactic Acidosis? Check out:
www.sheep101.info/201/diseasesa-z.html

Information was referenced from www.sheep101.info/201/diseasesa-z.html.

 


Information Summarized by:

ANSC 442 Spring 2007
Paige Leffel
Nicole Schmelz
Christine Johnson