Joe S. Smith and Amanda J. Kreuder Despite their worldwide population and agricultural importance, sheep and goats are minor species within North America, and many veterinarians will have had limited exposure to them. In the United States, Canada, the European Union, and worldwide, there are few licensed veterinary pharmaceutical products available for sheep and goats. For example, in the United States there are nine antimicrobials labeled for sheep and only five labeled for goats (only one of which is parenteral). Most of these approved products are for feed‐ or water‐based formulations. Furthermore, sheep and goats are classed as separate species by the regulatory authorities in most countries. This means that approved drugs are specifically licensed and withdrawal times and tolerances/maximum residue limits (MRLs) have been set for each species. This situation creates a great deal of confusion for veterinarians as well as sheep and goat producers. Journal articles, textbooks, and the internet provide accessible information from clinical trials and dose regimens for a wide variety of antimicrobials that are not licensed in small ruminants. In many cases, the safety and efficacy of the drug are well documented and if the antimicrobial product is commercially available, it may not be licensed for sheep or goats. Despite their similarities as ruminant species, the pharmacokinetics of antimicrobial drugs in sheep and goats can vary when compared to cattle, and can also vary when compared from sheep to goats. With this in mind, sheep and goats are not simply “small cows”; they react differently to certain medications and suffer from different diseases. Prudent antimicrobial use first requires a tentative diagnosis ideally followed by confirmation of the etiological agent by microbiological culture and antimicrobial susceptibility testing before commencing therapy. However, collection of samples from sheep and goats is not always feasible and even if samples are obtained, results usually take at least 2–3 days to process, and currently there are no species‐specific breakpoints for sheep and goats. Thus, empirical therapy is common and should be determined by a thorough physical examination and a presumptive diagnosis, knowledge of the most common pathogens, the expected antimicrobial susceptibility of those organisms, and the pharmacokinetics/pharmacodynamics of the antimicrobial in the species being treated. Table 31.1 contains information to help make these decisions. Table 31.1 Antimicrobial drug selection for common conditions of sheep and goats.
31
Antimicrobial Therapy in Sheep and Goats
General Recommendations
Condition
Species affected
Etiological agent(s)
Recommended treatment
Comments
Infectious abortion
Enzootic abortion of ewes (EAE)/ovine enzootic abortion (OEA)
Sheep and goats
Chlamydophila abortus
Tetracycline
Oxytetracycline
Tylosin
Prophylaxis in high‐risk flocks: tetracycline in feed for 6–8 weeks prior to breeding at a dose of 200–400 mg/head/day until lambed.
Outbreak: 400–500 mg/head/day tetracycline in feed until lambing finished. Poor efficacy if placental damage already present.
Not recommended for dairy goats because of milk withdrawal. Vaccination or biosecurity should be considered.
Outbreak or previous diagnosis: long‐acting oxytetracycline at label dosage starting 6–8 weeks before start of lambing every 10–14 days until finished.
Campylobacter spp. abortion (vibrionic)
Sheep
C. jejuni
C. fetus subsp. fetus
Penicillin G‐streptomycin; tetracycline
Oxytetracycline (resistance commonly reported)
Tylosin
Sulfamethazine
Prophylaxis: injections of penicillin‐streptomycin for 2–5 days. Antimicrobial susceptibility patterns should be established from any isolates. Vaccination in the face of an outbreak also very successful.
A tetracycline‐resistant clone of C. jejuni exists in the United States
Listeria abortion
Sheep and goats
L. monocytogenes
Oxytetracycline
Injectable long‐acting tetracycline to all animals at risk in the face of an outbreak.
Toxoplasma abortion
Sheep and goats
T. gondii
Monensin
Decoquinate
Mixed in feed at a dose of 15 mg/head/day from breeding to lambing.
Mixed in feed or premix to feed at a dose of 2 mg/kg/day for last 14 weeks of gestation.
Use of feed‐grade drugs for this purpose may be prohibited in some regions.
Salmonella abortion
Sheep and goats
S. typhimurium, S. abortus ovis, S. montevideo, S. dublin
IM or SC broad‐spectrum antimicrobials
Often widespread by the time diagnosis is made. Requires culture and susceptibility testing. Antimicrobials may not eliminate organism; consider culling and environmental management.
Leptospira abortion
Sheep and goats
L. hardjo, L. pomona
Penicillin G‐streptomycin; tetracyclines
Treat all pregnant animals at risk with injections.
Other infectious reproductive disorders
Metritis
Sheep and goats
Trueperella pyogenes, E. coli, mixed anaerobes including Clostridium spp.
Penicillin G; ceftiofur; broad‐spectrum antimicrobials
Treat for 3–4 days after clinically normal. Uterine evacuation with prostaglandins and tetanus vaccination should also be considered.
Lamb epididymitis
Sheep
H. somni, A. seminis, Corynebacterium pseudotuberculosis
Oxytetracycline
Prophylaxis: low levels in feed in situations where rams intensively managed, or injectable long‐acting oxytetracycline (IM or SC). Responds poorly to treatment.
Enzootic posthitis
Sheep and goats
C. renale group
Penicillin G; oxytetracycline
Remove from high‐protein diet and treat locally with antimicrobial ointments. May treat systemically for severe cases.
Brucella ovis ram epididymitis
Sheep
Brucella ovis
Oxytetracycline with dihydrostreptmycin
20 mg/kg oxytetracycline at 3‐day intervals for 5 treatments and 12.5 mg/kg dihydrostreptomycin 2×/day for 7 days decreases shedding of bacteria and improves semen quality but may not cure. Should consider culling.
Infectious diseases of lambs and kids, systemic
Enterotoxemia/pulpy kidney
Sheep and goats
C. perfringens type C and D
Oral virginiamycin, penicillin G, or bacitracin
Vaccinate all animals at risk. Withdraw carbohydrate source in diet, give C&D antitoxin and a balanced electrolyte solution (BES) parenterally.
Omphalophlebitis
Sheep and goats
T. pyogenes, E. coli, mixed anaerobes
Penicillin G; broad‐spectrum antimicrobials
Antimicrobial therapy alone not often effective. Local drainage, treatment with chlorhexidine or iodine, and possibly surgical removal should be considered.
Watery mouth (lambs)
Sheep
Probable E. coli endotoxin
Oral amoxicillin; apramycin
Prevention by ensuring clean environment and good colostrum ingestion. Early prophylactic treatment with oral antimicrobials.
Tick‐borne fever (tick pyemia)
Sheep
Anaplasma phagocytophilum and/or S. aureus
Long‐acting oxytetracycline
At 1–3 weeks of age and repeated at 5–7 weeks, in addition to dipping with an acaricide at those times.
Erysipelothrix polyarthritis
Sheep
E. rhusiopathiae
Penicillin G
Treat minimum of 3 days.
Infectious diseases of lambs and kids, digestive
Colibacillosis
Sheep and goats
Enterotoxigenic E. coli
Broad‐spectrum antimicrobials parenterally
Appropriate diagnosis is necessary (culture and susceptibility testing). Clean environment and adequate colostrum are important. Consider vaccination. Resistance to antimicrobials is common.
Salmonella dysentery
Sheep and goats
S. typhimurium and others
Broad‐spectrum antimicrobials
Often poor efficacy due to unpredictable susceptibility patterns. May not eliminate carriers if host‐adapted species. Risk of resistance development.
Abomasitis/abomasal hemorrhage
Sheep and goats
Clostridium spp.
Oral and systemic penicillins
Rarely effective. Should treat symptomatically with antitoxins, nonsteroidal antiinflammatory drugs, and BES. Use polyvalent clostridial vaccine.
Coccidiosis
Sheep and goats
Eimeria spp.
Monensin; lasalocid; decoquinate; salinomycin; amprolium; toltrazuril or sulfonamides
Mixing should be done at a feed mill and all feeds pelleted. Some products can be mixed with salt. Dose varies with feed management. Artificially raised lambs/kids can be medicated via milk replacer. Feed from 2 weeks of age until market age. Ionophores toxic to horses and dogs. Additional regulations may be present in some countries with feed‐grade drugs.
Infectious conditions of lambs and kids, respiratory
Pneumonic pasteurellosis
Sheep and goats
M. haemolytica, P. multocida
Tilmicosin; oxytetracycline; ceftiofur; florfenicol; tulathromycin
Long‐acting oxytetracycline, tilmicosin, or florfenicol can be used as prophylaxis and during an outbreak therapeutically. Tilmicosin should not be used in goats (therapeutic dose very close to toxic dose). Ceftiofur for daily treatment of affected animals when meat or milk withdrawal is an issue (e.g., market lambs close to slaughter, lactating dairy sheep). Tulathromycin can be used but will have longer meat or milk withdrawal recommendations.
Pasteurella septicemia
Sheep
Bibersteinia trehalosi
As with M. haemolytica
B. trehalosi will show artifactual resistance, due to no established breakpoints, and because the disease is peracute, vaccination is recommended for susceptible animals.
Necrotic laryngitis
Sheep and goats
Fusobacterium necrophorum
Penicillin G; oxytetracycline
Mycoplasma pneumonia
Sheep and goats
M. ovipneumoniae, M. arginini
Oxytetracycline; tylosin
Often seen in conjunction with pasteurellosis (atypical pneumonia) or alone.
Mycoplasma mycoides
Goats
M. mycoides subsp. mycoides large colony type
Oxytetracycline; lincomycin; tylosin
Treatment of peracute septicemia often ineffective. If goat survives, it will probably be a carrier.
Infectious conditions of the integument
Infectious keratoconjunctivitis (Mycoplasma)
Sheep and goats
M. conjunctivae
Spiramycin; oxytetracycline; tylosin, chlortetracycline, streptomycin; tulathromycin; tiamulin
Spiramycin or oxytetracycline repeated days 1, 5, and 10; tiamulin repeated days 1, 3, 6, and 9. Oxytetracycline eye ointment, either alone or with polymyxin B. NSAIDs typically required to decrease inflammation.
Chlamydophila keratoconjunctivitis
Sheep and goats
C. abortus and C. percorum
Spiramycin; oxytetracycline; tylosin, chlortetracycline, streptomycin; tulathromycin; tiamulin
Parenteral antimicrobials should be considered for lambs, due to concerns of polyarthritis. Treatment principles are similar to those for Mycoplasma keratoconjunctivitis.
Moraxella ovis keratoconjunctivitis
Sheep and goats
Moraxella ovis (formerly Branhamella ovis) may be opportunistic to M. conjunctivae or C. pecorum infections
Florfenicol; oxytetracycline; ampicillin; ceftiofur
Some isolates are resistant to oxytetracycline and penicillin. Topical therapies could be considered.
Secondary infection of contagious ecthyma (orf)
Sheep and goats
S. aureus
Tilmicosin; oxytetracycline; ampicillin
May also try local antimicrobials but wear gloves, as zoonosis is a concern.
Dermatomycosis (streptothricosis, lumpy wool, rain scald, rain rot)
Sheep
Dermatophilus congolensis
Long‐acting oxytetracycline; procaine pencillins G; ceftiofur
Decrease humidity (ventilation) if possible, and protect from rain. Topical treatment includes lime sulfur, iodophors, copper sulfate, zinc sulfate, and potassium aluminum sulfate.
Causative organism is thought to be susceptible to sulfonamides, bacitracin, and polymyxin B.
Caseous lymphadenitis
Sheep and goats
Corynebacterium pseudotuberculosis
No generally effective treatment. Tulathromycin and penicillin have been used
Although susceptible to penicillin and tulathromycin, treatment may not be effective because of the thick abscess wall. Techniques for abscess flushing and lavage have been described but risk introducing contaminated material into the environment. Recommend cull infected animals and avoid opening abscesses as it spreads the pathogen.
Infectious conditions of the foot and musculoskeletal system
Infectious/contagious pododermatitis (foot rot)
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