Small ruminant joint disorders

Infectious arthritis

Chlamydial polyarthritis

Chlamydial polyarthritis is a common contagious disease of feedlot lambs and likely occurs in goats, as well. Disease occurs in 1- to 8-month-old lambs, with 3- to 5-month-old lambs most commonly affected. In feedlots, outbreaks often occur a few weeks after lambs are introduced. Animals are febrile and reluctant to move. Multiple joints may be swollen. Chlamydial conjunctivitis can be seen simultaneously. Joint cytology may show elementary inclusion bodies. ELISA and PCR testing is confirmatory.  Morbidity can be as high as 80% but mortality is very low; most cases resolve without treatment in 10-14 days. Antibiotic therapy (erythromycin, tylosin, tetracycline) will speed recovery.

Mycoplasmal arthritis

Mycoplasmal arthritis is a highly fatal disease of goats. Affected animals show signs of  polyarthritis, septicemia, and mastitis. In the United States, most outbreaks are in large goat dairies. Morbidity and mortality rates as high as 90% have been reported in kids. The organism is usually introduced to the farm by an asymptomatic shedder. Antibiotic treatment does not usually resolve the infection. Prevent the disorder by feeding only pasteurized milk to goat kids. Sheep can also get mycoplasmal arthritis.

Caprine arthritis – encephalitis virus infection

Infection with caprine arthritis – encephalitis virus (CAEV )is widespread and chronic polyarthritis is the most common finding. Most infection is transmitted from doe to kid through the milk. Venereal disease and horizontal transmission are possible. Four clinical syndromes have been described for CAEV-infected goats: arthritis, leukoencephalomyelitis, interstitial pneumonia, and mastitis. Most animals are asymptomatic but are infected for life. Chronic progressive arthritis is seen in goats older than 6 months and is usually characterized by swelling of one or both carpal joints. Arthritis may affect other joints but it usually not detected.  Signs may wax and wane initially. Some animals deteriorate over a few years while others remain stable for much longer. Combining ELISA and PCR with repeated testing is the best way to detect positive animals. No treatment is available. Ovine progressive pneumonia is a similar disease in sheep that only occasionally affects joints.

NOTE: we often associate CAE with goats walking on their knees. This may be true (but would be weird) or may be association vs causation. For instance, maybe older goats are more likely to be both CAE+ and to have foot issues but these could be separate events. In older humans, we can have both arthritis and memory loss but we don’t claim that memory loss causes joint stiffness.

Lyme disease

Lyme disease (Borrelia burgdorferi) does affect deer, sheep and occasionally goats. Testing is challenging. Sheep seem to be able to avoid systemic infection but can enable tick to tick transmission. A typical treatment regimen is a 2- to 4-week course of oxytetracycline, ceftiofur, or penicillin. Prevention of the disease currently relies on tick elimination.

Erysipelothrix polyarthritis

Erysipelothrix polyarthritis is typically seen in 2- to 6-month-old lambs but it can also cause neonatal joint infections. Outbreaks may affect as many as 40% of the lambs in a flock. Animals present with fever and lameness but minimal joint swelling. Erysipelothrix polyarthritis will progress to chronic arthritis if not treated appropriately.

Septic arthritis

Septic arthritis is typically due to hematogenous spread in neonates (16% had an umbilical infection) and due to trauma in adults. Infections due to trauma are treated like they are in other species – joint lavage and antibiotics. In neonates, the entire animal needs treatment due to the septicemia and the inciting cause also needs to be treated (the umbilical infection, etc). Joint flushes are still needed, as well.

Degenerative osteoarthritis

Degenerative osteoarthritis is relatively common in older animals and can be exacerbated by CAEV.  Elbow OA seems to be particularly prevalent. Elbow joints will not have much effusion but will have decreased range of motion. Animals may have a stiff gait and many have overgrown feet. Disease is usually advanced by the time of diagnosis. Treatment is focused on NSAIDs but can include joint protectants and surgical arthrodesis.

Physitis and osteochondrosis are found in rapidly growing animals.

Congenital disorders

• Spider lamb syndrome/ Hereditary chondrodysplasia
  • Suffolk and Hampshire breeds are at greatest risk for this inherited condition that leads to stunted crooked legs
  • Chondrodysplasia may be seen at birth or develop within the first 6 weeks of life
  • Caused by a mutation in the fibroblast growth factor receptor 3; testing is now available
  • UC Davis spider lamb information and testing
  • A similar condition is found in beef cattle with hypomagnesemia

Kaltura version w/ captions: Spider Lamb Syndrome

• Arthrogryposis
  • congenital fixation  (contracture) of multiple joints associated with a variety of teratogens
  • inherited arthrogryposis has been reported in Suffolk and Corriedale sheep. Autosomal recessive mutation.
  • also caused by Schmallenberg virus
  • See this article for more images:
    Congenital arthrogryposis: An inherited limb deformity in pedigree Suffolk lambs
    • July 2000; The Veterinary record 146(26):748-53
• Patellar luxation
  • Affected animals will crouch due to inability to straighten the hindlimbs
  • differential – femoral nerve injury due to dystocia (rare in small ruminants)
  • genetic predisposition?
  • may not ingest colostrum due to inability to stand and nurse
  • surgical imbrication +/- trochleoplasty
• Flexural deformities
  • treat as for foals with oxytetracycline and bandaging
  • if surgery is needed, just cut the flexor tendons versus cutting the check ligaments
  • most are congenital