Hooo-Hooo Volume 11 Nr 1 - Page 13

South Africa. Ante-mortem diagnosis is very difficult. Intradermal tuberculin testing is unreliable in rhinos. Tracheobronchial and gastric lavage samples can be used for mycobacterial culture. Serology appears promising and there are some commercial kits available (Chembio VetTB DPP). Research on experimental cytokine assays is underway. Most diagnoses are made post-mortem, however. Paratuberculosis (M. avium subsp. paratuberculosis) – This has been diagnosed in a single captive black rhino. The animal had a 4 month history of diarrhoea and weight loss. M. avium subsp. paratuberculosis was isolated from a faecal culture. The rhino was treated with anti-mycobacterial drugs and clinically resolved. Leptospirosis – This is a zoonotic disease with worldwide distribution. Leptospirosis is caused by one of more than 250 pathogenic serovars of Leptospira. Rodents are the maintenance hosts. Antibodies have been reported in wild black and white rhinos in range countries. Urine-contaminated feed is the source of infection. Transmission occurs through contact of the bacteria with mucous membranes or damaged skin. Leptospires can colonize the liver, kidneys, lungs, genital tract, and CNS. Clinical signs are variable; acute, systemic febrile disease with renal and/or hepatic damage has been reported in black rhinos; uveitis, haemolytic anaemia, muscle pain, and abortion/stillbirth may also occur. Leptospirosis can be confirmed by identifying bacteria in blood, urine or tissues using immunofluorescence, PCR, or culture; however, it is more commonly diagnosed by elevated antibody titres using a microagglutination test. A 4-fold increase in serum samples taken 7-10 days apart or a single titre>1:800-1600 with compatible clinical signs are common criteria. Prevention includes good rodent control and vaccination using a polyvalent inactivated vaccine. Clostridial diseases – C. septicum: Malignant oedema occurs when there is bacterial contamination of wounds with local toxins causing severe oedema and necrosis. This disease may be a concern for rhinos if there is fighting, transport, or other wounds. C. tetani: There are rare cases of tetanus in rhinos associated with spore-contaminated wounds. Clinical signs are similar to those in domestic animals. Equine tetanus vaccine has been used in captive rhinos. C. sordelli: There has been a fatal outbreak in white and black rhinos under semi-intensive management. Presented with peracute sig ns; typically animals would collapse and progress rapidly to death. On post- mortem, haemorrhagic enterocolitis was evident. A vaccine has been developed. C. perfringens (Enterotoxaemia): This has resulted in 9 black rhino mortalities in Kenya, as well as morbidity in captive black and white rhinos. Clinical signs are often peracute with severe abdominal pain, laboured breathing, and death within hours. Severe necrotizing haemorrhagic enteritis is found at necropsy. Overgrowth of intestinal flora can be precipitated by change in diet, stress, and antibiotic treatment. Diagnosis of clostridial diseases usually requires anaerobic culture of gastric or small intestinal contents, or tissue (including wounds). There are PCR assays for toxin genes. A mouse bioassay can also be used to detect toxins. Histopathology provides supporting evidence. Treatment requires intensive supportive care and potential administration of antitoxin if diagnosed early. Prevention is the key and there are multivalent vaccines that have been used in rhinos. Streptococcal and Staphylococcal Infections – Beta- haemolytic Streptococcus has been isolated from skin lesions and wounds in rhinos; this may progress to septicaemia and death. It has also been linked to vegetative endocarditis, myocardial degeneration, meningoencephalitis, and Idiopathic Haemorrhagic Vasculopathy Syndrome in captive black rhinos. Methicillin-resistant Staphylococcus aureus (MRSA) has been isolated from chronic wounds on captive rhino feet (zoonotic threat). VIRAL DISEASES Encephalomyocarditis virus (EMCV) – Typically a peracute disease with signs consistent with cardiac failure. Non-suppurative myocarditis and pulmonary oedema found post-mortem. Survivors may have cardiac damage. Exposure is measured by antibody titres, with diagnosis confirmed using virus culture, 2017 MAY 13