Mycobacterium aviumssp.paratuberculosisHigh Shedding in an Adult Female Alpaca, and its Implications for the Rest of the Herd

Abstract

A 6-year-old female alpaca (case 1) was examined at the George D. Widener Hospital for Large Animals of the University of Pennsylvania for evaluation of lethargy, diarrhea, and weight loss of 3 months’ duration. A diagnosis of Mycoplasma haemolamae had initially been made by the referring veterinarian based on blood smear examination findings. The animal was treated with a long-acting form of oxytetracyline (10mg/kg SQ q24h) for 10 days but its clinical signs failed to improve. Serial fecal floatations performed before referral showed no parasite ova. Additional treatments received before referral included ivermectin, fenbendazole, B vitamins, injectable iron, procaine penicillin, oral sulfadimethoxine, and oral electrolytes. As the diarrhea and weight loss persisted, the alpaca was referred for further evaluation. The animal was pregnant (approximately 155 days gestation) at the time of presentation. The animal was from a herd of 78 alpacas, and was pastured with a group of pregnant females and young animals. Routine vaccinations on the farm included rabies, Clostridium perfringens Types C and D, and tetanus. On presentation, the alpaca was quiet but responsive and in poor body condition (body condition score 3/10), weighing 60 kg. Rectal temperature, heart rate, and respiratory rate were 98.21F, 56 beats per minute, and 20 breaths per minute, respectively. The alpaca appeared well hydrated with pale mucous membranes. It had green, watery feces, and a poor appetite. Initial laboratory abnormalities included mild nonregenerative anemia (PCV, 23%; reference interval, 25–46%), hypoproteinemia (total protein, 4.2 g/dL; reference interval, 4.6–6.9 g/dL), hypoalbuminemia (albumin, 1.40 g/dL; reference interval, 2.50–4.20 g/dL), and azotemia (serum creatinine concentration, 2.28mg/dL; reference interval, 0.6–1.80mg/dL). Blood smear examination was negative for Mycoplasma haemolamae organisms. Feces were submitted for fecal floatation, Mycobacterium avium spp. paratuberculosis (MAP) RT-PCR, acid-fast staining for Cryptosporidium, fecal occult blood, and bacterial cultures. Blood was submitted for MAP antibody detection with ELISA.No parasite ova were observed on fecal floatation, and the acid-fast staining was negative forCryptosporidium organisms. The occult blood test result was negative. Fecal bacterial cultures were negative for Salmonella spp. and Clostridium spp. Fetal and abdominal ultrasound examinations were performed. The sonographic appearance of the visible gastrointestinal structures was within normal limits. Fetal sonographic evaluation detected an irregular heart rate, suggestive of fetal distress. Additional diagnostic tests performed during the hospital stay included determination of serum trace mineral concentrations (Cu, Fe, Se, and Zn), fecal coronavirus detection with electron microscopy, and bovine viral diarrhea (BVD) testing by PCR on the buffy coat. Serum trace mineral concentrations were within the reference range. Results of coronavirus and BVD tests later returned negative. The patient remained hospitalized for 5 days while awaiting diagnostic test results. During that time, supportive care in the form of IV fluids (Normosol-R, 1.5mL/kg/h) and partial parenteral nutrition (1.5mL/ kg/h) were administered. Ranitidine (1.5mg/kg IV q8h) was also administered for prevention of 3rd compartment ulceration. RT-PCR results for MAP detection identified a strong positive result with duplicate values of 17.43 and 17.79 cycles to positive threshold (CT). Because of the animal’s advanced clinical signs and potential risk to the rest of the herd, permission was obtained for euthanasia. The alpaca was euthanized by administration of a barbiturate overdose and a postmortem examination performed. From the Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA (Fecteau, Ross, Tennent-Brown, Habecker, Sweeney, Whitlock); and the Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St Paul, MN (Sreevatsan). Dr Ross is presently affiliated with the Department for Environment, Food and Rural Affairs, Nobel House, 17 Smith Square, London SW1P 3JR, UK. Dr Tennent-Brown is presently affiliated with the Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA. This work was performed at the Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA. Corresponding author: Dr Marie-Eve Fecteau, Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, New Bolton Center, 382 West Street Road, Kennett Square, PA 19348; e-mail: mfecteau@vet.upenn.edu. Submitted June 16, 2009; Revised August 19, 2009; Accepted August 19, 2009. Copyright r 2009 by the American College of Veterinary Internal Medicine 10.1111/j.1939-1676.2009.0401.x Abbreviations: