Cerebrospinal Nematodiasis in 20 Camelids

Assessment of cerebrospinal fluid analysis and short-term survival outcomes in South American camelids: A retrospective study of 54 cases (2005-2021)

BACKGROUND

Cerebrospinal fluid (CSF) is commonly analyzed in South American camelids with suspected neurologic disease because of ease of collection and characteristic findings associated with certain diseases.

OBJECTIVES

To assess CSF findings associated with short-term survival or non-survival in South American camelids in which neurologic disease was a differential diagnosis based on history and physical examination.

ANIMALS

Twenty-one llamas and 33 alpacas that underwent CSF analysis at the University of Missouri Veterinary Health Center.

METHODS

Retrospective study. Medical records of camelids that underwent CSF analysis between January 2005 and September 2021 were studied. Short-term survival was defined as survival to discharge from the Veterinary Health Center. A Fisher's exact test was used to compare species, CSF results, and survival.

RESULTS

Odds of survival were 3.9 times higher in camelids with a total nucleated cell count (TNCC) <3 cells/μL (P = .04). No significant association was found between survival and total protein concentration (TPC; P = .15) or percentage of eosinophils (P = 1.0). No significant correlation was found between species and increased TNCC (P = .63), TPC (P = .55), or percentage of eosinophils (P = .30). Among camelids diagnosed with Paralephostrongylus tenuis infestation, odds of survival were 4.95 times higher in alpacas (P = .05).

CONCLUSIONS

Cerebrospinal fluid TNCC ≥3 cells/μL is associated with decreased odds of short-term survival in South American camelids.

First report about a cerebrospinal nematode infection in an alpaca (Vicugna pacos)

The number of New World camelids in European farms is rising and thus, the need for veterinary care towards these animals arises. However, veterinary care requires sophisticated knowledge on disease and pathogen occurrence within New World camelids. Here, an alpaca cria with neurological signs was admitted to the veterinary clinic. Although the animal was treated with antibiotics, vitamins and dexamethason, it refused to drink milk and the clinical status worsened. After euthanasia, necropsy and histopathological examination were carried out and revealed intracerebral nematode larvae. The morphology of these larvae strongly suggests them to be Baylisascaris procyonis, a parasite of raccoons. The extended history revealed that a fully grown raccoon was living within farm enclosures, suggesting an infection of the alpaca and the development of a cerebrospinal larva migrans. This zoonotic disease is characterized by aberrant larval migration that typically shows extraintestinal migration in dead-end hosts. The aim of this report is to sensitize practical colleagues towards this rare, but occasionally fatal infection in New World camelids while familiarizing diagnostic pathologists with the morphological characteristics of this disease.

Pharmacokinetics of Orally Administered Prednisolone in Alpacas

This study aimed to determine the pharmacokinetics of prednisolone following intravenous and oral administration in healthy adult alpacas. Healthy adult alpacas were given prednisolone (IV, n = 4), as well as orally (PO, n = 6). Prednisolone was administered IV once (1 mg/kg). Oral administration was once daily for 5 days (2 mg/kg). Each treatment was separated by a minimum 4 month washout period. Samples were collected at 0 (pre-administration), 0.083, 0.167, 0.25, 0.5, 0.75, 1, 2, 4, 8, 12, and 24 h after IV administration, and at 0 (pre-administration), 0.25, 0.5, 0.75, 1, 2, 4, 8, 12, 24 after the first and 5^th PO administration. Samples were also taken for serial complete blood count and biochemistry analysis. Prednisolone concentration was determined by high pressure liquid chromatography. Non-compartmental pharmacokinetic parameters were then determined. After IV administration clearance was 347 mL/kg/hr, elimination half-life was 2.98 h, and area under the curve was 2,940 h^*ng/mL. After initial and fifth oral administration elimination half-life was 5.27 and 5.39 h; maximum concentration was 74 and 68 ng/mL; time to maximum concentration was 2.67 and 2.33 h; and area under the curve was 713 and 660 hr^*ng/mL. Oral bioavailability was determined to be 13.7%. Packed cell volume, hemoglobin, and red blood cell counts were significantly decreased 5 days after the first PO administration, and serum glucose was significantly elevated 5 days after the first PO administration. In conclusion, serum concentrations of prednisolone after IV and PO administration appear to be similar to other veterinary species. Future research will be needed to determine the pharmacodynamics of prednisolone in alpacas.

Cerebrospinal nematodosis caused by Parelaphostrongylus species in an adult bull

A 2-y-old Brahman bull was presented with progressive hindlimb ataxia and paraparesis that led to recumbency. Postmortem examination revealed scattered pinpoint, red-brown foci within the brainstem and gray matter of the spinal cord, and a larger lesion within the spinal cord at the level of T13. Histology of the section of T13 contained cross-sections of nematodes consistent with Parelaphostrongylus tenuis. Evidence of inflammation was present in other affected areas of the spinal cord and brain. DNA extraction and nested PCR were performed, which demonstrated 98% identity and 100% coverage to both P. tenuis and P. andersoni. Our case highlights the utility of DNA sequencing in parasite identification.