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EQUINE VETERINARY EDUCATION
Equine vet. Educ. (2019) 31 (5) 236-241 doi: 10.1111/eve.12856
Case Report
Clinicopathological findings of an episode of mycotoxicosis in horses R. K. Dedar*
ICAR- National Research Centre on Equines, Hisar, India. *Corresponding author email:
rameshdedar@gmail.com
Keywords: horse; aflatoxins; gamma GT; liver cirrhosis; mycotoxins; pearl millet
Summary This report of mycotoxicosis in horses describes the clinical signs, post-mortem findings, histopathological findings and prognosis following the accidental feeding of mycotoxin contaminated fodder to the horses at a farm over a 3-year period. Variable clinical signs viz. weight loss, height retardation in foals, episodes of sudden weakness and staggering gait, ulceration in the oral cavity and at mucocutaneous junctions, yawning, decreased appetite to complete anorexia, rectal prolapse, and failure of blood clotting were observed in many horses at an organised equine farm over a period of 2–3 years. Post-mortem examination of these cases revealed liver cirrhosis and pathological changes in other organs too. On examination of the fodder, it was observed that pearl millet fodder fed to the animals had ergot infestation. On laboratory investigation of the fodder, aflatoxins levels ranged from 24 ppb to 70 ppb in pearl millet fodder. The analysis eventually led to discontinuation of the pearl millet fodder. On follow-up for 2 years, no new cases of hepatic cirrhosis were seen. Most of the horses at the farm including those that had shown high levels of serum gamma glutamyl transferase (GGT) and weight loss, recovered completely. The present episode demonstrates that there is a need for regular monitoring of cereal fodders of horses in subtropical and tropical areas to avoid mycotoxicosis. In the present episode, monitoring serum/plasma GGT levels was found to be a sensitive biochemical indicator to identify liver damage caused by mycotoxins.
Introduction
Fungal infestation of fodder plants and consequent occurrence of mycotoxicosis in domesticated animals has been widely reported. However, reports of naturally occurring cases of mycotoxicosis in horses are scarce. The present episode of mycotoxicosis in horses was observed to be associated with pearl millet (Pennisetum glaucum) fodder, which is widely used for horses in northwestern India (Pal et al. 2013) and is prone to mycotoxin contamination in the field (Cereser et al. 2004). Aspergillus, Penicillium and Fusarium are common mycotoxigenic fungi detected in pearl millet (Wilson et al. 2006). Clinicopathological manifestations in experimental mycotoxicosis in horses include inappetence, depression, fever, tremor, ataxia, cough, yellow-brown liver with centrilobular necrosis, icterus, haemorrhages, tracheal exudation and brown urine (Caloni and Cortinovis 2011). The present report describes a natural episode of mycotoxicosis in an organised equine farm due to exposure to mycotoxins from fodder over a period of 3 years.
© 2017 EVJ Ltd Case history
At an organised farm of approximately 150 equines (approximately 100 horses and 50 donkeys and mules), 20 horses had died after exhibiting various clinical signs in 3 years. Prior to death, these horses exhibited dullness, depression, yawning, skin lesions (Fig 1a and c), ulcers in the oral cavity (Fig 1b), tachycardia, behavioural changes, diarrhoea, colic, dystocia, rectal prolapse (Fig 1d), immunosuppression, body weight loss and inappetence to complete anorexia. Of the 20 affected horses, two died suddenly without showing any clinical signs. Histopathological examination of the necropsy samples revealed cirrhosis of the liver in all horses. These horses were being stall-fed with pearl millet as green and dry fodder, with sewan grass (Lasiurus scindicus) serving as dry fodder at the time of the last mortality; both fodders were completely weed-free. Oats, sorghum and lucerne were other green fodders being used seasonally. Concentrate feed included a mixture of oats, wheat bran and gram. After the initial deaths of four horses in the first year and similar histopathological findings of cirrhosis in all cases, feed and fodder were tested for the presence of aflatoxins. Aflatoxins levels in the feed and fodder were determined to be within permissible limits of <30 ppb; therefore, the feed and fodder remained unchanged. However, six more horses died in the second year, and ten horses died in the third year.
Clinical findings
There was loss of body weight in all the horses at the farm and growth of young animals was retarded. Frequencies of different clinical manifestations in all 20 dead horses are given in Table 1.
Diagnosis
In the present case report, histopathological findings and clinical signs revealed evidence of chronic liver cirrhosis. Causes of chronic liver disease in adult horses include pyrrolizidine alkaloid toxicosis, pasture-associated hepatopathy, amyloidosis, hepatic lipidosis, suppurative cholangitis, cholelithiasis, neoplasia and iron toxicity (Popenga 2009). Fodder provided to the horses in the present episode was
weed-free; therefore, there was no evidence of alkaloid or plant toxicity. Serum triglyceride levels (Table 2) were too low to indicate hepatic lipidosis (Mogg and Palmer 1995). Serum total iron binding capacity and serum transferrin saturation levels (Table 2) in the horses were not compatible with iron toxicity. Icterus is the primary sign in suppurative cholangitis and cholelithiasis, and it was not seen in most of the cases in
, N. Virmani, P. A. Bala, J. Singh, R. K. Vaid, R. A. Legha and B. N. Tripathi
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