CAHFS Connection September 2024

The San Bernardino laboratory offers equine infectious anemia virus serology

CAHFS San Bernardino has resumed equine infectious anemia virus serology testing by AGID and cELISA methods. Please submit refrigerated serum, in red top tubes, or serum separator tubes for testing. An accurate and complete USDA VS 10-11 (“Coggins form”; version February 2018 or later) form must be included with the submission for each horse being tested.

Avian

Infectious laryngotracheitis (ILT) was the cause of increased mortality in a backyard flock of over 300 chickens where 100 had died in a week. Affected birds exhibited frothy eye discharge, lethargy, drooped wings, and were not eating. A hen submitted had tan-yellow, friable caseonecrotic exudate covering the larynx and occluding the proximal trachea; similar exudate was also seen throughout the oral mucosa. Microscopically, there were typical ILT lesions including conjunctivitis and laryngotracheitis. ILT virus was detected by PCR.

Poxviral dermatitis was diagnosed in a juvenile American crow that was euthanized after showing progressive skin lesions. On gross examination, there were multiple, ulcerated skin nodules over the right wing tip, face, and neck. Microscopically, these nodules were consistent with poxvirus infection with numerous typical intracytoplasmic inclusion bodies. Poxviral particles were detected by electron microscopy; this, coupled with the presence of viral inclusions, confirmed the diagnosis.

Bovine

Yersinia pseudotuberculosis was the cause of enterocolitis in a four-month-old Holstein heifer calf from a 1000-head calf ranch where several had died and ten were sick at the time of submission. The ranch was experiencing an ongoing problem of four- to five-month-old calves developing watery, yellow diarrhea for a couple of days and failing to respond to treatment before death.  The calf had intestinal mucosal necrosis associated with colonies of bacteria, which is typical of yersiniosis. Y. pseudotuberculosis was isolated from both small intestine and colon.

Histophilus somni mastitis contributed to the death of an adult pastured beef cow that was found dead after an observed brief illness. Samples were collected from a field necropsy and submitted. Gross findings were mastitis and jaundice. Laboratory findings were a severe copper deficiency (2.4 ppm, normal range 25-100 ppm) and chronic mastitis from which H. somni was isolated.

Equine

Nerium oleander intoxication was diagnosed in a seven-year-old pregnant Fell pony horse. The mare presented to a veterinary clinic with ventricular tachycardia and injected mucous membranes. Despite treatment, the mare collapsed and died within 5 minutes.  At necropsy, the pericardial sac was filled with a large volume of yellow, serous fluid, and hemorrhage was noted in the wall of all heart chambers. The stomach contained a few leaf fragments compatible with oleander. The horse’s owners had landscaping work done and oleander leaves had been blown with a leaf blower. Although the horse was not observed to have ingested any leaves, oleander intoxication was highly suspected. Oleandrin, the cardiac glycoside in N. oleander, was detected in the tested liver, confirming the diagnosis.

Small Ruminant

Ovine progressive pneumonia/Maedi-visna was diagnosed in a one-year-old sheep with a history of chronic cough, weight loss, ill-thrift, and poor coat. Samples collected during a field necropsy were received. The main histologic lesion was lymphohistiocytic interstitial pneumonia with hyperplasia of the bronchial-associated lymphoid tissue. Small ruminant lentivirus antigen was detected in the lung lesions by immunohistochemistry. There was also concomitant chronic bacterial bronchopneumonia. Small ruminant lentiviruses can cause pneumonia, neurologic disease, arthritis, and mastitis in sheep and goats.

An eight-week-old Boer goat was diagnosed with septicemia caused by Mycoplasma mycoides subspecies capri. The kid developed a high fever, was limping, had swollen joints, and became recumbent and weak. At necropsy, both eyes were cloudy, the left hock joint was swollen, the lungs were congested and edematous, and there were infarcts in both kidneys. Microscopic lesions included anterior uveitis, interstitial pneumonia, splenitis, adrenalitis, myocarditis, glossitis, and cystitis. M. mycoides ssp. capri was isolated from the lung, liver, and joint fluid.