CAHFS Connection - September 2025

Avian

Coccidiosis was diagnosed in four, 2-month-old, game fowl chicks with a history of respiratory disease. All birds had severe necro-hemorrhagic enteritis with myriad intralesional coccidian forms seen on histology and many coccidian oocysts seen on intestinal wet mount smears and fecal floatation. A respiratory panel was negative on all birds. It is possible that the respiratory signs were associated with anemia and dehydration caused by the hemorrhagic enteritis.

Bovine

Bovine leukemia virus-associated lymphoma was diagnosed in a feedlot cow submitted for necropsy after being found dead without premonitory signs. The cow had multiple masses in the heart, abomasum, uterus, multiple lymph nodes, spleen, mesentery, omentum and retrobulbar adipose tissue. In addition, there was a large amount of hemorrhage in the abomasal lumen. The masses were histologically consistent with lymphoma. Bovine leukemia virus (BLV) ELISA was positive, confirming infection. Given the distribution of the lymphoma, and the positive ELISA results, this was likely an enzootic bovine lymphoma. The majority of cows infected with BLV will have no clinical signs, but some can have persistent lymphocytosis, and a small subset will develop lymphoma. This is more commonly seen in dairy cattle but beef cattle can also be affected.

Leptospira sp. infection was the cause of death in a 6-month-old Holstein heifer. Several heifers were noted to be “urinating blood” and 3 had died. On necropsy, most internal tissues were markedly icteric, the kidneys had pale tan, radiating streaks through the cortex, and there was hematuria. Leptospira sp. was detected in the kidney via PCR. A Leptospira serology panel was negative, which was not unexpected due to the acute nature of infection. Typically, antibodies are not detected until 7 or more days post-infection.

Equine

Cantharidin toxicosis was diagnosed in an 8-year-old stallion that presented with pain, apparent choke, sloughing of the oral and gastric mucosa, hypocalcemia, leukocytosis, and anemia.  Cantharidin was detected in the urine.  Cantharidin is produced by Epicauta spp., or blister beetles, and related insects.  It disrupts epithelial desmosomes, causing acantholysis, vesication, and ulceration of epidermis, gastrointestinal, and urinary tract mucosa, as well as myocardial necrosis.  All veterinary species are susceptible, but, because blister beetles are occasionally crushed into alfalfa hay at harvest, horses are most commonly impacted (Fig. 1).

Cervical vertebral compressive myelopathy (also known as cervical vertebral stenotic myelopathy or wobbler syndrome) and presumptive equine protozoal myeloencephalitis (EPM) were diagnosed in an eight-year-old Irish sport horse gelding. The horse had a history of acute onset of hindlimb weakness and ataxia that progressed over one month despite treatment for EPM. During the month the horse demonstrated a four-fold rise in both serum and cerebrospinal fluid antibody titers to Sarcocystis neurona. At necropsy there were degenerative joint changes and compression of the spinal cord from vertebrae C2 to C7; compression was dynamic from C2 to C5 and static from C5 to C7. Microscopically there was florid axonal degeneration and loss in the spinal cord at these sites. There also was mild myeloencephalitis suggestive of EPM, although no organisms were detected by histopathology or immunohistochemistry.

Porcine

Viral pneumonia was diagnosed in a 5-month-old pig that developed a cough and lethargy after being shipped to California from the Midwest. The pig was euthanized after several weeks with no response to therapy. In the lung samples submitted there was diffuse interstitial pneumonia with alveolar epithelial hyperplasia. The liver submitted had a diffuse hepatitis. Porcine circovirus 2 was detected in both the lung and liver and coinfection with PRRS virus was detected in the lung.

Blue Pigs. Diphacinone, an anticoagulant rodenticide, was detected in liver and stomach content from a feral pig.  A trapper had discovered bright blue adipose tissue and muscle at slaughter. Diphacinone baits contain blue dye and are commonly used to control ground squirrels; its use is restricted in California (Food and Agricultural Code section 12978.7). Another restricted use anticoagulant, warfarin, is found in some feral pig baits and also imparts a blue color to adipose tissue, intended to warn hunters of contamination.

Small Ruminants

Chronic congestive heart failure secondary to congenital defects was diagnosed in a yearling ram found dead on a pasture. At necropsy, the ram had severe right ventricular dilation, free wall hypertrophy, pulmonary artery dilation, aortic stenosis, hydropericardium and ascites. Histologic lesions in the lung and liver were consistent with chronic passive congestion. The cause for the chronic heart failure was presumed to be congenital.

Bibersteinia trehalosi septicemia resulted in the sudden death of a 36-hour-old triplet Boer goat kid. The dam was noted to have one swollen mammary gland and poor milk production. The submitted kid was dehydrated and had pulmonary emphysema. Histologic examination revealed disseminated vascular thrombosis and neutrophilic leukocytosis with bacteria in multiple organs and umbilical vein. B. trehalosi was isolated from lung and brain.