CAHFS Connection - March 2026

Managing Editor: Kerry Ballinger 
Design Editor: Lucy Gomes 
Contributors: Carmen Jerry, Cassie Powers, Emma Torii, Francisco Uzal, Hernando Acevedo-Patarroyo , Javier Asin Ros, Mark Anderson, Melissa Macias Rioseco, Nicolas Streitenberger, Patricia Blanchard

Avian

Gangrenous dermatitis due to Clostridium septicum was diagnosed in 47-day-old chicken broilers from three separate houses on the same premises, that were experiencing spikes in mortality over a 2-day period. Each house held roughly 20,000 birds. On external examination, all submitted birds had diffuse purple bruising on the skin, extending over the breast and thigh muscles. The skin of the thighs had occasional linear scratches. The subcutaneous tissue had copious red fluid and emphysema (Fig. 1). 

Some birds had multifocal hepatic necrosis. Histopathology of the skin showed characteristic features of gangrenous dermatitis. Anaerobic culture of affected skin and liver yielded Clostridium septicum. The primary causes of this disease are C. septicum and Clostridium perfringens type A. Other bacteria such as Escherichia coli and Staphylococcus aureus have also been reported. Poor litter conditions, high stocking density of birds, and other poor management practices that lead to skin scratches, and immunosuppressive agents can predispose this disease. 

Highly pathogenic avian influenza (HPAI) was diagnosed in two backyard chickens with no overt clinical signs from a flock where 3 of 15 birds had died. No gross lesions were evident on necropsy. Microscopically, multiple organs, particularly the pancreas and spleen, had multifocal necrosis (Fig. 2). 

HPAI virus was detected by PCR in both birds. HPAI is a severe, highly contagious, and frequently fatal viral disease affecting domestic and wild birds. Outbreaks cause rapid death, often with up to 100% mortality in flocks. 

Bovine

Bovine viral diarrhea virus (BVDv) was the cause of enterocolitis in a 3-week-old Holstein calf. On gross examination of tissues submitted, there was fibrin loosely attached to the mucosa of the small and large intestines. Histologically, there was enterocolitis consistent with BVDv infection. The calf was positive for BVDv on ear notch by antigen ELISA, spleen by PCR, and intestine by immunohistochemistry. Confirmation of whether a calf is persistently infected or not requires repeat testing after a few weeks, which is not possible in necropsy cases.

Pseudomonas aeruginosa systemic infection was diagnosed in a 2-year-old Angus cow with a history of weight loss. The main lesions were multifocal ulcers and erosions of the tongue, gingiva, esophagus, abomasum and rumen with associated thrombosis and bacterial colonies, multifocal renal infarcts and pneumonia. P. aeruginosa was isolated from lung, oral mucosa and liver. Extensive molecular testing ruled out foot-and-mouth disease virus, vesicular stomatitis virus, bovine viral diarrhea virus, malignant catarrhal fever–associated agents, bovine herpesvirus-1 and papular stomatitis virus. Heavy metal screening on liver identified mild to moderate deficiency of copper, manganese, and selenium.

Bacterial kidney infection was diagnosed in a 10-month-old Angus/Shorthorn crossbred steer with a history of "slowing down" and diarrhea. On necropsy there were multiple abscesses throughout the abdominal wall and multiple lymph nodes, and most of the right kidney was replaced by pus and marked inflammation (Fig 3). Escherichia coli was cultured from these abscesses. Due to the locations of the abscesses and destruction of the right kidney, a primary ascending urinary tract infection (pyelonephritis) was suspected. Pyelonephritis of cows, is a severe, often chronic infection commonly caused by Corynebacterium renale or E. coli. Clinical signs include fever, hematuria, colic, anorexia, and a sharp drop in milk production.

Equine

Equine herpesvirus-1 (EHV-1) was the cause of an outbreak of abortions in a group of Gypsy Vanner mares. Three mares aborted in a period of 30 days. Two fetuses with placentas, at 6-7 months gestation, were submitted. No significant lesions were observed grossly other than mild thoracic effusion and subcutaneous edema. Histology revealed multifocal hepatic necrosis with intranuclear inclusion bodies in hepatocytes of both fetuses. EHV-1 with the neuropathogenic marker was detected by qPCR in liver of both fetuses. EHV-1 usually causes abortions between 6-11 months of gestation. Vaccination of pregnant mares may help to prevent EHV-1 abortions. In this case, the mares had not been vaccinated.

Porcine

An umbilical hernia was diagnosed in a 3-month-old mixed breed piglet from a farm with multiple similarly affected piglets around the same time. There were no significant additional gross or microscopic findings in this case, therefore a genetic cause was deemed most likely. Umbilical hernias in piglets are due to a weakened abdominal wall around the navel that allows intestines to protrude. They can result from genetics, poor umbilical cord management, navel infection, or trauma by pen-mates.

Small Ruminants

Johne’s disease was diagnosed in a 3-year-old ewe with a history of chronic wasting. The ewe was emaciated, and had markedly thickened, corrugated distal small intestine with prominent lymphatic vessels. Histology was consistent with Johne’s disease, including granulomatous enteritis, hepatitis and lymphadenitis. The diagnosis was confirmed by PCR, serology and presence of acid-fast bacilli in the intestine. 

Selenium deficiency caused the death of a 7-month-old Boer goat kid from a herd of 17 in which three had died in three months. The clinical history included diarrhea and presence of Trichostrongylus spp. eggs in feces. The most significant findings were myocardial and skeletal muscle necrosis compatible with selenium deficiency. Liver selenium was 0.12ppm (normal 0.25—1.5ppm) despite receiving a selenium injection 48 hours prior to death. Copper was also markedly deficient (9ppm, normal 25-150ppm).  

Holiday Schedule

CAHFS is open but will have only limited services available on 3/27/2026, in observance of Cesar Chavez Day. Please contact the laboratory to plan your testing needs accordingly.

Employment Opportunities

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