CAHFS Connection - May 2026

Managing Editor: Kerry Ballinger 
Design Editor: Lucy Gomes 
Contributors: Cassie Powers, Emma Torii, Francisco Uzal, Nicolas Streitenberger, Patricia Blanchard, Roberto Olivares

Please join us in welcoming our new faculty members, Drs. Bischoff, Navarro, Olivares and Tsai to the CAHFS team.

Dr. Karyn Bischoff joined CAHFS-Davis as faculty toxicologist and Toxicology Section Lead in May 2025.   

She received her DVM from the University of Illinois Urbana-Champaign, followed by a residency in Veterinary Toxicology and MS in Veterinary Pathology at Oklahoma State, and an MS in Public Health from Cornell University.  She is board certified in Veterinary Toxicology and previously served as the Director of Analytical Toxicology at the New York State Animal Health Diagnostic Laboratory from 2004-2025 prior to joining CAHFS.  Dr. Bischoff’s research interests include heavy metal toxicoses in livestock as well as exploration of issues arising from diagnostic submissions.

 

Dr. Yu-Yang (Jerry) Tsai joined CAHFS-Turlock as a faculty diagnostician in February 2026. 

Dr. Tsai earned his DVM from National Chung Hsing University in Taichung, Taiwan, and his PhD in Comparative Biomedical Sciences from the University of Georgia. Prior to joining CAHFS, he worked as a poultry production veterinarian with Great Wall Enterprise Co., Ltd. in Taiwan. Dr. Tsai’s research focuses on poultry intestinal diseases, with particular interest in focal duodenal necrosis. His broader interests include poultry disease pathology, etiology, pathogenesis, and diagnostic interpretation.

Dr. Mauricio Navarro joined CAHFS-Turlock as a faculty pathologist in February 2026. 

Dr. Navarro completed his DVM and MSc in Animal Health degrees at the Universidad Austral de Chile. He received his PhD in Integrative Pathology from UC Davis and completed a three-year postdoctoral scholar position at CAHFS San Bernardino before becoming board certified in Veterinary Pathology by the American College of Veterinary Pathologists (ACVP). Prior to joining CAHFS, Dr. Navarro served as Assistant Professor of Veterinary Anatomic Pathology at the Universidad Austral de Chile. Dr. Navarro’s research focuses on infectious diseases of animals with special emphasis on clostridial diseases. 

Dr. Roberto Olivares joined CAHFS-Davis as a faculty pathologist in March 2026. 

Dr. Olivares received his DVM and PhD in Veterinary Sciences from the University of Buenos Aires, Argentina, and subsequently attained ACVP board certification in Veterinary Pathology.  Prior to joining CAHFS, Dr. Olivares worked as a Diagnostic Pathologist at the Department of Pathology, Faculty of Veterinary Sciences, University of Buenos Aires, Argentina and then became the Director and Chief Pathologist of the Diagnostic Pathology Service at Francisco de Asis School of Veterinary Medicine and Surgery at Universidad Veritas, Costa Rica before joining CAHFS in 2024 as a staff pathologist serving in all of our labs. His research focus includes mineral deficiencies in livestock. 

Avian

Systemic salmonellosis was diagnosed in an adult Barred rock hen with a history of lethargy, diarrhea, weakness and anorexia prior to death. On gross evaluation, the kidneys were enlarged and multinodular. On microscopic evaluation, there was marked inflammation in multiple organs. Large numbers of Salmonella group D1 were isolated from the lungs and liver. Clinical signs of salmonellosis in chickens include diarrhea, weakness, decreased egg production, and high mortality in young chicks. Often, infected birds have no clinical signs, acting as carriers that contaminate the environment, feed, and eggs.

Staphylococcosis was diagnosed in a 9-week-old Cornish cross rooster with a history of limping, ataxia, lethargy, and a pale comb. On necropsy, the liver and kidneys were diffusely enlarged, and both hocks were swollen and contained abundant straw-colored fluid. On histopathology, there was marked inflammation with intralesional cocci present in the lung, liver, and joints and Staphylococcus aureus was isolated from those tissues. Staphylococcus spp. are ubiquitous in the environment and are part of normal skin microbiota and mucous membranes of poultry and other animals. Infection occurs when Staphylococcus spp. gain access to tissues and the bloodstream after skin and/or mucous membranes are compromised. 

Bovine

Vetch-associated disease was diagnosed in multiple Angus cows with history of marked alopecia, suspected dermatitis along their neck and ventrum, or sudden death. On gross evaluation of 2 submitted cows, they had crusting and alopecia along the neck (Fig. 1) and ventrum. Both animals showed variably sized nodules throughout their kidneys. On microscopic evaluation, one cow had moderate granulomatous inflammation in the kidneys, skin, and brain, and the other cow had marked lympho-histiocytic and eosinophilic inflammation of the skin, kidneys, adrenal glands, lungs, liver, and heart. The gross and microscopic changes in this group of cows is pathognomonic for a diagnosis of vetch-associated disease. This disease is most commonly related to consumption of hairy vetch (Vicia villosa subspecies villosa). However, plants submitted in this particular case were identified as winter vetch, also known as hairy-fruited vetch or woolypod vetch (Vicia villosa subspecies varia), (Fig. 2) a subspecies of vetch not previously reported to produce these lesions.

Trueperella pyogenes abortion was diagnosed in a third trimester Jersey fetus from a dairy that had 4-5 abortions in the past month. The main findings included bronchopneumonia, omphalitis, conjunctivitis, and fibrin thrombi in the liver. T. pyogenes was isolated from the lung and abomasal content. T. pyogenes is a common cause of abortion in cattle, often in the form of single, sporadic events. Hence, it was difficult to know if this fetus was representative of the other abortions that had occurred in this herd.

Equine

Bilateral ocular melanoma was diagnosed in a 12-year-old Lusitano gelding with a history of previously resected melanomas in the rectum, penis, and prepuce. Arising from the iris of the right eye and occupying about 80% of the anterior chamber was a large black mass. Multiple additional smaller multinodular black masses were identified arising from and on the surface of the iris of the left eye (Fig. 3). An additional large mass was identified effacing the architecture of an anorectal lymph node. All these masses were diagnosed as melanomas microscopically. Up to 80% of gray horses over the age of 15 years develop melanomas. While often initially benign, they can become malignant, damaging surrounding tissue, metastasizing and impairing organ function.

Pigs/Porcine

Concurrent porcine reproductive and respiratory syndrome (PRRS) and porcine circovirosis (PCV2) was diagnosed in a 4-month-old male Hampshire pig with respiratory signs and decreased appetite over a one-month period. The main gross findings consisted of red-to-black swollen lungs and enlarged mediastinal and mesenteric lymph nodes. Histologically, there was pneumonia, nephritis, hepatitis, and lymphadenitis. Immunohistochemistry for PRRS virus and PCV2 was positive in lungs and lymph nodes, respectively. In addition, PCR on lung for PRRSV was positive. 

Small Ruminants

Copper Toxicosis was diagnosed in a five-year-old male neutered pygmy goat with a history of red urine and diffusely red kidneys at necropsy. On histopathology there was marked renal tubular and hepatocellular necrosis with copper confirmed by rhodamine special stains. The copper levels in the liver were very high (500 ppm; reference range: 25-150 ppm) (Fig. 4). Copper levels were also elevated in the grain and feed supplement. Copper concentrations in the total diet for goats should be between 15 and 25 ppm dry matter. Copper toxicity in goats is a severe condition caused by excessive copper intake, often from mineral supplements, which leads to a hemolytic crisis with signs including anemia, jaundice, and. Excess of other minerals such as molybdenum can also cause copper deficiency. Other potential sources for excessive copper intake include feeding cattle/pig feed (too high in copper), contaminated water (copper pipes), or high-copper plants, such as subterranean clover (Trifolium subterraneum). 

Wildlife

Verminous pneumonia and nasal bots were identified in two juvenile mule deer  with a history of dozens of sick and dead deer within the area. On gross evaluation, both deer had numerous thread-like worms within their major airways (Fig. 5). On cut section, the nasal cavities contained numerous botfly larvae (Fig. 6). Microscopic evaluation showed moderate pneumonia with cross-sections of lungworms. Lungworms in deer often cause coughing, labored breathing, weight loss, and reduced stamina, particularly in fawns or high-density populations. While many wild deer carry them without severe clinical signs, heavy infections can cause fatal pneumonia. Nasal bots are also common in the throat, guttural pouches, and nasal passages of deer. Adult flies deposit larvae around the nose/mouth, which migrate into the nasal cavity, causing irritation, sneezing, and coughing, but they generally cause little harm to the deer or meat safety.

Holiday Schedule

Memorial Day:  Monday, May 25, 2026 - Closed

Employment Opportunities

No postings at this time