JPC SYSTEMIC PATHOLOGY

URINARY SYSTEM

January 2024

U-T16

 

SIGNALMENT (JPC #1803541): Seven-year-old Angus cow.

 

HISTORY: Three of four ill animals in a herd of forty died following a two week illness. Clinical signs in this cow included bloody diarrhea. Other ill animals were constipated and several had a papular or scaly dermatitis.

 

HISTOPATHOLOGIC DESCRIPTION: Kidney: Scattered throughout the cortex and extending into the medulla are multifocal to coalescing aggregates of macrophages, eosinophils, multinucleated giant cell macrophages (foreign body and Langhans’ type), lymphocytes and plasma cells, admixed with minimal hemorrhage, fibrin and edema, which expand the interstitium and separate, surround, and replace medullary and cortical tubules and glomeruli. Tubules are mildly to moderately ectatic, contain sloughed tubular epithelial cells (cellular casts), and variable amounts of proteinaceous fluid (proteinosis) and necrotic cellular debris (granular casts).  Multifocally, tubular epithelium is either swollen with a vacuolated cytoplasm (degeneration), shrunken with a pyknotic nucleus and hypereosinophilic cytoplasm (necrosis) or has a basophilic cytoplasm with crowded and vesiculate nuclei and rare mitotic figures (regeneration). Multifocally, there is mild parietal epithelial hypertrophy that is occasionally attached to the glomerular tuft (synechia) with occasional ectatic Bowman’s spaces containing protein. 

 

MORPHOLOGIC DIAGNOSIS: Kidney: Nephritis, interstitial, granulomatous and eosinophilic, multifocal to coalescing, moderate, with tubular degeneration, necrosis, and regeneration, Angus, bovine.

 

ETIOLOGIC DIAGNOSIS: Hairy vetch (toxic) nephritis

 

CAUSE: Hairy Vetch (Vicia villosa Roth) toxicity

 

GENERAL DISCUSSION:  

• Hairy vetch is a legume genetically related to the lupines 

• Holstein, angus and cattle over 3 years of age are more commonly affected with low morbidity and high mortality, death occurring 10-20 days after the onset of illness

• Causes a multisystemic syndrome in cattle and horses 

• Granulomatous and eosinophilic inflammation in cattle

• Predominantly granulomatous and infrequent eosinophilic inflammation in horses

• Three syndromes in cattle:

• Dermatitis, conjunctivitis, diarrhea and granulomatous inflammation of many organs following consumption of vetch pasture (most common form; immunotoxic syndrome)
• Acute neurological disease/seizures and hemolysis after consuming seeds (unrelated to immunotoxic syndrome)
• Swelling of upper body with herpetiform eruptions of oral mucous membranes, respiratory distress and death following vetch pasture consumption

 

PATHOGENESIS:  

• Toxicity of vetch seeds is due to prussic acid (hydrogen cyanide)

• Binds metallic cofactor in metalloenzymes; also can cause inhibition of oxidative phosphorylation in acute intoxication (cytochrome C inhibition)
• Chronic toxicity leads to white matter demyelination

• The pathogenesis of granulomatous inflammation is unclear; suspect immunotoxin (lectin); prior exposure may be required

• Ingestion of vetch > antigen formation in the form of haptens or complete antigen that sensitizes lymphocytes > evokes cell-mediated immune response upon repeat exposure (similar to type IV hypersensitivity)

 

TYPICAL CLINICAL FINDINGS:

• Pruritic dermatitis, wasting, diarrhea (possibly bloody)
• Papules and crusts initially on udder, teats, escutcheon and neck; progresses to trunk, face and limbs

• Lymphocytosis and hyperproteinemia

 

TYPICAL GROSS FINDINGS:  

• Yellow nodular infiltrates disrupt architecture of a wide range of organs – most severe in myocardium, kidney, lymph nodes, thyroid and adrenal glands

• Kidney may have radially oriented cortical infiltrates that follow the vasculature

 

TYPICAL LIGHT MICROSCOPIC FINDINGS:  

• Granulomatous and eosinophilic inflammation in multiple organs is unique and often diagnostic when coupled with history of exposure to hairy vetch
• Infiltration by macrophages, lymphocytes, plasma cells, multinucleated giant cell macrophages, and eosinophils (in cow) in all affected organs
• Skin: In addition to inflammation, there is marked hyperkeratosis and dermal and epidermal edema

 

DIFFERENTIAL DIAGNOSIS:

• Histologic lesions are similar to those seen with other species of Vicia as well as citrus pulp toxicity, citrinin (a mycotoxin in feed), and 1,1-di-ureido-isobutane (DUIB) (a protein feed substitute) 

• Sarcocystis: Granulomatous and eosinophilic myocarditis with cyst rupture

 

COMPARATIVE PATHOLOGY:  

• Horse: Similar to cattle with lymphadenomegaly and dependent edema; infrequent eosinophils and lack of cardiac involvement
• Horses develop a similar condition with no history of vetch exposure: “vetch-like disease”

• Referred to as: “Idiopathic granulomatous disease involving the skin”; “systemic granulomatous disease”; “generalized granulomatous disease”; or equine sarcoidosis”

• Variable organ involvement
• Skin lesions: Scaling, crusting, facial and limb alopecia, with progression to generalized exfoliative dermatitis
• Deep perifollicular nodules of granulomatous inflammation

 

References:

1. Cianciolo RE, Mohr FC. Urinary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer's Pathology of Domestic Animals. 6th ed. Vol 2. St. Louis, MO: Elsevier; 2016: 432.
2. Mauldin EA, Peters-Kennedy J. Integumentary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol. 1. 6th ed. St. Louis, MO: Elsevier; 2016: 574.
3. Sula MM, Lane LV. The Urinary System. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022:748.
4. Welle MM, Linder KE. The Integument. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022:1223-1224.

 

 

 

Click the slide to view.

---