What are the most common causes of increased coat length?
How can hypopigmentation happen?
decreased melanin production
decreased dispersion of melanin granules
increased loss of melanin
What is leukotrichia?
acquired loss of melanin from the hair shaft, actual factors are unknown
What is albinism?
Recessive genetic defect in which a normal complement of melanocytes is present but a biochemical defect results in lack of ability to synthesize tyrosinase, so that melantoin is not produced. In true albinos there is a lack of pigment in all tissues
What is the most common cause of loss of pigmentation in FA?
Burns & other traumas
What is the most common cause of increased pigmentation in FA?
What does C. pseudotuberculosis cause?
Sheep & goats: caseous lymphadenitis (CLA)
Cattle: cutaneous granuloma
Horses: ulcerative lymphangitis
What is CLA or concern in sheep?
Condemnation of carcass (3-5% of mutton, 0.02-0.03% of lambs)
Downgrading of carcasses
Decreased wool production in Merino sheep
Decreased growth rates
What are the characteristics of C. pseudotuberculosis?
Facultative intracellular gram+ coccobacillus
Infects macrophages & monocytes
Soil borne, survives for months-years; even in sunlight
What is the pathogenesis of C. pseudotuberculosis?
Phospholipase D is a potent exotoxin & key virulence factor
-impairs chemotaxis of neutrophils
Increased vascular permeability
Leakage of plasma from vessels into tissue & lymphatics
Spread of organism regionally & systemically
Mycolic acid has local cytotoxic properties
-degenerative changes & death in phagocytozing leukocytes
-protection from hydrolytic enzymes within lysosomes→ survives phagocytosis → exists facultative intracellular → transport to local LN
-helps survival in the environment
What are the CS of internal CLA?
Hematogenous or lymphogenous spread
In sheep visceral lesions esp. lung
Lung parenchyma, mediastinal & bronchial LN Can lead to bronchopneumonia & pleuritis
pneumonia can be a pre-disposing factor like brisket disease
What are the characteristics of Cassia occidentalis (“coffee weed” or “sickle pod cassia”) toxicity?
Severe muscle degeneration
Coffee brown urine (myoglobinuria) → kidney failure
Chronic → cardiomyopathy
What are the characteristics of Persea americana (Avocado) toxicity?
Direct toxic effect on myocardium → heart failure
Brisket & neck edema, pulmonary edema
Acute death can occur
Cattle, goats have died from avocado poisoning
What are the characteristics of Phalaris arundinacea (reed canary grass) toxicity?
Tryptamine alkaloid toxin has effect on cholinegic receptors
2 clinical forms
Acute death: from cardiovascular collapse is 12 -72 hrs after placement on toxic pasture. CS include acute dyspnea, cyanosis, pounding heart sounds, irregular heart rate with alternating periods of extreme tachycardia & then bradycardia
Chronic: nervous form
What are the characteristics of bovine dilated cardiomyopathy (BDCMP)?
Autosomal recessive mutation in optic atrophy 3 gene
Usually ~2–4 years old
Systolic dysfunction → right sided heart failure
Hallmark: cardiomegaly with ventricular and atrial dilatation & hypertrophy
Which animals are most sensitive to ionophore toxicity?
Monensin: horse > sheep > cattle
Lasalocid: horse > cattle > sheep
see decrease in ventricular contraction
What are the characteristics of copper deficiency?
Primary: in milk fed animals or copper deficient pasture
Secondary: mineral imbalances (dietary Mo excess), most prominent signs in young growing animals
See fibrosis of the heart muscle
What are the characteristics of gossypol toxicity?
0.1–0.2% of total ration can be tolerated (cattle)
No more than 0.01% of total gossypol (swine)
If stressed lower tolerance, effects are cumulative
Acute toxicosis: large amounts of proteinaceous fluids in all body cavities causes myocardial degeneration & necrosis, and liver necrosis
Where is lymphoma seen?
What can cause myocarditis?
Bacterial: H. somni, Clostridium chauvoei (blackleg)
Protozoan: Toxoplasma, Sarcocystis
Parasitic: Cysticercus (T. solium pig), (T. saginata cattle), (T. ovis sheep)