Question

Obstructive urolithiasis is a common affection of urinary tract in castrated male animals. There are different factors that sequentially contribute to urolithiasis. Choose the most appropriate sequence from the below mentioned statements,
(A) The factors that facilitate precipitation of solutes.
(B) The factors that favor the development of nidus.
(C) Stasis of urine and difficulty in urination.
(D) The factors that favor concretion by cementing precipitated salts.
Choose the correct answer from the options given below:

• A. (A), (B), (C), (D).
• B. (A), (D), (C), (B).
• C. (B), (A), (D), (C).
• D. (C), (B), (D), (A).

Hint:

To remember the sequence of stone formation:
You must first have a core/center (Nidus), then minerals must Precipitate onto it, then these minerals Cement together into a solid stone, and finally this stone blocks the flow, causing Stasis/Dysuria.
This gives the order: (B), (A), (D), (C).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Urolithiasis is the formation of calculi (uroliths or stones) within the urinary tract.
In castrated male ruminants (such as steers, wethers, and bucks), this is a common and serious condition due to the long, narrow, and curved urethra (especially at the sigmoid flexure or urethral process).
The formation of these stones follows a multi-step pathological sequence.

Step 2: Detailed Explanation:
Let us trace the sequential pathogenesis of urolithiasis:
1. Development of a Nidus (B): The process begins with the formation of an organic matrix or "nidus."
This nidus typically consists of desquamated epithelial cells, mucus, proteins, or necrotic debris. It provides a physical surface upon which mineral salts can begin to deposit.
2. Precipitation of Solutes (A): Once a nidus is present, factors that promote the supersaturation of urine with minerals (such as high dietary phosphorus, alkaline pH, or low water intake) cause solute crystals to precipitate out of the urine and deposit onto the nidus.
3. Concretion by Cementing (D): As the minerals continue to precipitate, cementing agents (such as mucoproteins) bind the crystals together, leading to the growth and compaction of the stone.
4. Urinary Stasis and Dysuria (C): As the urolith grows, it eventually enters the narrow urethra and becomes lodged, causing physical obstruction.
This obstruction blocks urine flow, leading to urinary stasis, bladder distension, and the clinical sign of dysuria (difficulty and pain during urination).
Therefore, the correct chronological sequence of events is: (B) \(\rightarrow\) (A) \(\rightarrow\) (D) \(\rightarrow\) (C).

Step 3: Final Answer:
The correct option is (C).