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Friday, February 21, 2014

Recurrence of Pharyngeal Pythiosis in a Horse

The image in Figure 1 is that of a "normal" larynx and pharynx in a horse. In Figure 2-4, the pharynx is filled with granulomas that are nearly completely obstructing the larynx. The images in Figures 2-4 belong to a middle-aged quarter horse mare that has been treated several times over 2 years for pythiosis of the pharynx. After each treatment with systemic anti-fungal medication, the granulomas shrink in size and the hemorrhagic discharge stops (Figure 4) . However, once the medication stops, the granulomas slowly begin to re-grow and the discharge returns. The image in Figure 4 was taken approximately 12 months prior to Figures 2 and 3. Although the granulomas are present and there is some drainage, the over-all condition of the pharynx is better than what we see in Figures 2 and 3!

Figure 1

Figure 2

Figure 3

Figure 4
 The most likely scenario in this case is that the pythiosis pathogen resides within the granulomas and although they shrink and appear to become inactive, the pathogen persists. Once the medication is stopped, the pathogen is allowed to multiply and the granulomas grown unabated!  Pythiosis was once believed to be a fungi put is now described as an algae that lives in stagnant water throughout the southeastern United States. The pathogen gains access to the horse through small wounds in skin or mucosa. I have diagnosed pharyngeal pythiosis in over a dozen horses in the past 10 years. Every case has involved horses with access to free standing water and all have responded favorably to the systemic anti-fungal. The case imaged in the figures above has been refractory and proven difficult to completely resolve!!

Friday, February 14, 2014

Sabulous Cystitis in a horse!

The sample of urine in Figure 1 was collected from a gelding with the history of persistent urine dribbling or urinary incontinence.  The gelding was 20 years old and otherwise normal. A rectal exam revealed a large, distended urinary bladder that was so distended it hung over the brim of the pelvis!! The urine sample was milky and when allowed to settle there was a large concentration of sediment in the urine! These findings are consistent with sabulous cystitis in a horse!!

Figure 1

In Figure 2, the urinary bladder of the horse is labelled with the letter "B" and typically resides within the pelvis, immediately below the rectum. Emptying of the bladder or urination is a two-part process that involves relaxation of the bladder sphincter and simultaneous contraction of the bladder wall. This process is controlled by two distinct components of the nervous system which work together to empty the bladder and to keep urine in the bladder in between periods of voiding.

Figure 2
In the case of sabulous cystitis, the part muscle layer within the urinary bladder wall loses tone and does not contract properly during urination. As such, the bladder tends to remain full and will eventually over-distend. Fortunately for the horse, once the bladder over-distends, it begins to leak urine through the bladder sphincter and the horse dribbles urine on a regular basis. If the sphincter did NOT leak, the bladder would distend and ultimately rupture resulting in a medical/surgical emergency!! As a result of the over-filling, sediment tends to accumulate within the urinary bladder resulting in chronic irritation of the bladder lining and ultimately cystitis. The cause for the loss of bladder wall tone is unknown and there has been no proven treatment for this condition.These cases become management cases which includes regular "lavage" of the urinary bladder, systemic antibiotics for cystitis, and a reduction in any feed or supplements containing calcium.

Friday, February 7, 2014

Foundered Horse with Inadequate Shoeing!

A 10 year-old Arabian cross gelding presented for shifting foot lameness and pounding digital pulses. There was no history of laminitis/founder. The horse was not willing to walk on concrete and was a grade 3/5 lame in both front feet on soft ground. Physical exam noted a prominent fat pad over the tail head and the development of a cresty neck! A radiographic exam was performed on both front feet to determine the severity of the gelding's condition.

Figure 1
Figures 1-3 correspond to the lateral projection of the right front limb. There is a clear explanation for the shifting leg lameness and pounding digital pulses. In Figure 2, the yellow dotted lines correspond to the dorsal hoof wall and the dorsal border of the coffin bone. In a normal horse, these two lines are parallel. However, in the case of laminitis/founder with coffin bone rotation the yellow lines are NOT parallel. The small blue triangles labelled A and B correspond to the angles of the yellow lines with the horizon (red line). In this horse, angle A does NOT equal angle B. These findings confirm the diagnosis of laminitis with coffin bone rotation. The difference between angle A and B corresponds to the degrees of coffin bone rotation and in this case that number was 10-12 degrees. The left front limb was similar.

Figure 2
In addition, the gelding's cranial to caudal balance is extremely poor. The yellow line in Figure 3 corresponds to the "center of rotation" and in a normal horse should divide the foot evenly in half. As such, there should be equal amount of ground contact (red lines) in front of the yellow line (cranial) and behind the yellow line (caudal). In this horse, the amount of ground contact behind the yellow line is nearly zero compared to that in front of the yellow line. This is due in part to the extremely long "toe" and the shoe placement. The extremely long toe and cranial shoe placement adds significant leverage on the toe which will aggravate the laminitis and increase the horse's level of pain!. Initial management of this case involved removing the shoes and significantly reducing the length of the toe. In addition, a blood sample was tested for insulin resistance and the horse was confirmed to be suffering from insulin resistance secondary to metabolic syndrome. The gelding was treated with the appropriate diet, stall confinement, pain medication, and medical management for insulin resistance. Stay tuned for follow-up.....

Figure 3