Page 486 - Adams and Stashak's Lameness in Horses, 7th Edition

452 Chapter 4

treatment options based on the clinical response. The least one grade of lameness at day 56 compared with
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decision to use intrasynovial treatment is often made at 3% in the placebo group. At day 180, 65% of horses
VetBooks.ir on the clinical improvement in lameness. In most cases, lameness. An additional study has also suggested that
were still considered to have an improvement in their
the first or second shoeing interval and is usually based
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a single dose of clodronate reduced lameness in horses
treatment of the DIP joint is performed before treatment
of the bursa because it is easier to perform and has fewer with navicular syndrome without producing detectable
potential complications. However, horses with radio- effects on bone turnover markers. Clodronate is an
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graphic abnormalities confined to the flexor surface of FDA‐approved bisphosphonate licensed for treatment
the navicular bone would most likely respond better to of navicular syndrome in horses (Osphos®, Dechra
treatment of the navicular bursa than the DIP joint. Veterinary Products, Overland Park, KS). Current rec-
Intrasynovial medication strategies including whether to ommendations for Osphos administration are 1.8 mg/kg
use anti‐inflammatories vs. biologics may be greatly by IM injection with a maximum dose of 900 mg per
improved if a complete diagnostic picture of the foot horse (e.g. 900‐mg dose standard for a 500‐kg animal);
abnormalities can be determined with the help of MRI. 3 recommendations to divide the dose between three sites
Both TA (5–10 mg) and MPA (20–60 mg) may be are also given (Osphos). Tiludronate is currently not
used for intrasynovial treatment, but MPA is usually licensed for use in the United States but is labeled for use
reserved for use in the navicular bursa rather than the in other countries for horses with navicular disease,
DIP joint. In most cases the corticosteroid is combined bone spavin, and fetlock suspensory ligament enthesopa-
with HA, and amikacin is included when injecting the thies. The drug is currently recommended at a dose of
navicular bursa. 25,27,75 An immediate improvement in 1 mg/kg IV over 30 minutes as a single treatment instead
lameness is often seen in the majority of cases after of 10 daily treatments.
intrabursal treatment. 27,75,127 In the most recent study, Tiludronate has been used either systemically (1 or
75% of treated horses returned to their intended use for 0.1 mg/kg IV) or locally (0.1–0.2 mg/kg) using intrave-
a mean of 9.6 months. Horses treated within 6 months nous regional limb perfusion (IVRLP). 29,103,129 In one
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of becoming lame were more likely to return to perfor- clinical trial of 73 horses, tiludronate (0.1 mg/kg) given
mance. Intrabursal injections appear to reduce the clini- IV once daily for 10 days resulted in clinical improve-
cal signs of navicular disease in most horses for several ment of lameness, and horses returned to a normal level
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months, but repeated injections may be necessary and of activity 2–6 months’ posttreatment. Another study
potentially predispose to rupture of the DDFT in some reported that systemic tiludronate (1 mg/kg IV) appeared
horses. In general, horses with multiple abnormalities to be beneficial in horses with navicular syndrome but
within the foot and those with chronic adhesions from no horses became sound. Using tiludronate locally
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the navicular bone to the DDFT do not respond well to with IVRLP (0.1 and 0.2 mg/kg) was reported to pro-
intrabursal treatment. 75 vide no further improvement in lameness over therapeu-
tic shoeing and injection of the DIP joint. Further
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studies are necessary to determine the true efficacy of
Polysulfated Glycosaminoglycans
these drugs in treating horses with navicular disease/
PSGAGs have been used in horses with navicular dis- syndrome. See Chapter 8 for more information on
ease/syndrome based on the assumption that the etiol- bisphosphonates.
ogy may be similar to that of OA. One double‐blinded
clinical trial documented a benefit of 500 mg of PSGAG
IM at 4‐day intervals for eight treatments compared Surgical Tre atments
with saline controls. In addition, PSGAG given weekly Palmar Digital Neurectomy
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or every other week IM was thought to benefit western
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performance horses with chronic navicular problems. PD neurectomy remains the most commonly per-
PSGAG may be injected intrasynovially into the DIP formed surgical technique to manage horses with navic-
joint or navicular bursa, similar to corticosteroids, but ular disease/syndrome. It is usually performed as a last
no studies have documented the benefit of this in horses resort after other treatment options have failed. It should
with navicular disease. Therefore, intrasynovial PSGAG be done in conjunction with corrective hoof trimming
treatment is not commonly used in horses with navicu- and shoeing to reduce abnormal forces on the foot, thus
lar disease. slowing the progression of the degenerative changes
associated with the navicular syndrome. 4,115 A PD nerve
block should always be performed before the surgery to
Bisphosphonates: Tiludronate or Clodronate
document how much clinical improvement can be
Bisphosphonates, such as tiludronate and clodronate, expected following the neurectomy.
are drugs that have been suggested as a treatment for Horses with suspected or confirmed abnormalities of
horses with navicular disease because of their ability to the DDFT at the level of the navicular bone are usually
promote osteoclast‐mediated bone resorption. Areas of not good candidates for a neurectomy because of an
increased bone resorption and formation are often typi- increased risk of rupture of the DDFT. However,
cal of lesions within a diseased navicular bone and areas an increased risk of DDFT rupture post neurectomy has
of OA, and clinicians believe that reducing bone turno- not been documented, but a recent study recommended
ver in these conditions may have beneficial clinical that horses with core or linear lesions of the DDFT
effects. A multicenter, double‐blind, placebo‐controlled should not undergo a PD neurectomy as these horses
clinical trial using clodronate in horses with navicular experience residual lameness or recurrent lameness
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syndrome found that 75% of treated horses improved at aftersurgery. The decision of whether to perform a